Outcomes
· Conducts investigations to collect valid and reliable primary and secondary data information
· Selects and processes appropriate qualitative and quantitative data and information using a range of appropriate media
· Describes single cells as the basis for all life by analysing and explaining cells ultrastructure and biochemical processes
Content Focus
Cells are the basis of life. They coordinate activities to form colonial and multicellular organisms. Students examine the structure and function of organisms at both the cellular and tissue levels in order to describe how they facilitate the efficient provision and removal of materials to and from all cells in organisms. They are introduced to and investigate biochemical processes through the application of working scientifically skills processes.
These tools will be used throughout the course to assist in making predictions and solving problems of a multidisciplinary nature.
Content
· Investigate different cellular structures, including but not limited to;
· Examining a variety of prokaryotic and eukaryotic cells
Prokaryote
Similarities
Eukaryote
· May contain plasmids
· Can be multi or unicellular
· DNA is arranged in linear chromosomes
· Located in nucleus
· Plant cells
· Many plant cells have a large vacuole
· Many plant cells contain chloroplasts
· Note: not ALL plant cells have a chloroplast
· Example; cells in the underground roots cannot photosynthesise, so do not contain any chloroplasts
· Describe a range of technologies used to determine a cell’s structure and function
Light microscope:
Energy Source
Treatment
Stains can be applied to highlight different components of the cell
Image
Transmission electron microscope:
Treatment
Process
Image
Can display inside the cell or whole organism, multiple images can create a 3D image
Electron microscope:
· Highly detailed
· Higher resolution
Scanning electron microscope:
Treatment
Stained, dehydrated, fixed specimen, coated in a thin layer of metal atoms
Process
Image
· Investigate a variety of prokaryotic and eukaryotic cell structures, including but not limited to;
· Drawing scaled diagrams of a variety of cells
Estimating cell size:
Cell structure and function:
Cytoplasm:
· A watery, gel-like substance
· Place where chemical reactions, food storage and other “cellular activity” takes place
Nucleus:
· Control centre
· Explains how the cell should act
· When the cell makes a new cell it copies the DNA found here
Vacuoles:
· May store food or nutrients for the cell
Mitochondria:
· The powerhouse of the cell which releases energy from food
Endoplasmic reticulum:
· Forms a pathway to allow materials to move through the cell
Ribosomes:
· Found in animal cells
· Packs chemicals into small membrane vesicles for storage or secretion
· Example of this is the lysosome
· Lysosomes: Garbage disposal units which remove waste
· Modelling the structure and function of the fluid mosaic model of the cell membrane
Fluid mosaic structure:
· Selectively permeable membrane
· Can allow some substances to move into the cell while preventing others from entering
· These membranes are dynamic structures that can form, change and reform
· They are made from 2 thin sheets of phospholipid bilayer sandwiched together and contain many types of embedded molecules throughout its structure
· Phospholipid bilayers:
· Most important aspect of this layer is the structure of the individual phospholipid
· Made of;
Cell Function
Inquiry Question: How do cells coordinate activities within their internal environment and their external environment?
· Investigate the way in which materials can move into and out of cells, including but not limited to;
· Conducting a practical investigation modelling diffusion and osmosis
Diffusion:
· Passive movement of ANY particles in a solution from areas of high to a low concentration until equilibrium is reached
· Passive as molecules are moving along the concentration gradient
· Example; food dye in water
· Factors affecting the rate of diffusion:
· Concentration → greater difference in concentration = faster diffusion
· Temperature → higher temp = faster diffusion occurs
· Particle size → smaller particles = faster rate
Facilitated diffusion:
· Some larger particles do not readily pass through the phospholipid bilayer
· They require protein channels and carrier proteins to assist them
Osmosis:
· Occurs when the concentration gradient involves dissolved molecules or ions which CANNOT get through the membrane
· Refers to the net movement of water molecules across the semipermeable membrane
Practical: Diffusion and Osmosis
Aim → to observe and describe an example of diffusion and osmosis using a selectively permeable membrane
OBSERVATIONS
· Clear starch in tubing turned into a muggy, purple colour
· Colour suggests that yellow iodine from the water moved through the tubing and reacted with the starch
· The initial appearance of the tubing was clear, therefore meaning there was no obvious change
· Once the water mixed with solution and was heating, it turned a solid orange colour suggesting the glucose had moved from the tubing to the outside
Part A: Diffusion
Using 20ml of starch solution, pour into dialysis tubing and note weight and colour, place this tubing in a 200ml beaker of water and enough iodine that the water turns yellow. Leave for 20 minutes.
Part B: Osmosis
Using 20ml of 10% glucose solution, pour into dialysis tubing and note weight and colour, place the tubing into water and leave for 20 minutes. Collect 5ml of the water from the beaker and place into a test tube with 2ml of Benedict’s reagent added. Heat and note colour changes. (NOTE: Benedict's turns from Blue to Orange in the presence of glucose)
· Examining the roles of active transport, endocytosis and exocytosis
Passive and active transport:
· Diffusion and osmosis happen automatically and not with the cell having to use any energy → this is a passive transport process
· Many other proteins, carbohydrates and other molecules regularly move in and out of cells
· Cells have to deliberately move substances across the membrane using ways other than diffusion and osmosis
· These ways require the cell to use the energy (ATP from cellular respiration) to move substances → this is an active transport process
· Active transport process: Sodium-Potassium Pump
Endocytosis:
· Membrane pinching outwards to surround the desired substance and envelop it
· Membrane rejoins itself to seal the cell, leaving the targeted substance inside
· Phagocytosis: (phago = eating, cyto = cell)
· Cell engulf a solid material to form a food vacuole
· Pinocytosis: (pino = drink)
· Receptor-mediated endocytosis:
Exocytosis
· Specialised cells need to remove wastes to distribute them to other parts of the organism
· Exocytosis is the process by which cells are transported to the external environment of the cell
· Membrane-bound vesicle moves to the cell membrane, fuses with it and then releases its contents to the exterior of the cell
· Relating to the exchange of materials across membranes to the surface-area-to-volume ratio, concentration gradients and characteristics of the materials being exchanged
SA: V ratio:
· The surface-area-to-volume ratio gets smaller as the cell gets larger
· If the cell grows past a certain point, not enough material will be able to cross the membrane fast enough
· The amount of food, oxygen and other substances a cell needs depends on its volume
SA divided by the V
SA → Total area of the cell membrane
V → space taken up by the total contents of the cell
Concentration gradients:
· The relative concentration of the substance on either side of the membrane affects the rate of diffusion of that substance
· If the concentration gradient is high, then the substance will diffuse rapidly
· In order to maintain a rapid rate of diffusion, cells need to maintain a high concentration gradient
· As the concentration gradient decreases, the rate of diffusion will be slower
· Once the concentration reaches equilibrium, there will be no net movement across the cell membrane
· Investigate cell requirements, including but not limited to:
Cell requirements:
· Exchange gases
· Obtain energy
· Remove waste
· Have suitable forms of energy, including light and chemical energy in complex molecules
· Suitable forms of energy, including light energy and chemical energy in complex molecules
Energy (ATP):
· All cells use glucose as the main source of energy
· When glucose is broken down, it’s energy is released
· It is trapped and stored in high energy molecules called adenosine triphosphate
· Matter, including gases, simple nutrients and ions
Inorganic compounds:
· Compounds without carbon atoms or simple molecules with only 1 or 2 carbon atoms
· Water: makes up 70-90% of most organisms
· Oxygen: required for cellular respiration
· Carbon Dioxide: required for photosynthesis
· Nitrogen: key atom for 20 types of amino acids → proteins
· Minerals: important for building enzymes and vitamins
Organic Compounds:
· Complex chemicals: containing carbon and hydrogen atoms which are found in living things:
· Carbohydrates: important energy source
· Proteins: composed of amino acids
· Nucleic Acid: composed of nucleotides
· Carry genetic information
· Removal of wastes
· These MUST be removed
· Excretion is the removal of any waste from an organism
· Accumulation of these waste products can prevent the normal functioning of cells
· the cell membrane regulates the exit of waste products depending on size and concentration
Waste removal from autotrophs:
· Plants produce no true waste
· Aquatic plants release waste into the water
Waste removal from heterotrophs:
Photosynthesis:
· The process by which plants utilise energy, typically from the sun, which is trapped by chlorophyll
· It uses this energy to break apart water and carbon dioxide molecules, build them up to oxygen, energy-storing glucose molecules and water molecules
Cellular Respiration:
· All organisms break down glucose as a form of energy
· Glucose can be broken down either in the;
· Presence of oxygen (aerobic cellular respiration)
· Absence of oxygen (anaerobic cellular respiration)
· Conduct a practical investigation to model the action of enzymes in cells
Enzyme notes:
· All organisms are adapted to a characteristic temperature range
· This temp range allows the organism’s enzymes to control its metabolism by operating at their optimum efficiency within this range
· High temperatures → (80-100°C) → Thermophiles
· Extremely low temperatures → (0-4°C) → Psychrophiles
· Most mammals → (30-45°C)
· Most average around 37°C
Enzymes are biological catalysts. This means they lower the energy required to start a chemical reaction within a cell but do not get used up by the reaction.
Factors affecting enzymes:
· Lock-and-Key Model
· On the surface of the enzyme molecule is the “active site”
· According to the Lock-and-Key Model, the shape of an enzyme’s active site is a perfect fit for the substrate
· Induced Fit Model
· A modified version of the Lock-and-Key Model
· According to the Induced Fit Model, the active site is somewhat flexible and can change its shape in order to bond with the substrate
Practicals on Enzyme Activity:
2. Substrate concentration: Hydrogen peroxide concentration
3. pH
· Investigate the effects of the environment on enzyme activity through the collection of primary or secondary data
· Body temperature and pH are critical to survival because the vital enzymes can only perform efficiently in a narrow range of temperature and/or pH
BIOLOGY PRELIMINARY NOTES
Outcomes
· Solves scientific problems using primary and secondary data, critical thinking skills and scientific processes
· Communicates scientific understanding using suitable language and terminology for a specific audience or purpose
· Explains the structure and function of multicellular organisms and describes how the coordinated activities of the cells, tissues and organs contribute to macroscopic processes in organisms
Content Focus
Multicellular organisms typically consist of a number of interdependent transport systems that range in complexity and allow the organism to exchange nutrients, gases and wastes between the internal and external environments. Students examine the relationship between these transport systems and compare nutrient and gas requirements.
Models of transport systems and structures have been developed over time, based on evidence gathered from a variety of disciplines. The interrelatedness of these transport systems is crucial in maintaining health and in solving problems related to sustainability in agriculture and ecology.
Content
Inquiry Question: How are cells arranged in a multicellular organism?
· Compare the differences between unicellular, colonial and multicellular organisms by:
· Investigating structures at the level of the cell and organelle
Prac investigation: Comparing different types of cells
· Unicellular, colonial and multicellular organisms differ in their cell size, cell functions and cell specialisation
Page 9 of Module 2 Notes
Name of Specimen
Type of Cell
Eukaryotes
Eukaryotes
One cell carries out all the functions to sustain life
Individual animals,
Cells are specialised to perform specific functions by the organism
Cellular function
· Obtaining nutrients
· Exchanging gases
· Removing wastes
Functions are carried out with the cell
Functions are carried out by individuals with specific roles in the colony
Functions are carried out at cellular, tissue, organ and system level
Microscopic & Macroscopic
Usually macroscopic
Macroscopic
Increasing the number of cells allows for an increase in body size
Life Span
Short lifespan:
Long lifespan
Long lifespan
Usually, specific zooids are responsible for reproduction
Only cells specialised for reproduction (gametes) will reproduce
· Relating the structure of cells and cell specialisation to function
Structural organisation of multicellular organisms:
Organelles
· Membrane-bound compartment or structure in a cell that performs a special function
· Example: Mitochondria, vacuole
· Example: Root hair cell, lead guard cell
Tissues
· A group of similar cells working together to carry out a specific function in multicellular organisms
· Example: Muscle tissue, root tissue
Organs
· Two or more tissues that work together to perform one or more specialised tasks
· Example: Heart, liver, kidneys, flowers, leaves
Systems
· A group of organs that work together to perform a vital task
Cell specialisation and differentiation:
· Specialisation: a specialised function for a cell
· Differentiation: the process where a cell changes from one type to another, typically an unspecialised cell becoming specialised
Structure relating to function:
· Thin outer membrane allows oxygen to diffuse easily
· Shape increases SA: V which allows oxygen to be absorbed more efficiently
· No nucleus leaving room for haemoglobin
· Shape allows it to squeeze through vesicles and thin capillaries
Epidermal cell
· Has 2 layers to keep external and internal environments separate
Xylem cell
· Transports water and nutrients from the soil to stems and leaves
· Provides mechanical support and storage
· Internal hydrophobic surface facilitating water transport
· Tracheids are hollow and connect to each other to improve transport efficiency
· Think lignin coated cell walls provide shape and structure
Phloem cell
· Next to xylem for osmosis of water
· Has a source and sink as transport for substance
Guard cell
· Multiple chloroplasts for photosynthesis
· One thicker wall for stability and a thinner wall for differentiation
· Close stomata when they lose potassium ions
Palisade mesophyll cells
· The main function is light absorption
· Multiple chloroplasts for photosynthesis
Root hair cell
· Extremely narrow tubes
· Have thin hairs which protrude outwards, allowing an increase in SA: V for osmosis
· Long and thin to penetrate between soil particles and prevent harmful organisms from entering the plant
Cohesion: water molecules stick together because they are attracted to each other due to their charges
Adhesion: water molecules stick to surfaces
Capillarity: water molecules move up thin tubes (xylem)
· Investigate the structure and function of tissues, organs and systems and relate those functions to cell differentiation and specialisation
Circulatory system
· Equalises body temperature
· Delivers oxygen to the blood
Excretory system
· Performs the breakdown and discharge of wastes in the body
Digestive system
· Removes waste from undigested food
· Justify the hierarchical structural organisation of organelles, cells, tissues, organs, systems and organisms
For multicellular organisms to function effectively and live successfully in order to reproduce, there needs to be a high level of organisation in the arrangement of their specialised cells.
Atoms → Molecules → Organelles → Cells → Tissues → Organ Systems → Organisms
Level of Organisation
Atomic level
Atoms are the smallest unit of an element that still maintains the property of that element
Carbon, Hydrogen, Oxygen
Molecular level
Atoms form to combine into molecules which can have entirely different properties than the atoms they contain
Water, DNA, Carbohydrates
Cells are the smallest unit of life.
Cells are enclosed by membrane or cell wall and often perform specific functions
Muscle cell, Skin cell, Neutron
Tissue level
Muscle, Connective
Organ level
Organs are 2 types of tissue that work together to complete a task
Heart, Liver, Stomach
Organ system level
Group of organs that carry out a more generalised set of functions
Digestive system, Circulatory system
Human
· Allows the intake and expel of oxygen and carbon dioxide
Muscular System
· Speech
· Eating
· Removes waste from undigested food
Urinary System
· Removes waste from the blood and excretes them
Endocrine System
· Pituitary gland
· Thyroid gland
· Equalises body temp
Male Reproductive System
Female Reproductive System
· Supports embryo and gametes until birth
· Produces milk for infant
Nutrient and Gas Requirements
Inquiry Question: What is the difference in nutrient and gas requirements between autotrophs and heterotrophs?
Distinguishment between autotrophs and heterotrophs:
Autotrophs can produce their own organic compounds from inorganic compounds surrounding them whereas heterotrophs must consume other organisms for organic substances for energy.
Autotroph: Can produce its own food using photosynthesis
→ Producers
Heterotroph: Cannot make its own food, therefore derives its food nutrition from other sources
→ Consumers
· Investigate the structure of autotrophs through the examination of a variety of materials, for example:
· Dissected plant materials
· Using a range of imaging technologies to determine plant structure
· Investigate the function of structures in a plant, including but not limited to:
· Tracing the development and movement of products of photosynthesis
Photosynthesis is the process by which energy from light converts water and carbon dioxide molecules into glucose and oxygen. The oxygen is released from the leaves while the energy contained by the glucose molecules is used for the plant's growth.
· Investigate the gas exchange structures in animals and plants through the collection of primary and secondary data and information, for example:
· Microscopic structures: alveoli in mammals and leaf structure in plants
Plants:
· Forms a divide between the plant and external environment
Stomata:
· The leaf epidermis is covered with tiny pores, called stomata
· Each stomata has a guard cell on each side
· The stomata allow gases to move into and out of the leaf
· Water vapour escapes through the stomata into the surrounding air
· Stomata and water loss:
· The plant has to balance the need for carbon dioxide (open stomata)
· Against the need to reduce water loss (closed stomata)
· How stomata open and close:
· Guard cells control the diameter of the pore by changing shape
· When guard cells take up water (via osmosis) they swell and become tight
· This makes the pore wider
· Gain → wider
· When the guard cells lose water they shrink and become flaccid
· Pores become smaller
· Lose → smaller
Stomata are open in the light and close in the dark
Mammals:
· Gaseous exchange occurs in all animals and involves the movement of gases between the internal and external environments by diffusion across cell membranes
· Oxygen is essential for all cells to carry out cellular respiration to release energy from the nutrients they have consumed
· The respiratory system enables the exchange of gases between an organism and it's environment
· Macroscopic structures: respiratory systems in a range of animals
Fish:
· Need to obtain oxygen in order to remove carbon dioxide
· Water flowing over them ensures maximum oxygen uptake
· As the water is only flowing in one direction the water can enter and flow over the gills and then leave via the gill slit
Insects:
· Spiracles → breathing pores
· Tracheal tubes
· Interpret a range of secondary-sourced information to evaluate processes, Claims and conclusions that have led scientists to develop hypotheses, theories and models about the structure and function of plants, including but not limited to:
· Photosynthesis
· An incorrect conclusion that water makes plants grow, not water
· John Priestly
· Jan Ingenhousz
· Jean Senebier
· Transpiration-cohesion-tension theory
· Creates negative pressure: tension
· Tension extends from leaves to roots
· Transpiration’s effect on water = straw
· Trace the digestion of foods in a mammalian digestive system, including:
· Physical digestion
· Begins in the mouth when teeth break food by cutting or tearing food
· Chemical digestion
· Process of using digestive enzymes to chemically break down the larger, complex molecules in food
· Absorption of nutrients, minerals and water
· Mainly occurs in the jejunum section of the small intestine
· Products diffuse or use active transport through villi, which lines the intestinal wall
· Glucose and amino acids are absorbed into the capillaries
· Elimination of solid waste
· Faeces are formed and stored in the rectum before being passed out of the body through the anus.
· Compare the nutrient and gas requirements of autotrophs and heterotrophs
Nutrient/ Gas Requirement
Diffuses through the respiratory surface
Carbon dioxide gas
Glucose
Produced by photosynthesis
Ingested into the digestive system as either simple or complex carbohydrates, and absorbed into the bloodstream
Lipids/ proteins
Produced by the plant from glucose and mineral ions
Ingested into the digestive system and absorbed into the bloodstream as amino acids, fatty acids or glycerol
Mineral ions
Move into the plant through the roots by diffusion and active transport
Ingested into the digestive system and absorbed into the bloodstream
Transport
Inquiry Question: How does the composition of the transport medium change as it moves around an organism?
· Investigate transport systems in animals and plants by comparing structures and components using physical and digital models, including but not limited to:
· Macroscopic structures in plants and animals
· Microscopic samples of blood, the cardiovascular system and plants vascular system
Xylem:
· It is made of specialised xylem tissue
· Water enters the root system via osmosis
Phloem:
· Phloem is the vessel that transports products of photosynthesis via active transport
· Phloem consists of two types of living cells;
Companion cells
· Smaller cells found along the side of the sieve tube cells
· Contain nucleus, mitochondria, vacuoles and other cell organelles
· Control the activities of sieve tube cells
Sieve tube cells
· Long and thin with large pores through the cell wall at either end
· No nuclei, mitochondria or vacuole
· Arranged end to end in sieve tubes
· Investigate the exchange of gases between the internal and external environments of plants and animals
· Compare the structure and function of Transport systems in animals and plants, including but not limited to:
· Vascular systems in plants and animals
· Opened and closed transport systems in animals
Comparing the roles of respiratory, circulatory and excretory systems:
Similarities
· Controlled systems (all act to maintain homeostasis)
· Homeostasis → the ability to maintain internal stability in organisms
· This includes; the control of body temperature, carbon dioxide, oxygen hormones and blood pressure
· All regulate against external changes
· Water/ salt concentrations
· Involves pump
· Sweat
MODULE 3: BIOLOGICAL DIVERSITY
· Develops and evaluates questions and hypotheses for scientific investigation
· designs and evaluates investigations in order to obtain primary and secondary data and information
· Communicates scientific understanding using suitable language and terminology for a specific audience or purpose
· Describes biological diversity by explaining the relationships between a range of organisms in terms of specialisation for selected habitats and evolution of species
Content Focus
Biodiversity is important to balance the earth's ecosystems. biodiversity can be effected slowly or quickly over time by natural selective pressures. human impact can also affect biodiversity over a shorter time period. in this module, students learn about the theory of evolution by natural selection and the effect of various selective pressures.
Monitoring biodiversity is key to being able to predict future change. Monitoring, including the monitoring abiotic factors in the environment, enables ecologists to design strategies to reduce the effects of adverse biological change. Students investigate the adaptations of organisms that increase the organisms ability to survive in their environment.
Content
Effects of the Environment on Organisms
Inquiry Question: How do environmental pressures promote a change in species diversity and abundance?
· Predict the effects of selection pressures on organisms in ecosystems, including:
Selection pressures:
Biotic and abiotic factors in an organism’s environment can affect behaviour, survival and reproduction
· Population changes:
· Emigration: organisms moving out of a population
Abundance: the number of individuals per unit area. Can be measured through quadrats
Distribution: the spread of a population over space
· Biotic factors
Non-living components of an environment such as; temperature, light and chemical components
· Abiotic factors
Living components of an environment such as; bacteria, fungi, plants and animals
· Dynamic → tide, water, wind
· Chemical → salinity, nutrients, pH
In ecosystems, organisms interact and depend on one another for survival. Individual: a single organism such as one animal, plant, fungus or unicellular organism
Species: a group of organisms that can reproduce and produce fertile offspring Population: a group of individuals of the same species that live together
Community: an ecological group of different species living together and interacting with each other Biomes: a group of communities that have similar structures and habitats extending over a large area system formed by communities of organisms interacting with one another and their surroundings Biosphere: largest and most complex ecosystem, a sum of all ecosystems on Earth
· Investigate changes in a population of organisms due to selection pressures over time, for example:
· Cane toads in Australia
· Quickly spread;
· No known predators
· Prickly pear distribution in Australia
· Introduced from Spain for the dye industry
· Whenever its branches come into contact with soil it grows
· Allowed the plant to grow rapidly
· Introduction of a moth to reduce numbers
Adaptations
Inquiry Question: How do adaptations increase the organism’s ability to survive?
· Conduct practical investigations, individually or in teams, or use secondary sources to examine the adaptations of organisms that increase their ability to survive in their environment, including:
Adaptations: characteristic that an organism inherits that makes them more suited to their environment. This occurs as a result of selection pressures or environmental factors to increase the chances of survival and reproduction
· Structural adaptations
Modifications of specific structures that give an organism an advantage in a particular environment
· SA: V
Affect functioning at different levels. Can affect biochemical reactions in organelles or physiological functions at a whole organism level
· Camoflague
· Evaporative cooling
· Behavioural adaptations
Actions that only an organism takes to improve survival or reproduction
· Burrowing
· Migration
· Investigate, through secondary sources, the observations and collection of data that were obtained by Charles Darwin to support the theory of evolution by natural selection, for example:
Natural selection:
The process by which organisms that are best suited to their environment reproduce, passing on their favourable traits, characteristics include;
· Organisms produce more offspring that can survive
· Variation occurs amongst species
· Some variations help individuals survive
· Over time, favourable traits cause a population to change
· Finches of the Galapagos Islands
· Darwin observed small ground finches on the Galapagos Islands and collected the specimens that were living on each of the islands
· Notes that the finches had naturally occurring variation in, for example; beak size, colour and leg length
· The descendants of these birds gradually populated other islands, each of which had different environmental conditions
· The finches which were not adapted to the environmental conditions died out
· Australian flora and fauna
Darwin’s Observations
How Darwin's observation related to his theory of evolution by natural selection
Magpies and crows are similar to the jackdaws in England, but obviously belonging to different species
The potoroo (rat-kangaroo) is similar to the rabbit in England
The potoroo is a miniature kangaroo the size of a European rabbit, behaving somewhat like a rabbit, darting about in the undergrowth
The platypus is similar to water rats
Darwin's observations of birds, marsupials and monotreme mammals in Australia revealed the similarities with European mammals that lived in similar environments.
This led to the idea that organisms could evolve to become similar
· (convergent evolution)
If organisms live in similar habitats, similar variations that they process would be favoured by natural selection to enable them to survive and breed in those conditions.
· These favourable variations would then be passed onto the next generation
Vegetation: Darwin describes eucalyptus, “ the nearly level country is covered with thin scrubby trees, bespeaking the curse of sterility”.
In Darwin's observations of plant life in Sydney, he made the link between the harsh environment and the adaptations observed in the vegetation. he also mentions that many of the trees in Australia and other Southern continents are Evergreen as opposed to those in the Northern Hemisphere
Theory of evolution by natural selection
Inquiry Question: What is the relationship between Evolution and biodiversity?
· Explain biological diversity in terms of the theory of evolution by natural selection by examining the changes in and biodiversification of life since it first appeared on the Earth
Biological diversity and the Theory of Evolution by Natural Selection:
· Biological diversity refers to the variety of all forms of life on earth
· Diversity within a population is what allows it to adapt to changes within the environment
Biodiversity type
Genetic Diversity
Total number of genetic characteristics in the genetic make-up of a species
Species Diversity
Measure of the diversity of different species in an ecological community
Ecological Diversity
Population change and allele frequencies:
Cause of population change
description of the Factor
Exchange of alleles between populations
When migrating animals or dispersed seeds reproduce in a new location
Blue-eyed people from Sweden migrate to a small town in Mexico
Genetic drift
Can change the distribution and proportion of alleles
American bison
Founder effect
When a population of individuals are isolated and for new population
Amish people in Pennsylvania have high incidences of polydactyly
Genetic bottleneck
When a large population is dramatically reduced in size thereby reducing its genetic variation
Hunting and poaching of many of the African elephants
· Analyse how an accumulation of microevolutionary changes can drive evolutionary changes and speciation over time, for example:
Microevolution:
Macroevolution:
· The evolution of groups larger than species
· What is observed when looking at the history of life on Earth
· Evolution of the horse
· Over 50 million years ago the horse evolved from a dog-sized, forest-dwelling animal
· Fossils show changes in body size, number of teeth and foot shape
· The first horses were 25-50m tall with a long tail, short legs, snout and back
· Ate fruits and soft plants
· Evolved due to drier climate, shrinking forests and growth of more grass
· Evolution of the platypus
· Has many genes in common with both reptiles and birds
· Explain, using examples, how Darwin and Wallace's theory of evolution by natural selection accounts for:
· Convergent evolution
Evolution through natural selection of similar features in unrelated organisms
· Example; dolphins and sharks
· Divergent evolution
Separated populations diverge, whether that be by random factors such as genetic drift or natural selection
· Explain how punctuated equilibrium is different from the gradual process of natural selection
· Punctuated equilibrium → evolution occurs in spurts of rapid change with long periods of no change
· Gradual process → slow, gradual change, occurring in small periodic changes in the gene pool
Evolution - the Evidence
Inquiry Question: What is the evidence that supports the theory of evolution by natural selection?
· Investigate, using secondary sources, evidence in support of Darwin and Wallace's Theory of Evolution by natural selection, including but not limited to:
· Biochemical evidence, comparative anatomy, comparative embryology and biogeography
Evidence type
Humans and chimps
Palaeontology
· Palaeontology is the study of fossils
· Provides direct evidence
Fossil evidence:
Relative dating:
· Relies on the assumption that that fossils found higher up in rock strata are younger than the lower fossils
Absolute dating/radiometric dating:
· The actual age of the specimen is determined by using the radioactive elements which are presented in the specimen
· Explain modern-day examples that demonstrate evolutionary change, for example:
· The cane toad
· Antibiotic-resistant strains of bacteria
· Some strands of bacteria randomly become resistant to modern antibiotics
· These strands then reproduce and become more resistant