answering unit 1 - biology ( ed excel )

8/16/2019 Answering Unit 1 - Biology ( Ed excel )

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VIHS / Grade 11 / Answering Unit 1 - compiled by J. Sharmila Christy of 42

VIHS / AS ANSWERING UNIT 1

NOTE:

o Use this compilation only as a guide to revise for your Exam.

o Topics that have been repeatedly asked are cited here

o The best answers that had scored maximum marks are illustrated here.

I.Explain the meaning of the term

a. recessive genetic disorder.

Recessive genetic disorders (RGD) result from inheriting two defective recessive alleles of a gene, one from

each parent

b. causal relationship : Causation is when a change in one variable is responsible for a change in another

variable

c. Biological Catalyst : are molecules that speed up reactions by lowering the activation energy , without

getting involved in it

d. Hydrolysis : A chemical reaction which splits a polysaccharide or disaccharide into specific

disaccharides or monosaccharide by addition of water

e. Gene : is a part of a DNA that codes for a specific protein.

f. Allele : is an alternate form of gene found at a specific locus on a chromosome

g. Gene mutation : A gene mutation is a permanent alteration in the DNA sequence that makes up a

gene,

h. Activation energy : The activation energy is the energy required to start a reaction

i. cardiovascular disease : Cardiovascular disease generally refers to conditions that involve narrowed

or blocked blood vessels that can lead to a heart attack, chest pain (angina) or stroke.Other heart conditions, such as those that affect your heart's muscle, valves or rhythm, also areconsidered forms of heart disease.

1 Molecular structures & properties of water, carbohydrates, lipids, proteins & nucleic acids

2 Circulatory system – heart, blood vessels, CVD, Risks of CVD, Benefits and Risks of treatment

3 Analyze & Interpret Data on CVD, LDL, HDL / Graph Analysis

4 Gaseous Exchange – adaptations of lungs /

Transport across membranes – Diffusion, osmosis & active transport)5 Cell Membrane – Structure & Properties / Enzyme – Structure, Function & Properties

6 DNA – Structure & Replication / Protein synthesis – full process in detail

7 Genetics, Mutation & Cystic Fibrosis

8 Practical Question (on any one of the core practical’s)

http://science.jrank.org/pages/2975/Genetic-Disorders-Recessive-genetic-disorders.html

http://science.jrank.org/pages/2975/Genetic-Disorders-Recessive-genetic-disorders.html




j. fluid mosaic model of cell membrane : Fluid means that the molecules can change places within the

membrane. Mosaic means that proteins are randomly embedded into the phospholipid bilayer.

k. osmosis : Osmosis is the spontaneous net movement of solvent molecules through a semi-permeable

membrane into a region of higher solute concentration, in the direction that tends to equalize the soluteconcentrations on the two sides

l. genotype :

m. Mutation :




n. Genetic code :

II. Differentiate between

a. Monosaccharides and disaccharidesMonosaccharide are single-unit sugars (the smallest) and are the building blocks of the other two whereasDisaccharide consist of two monosaccharide linked together

Monosaccharides do not have glycosidic bonds whereas Disaccharides are joined in condensation reaction byglycosidic bonds

b. Diffusion and active transport

Differences: Passive transport doesn't require energy (ATP), active transport does require energy. Passive

transport moves molecules WITH the concentration gradient (high to low), while active transport moves

molecules AGAINST the concentration gradient (Low to High).

Similarities:They both allow the cell to maintain homeostasis by maintaining an equilibrium of subtances in

and out of the cell.They both involve moving material across or through the plasma membrane.




c. DNA and RNA

The key differences between DNA are RNA are as follows:

DNA:-deoxyribose sugar, -codes genetic information, -contains base thymine (TCAG),-double stranded-found in nuc leus, -B-form

RNA:-ribonucleic sugar,,-codes for proteins,-contains base uracil and not thymine (UCAG)-single stranded,,-found in nucleus, cytoplasm, and ribosome

-A-form

Similarities

Both DNA and RNA are both composed of nucleotide monomers and share three common nitrogenous bases,

includ ing adenine, cytosine, and guanine. Both contain pentose sugars and have phosphate groups in the

nucleotides. The cell needs DNA and RNA to produce proteins

o. Correlation and causation : Causation is when a change in one variable is responsible for a change in

another variable whereas Correlation is when a change in one variable reflects a change in another

variable

d. tRNA and mRNA

e. saturated and unsaturated fatty acids :

Saturated fats (meats, butter, dairy products) are solid at room temperature, whereas unsaturatedfats (vegetable oils) are liquid at room temperature

Saturated fats have no double bond between molecules, which means there are no gaps andthe fat is saturated with hydrogen molecules, whereas Unsaturated fatty acids have either one or morethan one Carbon carbon double bonds (like in MUFA or PUFA )

Saturated Fatty acids are not branched but unsaturated are branched




f. transcription and translation

Transcription is the process of making an RNA copy of a gene sequence. This copy, called a messenger RNA (mRNA)molecule, leaves the cell nucleus and enters the cytoplasm, where it directs the synthesis of the protein, which itencodes. Whereas Translation is the process of translating the sequence of a messenger RNA (mRNA) molecule to asequence of amino acids during protein synthesis.




g. MUFA and PUFAMonounsaturated fatty acids (MUFAs) are fatty acids that are missing one hydrogen pair on their chain. They areassociated with lowering LDL cholesterol and total cholesterol while at the same time increasing the production ofthe 'good' cholesterol, HDL cholesterol. You find monounsaturated fats in vegetable oils like canola, peanut andolive oil, as well as in nuts. These fats are usually liquid at room temperature.

Polyunsaturated fatty acids (PUFAs) are missing two or more hydrogen pairs on their fatty acid chains. Theytrigger lower blood/serum cholesterol as well as lower LDL and HDL production. You can find these fats in vegetable

oils like corn, sesame, sunflower, safflower and soybean, as well as in fatty fish. These fats are usually liquid atroom temperature.

h. Capillary and vein

Capillaries carry blood away from the body and exchange nutrients, waste, and oxygen wi th tissues atthe cellular level. Veins are blood vessels that bring blood back to the heart and drain blood fromorgans and limbs.

i. LDL and HDL

LDL cholesterol is usually referred to as “ bad” cholesterol because it deposits i ts cholesterol on thewalls of arteries. LDL is also the type of cholesterol that becomes oxidized and damages the lining of

your arteries, setting the stage for mineral and fat deposits.

HDL hangs on tightly to the cholesterol it carries and won’t let it get loose to attach to arterial walls. Insome cases, it may even snatch up additional cholesterol already stuck to a wall, reducing the size of aplaque or buildup. HDL keeps cholesterol in solu tion and moves it safely throughout the body. Forthese reasons, HDL cholesterol is considered to be “good” cholesterol.




j. Amylose and amylopectin

k. CVD and CHD

Coronary heart disease is a type of cardiovascular disease. The four most common types ofcardiovascular disease are coronary heart disease (which includes heart attack and angina pectorisor chest pain), stroke, high blood pressure and heart failure.

Other forms include rheumatic fever/rheumatic heart disease, congenital cardiovascular defects,arrhythmias (disorders of heart rhythm); diseases of the arteries, arterioles and capillaries (includingrhythm); diseases of the arteries, arterioles and capillaries (including atherosclerosis and Kawasakidisease); bacterial endocarditis; cardiomyopathy; valvular heart disease; diseases of pulmonarycirculation; diseases of veins and lymphatics and other diseases of the circulatory system.

A cardiovascular disease is a disease effecting the cardiovascular system, the heart and bloodvessels. A heart disease is a kind of cardiovascular disease which is specific to the heart.

Cardiovascular disease is an illness that affects the heart and blood vessels.

It include coronary heart disease (coronary artery disease, ischemic heart disease); stroke (brainattack); high blood pressure (hypertension); and rheumatic heart disease.

l. Fibrous and globular protein




m. Primary and secondary structure of protein

1.Water – structure and property1. Explain why water is an effective molecule for transporting other molecules around living organisms. (3)

(Jan 2014)

1.idea that water is a solvent ;2. idea that water is {slightly charged / dipole /polar / eq} ;3. idea that {polar molecules / ions / eq} can dissolve in water ;4. idea that water is {viscous / fluid / eq} ;

5. idea of water as a liquid assists mass flow6. correct reference to cohesion / adhesion ;

2.Carbohydrates – structure and function

(1) Describe how two monosaccharides join to form a carbohydrate. (3)

Disaccharides are formed when two monosaccharides join together by the dehydration synthesis reactionresulting in a glycosidic bond between the two monosaccharide molecules. The reaction produces water as aside product.

2.Enzymes act as biological catalysts. Amylase is an enzyme present in saliva that catalyzes the hydrolysis of

starch into maltose.

(i)* Describe the structure of starch. (5) Jan 2013

(ii) Describe the structure of starch and explain why this structure makes it a suitable molecule for storing

energy. (4)

•

Starch is a Polysaccharide made up of many α glucose residues linked by glycosidic bonds. Its madeup of amylose and amylopectin

Amylose : Amylose is composed of α glucose residues linked by 1,4-glycosidic bonds formed by

condensation reactions , The unbranched chain is then coiled into an amylose helix due to formation

of H bonds between the glucose residues, Six glucose residues per turn of the helix




Amylopectin : Also made up of α glucose residues. However the glucose residues form a branched

chain, Branches formed due to 1,6-glycosidic bonds, 1,4-glycosidic bonds are found in unbranched

part , Branches form after every 20 to 30 glucose residues

• Function: energy storage molecule in plant cells

Compact – so it takes up less space in the cell

Insoluble – so cannot leave the cell easily & it does not have an osmotic effect

Insoluble and unreactive – so it does not get involved in chemical reactions of the cell

Amylose and amylopectin can be easily be hydrolysed by enzymes into maltose

3. Fats and carbohydrates such as glycogen are important energy storage molecules. These are broken down

during exercise.

(i)Describe the structure of glycogen and explain why it is a suitable molecule for storing energy. (4) Jan 2012

• Made up of α glucose residues. However the glucose residues form a branched chain

• Branches formed due to 1,6-glycosidic bonds, 1,4-glycosidic bonds are found in unbranched part

• Branches form after every 8 to 10 glucose residues

• Glycogen is compact so it takes up less space in the cell

• It is insoluble so it cannot leave the cell easily and does not have an osmotic effect.

• It is relatively unreactive so it does not get involved in chemical reactions in cell• Easily hydrolysed by enzymes into glucose and used for respiration in cells

(ii)Describe the structure of glycogen. (3) Jan 2015

3.Circulatory System – (Heart / Blood vessels) structure & function

4. Many animals, such as mammals, have a heart and circulation. This helps them to meet their requirements

by overcoming the limitations of diffusion.*(i) Describe the structure of the mammalian heart. (5) Jan 2012




5.Giraffes are very tall mammals found roaming the plains of Africa.

Two giraffes are shown in the photograph below.

(i)Using the information in the photograph and your own knowledge, explain

the importance of the heart and circulation to the giraffe. (4) Jun 2012




Many animals have a heart and circulatory system.

(ii) Explain why animals need a heart and circulatory system. (4) Jan 2016




(iii) Explain why multi-cellular animals require a respiratory system and a circulatory system. (4) Jun 2014




6. Describe and explain the events that occur during ventricular systole in the cardiac cycle (4) (sample paper)

Ventricles contract from base upwards increasing the pressure, pushing the blood up and out

through semilunar valves into the aorta on the left side and the pulmonary artery on the right

side.

The pressure of blood against the atrioventricular valves closes them and prevents and prevents

back-flow into the atria.




7.* Describe the role of the heart valves in the cardiac cycle. (6) Jan 2015

The valves of the heart are located within the chambers of the heart and are critical to the proper flowof blood through the heart. All of the valves, when functioning normally, act as one-way valves,allowing blood to flow either from one chamber to another, or allowing blood to flow out of the heart,in only one direction.The valves control the flow of blood through the heart by opening and closing during the contractionsof the heart.The opening and closing functions of the valves are controlled by pressure differences generatedwithin the heart, as well as some muscles located within the heart.

1. atria contract / reference to atrial systole ;2. atrioventricular valves open so blood flows from atria to ventricles ;3. ventricles contract / reference to ventricular systole ;4. atrioventricular valve closes to prevent backflow of blood into atria ;5. semilunar valves open so blood {leaves ventricles / enters named artery} ;6. ventricles relax / reference to ventricular diastole ;

7. semi lunar valves close ;8. to prevent backflow of blood {from the aorta or pulmonary arteries / to the ventricle} ;




8.(i)Explain how the structure of the aorta relates to its function. (3) Jan 2013

1.idea that wall of the aorta is {thick / contains collagen} 2. to withstand pressure ;

3. wall of the aorta contains {elastic fibres / elastic tissue / elastin} ;

4. allowing (the wall of) the aorta to stretch and recoil ;

5. (recoil) helps to maintain {high pressure / rapid flow / eq} ;

6. (semilunar) valve present (at the start of aorta) ;

7. that prevents back flow of blood (during diastole) ;

1. Idea that there is a {thick wall / lots of collagen / thick layers / thick tunica media / eq} ;2. Idea that it needs {to avoid rupture / to withstand high pressure / eq} ;3. {elastic / muscular / eq} {layer / fibres / wall/ eq} ;

4. Control the flow of blood / maintain blood pressure / elastic recoil / eq ;5. smooth endothelial wall / eq ;6. to reduce {friction / resistance / eq} ;7. semi lunar valve present ;8. to prevent backflow (during diastole) ;9. large lumen ;10. idea of accommodating large volumes of blood / eq ;11. branches ;12. to supply blood to different parts of the body (including coronary arteries) / eq ;

(ii) When the human heart contracts, blood from the left ventricle enters the aorta. Describe how the

structure of the aorta is related to its function. (4) Jan 2016




9.Asim has been warned by his doctor that he is at an increased risk of cardiovascular disease (CVD) because

of his current high-fat diet and low activity levels.

*(a) Explain why the combination of a high-fat diet and low activity levels may lead to CVD. (5) (Jan 2014)

1.idea of energy imbalance ; 2. idea of individual becoming {overweight / obese / eq } ;3. idea of increased blood pressure ; 4. idea of obesity leads to diabetes (a CVD riskfactor) ;5. idea of increased (blood) {cholesterol / LDL levels / LDL to HDL ratio} ;

6. idea of {damage to endothelium / overloading of receptors} ;7. formation of { atheroma / plaque / atherosclerosis } / eq ;8. idea of {loss of elasticity of artery / narrowing of lumen / eq } ;

10.Cardiovascular disease (CVD) is responsible for many deaths.

*(a) One cause of CVD is atherosclerosis. Describe how atherosclerosis develops. (4)




11.A stroke can be caused by cardiovascular disease (CVD) affecting arteries leading to the brain. Callum’s

family has a history of strokes.

(i) Explain why a blood clot in an artery leading to the brain could cause a stroke. (3) June 2013

1. idea of {reduced blood flow / bleeding} ;

2. {less/no} {oxygen /glucose} (reaches brain) ;3. idea of {less/no} (aerobic) respiration ;4. idea of {less / no} ATP produced ;

5. idea that brain needs lots of {energy / ATP} to function ;6. lactic acid produced (from anaerobic respiration);7. lactic acid {inhibits enzymes / toxic / eq };

12.There are many venomous (poisonous) snakes in the world. Many of the venoms from these snakes affect

the blood clotting process. *(a) Describe the blood clotting process. (4) Jan 2010

4.Gaseous Exchange

13(i) Describe and explain how the lungs of a mammal are adapted for rapid gas exchange. (5) (June 2013)

(ii) Living organisms exchange gases with their environment. Describe how the structure of the human

lungs is adapted for efficient gas exchange. (4) Jan 2015

(iii) The circulatory system is vital for efficient gas exchange in mammals.

Explain how the circulatory system in mammals enables efficient gas exchange. (5) (Jan 2014)

(iv) Explain why multi-cellular animals require a respiratory system and a circulatory system. (4) June 2014

(v)Use your knowledge of the structure of the lung and its adaptations for gas exchange to explain why a

person with emphysema has problems with gas exchange. (4) (Jan 2009)




*(vi) Using the information shown in the photograph and your own knowledge, suggest how gas exchange

occurs in an amoeba. (4) Jan 2012




5.PROTEIN SYNTHESIS

TRANSCRIPTION, TRANSLATION & PROTEIN SYNTHESIS14. Describe the replication of DNA. (5) (June 2014)




15*(i) Translation follows transcription. Describe how translation produces a polypeptide chain, using the code

from this template strand of DNA. (6) (June 2015)




(ii)Messenger RNA (mRNA) and transfer RNA (tRNA) are important nucleic acids involved in the process of

protein synthesis. (a) Describe how a molecule of mRNA is made during transcription. (4) Jan 2013

*(iii) Describe how RNA is involved in the synthesis of proteins. (5)

(iv)Describe how mRNA is synthesized. (4) Jun2011




6.Protein structure & Enzyme16.*(i) Enzymes are proteins. Explain how the primary structure of an enzyme determines its three-

dimensional structure and properties. (5) June 2014

(ii)Using the diagram and your own knowledge of enzymes, explain the importance of the primary structure of

an enzyme to its function. (5) Jan 2011




(iii)Describe the three-dimensional (tertiary) structure of an enzyme. (3) Jan 2012




When referring to the structure and functioning of an enzyme, always write aboutthe shape of the active site.

(iv)Lipoproteins are composed of phospholipids, cholesterol and proteins.

Proteins are made up of amino acids. Describe how amino acids join together to form the three-dimensional

structure of a protein. (4) Jan 2013

1. reference to peptide bonds (joining amino acids);

2. between amino group (of one amino acid) and carboxyl group (of another) / eq ;3. the sequence of amino acids is the primary structure of the protein / eq ;4. reference to folding (of primary structure) held together by bonds / eq ;5. {disulfide bridges / eq} / {hydrogen / H} bonds / ionic bonds / Van der Waals forces ;6. between the R groups / eq ;




7.Mutations17.(i) Galactose is broken down by an enzyme called Gal-1-PUT. In some types of galactosaemia, this enzyme

does not function properly. Explain why a mutation in the gene coding for the enzyme Gal-1-PUT could lead to

the inability to break down galactose. (4) Jan 2014 /

(ii)Explain how a change in the DNA sequence of the PAH gene might lead to a loss of enzyme activity. (3) Jan

2015

(iii)Cystic fibrosis and glycogen storage disease type (II) are examples of recessive genetic disorders.

Glycogen storage disease type (II) is caused by mutations in the GAA gene. This results in a deficiency of an

enzyme called acid alpha-glucosidase.

* Explain how a mutation in the GAA gene could result in a change in the activity of the enzyme acid alpha-

glucosidase. (5)

(iv) Suggest how a mutation in the GALC gene could result in a change in the enzyme galactocerebrosidase. (3)

Jun 2012

8.Cell Membrane Models

18.(i) The fluid mosaic model has been developed from the knowledge of the structure and properties of cell

membranes. It can explain how molecules can enter and leave a cell.

Describe the structure of a cell membrane. (You may use a labelled diagram to support your answer). (5)

(June 2013)

(ii) Explain why the phospholipid molecules form a bilayer. (3)

(iii)




Explain how the properties of the parts labelled A and B contribute to the structure of the cell surface membrane. (3)

June 2014




9.Cystic Fibrosis19.(i)Cystic fibrosis is a genetic disease that can affect many body systems, including the respiratory system.

*Explain how a gene mutation causes a buildup of mucus in the respiratory system of a person with cystic

fibrosis. (5) Jun2010

(ii) People with cystic fibrosis have a reduced rate of gaseous exchange and lower peak flow rates than people

who do not have this condition. Explain why people with cystic fibrosis have a lower peak flow rate.

(4) (June 2015)

(iii)Cystic fibrosis is a genetic disorder caused by one of a number of possible gene mutations. Prenatal testing

can be used to determine whether or not a fetus has cystic fibrosis.

Name one method of prenatal testing and explain how it can be used to detect cystic fibrosis. (3) Jun 2009

(iv)Cystic fibrosis is a genetic disease that can affect many body systems, including the digestive system. In a

carrier of this disorder, preimplantation genetic diagnosis can be used to detect the presence of an allele forcystic fibrosis. *(a) Explain how cystic fibrosis affects the digestive system. (4) Jun 2011

(v)Cystic fibrosis is a genetic disease that can affect many body systems, including the respiratory system.

*Explain how a gene mutation causes a buildup of mucus in the respiratory system of a person with cystic

fibrosis. (5) June2010




Genetic Diagram & Probability

20.(i) Using your knowledge of monohybrid crosses, calculate the probability of having a child with cystic

fibrosis if both partners are found to be carriers. Draw a genetic diagram to explain how you calculated this

probability. (5) Jan 2010

(ii)Two parents are both carriers of the recessive allele for Krabbe disease. In the space below, draw a genetic

diagram to show the possible genotypes and phenotypes of their children. Use the genetic diagram to find the

probability of these parents having a child with Krabbe disease. (5) Jun 2012




(iii) Achondroplasia is an inherited condition that results in restricted growth in humans. This condition is

caused by a dominant allele (A). Fetuses which are homozygous for the allele for achondroplasia are rarely

born alive. Two parents who both have achondroplasia would like to have children.

They are concerned about the risk of their child inheriting two dominant alleles and dying before birth.

In the space below, draw a suitable genetic diagram to show the probability of a child from these parents

growing up without achondroplasia. (4) Jun 2013

(iv) The pedigree diagram below shows the inheritance of galactosaemia in a family. Use a genetic diagram to

calculate the probability that Sahan and Alina’s first child will be heterozygous (a carrier) if Sahan is

heterozygous. (4) Jun2010




10.Gene Therapy21*(i) Suggest how somatic gene therapy could enable cells lining the lungs to function normally in people

with cystic fibrosis. (4) June 2013

(ii) Gene therapy could potentially be used to treat beta thalassemia. Suggest how gene therapy could be

carried out to treat this disorder. (4) (Jan 2011)

(iii)Cystic fibrosis is a genetic disorder caused by mutations in the CFTR gene. One aim of somatic gene therapyis to overcome the effects of defective genes. Describe the difference between somatic gene therapy and

germ line gene therapy. (2)

*(iv) Suggest how somatic gene therapy could enable cells lining the lungs to function normally in people with

cystic fibrosis. (4) Jun 2013

(v)Explain how preimplantation genetic diagnosis is performed to detect cystic fibrosis. (3) Jun2011

(vi)*Suggest how somatic gene therapy could enable cells lining the lungs to function normally in people with

cystic fibrosis. (4) June 2013




*(vii) Tay-Sachs disease is caused by a gene mutation that results in the buildup of lipid in the brain. It is hoped

that gene therapy will be able to treat this disease in the future. Sheep can also suffer from Tay-Sachs disease.

Investigations have found that gene therapy increases the life span of these animals.

Suggest how these gene therapy investigations could have been carried out. (5) Jan 2013

1. {isolation / identification / eq} of normal gene / eq ;2. {inserted / eq} into vector / stem cells / eq ;3. vector named as {liposome / virus} ;

4. injection of {vector / modified stem cells} into {blood / brain / target cells / eq} / eq ;5. ref to use of control injection ;6. further detail of control injection e.g. use empty liposome / virus without gene inserted ;7. progression of disease monitored / eq ;8. life spans recorded / eq ;9. reference to appropriate comparison with control eg untreated sheep ;10.idea that treatment needs to be repeated;11.idea of replication of investigation;




Genetic screening can be used to identify the cystic fibrosis allele. By considering contrasting ethicalviewpoints, discuss one reason in favour and one reason against genetic screening for cystic fibrosis.

Award one mark for identifying a potential benefit and a further mark for an explanation of the benefit.For example1. to determine whether or not a parent is a carrier;2. therefore can make informed decision about havingchildren;or3. determine whether or not embryo has disease;4. informed decisions can be made about {future care for child / termination of pregnancy} / treatment couldstartimmediately;

Award one mark for identifying a potential disadvantage and a further mark for an explanation of thedisadvantage.For example5. ref to false positives / negatives;6. decisions on whether to terminate a pregnancy or not arebased on wrong information;or7. other abnormalities may be found;8. some social implication e.g. life insurance, finding {partner/ job}, depression;




11.PRACTICAL QUESTIONS

1. DAPHNIA PRACTICAL(i)A friend of the student suggested that herbal tea might have a lower caffeine content than these drinks.

The student decided to use Daphnia to compare the caffeine content of herbal tea with the caffeine content

of these other drinks.

Describe an experiment that the student could perform, using Daphnia, to confirm that herbal tea has thelowest caffeine content. (4) (Jan 2010)

(ii)The hypothesis that higher concentrations of caffeine will increase heart rate can be investigated practically

using Daphnia (water fleas).

Describe a reliable procedure that could be used to test this hypothesis. (6) (Sample paper)

Award one mark for each of the following points in context to a maximum of three.1. place Daphnia on {cavity slide / eq} with caffeine;2. (focus on heart) using microscope;3. ref. to range of caffeine concentrations;4. ref. to repeats;5. ref. to {water as control / zero caffeine concentration};Award one mark for each of the following points in context to a maximum of three.1. control temperature;2. reference to similar organisms used;3. accurate measurement of DV;4. reference to pretreatment;

2.VITAMIN C PRACTICAL(i) Describe how this chemical can be used to measure the vitamin C content of samples of broccoli. (3) (June

2013)

(ii)The photograph below shows broccoli, a green vegetable. Green vegetables are a source ofvitamin C. Cooking can reduce the vitamin C content of vegetables. Describe how the vitamin

C content of broccoli could be measured. (4) Jan 2016

(iii)Paraná state is another region in South America that produces camu-camu fruit. The camu-camu fruit from

this region have a different vitamin C content from those grown in the Amazon region.

Describe how an investigation could be carried out to compare the effect of storage time on the vitamin C

content of the Paraná state camu-camu fruit with those from the Amazon region. (5) Jun 2009

*(iv) It has been suggested that cooking food in a microwave oven does not reduce the nutrient content offoods by as much as cooking in boiling water. A student wanted to test this idea on the vitamin C content of

carrots.

Describe an investigation that the student could carry out to compare these two methods of cooking on the

vitamin C content of carrots. (5) Jun2011




3. MEMBRANE PERMEABILITY (BEETROOT)

(i) The size and solubility of molecules has an effect on their ability to be taken up by cells.

* Describe an experiment you have carried out to investigate the permeability of cell membranes. (5) Jan 2011




4.ENZYME PRACTICAL*(i) Describe an experiment to investigate the effect of cooking on catalase activity in potatoes. (6)(June 2015)

(iii)Describe how this apparatus could be used to compare the catalase activity in two different types of

mussel. (4) Jan 2012



*(iv) Describe an experiment to investigate the effect of cooking on catalase activity in potatoes. (6) Jun 2015

(v)Describe an experiment that could be carried out to investigate the effect of enzyme concentration on the

initial rate of reaction. (4) June 2013

*(vi) The action of lipase can be investigated using a triglyceride as the substrate. Describe an experiment,

using lipase and a triglyceride, that could be carried out to collect data to plot a graph similar to the one

shown in part (a). (5) Jun 2012

answering unit 1 - biology ( ed excel )

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