maintaining a balance 1. organisms are active in a limited ... · hsc biology v repaci education ...

HSC Biology V Repaci Education www.hsctutoringsydney.com 0424927473

HSC Biology V Repaci Education www.hsctutoringsydney.com

Maintaining a balance

1. Most organisms are active in a limited temperature range

1.1 ‐ Identify the role of enzymes in metabolism, describe their chemical composition and use a simple model to describe their specificity on substrates.

• Enzymes are biologically catalysts.

• Increase reaction rate by lowering activation energy

• Needed to allow reactions to occur fast enough to support life.

Enzyme activity models

• Lock and key model: enzyme fits substrate like a lock fits a key

• Induced fit model: Enzyme changes shape slightly to fit the substrate



1.2 ‐ Identify the pH as a way of describing the acidity of a substance.

Scale of acidity to basisity

• 1‐7: acidic

• 7: neutral

• 7‐14: base

The pH scale is a log scale meaning that every pH unit has 10x less or more H+

1.3 ‐ Explain why the maintenance of a constant internal environment is important for optimal metabolic efficiency.

A constant environment is needed because:

• Enzyme catalysed reaction rates decrease

• Affects the functioning of enzymes causing inefficient cell function

1.4 – Describe homeostasis as the process by which organisms maintain a relatively stable internal environment

• Homeostasis is the process of keeping an internal environment stable.

• It is a constant counteraction of change to try maintain a balance.

1.5 ‐ Explain that homeostasis consists of two stages:

• Detecting changes from the stable state

• Counteracting changes from the stable state

1. An ability to detect a change from the stable state

2. Way to counteract this change back to stable state.



1.6 ‐ Outline the role of the nervous system in detecting and responding to environmental changes

consists of the central nervous system (CNS) and the peripheral nervous system (PNS)

• The CNS consists of the brain and spinal cord

• PNS consists of the sensory nerves and the effector nerves

• Sensory neuron conducts a nervous impulse to the hypothalamus

• Nerve impulses pass this information from the receptors to effector neurons then onto effectors

1.7 ‐ Identify the broad range of temperatures over which life is found compared with the narrow limits for individual species.

• Life is found from ‐ 40oC to +120oC

• Majority of living organisms are found in the ‐ 2oC to +40oC range

• For each individual species the range is even narrower.

1.8 ‐ Compare responses of named Australian exothermic and endothermic organisms to changes in the ambient temperature and explain how these responses assist temperature regulation

Endotherms Ectotherms • In hot conditions, the red kangaroo licks

the inside of its paws, where skin is thinner, and blood supply is closer to surface, so that heat transfer to the environment occurs easily. Evaporation from saliva promotes the loss of heat from the blood.

• The large ears of the rabbit‐eared bandicoot provide a large surface area to pass excess heat when it is burrowing during the heat of day and when it is active at dusk.

• Bogong moths are able to avoid their bodies freezing by supercooling their tissues. This process involves reducing the temperature of body fluids below their usual point of freezing and as a result, ice crystals do not form and destroy the cells.

• Insects in alpine areas, as a rule, tend to be smaller, darker and use basking behaviours to absorb what heat is available.

• Antarctic ice fish produce antifreeze (glycoproteins) that prevent ice formation.



1.9 ‐ Identify some responses of plants to temperature change

• Plants are damaged at temperature extremes because enzymes and membranes are altered and change their properties.

• In cold conditions, extracellular ice formation causes dehydration. Some plants tolerate freezing temperatures by altering their solute concentrations and through the lack of ice‐nucleating sites in cells to prevent intracellular freezing.

• In hot desert conditions, plants compromise between access to gases for photosynthesis and access to gases for respiration by keeping their stomates open and cooling by evaporation.



1.10 ‐ Identify data sources, plan, choose equipment or resources and perform a first‐hand investigation to test the effect of:

• increased temperature • change in pH • change in substrate concentrations on the activity of named enzyme(s)

Title: Effect of temperature on enzyme activity

Aim: To determine the effect of temperature on enzyme activity

Method

1. Heat each water bath to the set values using a Bunsen burner for higher than room temperatures and ice cubes for lower than room temperatures. Use thermometers to check temperature.

2. Fill all 16 test tubes with 5ml of milk using a pipette. 3. Add 3 drops rennin to 8 test tubes and then place 2 test tubes, one with rennin and one

without, into each water bath. 4. Time how long it takes for the milk to curdle. Check the test tubes regularly to ensure a

more accurate time.

Discussion

• Enzymes are biological catalysts.

• A catalyst increases the rate of reaction for a particular chemical reaction.

• Temperature has a strong effect on the effectiveness of enzymes. Too hot and the enzyme denatures, too cold and the activation energy is not achieved rapidly enough.

Conclusion: The conclusion that can be drawn from this experiment is that there is a direct relationship between temperature and enzyme activity. The optimal temperature for enzyme activity is around 50°C and drops of either side of this value.

Title: Effect of pH on enzyme activity

Aim: To determine the effect of pH on enzyme activity.

Method

1. Fill each test tube with 10ml respective solution leaving one empty 2. Add 10ml of milk to all 5 test tubes 3. Add universal indicator to confirm the pH of the solution 4. Add 3 drops of rennin to each test tube and time how long it takes for the milk to curdle 5. Record results in a table shown below



Discussion

• pH has a strong effect on the effectiveness of enzymes.

• Enzymes are adapted for a specific environment in which the pH is fairly constant.

• Different enzymes are specialised for different pHs.

• The narrow pH band that enzymes work in is due to charges on the active site which give the enzyme its shape. Due to interactions with H+ and OH‐ ions, this shape is altered and the enzyme loses its activity.

Conclusion: From the experimental results the trends that can be drawn are that pH has a relationship with enzyme activity and rennin has an optimum pH greater than three.

Title: The effect of substrate concentration on enzyme activity

Aim: To determine the effect of substrate concentration on enzyme activity.

Method

1. Label the five test tubes 1–5. 2. Pipette the volumes of hydrogen peroxide and water (as shown in Table) into each test

tube. 3. Prepare five rectangles of potato about 8 mm in width and 30 mm long. 4. Place a piece of potato into each test tube. Mark the height of the liquid in each tube with a

marking pen. 5. After 5 minutes, measure the height of the bubbles of oxygen that form over the contents

of the tubes by marking with a marking pen on the test tube at the top level of the bubbles and then measure the height.

6. Record your data in a table.

Discussion

• A substrate is a molecule which attaches to the enzyme in order for it to be broken down into simpler molecules.

• Once a saturation point is reached, enzyme activity peaks meaning that the substrate may not be broken down fast enough for metabolic activities.

• Initially, increasing substrate concentration increases the rate of reaction, but once all active sites are filled the enzyme activity peaks and becomes saturated.

Conclusion: The conclusion drawn from this experiment is that substrate concentration increases enzyme activity until the saturation point is reached.



1.11 ‐ Gather, process and analyse information from secondary sources and use available evidence to develop a model of a feedback mechanism

1.12 ‐ Analyse information from secondary sources to describe adaptations and responses that have occurred in Australian organisms to assist temperature regulation

Organism Endo/Ecto Adaptations Thorny Devil Ecto Burrows into sand to avoid hot temperatures at mid day. Water

can be directed from anywhere on body to mouth for cooling and water absorption.

Crocodilians Ecto Various basking behaviours. Mouth gaping, body orientation in regards to the sun, etc

Alpine Pygmy Possum

Endo Sleeps in tightly wound ball to retain heat. Huddling with other individuals in order to keep warm.

Platypus Endo Goes through periods of hibernation. It has an insulting coat that retains heat when swimming in cold water. Has sweat glands in important areas to cool organism during hot weather.



2. Plants and animals transport dissolved nutrients and gases in a fluid medium

2.1 ‐ Identify the form(s) in which each of the following is carried in mammalian blood:

Carbon dioxide Most carbon dioxide is combined with water to form bicarbonate ions (HCO3

‐). Some is attached to haemoglobin molecules in red blood cells and a small percentage is transported in plasma as dissolved CO2.

Oxygen Oxygen attaches itself to haemoglobin in the red blood cells, becoming oxyhaemoglobin (HbO2).

Water Liquid water is the solvent making up 90% of the plasma. Salts Salts are carried as dissolved ions in the plasma. Lipids Lipids are carried with phospholipids and cholesterol in chylomicron. Nitrogenous waste The nitrogenous wastes (urea, uric acid and creatinine) are dissolved in

blood plasma. Others Sugars, amino acids and various vitamins, are transported in the plasma.

2.2 ‐ Explain the adaptive advantage of haemoglobin

• Oxygen is not very soluble. Therefore, another transport is needed.

• Most of the oxygen is carried by haemoglobin in the red blood cells.

• Organisms with haemoglobin are able to deliver oxygen to cells more efficiently

• The net effect is that these organisms are more effective operators in a given environment than their competitors.

2.3 ‐ Compare the structure of arteries, capillaries and veins in relation to their function

Artery Veins Capillary Thick muscular wall to cope with blood pressure Carries blood away from the heart

Thin walls. Less pressure Valves that prevent blood backflow Carry blood towards the heart

Wall is only one cell thick to facilitate diffusion Forms a network.



2.4 ‐ Describe the main changes in the chemical composition of the blood as it moves around the body and identify tissues in which these changes occur

The blood circulates through two systems in the body: the pulmonary system and the systemic system.

Increase Decrease CO2 ‐ Lungs O2 Lungs ‐ Urea ‐ Kidney Nutrients Small intestine ‐ Water Large intestine ‐

2.5 ‐ Outline the need for oxygen in living cells and explain why removal of carbon dioxide from cells is essential

• Cells require oxygen in the process of aerobic respiration: Glucose + oxygen → carbon dioxide + water + energy (in the form of ATP)

• Carbon dioxide must be removed to maintain the normal pH.

• By removing excess carbon dioxide, it prevents a build up of carbonic acid, which causes the lowering of the pH, and therefore increasing breathing rate and depth.

• The carbon dioxide ‐ bicarbonate ion (HCO3‐) equilibrium is an important mechanism for

buffering the blood to maintain a constant pH

CO2 + H2O ↔ H2CO3



2.6 ‐ Describe current theories about processes responsible for the movement of materials through plants in xylem and phloem tissue

Xylem

Methods of passive transport

Cohesion and adhesion

• Cohesion is the “sticking” together of water molecules so that they form a continuous stream of molecules extending from the leaves down to the roots.

• Water molecules also adhere to the cellulose molecules in the walls of the xylem.

Transpiration pull

• As water molecules are removed by transpiration in the leaf, the next molecule moves upwards to take its place, pulling the stream of molecules continuously along.

Phloem

Method of active transport

Source to Sink model or Translocation

• At the sugar sink (where it is needed) water and sugar leave the phloem reducing pressure in tube.

• At the source, sugar and water are introduced and pressure increases. • The difference in pressure means that the water and anything dissolved in it moves from

source to sink (high to low pressure).



2.7 ‐ Perform a first‐hand investigation to demonstrate the effect of dissolved carbon dioxide on the pH of water

Title: Effect of Carbon Dioxide on pH

Aim: To determine if carbon dioxide is dissolved into water, then the solution will become more acidic.

Method

1. Fill two test tubes with 10 mL of distilled water and one with 10 mL of lime water. 2. Place 5 drops of universal indicator into all three test tubes. 3. In the fourth test tube, place 3 – 5 calcium carbonate chips before adding the hydrochloric

acid. 4. Seal this test tube with a rubber stopper and insert the plastic pipe into the test tube with

lime water. 5. Wait 10 minutes, using the stop watch for accuracy, and record observations. 6. Repeat step 3 – 5 with the fifth test tube but insert into one of the test tubes filled with

distilled water. 7. Repeat step 1 and 2. 8. Using straws, breathe into test tubes and record results. 9. The test tube that was not exposed to carbon dioxide is the control. 10. For reliability, compare results with other groups.

Discussion

• The acidity of a substance is based on the concentration of H+ ions, while the concentration of OH‐ ions determines the alkalinity of a substance.

• Carbon dioxide is partly soluble in water, and through a series of reactions, increases the H+ concentration, thus lowering the pH.

• Carbon dioxide dissolves into the blood plasma making it more acidic. This is a serious problem as enzyme activity is highest for only specific pHs as shown in an above experiment.

• Controlling carbon dioxide concentration controls the pH in the blood. The body does this by creating a buffer which maintains the pH at a particular value unless large, rapid change occurs.

Conclusion: The conclusion that can be drawn from this experiment is that carbon dioxide lowers the pH of a solutions.



2.8 ‐ Perform a first‐hand investigation using the light microscope and prepared slides to gather information to estimate the size of red and white blood cells and draw scaled diagrams of each

Title: Estimating the size of blood cells

Aim: To determine the size of different types of blood cells.

Method

1. Place prepared red blood cell slide under light microscope. 2. Focus and magnify microscope to the highest magnification. 3. Place the 0.1mm grid over the top of the slide and estimate the size of the red blood cells. 4. Repeat experiment with white blood cells. 5. Repeat experiment 3 time for reliability.

Discussion

Conclusion: Red blood cells were found to be 7.5 micrometers and white blood cells slightly larger.



2.9 ‐ Analyse information from secondary sources to identify current technologies that allow measurement of oxygen saturation and carbon dioxide concentrations in blood and describe and explain the conditions under which these technologies are used

Pulse Oximeter

• The colour of blood changes depending on the oxygen saturation. • High oxygen saturation is bright red while low is a darker colour. • Blood passes through pulse oximeter and a sensor that emits a light signal detects the

colour of a patient's blood. • The information is process and oxygen saturation is determined in a percentage reading on

the pulse oximeter.

Arterial Blood Gas Analysis Machine (ABG)

• Work by measuring the diffusion rate of carbon dioxide and oxygen across an artificial membrane that is permeable to these gases.

• When these pass across the membrane an electrical signal is produced proving the presence of the gases.

• Carbon dioxide concentration is found by pH of blood which allows oxygen levels to be found as well.

Conditions of Usage

• Heavy sedation/anesthesia • Ventilator/artificial breathing machine • Stress testing • Sleep laboratories • Checking the body's response to different medications • Monitoring patients with breathing difficulty



2.10 ‐ Analyse information from secondary sources to identify the products extracted from donated blood and discuss the uses of these products

Red blood cells (RBCs)

• RBCs help patients who need to be able to carry more oxygen. • RBCs may also be used to help replace cells lost following significant bleeding.

Platelet concentrate

• Platelets are essential for the coagulation of blood. • Used to treat bleeding caused by conditions where the platelets are not functioning.

Fresh frozen plasma (FFP)

• FFP contains all coagulation factors except for red cells, white blood cells and platelets. • It is used for patients who require immediate clotting effects, such as those undergoing

warfarin therapy (blood thinning) or when massive transfusions have taken place.

Cryoprecipitate anti‐haemophilic factor

• Cryoprecipitate AHF is a concentrate of clotting proteins • It is used for replacement of the clotting proteins, fibrinogen, Factor XIII and Factor VIII.



2.11 ‐ Analyse and present information from secondary sources to report on progress in the production of artificial blood and use available evidence to propose reasons why such research is needed

• Blood transfusions and using donor blood has occurred since the early 1900s. • There was no need for artificial blood until the 1980s with the HIV epidemic. • Sensitive screening procedures are now used and limit the need for blood substitutes. • From around the 1990s to now numerous successful and effective blood substitutes have

been found are have been used.

Even more effective substitutes must be found because:

• Demand and supply. More blood being needed with less donors. • Disease free. Many regions in Africa, such as Nigeria, have a HIV infection rate of over 40%.

This means that most blood donated contains the HIV virus. • Saves time of finding appropriate blood type. Medical care in the armed services would

benefit from a safe, easy way to manage blood supply. • Great benefit could be derived from the rapid treatment of patients in trauma situations.

Because these blood substitutes do not contain any of the antigens that determine blood type, they can be used across all types without immunologic reactions.

• No prion screening in blood. Artificial blood has no contamination. • Transfused blood is currently more cost effective, but there are reasons to believe this may

change. For example, the cost of blood substitutes may fall as manufacturing becomes refined.

• Blood substitutes can be stored for much longer than transfusable blood, and can be kept at room temperature. Most haemoglobin‐based oxygen carriers in trials today carry a shelf life of between 1 and 3 years, compared to 42 days for donated blood, which needs to be kept refrigerated.

• Blood substitutes allow for immediate full capacity oxygen transport, as opposed to transfused blood which can require about 24 hours to reach full oxygen transport capacity due to 2,3‐diphosphoglycerate depletion. Also, in comparison, natural replenishment of lost red blood cells usually takes months, so an oxygen‐carrying blood substitute can perform this function until blood is naturally replenished.

• Oxygen carrying blood substitutes also would become an alternative for those patients that refuse blood transfusions for religious or cultural reasons, such as Jehovah's Witnesses.



2.12 ‐ Choose equipment or resources to perform a first‐hand investigation to gather first‐hand data to draw transverse and longitudinal sections of phloem and xylem tissue



3. Plants and animals regulate the concentration of gases, water and waste products of metabolism in cells and in interstitial fluid

3.1 ‐ Explain why the concentration of water in cells should be maintained within a narrow range for optimal function

• Water is the solvent for metabolic reactions in living cells.

• Many molecules and all ions important for the life of the cell are carried in an aqueous solution and these diffuse to reaction sites through the water in the cell.

• Metabolic reactions within the cell can occur only in solution where water is the solvent.

• The efficiency of these reactions is crucial for life. This is why it must be constant.

3.2 ‐ Explain why the removal of wastes is essential for continued metabolic activity

• Metabolic wastes are the product of metabolic reactions.

• If they are not removed their concentration in the cell increases and pH decreases.

• This inhibits the reactions that produce them, interfering with normal metabolic activity.



3.3 ‐ Identify the role of the kidney in the excretory system of fish and mammals

• It plays a central role in homeostasis, forming and excreting urine while regulating water and salt concentration in the blood thus maintaining the precise balance between waste disposal and the animal's needs for water and salt.

Salt water fish

• The kidneys excrete small quantities of isotonic (same concentration as sea water) urine. • This helps conserve water and excrete the excess salt they gain from their hyperosmotic

environment.

Fresh water fish

• Kidneys work continuously to excrete copious quantities of dilute urine, which also has a very low salt concentration.

• This helps to remove excess water gained from the hypo‐osmotic environment.

3.4 ‐ Explain why the processes of diffusion and osmosis are inadequate in removing dissolved nitrogenous wastes in some organisms

• Diffusion and osmosis are both examples of passive transport, relying on random movements of molecules.

• Diffusion is too slow for the normal functioning of the body and does not select for useful solutes.

• Osmosis only deals with the movement of water and thus would only allow water to move out of the body, not the nitrogenous wastes.



3.5 ‐ Distinguish between active and passive transport and relate these to processes occurring in the mammalian kidney

Active transport

• Involves expenditure of energy in order to move a substance against the concentration gradient.

Passive transport

• No energy expenditure needed as the materials follow a concentration gradient.

In the mammalian kidney, both active and passive transport processes occur.

• Passive transport: Once filtration has occurred in Bowman's capsule, water returns to the blood stream by osmosis where the high concentration of water in the tubule moves to the capillaries via the interstitial fluid.

• Active transport: Depending on their concentration, the ions in the blood (Na+, K+, Cl‐ , H+ and HCO3

‐) can be transported to cells in the nephron tubule and then secreted by the cells into the tubule.

3.6 ‐ Explain how the processes of filtration and reabsorption in the mammalian nephron regulate body fluid composition

• Filtration of the blood occurs in Bowman's capsule where high blood pressure in the glomerulus forces all small molecules out of the blood into the capsule.

• Water, urea, ions (Na+, K+, Cl‐ , Ca2+, HCO3‐), glucose, amino acids and vitamins are all small

enough to be moved into the glomerular filtrate. • Blood cells and proteins are too large to be removed. • This filtering process is non‐selective and therefore many valuable components of the blood

must be recovered by reabsorption. • Reabsorption takes place selectively at various points along the proximal tubule, loop of

Henle and distal tubule. • All glucose molecules, amino acids and most vitamins are recovered, although the kidneys

do not regulate their concentrations. • The reabsorption of the ions Na+, K+, Cl‐ , Ca2+ and HCO3

‐ occurs at different rates depending on feedback from the body. In some cases, active transport is required.

• Water is reabsorbed in all parts of the tubule except the ascending loop of Henle. The amount of water reabsorbed depends on feedback from the hypothalamus. If no water were reabsorbed human would soon dehydrate, losing water at a rate of around 7.5 L per hour.

• The chemical composition of the body fluids is precisely regulated by the control of solute reabsorption from the glomerular filtrate.



3.7 ‐ Outline the role of the hormones, aldosterone and ADH (anti‐diuretic hormone) in the regulation of water and salt levels in blood

Aldosterone

• Secreted by the adrenal gland. • Its function is to regulate the transfer of sodium and potassium ions in the kidney. • When sodium levels are low, aldosterone is released into the blood causing more sodium to

pass from the nephron to the blood. • Water then flows from the nephron into the blood by osmosis. This results in the

homeostatic balance of blood pressure.

Antidiuretic hormone (ADH/Vasopressin)

• Controls water reabsorption in the nephron. • When levels of fluid in the blood drop, the hypothalamus causes the pituitary to release

ADH increasing the amount water to be absorbed from the urine into the blood. The resulting urine is more concentrated.

• When there is too much fluid in the blood, sensors in the heart cause the hypothalamus to reduce the production of ADH in the pituitary, decreasing the amount of water reabsorbed in the kidney. This results in a lower blood volume and larger quantities of more dilute urine.

3.8 ‐ Define enantiostasis as the maintenance of metabolic and physiological functions in response to variations in the environment and discuss its importance to estuarine organisms in maintaining appropriate salt concentrations

• Enantiostasis is the maintenance of normal metabolic and physiological functioning, in the absence of homeostasis, in an organism experiencing variations in its environment.

• All organisms living in an estuary experience large changes in salt concentration. • One strategy to withstand such changes in salt concentration is to allow the body's osmotic

pressure to vary with that of the environment. Organisms that do this are osmoconformers. • For normal functioning to be maintained, another body function must be changed in a way

that compensates for the change. • One example of enantiostasis is when a change in salt concentration in the body fluid,

which reduces the efficiency of an enzyme, is compensated for by a change in pH, which increases the efficiency of the same enzyme.



3.9 ‐ Describe adaptations of a range of terrestrial Australian plants that assist in minimising water loss

Adaptations of Australian xerophytes (plants adapted to dry conditions) include:

• hard leathery, needle‐shaped leaves with reduced surface areas such as in Hakea sericea (needlebush) and coastal tea trees

• use of phyllodes for photosynthesis rather than leaves that would lose water by transpiration, as in many acacias

• some salt bushes, e.g. Atriplex, change the reflectiveness of their leaves during leaf development so that they have highly reflective leaves during summer

• Eucalypts avoid high radiation in the middle of the day by hanging their leaves vertically to present less surface area to sun

• heat loss is greater for small leaves or highly dissected leaves than it is for larger leaves and many Acacias have fronds of bipinnate leaves

• waxy cuticle prevents evaporation in many Eucalypts

3.10 ‐ Perform a first‐hand investigation of the structure of a mammalian kidney by dissection, use of a model or visual resource and identify the regions involved in the excretion of waste products



3.11 ‐ Gather, process and analyse information from secondary sources to compare the process of renal dialysis with the function of the kidney

Renal Dialysis Kidney Function Removing some molecules

from blood while returning others

Control waste production to reabsorb nutrients while removing excess nutrients and nitrogenous waste (Urine)

Process Passed through artificial tubing that allows some molecules (water, some ions) to pass into dialysing solution. Urea and excess salts diffuse out from the blood. Essential substances like HCO3

‐ diffuse into blood from solution.

Blood fitrate collected in the Bowman's capsule is passed through the nephron. Absorption takes place in tubules through pressure filtration.

Efficiency Slow and inefficient Filters entire blood volume in 30mins

3.12 ‐ Present information to outline the general use of hormone replacement therapy in people who cannot secrete aldosterone

• Hypoaldosteronism is a condition where people fail to secrete aldosterone. • A replacement hormone, fluorocortisone (Florinef), is used to treat this condition but a

careful monitoring must be maintained to avoid fluid retention and high blood pressure.



3.13 ‐ Analyse information from secondary sources to compare and explain the differences in urine concentration of terrestrial mammals, marine fish and freshwater fish

Terrestrial mammals Marine fish Freshwater fish Urine concentration

Variable Very concentrated Very dilute

Environment Water conservation is a prime concern as terrestrial mammals cannot afford to excrete large volumes of water when removal metabolic waste

Marine environment is hyperosmotic where the osmotic gradient is from the fish to the water as salt concentration is greater outside fish.

Freshwater environment is hypo‐osmotic where the osmotic gradient is into to the fish.

3.14 ‐ Use available evidence to explain the relationship between the conservation of water and the production and excretion of concentrated nitrogenous wastes in a range of Australian insects and terrestrial mammals

• Ammonia is very toxic and must be removed immediately. Ammonia is the immediate product of breakdown of amino acids and no energy is required to make it.

• Urea is toxic, but 10 000 times less toxic than ammonia, so it can be safely stored in the body for a limited time. It is made from amino acids but requires more steps and energy to make than does ammonia.

• Uric acid is less toxic than ammonia or urea, so can be safely stored in or on the body for extended periods of time. It is a more complex molecule than urea so it requires even more energy to produce.

Organism Terrestrial/aquatic

Waste product Explanation

Spinifex Hopping Mouse (Notomys alexis)

terrestrial urea in a concentrated form

The animal lives in a very arid environment. It drinks very little water and excretes urea in a concentrated form, so that water can be conserved.

Euro, wallaroo (Macropus robustus)

terrestrial concentrated urine

Euros have a very efficient excretory system that recycles nitrogen and urea to make a very concentrated urine. This allows them to survive in very arid environments

Insects (Cordulephya pygmaea)

terrestrial uric acid Insects are covered with a cuticle impervious to water. They conserve water by producing a dry paste of uric acid.



3.15 ‐ Process and analyse information from secondary sources and use available evidence to discuss processes used by different plants for salt regulation in saline environments

• The grey mangrove, Avicennia marina, has special salt glands in its leaves that excrete salt. Other mangroves exclude salts at their roots through ultrafiltration and a third mechanism is to store salt in leaves and then drop the leaves.

• Another mechanism involves the efficient control of transpiration. Some mangroves have small leaves hanging vertically to reduce the surface presented to the sun and thus reducing transpiration.

• Another form of salt stress can occur in salt laden air such as in coastal environments. Some coastal plants, such as the Norfolk Island pine, have a mesh of cuticle over their stomates, which prevents small water droplets from entering the leaf.

3.16 ‐ Perform a first‐hand investigation to gather information about structures in plants that assist in the conservation of water

Plant Adaptation Casuarina phyllodes or cladodes rather than leaves Grevillea alpina hairy leaves Wollemi pine leaves reduced to spines Eucalypts leaves rolled inwards Grey Mangrove tree the reflective nature of the leaf surface Cacti Store water in stem



Blueprint of Life

1. Evidence of evolution suggests that the mechanisms of inheritance, accompanied by selection, allow change over many generations

1.1 – Outline the impacts on the evolution of animals and animals of:

• changes in physical conditions in the environment

• changes in chemical conditions in the environment

• competition for resources

Changes in physical conditions in the environment

• Include natural conditions, such as temperature and the availability of water. • The Australia landmass has become drier over time and this has lead to changes in the

species of the present day.

Changes in chemical conditions in the environment

• Chemicals that can affect the evolution of species include salts and elements, such as iron. • The sheep blowfly, Lucilia cuprina, can be lethal to sheep when larvae, laid by females,

burrows into wounds and wet wool. • Chemicals, such as dieldrin and organophosphates, have been used extensively to control

the blowfly. However, genetic resistance has occurred within the fly population that has made these chemicals ineffective.

• Continued use of the insecticide has resulted in the mutation of a modifier gene that increases and maintains the resistance. Thus, the insecticides can never be effective again, regardless of the number of blowfly generations that pass.

Competition for resources

• This occurs within a species and between species. If a new species is introduced into an area then the competition may lead to different species using different resources.

• Resources can include food, space or mates. • Some species of fruit fly have evolved into different species with each confined to a

different type of fruit tree. This is possible if there are different flowering and fruiting times on each tree type suited for different breeding cycles in the fruit flies. Eventually, two distinct species can result.



1.2 ‐ Describe, using specific examples, how the theory of evolution is supported by the following areas of study:

• palaeontology, including transitional forms • biogeography • comparative embryology • comparative anatomy • biochemistry

Palaeontology

• Some parts of the fossil record show a gradual change in life forms over millions of years. • Of particular interest are transitional fossils that have characteristics belonging to ancestral

and descendant groups. The most famous transitional form is Archaeopteryx. Its reptilian features include teeth and a reptilian‐like skeleton, but also had feathers.

• This provides evidence of an evolutionary pathway from dinosaurs to birds.

Biogeography

• Charles Darwin and Alfred Russell Wallace both observed the distribution of species into different biogeographic regions with similar conditions and found that there were completely different organisms, despite the same selective pressures.

• They argued that animals in different regions had come from ancestors in that region and had adapted over time to the conditions there.

Comparative embryology

• There is an obvious similarity between embryos of fish, amphibians, reptiles, birds and mammals. This indicates a fundamental step that is common to all vertebrates and supports the idea of a common ancestor.

Comparative anatomy

• Anatomical structures on different organisms that have the same basic plan but perform different functions are called homologous structures.

• An example of an homologous structure is the pentadactyl limb found in amphibians, reptiles, birds and mammals. The basic plan consists of one bone in the upper limb, two in the lower limb leading to five fingers or toes

Biochemistry

• Comparison of organisms on a molecular basis rather than simply comparing structures. • The study of amino acid sequences shows that more closely related species share more

common sequences than do unrelated species.



1.3 ‐ Explain how Darwin/Wallace’s theory of evolution by natural selection and isolation accounts for divergent evolution and convergent evolution

• Divergent evolution occurs when closely related species experience quite different environments and as a result vastly different characteristics will be selected. The species, over time, will evolve differently and will eventually appear quite different.

• Convergent evolution occurs when two relatively unrelated species develop similar structures, physiology or behaviours in response to similar selective pressures from similar environments.

1.4 ‐ Plan, choose equipment or resources and perform a first‐hand investigation to model natural selection

Aim: To mimic the process of natural selection

Method

1. Section off a 10m square of grass 2. Spread one packet each of green, red, and yellow pasta in the square 3. For 5mins, pick up as many pieces of pasta as possible 4. Record numbers of each colour

Results

Green = least found

Discussion

Green colour in green environment = camouflage = WINNING

Conclusion: green survived best as it was hard to spot, and would thrive due to its suitability to the selective pressures present in the green, grassy environment

1.5 ‐ Analyse information from secondary sources to prepare a case study to show how an environmental change can lead to changes in a species

• Kangaroos were small and omnivorous, with unspecialised teeth, eating a variety of foods from the forest floor 25mya due to large rainforests being present.

• As Australia became more arid and grass became the dominant vegetation, environmental selective pressure resulted in larger kangaroos favouring teeth suitable for grass.



1.6 ‐ Perform a first‐hand investigation or gather information from secondary sources (including photographs/diagrams/models) to observe, analyse and compare the structure of a range of vertebrate forelimbs

• All vertebrate forelimbs have the same basic pentadactyl limb. • Fish, birds, and mammals all have something that resembles a hand and a similar bone

structure

1.7 ‐ Use available evidence to analyse, using a named example, how advances in technology have changed scientific thinking about evolutionary relationships

• Biochemistry and genetic mapping have allowed more accurate methods of classification of organisms. For example, rhinos and whales are more closely related than dolphins and whales. Yeah... weird shit

1.8 ‐ Analyse information from secondary sources on the historical development of theories of evolution and use available evidence to assess social and political influences on these developments

• Religion held influence over both political and social environments and still does. Evolution was once considered blasphemy even though evidence had disproved theories like Special Creation.

• Now, scientific influence is quickly becoming more powerful than religious influence so evolution is accepted as the most probable develop of modern organisms.



2. Gregor Mendel's experiments helped advance our knowledge of the inheritance of characteristics

2.1 – Outline the experiments carried out by Gregor Mendel.

Mendel examined the following seven characteristics found in peas:

• Flower colour, purple or white • Flower position, axial or terminal • Seed colour, yellow or green • Seed shape, round or wrinkled • Pod shape, inflated or constricted • Pod colour, green or yellow • Stem height, tall or short.

• Mendel needed to control fertilisation. Self‐fertilisation was ensured by placing a bag over

the flowers to make sure pollen from the stamens lands on the carpel of the same flower. • Cross‐fertilisation was ensured by cutting off stamens from a flower before pollen was

produced, then dusting the carpel of the flower with pollen from another plant. • To ensure reliability, Mendel used thousands of plants in each experiment.

Method

• Mendel first cross‐fertilised two true‐breeding plants for one characteristic, for example tall plants were crossed with short plants (Mendel called these plants a P1 parent generation).

• The offspring produced are called F1 (1st filial) generation.

• The F1 generation were then self‐fertilised or cross‐fertilised to produce a second generation, F2.

Results

• Each of the seven traits that Mendel studied had a dominant and a recessive factor. • When two true‐breeding plants were crossed, only the dominant factor appeared in the

first generation. The recessive factor appeared in the second generation in a 3:1 (dominant : recessive) relationship.



2.2 ‐ Describe the aspects of the experimental techniques used by Mendel that led to his success

Mendel was successful because he:

• used peas, which were easily grown and produced successive generations rapidly • selected easily observable characteristics • strictly controlled the fertilisation process • used mathematics rigorously to analyse his results • used large numbers of plants • studied traits that had two easily identified factors.

2.3 ‐ Describe outcomes of monohybrid crosses involving simple dominance using Mendel’s explanations

• Mendel predicted that the plants had two traits that determined characteristics (TT, tt, etc.)

• Mendel found that F1 were all tall. He called this trait the dominant trait. (T) • By crossing two F1 plants he discovered the 3 tall: 1 short ratio. Using a monohybrid cross

this result could be observed

T t T TT (tall) Tt (tall) t Tt (tall) tt (short)

Thus, Mendel was able to explain his observed ratios by considering one trait dominant and one recessive

2.4 ‐ Distinguish between homozygous and heterozygous genotypes in monohybrid crosses

T t T TT (tall) (homo) Tt (tall) (hetero) t Tt (tall) (hetero) tt (short) (homo) • Heterozygous genotypes can donate either a dominant or recessive trait.

• Homozygous can only dominate either a dominant or recessive trait.



2.5 ‐ Distinguish between the terms allele and gene, using examples

• A gene is a section of DNA coding for proteins that expresses itself as the phenotype of an organism.

• Alleles are alternative forms of a gene. e.g. tall (T) and short (t) are two alleles for the gene which expresses the height characteristic.

2.6 ‐ Explain the relationship between dominant and recessive alleles and phenotype using examples

• Phenotype is the outward appearance of an organism. If a dominant allele is present in the genotype, then it will be expressed, whether or not the organism is heterozygous (Tt) or homozygous (TT)

• In order for recessive alleles to be expressed it must be homozygous(tt)

2.7 ‐ Outline the reasons why the importance of Mendel’s work was not recognized until sometime after it was published

• Mendel was not a recognized, high profile member of the scientific community

• he presented his paper to only a few people at an insignificant, local, scientific meeting

• other scientists did not understand the work or its significance.



2.8 ‐ Perform an investigation to construct pedigrees or family trees, trace the inheritance of selected characteristics and discuss their current use

2.9 ‐ Solve problems involving monohybrid crosses using Punnett squares or other appropriate techniques

F2 T t T TT (tall) (homo) Tt (tall) (hetero) t Tt (tall) (hetero) tt (short) (homo)

2.10 ‐ Process information from secondary sources to describe an example of hybridisation within a species and explain the purpose of this hybridisation

Hybrid Cross Purpose Grapefruit Pomelo and Jamaican sweet

orange Taste grows in a wider variety of conditions



3. Chromosomal structure provides the key to inheritance

3.1 ‐ Outline the roles of Sutton and Boveri in identifying the importance of chromosomes

• Two scientists are credited with the discovery of the role of chromosomes in 1902. They were the German scientist Theodor Boveri and the American microbiologist Walter Sutton.

• Boveri worked on sea urchins and showed that their chromosomes were not all the same and that a full complement was required for the normal development of an organism.

• Sutton worked on grasshoppers and showed that chromosomes were the carriers of hereditary units.

• Together their work became known as the Sutton‐Boveri chromosome hypothesis.

3.2 ‐ Describe the chemical nature of chromosomes and genes

• Chromosomes consist of 40% DNA and 60% protein (histone).

• Short lengths of DNA make up genes so genes have the same chemical composition as DNA.

3.3 ‐ Identify that DNA is a double‐stranded molecule twisted into a helix with each strand comprised of a sugar‐phosphate backbone and attached bases – adenine (A), thymine (T), cytosine (C) and guanine (G) – connected to a complementary strand by pairing the bases, A‐T and G‐C

• DNA is a nucleic acid in the shape of a double helix.

• Each strand of the helix consists of four different nucleotides made up of deoxyribose sugar, a phosphate molecule and a nitrogen base.

• The bases form between the sides of deoxyribose sugar and phosphate molecules and are complementary

• Adenine pairs with thymine and guanine pairs with cytosine.

3.4 ‐ Explain the relationship between the structure and behaviour of chromosomes during meiosis and the inheritance of genes

• Chromosomes are made of DNA. • Genes are coded within the DNA on the chromosomes. • The genes are duplicated during the first stage of meiosis and are then randomly assorted

depending on which chromosomes from each pair enters which new haploid cell during the first and second division.



3.5 ‐ Explain the role of gamete formation and sexual reproduction in variability of offspring

• Gametes are formed during the process of meiosis. In meiosis there are two stages that lead to variability. These are:

o random segregation of individual chromosomes with their associated genes ie, different new combinations of the original maternal and paternal chromosomes and

o the process of crossing over where the maternal and paternal chromosomes of each pair may exchange segments of genes making new combinations of genes on the chromosomes.

• Sex cells are haploid and has a random assortment of genes from the parent. • The genes are separated and the sex cells have a random assortment of dominant and

recessive genes. • The resulting embryo has a completely different set of genes from either of the parents.

3.6 ‐ Describe the inheritance of sex‐linked genes, and alleles that exhibit co‐dominance and explain why these do not produce simple Mendelian ratios

• Sex linked diseases occur on the X chromosome and are always recessive. • They do not produce Mendelian ratios because a male has only one X chromosome, so if

that X chromosome carries the recessive allele, it will be expressed. • A heterozygous organism will express recessive traits, contrary to Mendel's experimental

results

• Co‐dominance occurs when two alleles are equally dominant and are both expressed fully. • This leads to differing ratios in the genotype and phenotype as a new trait can arise that is

not present in the homozygous parent cross

3.7 ‐ Describe the work of Morgan that led to the understanding of sex linkage

• Thomas Morgan worked on the fruit fly Drosophila melanogaster.

• He looked at crosses between red‐ eyed and white‐eyed flies and found that the results could not be accounted for by simple Mendelian crosses.

• He showed that some genes were sex‐linked because they were located on the X chromosome.



3.8 ‐ Explain the relationship between homozygous and heterozygous genotypes and the resulting phenotypes in examples of co‐dominance

An example of co‐dominance is in coat colour of Shorthorn cattle. These animals have an allele for both red and white hair. As neither is dominant, cattle with both alleles have a mixture of red and white hairs scattered over their bodies and are called roan. Red cattle have the alleles RR while white cattle have WW. In the F1 (first) generation all of the offspring will be roan, RW.

R R W RW RW W RW RW 3.9 ‐ Outline ways in which the environment may affect the expression of a gene in an individual

• The appearance of an individual is not based solely on their genetic information. The environment of the organism also plays a part.

• Hydrangeas are plants that have different flower colour (pink or blue) depending on the pH of the soil they are grown in. In acid soils (less than pH 5) Hydrangeas are blue. In soils that have a pH greater than 7 Hydrangeas are pink. The pH has an effect on the availability of other ions in the soil and it is these ions that are responsible for the colour change.

3.10 ‐ Process information from secondary sources to construct a model that demonstrates meiosis and the processes of crossing over, segregation of chromosomes and the production of haploid gametes



3.11 ‐ Solve problems involving co‐dominance and sex linkage

R R W RW RW W RW RW

All roan cattle

XN Y XN XN XN XN Y Xn XN Xn Xn Y

Half males have haemophilia. All females do not have the disease

3.12 ‐ Identify data sources and perform a first‐hand investigation to demonstrate the effect of the environment on phenotype

• Hydrangeas are plants that have different flower colour (pink or blue) depending on the pH of the soil they are grown in. In acid soils (less than pH 5) Hydrangeas are blue. In soils that have a pH greater than 7 Hydrangeas are pink. The pH has an effect on the availability of other ions in the soil and it is these ions that are responsible for the colour change.



4. The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism

4.1 ‐ Describe the process of DNA replication and explain its significance

The process of DNA replication consists of the following steps

1. DNA double helix is unwound by an enzyme 2. The DNA unzips forming two single strands (Helicase) 3. Nucleotides are added to the single strand resulting in two identical strands of DNA

(Polymerase) • DNA replication is significant as it contains the genetic material that determine the

structure and function of cell. Without DNA, a cell cannot express characteristics

4.2 ‐ Outline, using a simple model, the process by which DNA controls the production of polypeptides

4.3 ‐ Explain the relationship between proteins and polypeptides

• A protein is made up of one or more polypeptides.

• A polypeptide is made up of a chain of many amino acids.

4.4 ‐ Explain how mutations in DNA may lead to the generation of new alleles

• Any change in the base sequence in DNA results in changes to the polypeptides that are produced and is a source of new alleles.

• To produce changes in alleles, the mutation must occur in the sex cells of the organism which are then passed on to the next generation.



4.5 ‐ Discuss evidence for the mutagenic nature of radiation

• Environmental factors that may increase the rate of mutation include X‐rays, radiation from atomic bombs and ultraviolet light.

• A mutagen is a natural or human‐made agent which can alter the structure or sequence of DNA. Mutagens can be carcinogens (cancer causing) or teratogens (birth defects causing).

• Radiation was the first mutagenic agent known. • Its effects on genes were first noticed in the 1920's. • Most of the first generation of scientists who worked with radiation died of cancer. Famous

examples are Marie Curie and her daughter who both died of leukaemia. • Hans Muller received the Nobel Prize in 1927 for showing that genes had the ability to

mutate when exposed to X‐rays. Beadle and Tatum used X‐rays to produce mutations in bread mould in the formulation of their “one – gene one – polypeptide” hypothesis.

• The atomic bombs dropped on Hiroshima and Nagasaki also increased the evidence for mutations caused by radiation. There was a tenfold increase in cancer deaths directly after the bombs were dropped.

• Mutagens may cause death in the individual but unless they affect the sex cells the effect is not passed on to the next generation.

4.6 ‐ Explain how an understanding of the source of variation in organisms has provided support for Darwin’s theory of evolution by natural selection

• The basis of this variation is the genetic makeup of the individuals in a species. It is this variation that selection acts upon.

• Mutation of DNA provides a source of new variations thus supporting Darwin's theory of evolution.

4.7 ‐ Describe the concept of punctuated equilibrium in evolution and how it differs from the gradual process proposed by Darwin

• Punctuated equilibrium is long periods where there is little change in organisms, followed by a shorter period where there are rapid changes.

• The evidence for this comes from the fossil record where there are mass extinctions of organisms followed by the appearance of new species.



4.8 ‐ Perform a first‐hand investigation or process information from secondary sources to develop a simple model for polypeptide synthesis

4.9 ‐ Analyse information from secondary sources to outline the evidence that led to Beadle and Tatum’s ‘one gene – one protein’ hypothesis and to explain why this was altered to the ‘one gene – one polypeptide’ hypothesis

• Beadle and Tatum used bread mould to investigate nutritional mutations. • Using X‐rays, they produced mould that was unable to produce a specific amino acid. The

mould was unable to grow unless the amino acid was added. • They showed that genes controlled biochemical processes. • Their hypothesis was that for each gene there was one enzyme or protein. • The enzymes that they studied consisted of one polypeptide but many enzymes consist of

chains of polypeptides. Therefore, the hypothesis has been changed to the “one – gene one – polypeptide” hypothesis.

4.10 ‐ Process information to construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity

DNA TAC GTC TAT TTG CGA ATT ACG TCT ATT TGC GAC GTA TT mRNA AUG CAG AUA AAC GCU UAA UGC AGA UAA ACG CUG CAU AA Amino acid Met gin ile asn ala ala atop Cis arg stop Polypeptide Functional enzyme Dysfunctional enzyme

By removing the first thymine(T) in the DNA strand it can be seen that a large difference can occur in the polypeptide, which determines cell function and activity



4.11 ‐ Process and analyse information from secondary sources to explain a modern example of ‘natural’ selection

• Amongst large numbers of bacteria offspring, some individuals may carry genes that give them resistance to antibiotics.

• These individuals are then able to survive and reproduce with reduced competition from other members of the same species.

• Each generation will produce a higher percentage of individuals containing the resistant genes. This has been the story for antibiotics since they were first used.

• The initial use of an antibiotic results in good protection from bacteria. Over time the chemicals become less and less effective.

• A case study provides a good example of how natural selection occurs. A similar situation occurs in the resistance of insects to insecticides.

• Selecting those individuals that are able to survive and reproduce increases the frequencies of those genes in the population. This is “survival of the fittest” where the fittest are those that have a natural resistance to a selecting factor.

4.12 ‐ Process information from secondary sources to describe and analyse the relative importance of the work of:

• James Watson • Francis Crick • Rosalind Franklin • Maurice Wilkins

in determining the structure of DNA and the impact of collaboration and communication in scientific research

• Rosalind Franklin and Maurice Wilkins were from King's College London and James Watson and Francis Crick were from Cambridge University

• Franklin's work on X‐ray diffraction showed that DNA had the characteristics of a helix. She wished to gather more evidence of this result but Maurice Wilkins showed her results to Watson and Crick without her permission or knowledge.

• This information was enough to encourage Watson and Crick to develop their model of the double helix for the structure of DNA.

• Rosalind Franklin died of cancer in 1958 at the age of 37. Watson, Crick and Wilkins received the Nobel Prize for their work in 1962



5. Current Reproductive technologies and genetic engineering have the potential to alter the path of evolution

5.1 ‐ Identify how the following current reproductive techniques may alter the genetic composition of a population:

• artificial insemination

• artificial pollination

• cloning

• In the case of all the technologies mentioned, the donor gametes or body cells have been carefully selected for predetermined characteristics – or artificially selected.

• In most cases, one exemplary donor contributes all the genetic material and this results in uniform offspring.

• Over generations, genetic variability within the species has been reduced.

5.2 ‐ Outline the processes used to produce transgenic species and include examples of this process and reasons for its use

• Transgenic organisms contain a gene (transgene) from another species. • This is achieved through recombinant DNA technology. • Recombinant DNA technology manipulates DNA by the use of restriction enzymes, ligases

and PCR (polymerase chain reaction). • Restriction enzymes are used to cut DNA in specific places. These enzymes are also known

as gene scissors or gene shears. Different restriction enzymes cut DNA in specific parts. • The cut ends are known as 'sticky ends'. • Ligases are used to repair and strengthen DNA especially after it has been cut by restriction

enzymes. • PCR is used to produce many copies of the recombinant DNA formed by the previous

processes. • Once the recombinant DNA is produced there are processes used to insert the DNA into the

host species. These processes include microinjection, Ti plasmid insertion, gene gun and electroporation.

• In microinjection a fine glass needle is used to insert the recombinant DNA into the nucleus of the host cell.

• Ti (tumour inducing) plasmid insertion uses a bacterium called Agrobacterium tumefaciens. • The gene gun blasts small metal pieces coated with DNA into the nucleus of the host cell. • Electroporation uses electric pulses to create small pores in the nuclear membrane through

which DNA is inserted. • Examples of transgenic species are genetically engineered salmon which have the gene

coding for the protein, bGH (bovine growth hormone), and tomato bushes that have Atlantic salmon genes to produce antifreeze to reduce frost damage



5.3 ‐ Discuss the potential impact of the use of reproduction technologies on the genetic diversity of species using a named plant and animal example that have been genetically altered

• Crops, such as rice, have been genetically engineered to suit a particular climate and topography, making then resistant to herbicides and pesticides commonly used in a particular region.

• Transgenic animals present greater problems with lower success rates so far. One important use is seen to be the preservation of numbers of endangered species. The first cloned endangered mammal was a guar (an endangered wild ox from SE Asia), but unfortunately it did not survive

5.4 ‐ Process information from secondary sources to describe a methodology used in cloning

1. Recently, plants have been cloned using tissue culture propagation. 2. Tissue from the roots is taken and the root cells separated. These cells are then grown

(cultured) in a nutrient‐rich medium where they become unspecialised. The unspecialised cells are called calluses.

3. After treatment with the appropriate plant hormones, the calluses are able to develop into seedlings, that go on to grow into fully mature plants. These plants are genetically identical to the original ‘parent’ plant

1. In animals, current techniques require an unfertilised egg to act as a ‘host’ for genetic material from a specialised cell.

2. The donor egg has had its nucleus physically removed, and the nucleus from a cell of the species to be cloned is inserted.

3. An electrical stimulus is used to fuse the nucleus with the egg cell and to stimulate cell division. At a certain stage in cell division, the embryo is introduced into a surrogate mother where it continues its development.



5.5 ‐ Analyse information from secondary sources to identify examples of the use of transgenic species and use available evidence to debate the ethical issues arising from the development and use of transgenic species

Genetically engineered salmon

• The gene coding for the protein, bGH (bovine growth hormone), is incorporated into the genes of salmon.

o Outcome – larger, faster growing fish o Evaluation – Possible farmed source of fish as food. However, the fish are kept in ponds that

offer no escape to the wild because there is much concern that they will upset or destroy natural ecosystems.

Potato plants

• A pea gene for lectin has been incorporated into potato plants. o Outcome – protection against insect attack. Lectin is a protein which interferes with

digestion in insects. It is termed an ‘antifeedant’. o Evaluation – As potatoes are a staple food source for many populations throughout the

world, it is important to maintain and increase production. Protection against insect attack improves the success of growing potatoes. Concerns exist about controlling the ‘escape’ of these transgenic potatoes into the wild as the technology is only recent and long‐term impacts on the environment have yet to be observed or evaluated.



9.4 The Search for Better Health

1 ‐ What is a healthy organism?

1.1 ‐ Discuss the difficulties of defining the terms ‘health’ and ‘disease’

The difficulties of defining the terms health and disease include that:

• it is possible for a person to be healthy and have a disease at the same time • the terms are used in general conversation and have different meaning to the scientific

definition.

1.2 ‐ Outline how the function of genes, mitosis, cell differentiation and specialisation assist in the maintenance of health

• Genes are the units of inheritance. • They control the process of protein synthesis. • They assist the maintenance of health by producing new cells for growth and repair, and

enzyme production • Mitosis is cell division that produces identical cells for growth and repair • Cell differentiation is the process undergone by the cells that are formed after mitosis. • Each cell normally differentiates to become a specialised cell, with a specialised structure

and function. • Many types of cells have specialised roles in maintaining the health of an organism. • For example, there are specialised blood cells that produce antibodies to attack a disease

causing micro‐organism.

1.3 ‐ Use available evidence to analyse the links between gene expression and maintenance and repair of body tissues

• Gene expression refers to the transfer of information from a gene to produce a protein or RNA.

• If you cut yourself, the genetic code contained in all your cells is used to form the new tissue to repair the damage from the cut.



2 ‐ Over 3000 years ago the Chinese and Hebrews were advocating cleanliness in food, water and personal hygiene

2.1 ‐ Distinguish between infectious and non‐infectious disease

• An infectious disease is one that is caused by an organism and that can be transferred from one person to another

• Non‐infectious diseases are diseases that are not due to disease‐causing organisms

2.2 ‐ Explain why cleanliness in food, water and personal hygiene practices assist in control of disease

• The intake of food and water provide an easy way for micro‐organisms to enter our bodies

• Therefore, minimising the number of such organisms in our food and water reduces the risk of infection

• Good personal hygiene ensures that body openings, including broken skin, are clean, so that the number of micro‐organisms that might gain entry to our bodies is kept low

2.3 ‐ Identify the conditions under which an organism is described as a pathogen

• A pathogen is any organism that can produce an infectious disease.



2.4 ‐ Identify data sources, plan and choose equipment or resources to perform a first‐hand investigation to identify microbes in food or in water

Identification of Microbes Trends Table Sample Trend Cheese Cheese had the most microbial growth. This could be for two reasons. The

first is that dairy products are an excellent source of nutrients for micro organisms. The second is that cheese is produced using bacteria such as Streptococcus salivarius thermophilus or some kind of Lactobacillus which, when exposed to the perfect conditions of the agar plate and the incubator, thrives and spreads throughout the plate

Bread Bread had the second largest amount of microbial growth and, trend wise, is very similar to the cheese. Bread is an ideal habitat for mould and this may have been what was on the agar plate. More likely, however, is that the growth is bread yeast, Saccharomyces cerevisiae.

Yoghurt Yoghurt had no microbial growth and was the only food to have no micro organism present. This was strange as yoghurt, like cheese, is made with bacteria and is an ideal habitat for microbes. The probable cause for the lack of group was that the yoghurt was pasteurised. This demonstrates that pasteurisation effectively destroys are microbes present and is why no growth was observed.

Pond water Pond water had the most growth out of all water samples. This is because it is completely untreated, therefore, microbial growth was observed.

Tap water Tap water had very limited growth. There was one or two tiny colonies. This shows that the treatment of water, such as chlorination, is highly effective, but not completely.

Sterilised distilled water

This plate is consider an anomaly. They was four colonies found growing on the plate. This colonies were not on where the water had been placed on the agar. It was predicted that human error had placed some microbes on the agar. However, the distilled water sample may have been contaminated somehow, but this is unlikely.

Control There was no growth at all. This shows that the agar contained no microbes and it was the food or water that was contaminated with micro organisms.



2.5 ‐ Gather, process and analyse information from secondary sources to describe ways in which drinking water can be treated and use available evidence to explain how these methods reduce the risk of infection from pathogens



3 ‐ During the second half of the nineteenth century, the work of Pasteur and Koch and other scientists stimulated the search for microbes as causes of disease

3.1 ‐ Describe the contribution of Pasteur and Koch to our understanding of infectious diseases

Pasteur

• He disproved the theory of spontaneous generation • He showed that micro‐organisms came from pre‐existing micro‐organisms.

Koch

• The work of Robert Koch (1843 ‐ 1910) provided the proof that was needed to convince people that microscopic pathogens cause disease.

• His first experiments were with the disease anthrax in sheep. Later, he obtained similar results for tuberculosis and cholera.

• After his experiments with anthrax, Koch was able to state a series of steps called Koch's postulates.

o Step 1: All infected hosts must contain the suspect organism. o Step 2: A pure culture of the suspect organism must be obtained. o Step 3: A healthy organism infected with the pure culture must have the same

symptoms as the original host. o Step 4: The suspect organism must be isolated from the second host, grown in pure

culture and prove to be identical to the first culture. • Koch's postulates can be used to identify the causative organism of an infectious disease.



3.2 ‐ Distinguish between:

• prions

• viruses

• bacteria

• protozoans

• fungi

• macro‐parasites

and name one example of a disease caused by each type of pathogen

Pathogen Description Examples

Prions Protein that has been altered from its normal structure and can then alter other proteins (No nucleic acids)

mad cow disease Creutzfeldt‐Jakob (CJD)

Viruses Consist of single stranded DNA or double stranded RNA enclosed in protein, live inside living cells. (0.005=0.1µm)

Influenza herpes HIV/AIDS

Bacteria Very simple cells with no internal membranes. Prokaryotic (.25µm‐ 5µm)

Cholera Legionnaire's disease Tuberculosis

Protozoa Microscopic single‐celled organisms with internal membranes. Eukaryotic (1µm‐100µm)

Amoebic dysentery Giardia Malaria

Fungi Heterotrophic organisms. Some (e.g. yeasts) are unicellular, others consist of long branching threads.

Ringworm Tinea Thrush

Macro‐organisms

Organisms that are visible to the naked eye, also called parasites.

Fleas tapeworms aphids

3.3 ‐ Identify the role of antibiotics in the management of infectious disease

• They are naturally occurring compounds produced by one organism to prevent the growth of bacteria.

• Before the discovery of antibiotics, many people died of what we now would think of as simple infections.



3.4 ‐ Perform an investigation to model Pasteur’s experiment to identify the role of microbes in decay

Title: Identification of the role microbes have in decay

Aim: To determine the role of microbes in decay

Method

1. Fill both conical flasks with sterilised broth. 2. Cap the flasks with rubber stoppers 3. With one of the flasks, wrap foil around the top where the stopper is. 4. Slide the plastic piping over the glass pipe for the flask with the foil and create a loop. Use

the rubber bands to hold this shape. 5. Pour some sterilised water in the loop so it does not go into the broth, but enough so the

diameter of the plastic is completely closed in one section. 6. Take a photograph before leaving to sit for a week. 7. After a week has past, photograph the flasks again and compare.

Discussion

• The trend of this experiment is that the flask that was open to the environment went off and became cloudy, where as the other flask did not.

• This was predicted to be due to microbial growth in the open flask which caused the broth to decay.

• There was no evidence of microbial growth in the swan neck equivalent flask and no change in the clarity of the broth was observed.

• Therefore, it can be said that microbes play a role as decomposers and cause decay.

Conclusion: It was concluded that microbes play a prominent role in decay as the broth contained in the open flask decayed and in the swan necked flask it did not which verified Louis Pasteur's own conclusions.



3.5 ‐ Gather and process information to trace the historical development of our understanding of the cause and prevention of malaria

Date Development

18 BC The disease malaria was described by the Romans. Malaria was thought to come from swamps so the name means 'bad air'

1820 Quinine used to prevent the disease

1880 Charles Laveran a French army doctor observed the malarial parasite

1886 Golgi observed asexual reproduction in the protozoan Plasmodium and identified two species

1898 Giovanni Grassi named the Anopheles mosquito as the carrier of the malarial parasite

1897 Ronald Ross discovered that Plasmodium was the protozoan that caused the disease malaria.

1940 Chloroquinine the first synthetic anti‐malarial drug was used 3.6 ‐ Identify data sources, gather process and analyse information from secondary sources to describe one named infectious disease in terms of its:

• cause

• transmission

• host response

• major symptoms

• treatment

• prevention

• control

Malaria Factors Description Cause The parasitic protozoan, Plasmodium Transmission Female Anopheles mosquito is the insect vector. Blood from a malaria

victim contains Plasmodium sex cells. These form zygotes in cysts and mature into sporozoites. The sporozoites travel to the mosquito salivary glands, from where they are transferred to the victim of the mosquito bite. Male and female gametes are produced from these sporozoites, which are then taken in the blood the next time a mosquito bites.

Host response When in the blood cells the host produces antibodies against Plasmodium Major symptoms Chills, fever, sweating, delirium and headache Treatment Anti‐malarial drugs such as quinine and chloroquinine Prevention Cover up after dark and use personal insecticide, mosquito nets Control Draining swamps, spraying with insecticides.



3.7 ‐ Process information from secondary sources to discuss problems relating to antibiotic resistance

• Unfortunately, the overuse of antibiotics has led to the selection of more virulent bacteria that are resistant to antibiotics.

• When antibiotics were first introduced, they had a dramatic effect on the pathogens that cause disease.

• Over time the development of drug resistance in the pathogen occurred.

• Each time an antibiotic is used, there may be some individual pathogens that have a natural resistance to the drug. These naturally resistant individuals are left to breed the next generation and pass on the genetic information that made them resistant.

• Overuse of antibiotics has resulted in "superbugs". These strains are resistant to antibiotics and include vancomycin resistant golden staph (Staphylococcus aureus).

• Many household products and cleaning agents now contain antibiotics. These do not kill all bacteria so act as a selecting agent for antibiotic resistant bacteria.

• The use of antibiotics in farm animals also has the same effect of selecting for antibiotic resistant bacteria.

• It is important to complete a course of antibiotics even when the symptoms are gone. This will ensure that the bacteria have been completely destroyed. Not finishing antibiotics can lead to the selection of antibiotic resistant strains.



4 ‐ Often we recognize an infection by the symptoms it causes. The immune response is not so obvious, until we recover

4.1 ‐ Identify defence barriers to prevent entry of pathogens in humans:

• skin

• mucous membranes

• cilia

• chemical barriers

• other body secretions

Line of defence Description What it does

skin Skin is acidic and dry. Cells fit tightly together to form a protective layer covered by dead cells.

When unbroken, skin prevents the entry of pathogens. Pores in the skin secrete substances that kill bacteria.

mucous membrane cells lining the respiratory tract and openings of the urinary and reproductive systems that secrete a protective layer of mucus

Mucus is sticky and traps pathogens and other particles. When there are many pathogens more mucus is produced to flush them out.

cilia Hair‐like projections from cells lining the air passages

Move with a wavelike motion to push pathogens from the lungs up to the throat.

chemical barriers acid in the stomach; alkali in the small intestine; the enzyme, lysozyme, in tears

Stomach acid destroys pathogens. Alkali destroys acid resistant pathogens. Lysozyme dissolves the cell membranes of bacteria.

Other body secretions secretions from sweat glands and oily secretions from glands in hair follicles

Contain chemicals that destroy bacteria and fungi.

4.2 ‐ Identify antigens as molecules that trigger the immune response

• Any molecule that the body recognises as being foreign is called an antigen.

• Antigens activate the immune response.



4.3 ‐ Explain why organ transplants should trigger an immune response

• Organs from another organism are recognised as foreign by the human immune system.

• The surfaces of the new organ contain antigens.

• These trigger an immune response and body attacks the new organ as if it were a pathogen.

4.4 ‐ Identify defence adaptations, including:

• inflammation response

• phagocytosis

• lymph system

• cell death to seal off pathogen

Inflammation response

• Inflammation occurs when blood flow increases around an infected area • The release of histamines by the damaged tissue increases the permeability of the blood

vessels, which allows white blood cells to move into the damaged tissue.

Phagocytosis

• Macrophages and neutrophils can very easily change their shape so they engulf particles • They then break down the particles using enzymes.

Lymph system

• Returns intercellular fluid to the blood system • Filters cell debris • Produces white blood cells responsible for the immune response

Cell death to seal off pathogen

• Macrophages and lymphocytes surround a pathogen so that it is enclosed in a cyst. • The white cells die so that the pathogen is isolated from its food supply and also dies.

4.5 ‐Ggather process and present information from secondary sources to show how a named disease results from an imbalance of microflora in humans

Cause Over growth of yeast Candida Albicans (Vulvovaginal Candidiasis) Major symptoms Severe itching, burning, soreness, irritation, and a whitish or whitish‐gray

cottage cheese‐like discharge, often with a curd‐like appearance Treatment Anti‐fungal drugs such as topical clotrimazole, topical nystatin, fluconazole,

and topical ketoconazole.



5 ‐ MacFarlane Burnet’s work in the middle of the twentieth century contributed to a better understanding of the immune response and the effectiveness of immunization programs

5.1 ‐ Identify the components of the immune response:

• antibodies

• T cells

• B cells

Name What it is What it does

antibodies proteins that the body produces when it detects antigens. Each different antigen stimulates the production of its own particular antibody.

join with antigens so that they are clumped together and can be more easily recognised and destroyed by macrophages

B cell a special kind of lymphocyte produced in the bone marrow (thus B cell)

When a B cell recognises an antigen, it divides repeatedly to produce a mass of identical cells (clones) that work as antibody producers (plasma cells).

T cell another kind of lymphocyte, that is passed through the thymus gland (thus T cell)

Some produce toxic substances that destroy cells that have been invaded by a virus. Others help the B cells to divide rapidly.



5.2 ‐ Describe and explain the immune response in the human body in terms of:

• interaction between B and T lymphocytes

• the mechanisms that allow interaction between B and T lymphocytes

• the range of T lymphocyte types and the difference in their roles

Interaction between B and T lymphocytes

• B and T lymphocytes interact as they are both attacking the same antigen

• Helper T cells stimulate B cells and T cells

The mechanisms that allow interaction between B and T lymphocytes

• The T lymphocytes that help B lymphocytes are called helper T cells (Th cells).

• If a B cell has an antigen on its surface, there is a risk that a T cell will recognise the antigen and attack it.

• This does not happen because T cells are able to recognise “self” molecules that are on the surface of B cells.

• Only identical twins have the same “self” molecules on their B cells.

The range of T lymphocytes types and the difference in their roles

Type of T cell Roles

killer T cells (Tc cells) attack and destroy macrophages that have engulfed an antigen with cytotoxin

helper T cells (Th cells) secrete chemicals that stimulate cloning in B and T cells

memory T cells remain in the body and reactivate quickly with subsequent infections by the same antigen

suppressor T cells stop the reaction when the antigen is destroyed



5.3 ‐ Outline the way in which vaccinations prevent infection

• Vaccination introduces harmless pathogenic antigens into the body • B cells are activated to produce large amounts of antibody and memory B cells that are

stored in the lymph system ready for a future attack by the particular pathogen.

5.4 ‐ Outline the reasons for the suppression of the immune response in organ transplant patients

• When an organ is transplanted it is recognised by the immune system as non‐self and the organ is attacked like an invading pathogen.

• To overcome this, transplant patients are given drugs to suppress their natural defences.

• This can lead to complications, as the patient has reduced defences against any pathogen

5.5 ‐ Process, analyse and present information from secondary sources to evaluate the effectiveness of vaccination programs in preventing the spread and occurrence of one common diseases, including smallpox, diphtheria and polio

• Once common diseases, such as small pox, diphtheria and polio, are now uncommon because of successful vaccination programs.

• The small pox vaccination program that was started in the 1960s was so successful that the World Health Organisation (WHO) has declared it eradicated.

• Diphtheria vaccine is given as part of a triple antigen injection that protects against diphtheria, tetanus and whooping cough.

• In 1990, WHO stated that 80% of children had been vaccinated against this disease.

• There continues to be outbreaks of this disease and continued vaccination is recommended

• Polio caused thousands of children to become paralysed every year. A vaccine was introduced in 1955. It became available as an oral vaccine in the 1960s.

• Worldwide, the number of polio cases is down by 80%.



6 ‐ Epidemiological studies involve the collection and careful statistical analysis of large quantities of data. Such studies assist the causal identification of non‐infectious diseases

6.1 ‐ Identify and describe the main features of epidemiology using lung cancer as an example

• Focus on large groups of people which allows statistics to be used to identify trends and possible causative factors.

• Use populations where there is occurrence of the disease and where there are unequal exposures to the suspected or possible causes.

• No conclusions about the effect of smoking could be drawn from a group of people who each smoke 20 cigarettes a day

• Allow for analysis of factors that might contribute to the occurrence of the disease among those afflicted, such as age, sex, ethnic group, and occupation.

6.2 ‐ Identify causes of non‐infectious disease using an example from each of the following categories:

• inherited diseases • nutritional deficiencies • environmental diseases • Inherited diseases result from mutations that lead to the production of different or faulty

enzymes, resulting in impaired body function. • Down syndrome is an inherited disease that results in three chromosomes and not the usual

two (trisomy 21). • People with Down syndrome have a characteristic appearance and may have a shortened

life span.

• The effect of nutritional deficiencies depends on the kind of deficiency. • In some parts of the world diets may be deficient in certain elements, such as iodine,

copper, iron or zinc. • Scurvy is caused by a deficiency in vitamin C.

• Environmentally caused diseases include those due to lifestyle, such as smoking‐related

diseases, as well as those caused by something in the environment, such as lead or substances that cause allergies.

• Mesothelioma is caused by exposure to asbestos and patients don't get any symptoms until 20 to 30 years after exposure.

• There is no cure and treatment can only slow down the progression of the disease.



6.3 ‐ Gather, process and analyse information to identify the cause and effect relationship of smoking and lung cancer

• Cause and effect is difficult to establish. This difficulty arises with epidemiological studies. • Smoking and lung cancer have been linked by research time after time but it is difficult to

get the manufacturers of tobacco products to accept that it is a direct cause and effect relationship, that is, smoking causes lung cancer.

6.4 ‐ Identify data sources, plan and perform a first‐hand investigation or gather information from secondary sources to analyse and present information about the occurrence, symptoms, cause, treatment/management of a named non‐infectious disease

Name of disease Scurvy Occurrence Young children, elderly, sailors, any diet without vitamin C, usually

from a lack of fresh fruit Symptoms Malaise, lethargy, myalgias, easy bruising, tooth decay, gum

disease, jaundice, oedema, fever, convulsions, oliguria, death Cause Lack of vitamin C Treatment/Management Vitamin C supplements or diets



7 ‐ Increased understanding has led to the development of a wide range of strategies to prevent and control disease

7.1 ‐ Discuss the role of quarantine in preventing the spread of disease, plants and animals into Australia or across regions of Australia

• Quarantine seeks to prevent the entry of harmful diseases into Australia and to stop the spread of diseases within Australia.

• These diseases cause huge financial losses to farmers in other countries. • Australia is able to sell its products to overseas markets because of the absence of diseases,

like mad cow disease and foot‐and‐mouth. • Australia also has declared fruit‐fly free areas where the produce is sold • This can be done by having inspections and bins to put fruit in when entering areas.

7.2 ‐ Explain how one of the following strategies has controlled and/or prevented disease:

• public health programs • pesticides • genetic engineering to produce disease resistant plants and animals

Public health programs

• These provide quarantine, sanitation, safe drinking water and immunisation. • Also responsible for advertising campaigns that target cancer and AIDS. • Successful health campaigns are the Slip! Slop! Slap! skin cancer advertisements

Pesticides

• Pesticides, such as DDT, have been used to destroy mosquitoes, which are the vectors of some diseases, such as malaria and dengue fever.

Genetic engineering to produce disease resistant plants and animals

• Genetically engineered plants can now kill their own pests because of the insertion of a gene from a soil bacterium, Bacillus thuringiensis (Bt).

• Bt cotton was the first genetically engineered crop grown in Australia. • The bacteria contain a gene that produces chemicals that kill certain insects. By taking that

gene from the bacteria and inserting into the genome of plants, the plants now produce the chemical that will kill insect pests.



7.3 ‐ Perform an investigation to examine plant shoots and leaves and gather first‐hand information of evidence of pathogens and insect pests

7.4 ‐ Process and analyse information from secondary sources to evaluate the effectiveness of quarantine in preventing the spread of plant and animal disease into Australia or across regions of Australia

7.5 ‐ Gather and process information and use available evidence to discuss the changing methods of dealing with plant and animal diseases, including the shift in emphasis from treatment and control to management or prevention of disease

• This can be seen in agriculture where genetically resistant crops are grown so that the plants do not have to be sprayed for diseases later in life.

• Animal and plant diseases have been managed by quarantine restrictions in Australia. Diseases, such as foot and mouth, rabies and plum pox, are managed by not allowing infected organisms to enter the country.

• World‐wide immunisation has caused diseases such as small pox to be eradicated.



Biotechnology

1. The origins of biotechnology date back at least 10 000 years

1.1 ‐ Describe the origins of biotechnology in early societies who collected seeds of wild plants and domesticated some species of wild animals

• Early societies collected seeds and wild animals and selected the individuals and the species that were most useful to them.

1.2 ‐ Explain why the collection of seeds and breeding of animals with desired characteristics, could be described as early biotechnology

• By collecting seeds from plants with desirable characteristics such as heads that matured at the same time and produced seeds that tended not to be blown by the wind easily, the people were controlling the genetic makeup of the next generation of plants.

• Similarly by choosing animals, such as cattle with characteristics they favoured, such as more placid nature, the genes of their domestic stock would be different from those of the wild animals.

1.3 ‐ Describe the changes in one group of animals and one group of plants as a result of artificial selection of characteristics suitable for agricultural stock

Sheep

• They were probably bred from the wild mouflon of western Asia. They were useful for both clothes and for food.

• The Romans took sheep with fine wool to Spain where further breeding produced the Merino breed.

• In England during the eighteenth century there was deliberate breeding of sheep to produce favourable varieties such as the Leicestershire.

• Today there are five main types of sheep based on wool type.

Wheat

• The domestication of wheat involved both human intervention and natural hybridisation between closely related species.

• Harvesting them changed them genetically by selecting the seed that naturally clung to the plant instead of being blown off by the wind.

• This resulted in domesticated plants that cannot naturally reproduce themselves without human intervention.

• Modern wheat is husk free, typically short and stands well in highly fertile situations.



1.4 ‐ Use available evidence to describe the changes in a species of grain or animal as a result of domestication and agricultural processes

• During domestication, livestock decreased in size from the wild varieties to make them less likely to do harm.

• Plants generally were bred to be bigger and easier to eat.

• Grain became less likely to be spread by the wind and more likely to stick closely in the heads of the plants so they could be harvested.

1.5 ‐ Process information to outline an ancient Aboriginal use of biotechnology

• The domestication of wild dingoes was done by some groups.

• Dingoes were used to sniff out certain animals

2. Biotechnology has come to be recognised as the use of living organisms to make or modify a product, to improve plants or animals or to utilise micro‐organisms for specific uses

2.1 ‐ Outline the key events that led to the use of biotechnological practices, including:

• yeast in the manufacture of bread

• yeast and fermentation for alcohol production

• the use of other micro‐organism for the manufacture of yoghurt and cheeses

• Yeast in the manufacture of bread has been occurring for at least 5 000 years.

• It is believed that natural contaminants of flour such as wild yeast and lactobacillus may have been introduced possibly by the addition of milk.

• Wine will form naturally from fruit juices as the yeast grows on the skin of fruit. The production of wine was an ancient practice during ancient Greek times.

• Beer was made from barley in Ancient Egypt.

• The first cheese was made when milk was put into a sheep's stomach carry bag and the milk had changed into curds and whey as a result of the enzyme rennin found in stomachs.

2.2 ‐ Plan, choose equipment or resources, perform a first‐hand investigation to demonstrate the use of fermentation processes in bread or alcohol production

C6H12O6 2C2H5OH + 2CO2 (yeast catalyst in anaerobic environment)

Glucose ethanol carbon dioxide



3. Classical biotechnology exploited knowledge of cell biochemistry to produce industrial fermentation procedures

3.1 ‐ Describe the expansion of fermentation since the early 18th century to include the production of several organic compounds, including glycerol, lactic acid, citric acid and yeast biomass for baker’s yeast

• Other organic compounds were fermented by using different carbohydrates and micro‐organisms. These products included glycerol, lactic acid, citric acid and yeast biomass.

• Glycerol was made by adding sodium bisulfite to the fermentation of sugar.

• Citric acid is produced using the fungus Aspergillus niger on the submerged fermentation of glucose. It is used in the food industries as a flavour enhancer.

• The milk sugar lactose is fermented to lactic acid by many types of bacteria to produce products such as cottage cheese, yoghurt and sour milk.

3.2 ‐ Describe strain isolation methods developed in the 1940s

• Strain isolation were methods of separating a particular strain of a micro‐organism, such as a bacterium, virus or fungus to then grow that particular strain and use it to benefit humans

• Pathologist Howard Florey and biochemist Ernst Chain isolated penicillin from Fleming’s mould cultures, however, they couldn’t isolate enough of the penicillin from the mould to be commercially viable.

• The use of huge deep fermentation tanks provided with a good supply of air made it possible to produce more of the wonder drug, because the mould could grow throughout the 25 000 gallon tanks instead of just on the top.

3.3 ‐ Describe, using a specific example, the benefits of strain isolation methods used in biotechnology in the 20th century

• Strain isolation enabled scientists to find a strain of penicillin in a relatively short time.

• The penicillin was needed to treat wounded troops in WWII

• Penicillium notatum, the penicillin mould first discovered by Fleming, would never give enough of the drug to be useful commercially.

• Mutations created new strains and through strain improvements, improved culture media and better aeration, the yields of penicillin increased to 25000 units per mL.

• Researchers continued to find higher‐yielding Penicillium moulds, and also produced higher yielding strains by exposing moulds to x‐rays or ultraviolet light.



3.4 ‐ Identify that developments in the 1950s led to biotransformation technologies that could produce required organic compounds such as cortisone and sex hormones

• Biotransformation is the process where one chemical is changed into another by a chemical reaction that occurs in a living organism.

• Over the past years biotransformations have gained in importance as intermediate in chemical synthesis predominantly if reactions are not possible or only possible with great effort.

3.5 ‐ Gather and process information from secondary sources to:

• identify and describe a named industrial fermentation process

• identify the micro‐organism used in the fermentation and the products of the fermentation

• outline the use of the product of the fermentation process

• use available evidence to assess the impact of the use of the fermentation product on society at the time of its introduction

Industrial process Alcohol production Micro organism Saccharomyces cerevisiae Products Ethanol and carbon dioxide Use of alcohol Drinking

Can be used as a fuel alternative Used in preservation In perfumes Universal solvent due to polar and non polar areas of the alkanol molecules Used in a variety of cleaning agents Steriliser

3.6 ‐ Process and analyse information from secondary sources to demonstrate how changes in technology and scientific knowledge have modified traditional uses of biotechnology, such as fermentation

• Larger scale production

• Improved knowledge of genetics allows for greater control of organism traits that are beneficial to humans

• Numerous alternatives to processes that improve yield and economic viability



4. Cell chemistry is utilised in biotechnology

4.1 ‐ Outline, simply, the steps in the synthesis of protein in the cell, including:

• the difference between DNA and RNA

• the production of messenger RNA

• the role of transfer RNA

• the formation of the polypeptide chain(s)

• the formation of the protein from polypeptide chains

DNA RNA Double stranded Single stranded Contains deoxyribose sugar Contains ribose sugar Contains thymine Contains uracil One type Two types (transfer and messenger)

• The first process in the synthesis of protein from DNA is transcription.

• The DNA molecule in the nucleus partly unzips and the code of nitrogen bases on the DNA is transferred to messenger RNA (mRNA).

• A matches up with U and G matches up with C

• The second process is translation.

• Transfer RNA (tRNA) picks up amino acids in the cytoplasm and brings them to the mRNA that is attached to a ribosome.

• The first and second amino acids brought to the ribosome attach together, forming a peptide bond.

• The amino acids that link together will be determined by the order of bases on the mRNA.

• This linking continues down the code on the mRNA until a stop code is reached

• The last process is the forming of a protein and this happens by the long polypeptide chain folding in particular shapes. T

• he way they fold largely depends on the order of the amino acids.

4.2 ‐ Plan and perform a first‐hand investigation to test the conditions that influence the rate of enzyme activity

• No. I'm not doing it twice. It's pH, temperature, and substrate concentration



5. Modern biotechnology includes recombinant DNA technology

5.1 ‐ Describe the three essentials of gene manipulation as:

• cutting and joining DNA

• monitoring the cutting and joining

• transforming hosts, such as bacteria, with the recombinant DNA

Cutting and Joining

• The DNA that is required is cut using enzymes.

• An example is the gene for making human insulin is cut from a human pancreas cell using a restriction enzyme.

• A circular piece of DNA, called a plasmid, that is present in bacterial cells, is removed from the cells and is cut open using the same restriction enzyme.

• The cut out human gene is then mixed with the bacterial plasmids. As they have been cut with the same enzyme, the ends of the plasmid and the end of the human gene match.

• The enzyme DNA ligase is used to stick the ends together.

Monitoring

• Unwanted DNA fragments have to be removed. This is done by electrophoresis.

• All the DNA are placed in depressions at one end of a slab of agar gel. Electrodes are placed at each end of the gel to create an electric field.

• Because the DNA molecules are negatively charged, the DNA fragments travel through the gel towards the positive end. Since smaller pieces move faster than larger ones, the various fragments are separated by size and the required ones can be easily obtained.

Transforming hosts

• This refers to replacing the plasmids that contains the introduced gene (recombinant DNA) into the E coli bacteria so they can multiply and make more of the gene.

• It can be done by combining them in a test tube with calcium chloride.

• The high concentration of calcium ions makes the membranes of the bacteria more porous.

• This then allows the plasmids to move into the bacterial cells.



5.2 ‐ Describe the following recombinant DNA techniques used in biotechnology, including:

• gene splicing using restriction enzymes and ligases to produce recombinant DNA

• polymerase chain reaction to amplify or modify DNA sequences

• use of DNA vectors and microinjection for carrying genes into nuclear DNA in the production of transgenic multicellular organisms

Gene splicing using restriction enzymes and ligases to produce recombinant DNA

• DNA is cut using a class of enzymes called restriction enzymes. There are well over a hundred restriction enzymes, each cutting in a very precise way a specific base sequence of the DNA molecule.

• This segment is "glued" into place using an enzyme called DNA ligase. The result is an edited, or recombinant, DNA molecule. The bacterial cells divide very rapidly making billions of copies of themselves, and each bacterium carries the recombinant

Polymerase chain reaction to amplify or modify DNA sequences

• This is the most successful method of amplifying (making many copies) DNA sequences.

• The process is done in a test tube: the DNA required is isolated, fragmented with restriction enzymes and separated by gel electrophoresis.

• The DNA fragments are denatured (ie, made single stranded) by heating to about 95 degrees C. These single stranded DNA are exposed to a solution containing a radioactive DNA “probe”.

• With correct temperature of about 50 – 65 degrees C, salt and correct pH the probe will bind to its corresponding sequence of the target DNA and nowhere else.

• As the process proceeds the DNA doubles after each cycle. Following thirty such cycles a theoretical one billion copies of DNA can be produced.

Use of DNA vectors and microinjection for carrying genes into nuclear DNA in the production of transgenic multicellular organisms

• Commonly used vectors (carriers) are viruses

• A viral vector is first modified so that it will not replicate or cause disease in the target cells of the host embryo.

• The gene of interest is incorporated into the viral genome and the virus is then used to infect an embryo. The viral vector binds uniformly to the embryonic cells and acts as a vehicle to allow transfer and integration of the transgene into the host genome

• Retroviruses are used as vectors because of their ability to infect host cells in this way.



5.3 ‐ Perform a first‐hand investigation to extract and identify DNA from a suitable source

1. Blend kiwi fruit flesh. 2. Add meat tenderiser, and salt 3. Filter. 4. Poor filtrate into test tube. 5. Add 100% ethanol.

5.4 ‐ Process information to produce a flow chart on the sequence of events that result in the formation of recombinant DNA

5.5 ‐ Gather and analyse information to outline the purpose of a current application of transgenic technology, naming the organism and gene transfer technique involved

Insulin is used by inserting human pancreas genes into E coli



6. There are many applications and areas of research in biotechnology

6.1 ‐ Outline one way that forensic scientists can use DNA analysis to help solve cases

Briefly one method is:

• Scientists find the markers in a DNA sample by designing small pieces of DNA (probes) that will each seek out and bind to a complementary DNA sequence in the sample.

• A series of probes bound to a DNA sample creates a distinctive pattern for an individual.

• A marker by itself usually is not unique to an individual; if, however, two DNA samples are alike at four or five regions, odds are great that the samples are from the same person.

6.2 ‐ Describe one example from the following applications of biotechnology in medicine:

• tissue engineering using skin transplantation as an example

• gene delivery by nasal sprays

• production of a synthetic hormone, such as insulin

Tissue engineering using skin transplantation

• Novartis launched tissue engineering in 1997 with Apligraf, (Graftskin), a product developed by partner Organogenesis, for the treatment of venous leg ulcers.

• Apligraf, a bi‐layered skin substitute, has since been approved for use in the treatment of diabetic foot ulcers of greater than three weeks duration.

Development of new rheumatoid arthritis "nasal spray"

• A team has carried out preliminary work using nose drops in a model system to deliver a modified gene coding for a naturally derived anti‐inflammatory substance called Interleukin‐10 (IL‐10) for the treatment of rheumatoid arthritis

• They have made the novel and exciting observations that IL‐10 administered in this way acts by "switching off" the harmful, inflammatory process that causes RA, and “switching on” populations of cells that can re‐educate, or hold in check, the harmful cells.

Production of a synthetic hormone such as insulin

• In 1978, a synthetic version of the human insulin gene was constructed and inserted into the bacterium Eschericia coli.



6.3 ‐ Describe one example from the following applications of animal or plant biotechnology:

• the production of monoclonal antibodies

• recombinant vaccines to combat virulent animal diseases

Monoclonal antibodies

• Monoclonal antibodies are produced by fusing the antibody producing mammalian cells (B‐cells) with cells that will continue to repicate endlessly.

• The result of this cell fusion is called a hybridoma.

• Used to protect against disease

• Diagnose a wide variety of illnesses

• Detect the presence of drugs, viral and bacterial products, and other unusual or abnormal substances in the blood.

Recombinant vaccines

• Instead of growing viruses in eggs or other hosts, recombinant vaccines are produced by producing only one viral protein (ie, not the whole virus) in a yeast or bacteria.

• The vaccine is then incapable of infection through accidental failure to kill all virus particles.

• Drawbacks would include allergic reactions to the preservatives or to small amounts of proteins from the bacteria or yeast.



6.4 ‐ Describe one example from the following applications of aquaculture:

• the production of a pharmaceutical from alga

• the farming of a marine animal

The production of a pharmaceutical from alga

• Seaweeds and other algae are rich natural sources of essential amino acids, polyphenol glycosides, minerals, hydrosoluble vitamins and trace elements.

• In colour cosmetics, some iron oxide pigments can be replaced with green, red, blue, brown and yellow algae. All these materials have strong antioxidant action.

The farming of a marine animal‐ Freshwater Yabbies

• Farmers have frequently grown yabbies in their dams, either for personal use or to supplement their income.

• Recently there has been a movement towards supplementary feeding with food grains, better water quality management, and the establishment of purpose‐built ponds

Development of a genetically improved strain of yabby

• One advantage of genetic improvement over the manipulation of the environment is that the progress is permanent and sustainable for long periods of time.

• For profitable aquaculture, an ideal freshwater yabby should grow quickly to market size, efficiently convert food into meat, have a high yield of edible flesh, and be very tasty when cooked.

• Unfortunately, yabbies currently used in commercial aquaculture do not fit this ideal model. This is not surprising considering that in their native habitat, natural selection has favoured animals that are intermediate performers.

• However, contained within these populations, at low frequencies, are yabbies with great genetic potential in performance traits such as rapid growth, late maturity and efficient food conversion ratios.

• In order to utilise this natural variation, Livestock Industries has undertaken research at Armidale to identify yabby populations with characteristics that will render them more profitable for aquaculture



6.5 ‐ Identify data sources, gather, analyse and process information to present one case study on the application of biotechnology in each of the following:

• medicine

• animal biotechnology

• aquaculture

These case studies should:

• give details of the process used

• identify the organism or tissue involved

• describe the outcome of the biotechnological process

• evaluate the efficiency of the process and discuss advantages and disadvantages associated with either the product or the process

Development of a genetically improved strain of yabby

• For profitable aquaculture, an ideal freshwater yabby should grow quickly to market size, efficiently convert food into meat, have a high yield of flesh, and be tasty when cooked.

• However, at low frequencies, are yabbies with great genetic potential in performance traits such as rapid growth, late maturity and efficient food conversion ratios.

• In order to utilise this natural variation, Livestock Industries has undertaken research at Armidale to identify yabby populations with characteristics that will render them more profitable for aquaculture



7. Ethical issues relevant to the use of biotechnology are important and need to be considered

7.1 ‐ Explain why different groups in society may have different views about the use of DNA technology

• Different groups of people have different viewpoints because of their cultural background and their previous experiences.

• For some in big business the driving force is to make money to satisfy their shareholders.

• Other groups, such as animal liberationists, are against the use of animals in biotechnology without considering the benefits that come from such research as they consider that the welfare of the animal is paramount.

7.2 ‐ Identify and evaluate ethical issues related to one of the following:

• development of genetically modified organisms (GMOs)

• animal cloning

• gene cloning

Development of genetically modified organisms (GMOs).

Some arguments for:

• Greater production of food especially for developing countries would allow these countries to produce enough food for their population.

• Less chemicals on crops is better for the environment so for example if cotton can be bred that needs fewer sprays preventing the spray drifting into the neighbouring bushland.

• Vaccines can be produced in plants for better human health outcomes.

• Produce may reach the consumer in better condition with less spoilage.

Arguments against:

• The transgene in the products may cause allergic reactions in people.

• Genetically identical plants and animals leads to a loss of biodiversity.

• The new species may escape into the wild populations and super weeds could be formed by the cross‐fertilisation of wild species and transgenic species.

• Business has control of the products being produced and their motive is profit , which may not be in the best interest of farmers.



7.3 ‐ Use available evidence to identify and discuss ethical and social issues associated with the use of biotechnology

economic and qualitative considerations

• The benefits from the use of the technology should not be just economic but should include a better quality of life in terms of health and a cleaner environment.

openness

• The use of biotechnology should be open and different viewpoints should be respected.

self‐determination, dignity, integrity and vulnerability

• Self‐determination of humans must be allowed to occur and the dignity and integrity of the whole of society and the environment should be maintained.

just distribution of benefits and burdens

• The benefits and disadvantages are distributed fairly between different groups in society and are not just a benefit to one group while disadvantaging another.

maintaining a balance 1. organisms are active in a limited ... · hsc biology v repaci education ...

Documents