Topic 1 and 2 extras

Question 1

Advantages of glycogen as an energy storage molecule

Answer 1

1. large molecule/made up of many monomers allows
   storage of large amounts of energy;
2. compact therefore large amounts can be stored in a cell;
3. insoluble therefore does not have an osmotic effect/eq;
4. inert so not affected by other reactions in cells;
5. large molecule therefore cannot pass out of cells;
6. can be hydrolysed to release large amounts of energy /
   glucose when required;

Question 2

Suggest how high blood pressure can result in less oxygen reaching heart muscle.

Answer 2

1. damage to artery walls;
2. ref. to blood clot;
3. blood clot can block arteries;
4. ref. to coronary arteries;
5. lack of (oxygenated) blood flow to heart muscle;

Question 3

Describe and explain the events that occur during ventricular systole in the cardiac cycle.

Answer 3

1. ventricle (muscle) contracts;
2. higher pressure in ventricles relative to atria;
3. (pressure) closes atrioventricular valve;
4. higher pressure in ventricles relative to the {aorta /
   pulmonary artery / arteries};
5. (pressure) opens the semilunar valve;
6. blood forced into the {aorta / pulmonary artery /
   arteries};

Question 4

Percentage change

Answer 4

Percentage change= original - new/original

Question 5

Explain the changes in blood pressure in the arteries.

Answer 5

(pulses)/fluctuates due to {elastic recoil/eq}

Question 6

Explain why the model used to describe the structure of this cell membrane is called the fluid mosaic model.

Answer 6

1. Fluid because phospholipids moving (within membrane);
2. Causing proteins to move;
3. Mosaic due to presence of proteins/eq;

Question 7

Conversions

Answer 7

1 cubic centimetre = 1000 cubic millimetres
1 cubic decimetre = 1000 cubic centimetres
1 cubic metre = 1000 cubic decimetres

Question 8

Surface area to volume ratio

Answer 8

divide surface area by volume

dividing the surface area by the volume of any object.

Question 9

Magnification

Answer 9

magnification = size of image

size of real object

Question 10

Percentage error

Answer 10

approximate value - exact value/ exact value

Percentage = Error Uncertainty / Reading x 100

Question 11

Surface area and volume of shapes

Answer 11

Cylinder A=2πrh+2πr2 V=πr2h

Sphere V=4/3 x πr3 A=4πr2

Question 12

what is meant by template?

Answer 12

idea that the (RNA) nucleotides attach to this strand

codes for mRNA

Question 13

One advantage of DNA having two complementary strands is that

Answer 13

semi-conservative replication is possible

Question 14

Describe differences between the processes of replication and transcription of DNA.

Answer 14

1
replication uses DNA nucleotides
transcription uses RNA nucleotides / eq ;
2

replication uses DNA polymerase / eq
transcription does not use DNA polymerase / uses RNA polymerase ;
3
replication reference to semi- conservative
transcription not semi-conservative / eq ;
4
replication (copies) both DNA strands / eq
transcription (copies) only {one strand / template / gene / eq} ;
5
replication makes DNA double helix / eq
transcription Makes single strand mRNA / eq ;

Question 15

Recessive allele

Answer 15

idea that both of these alleles need to be present in order for the recessive phenotype to be expressed ;
AND
2. different form of a gene / eq ; 3. same locus /position / eq ;
4. different base sequence / eq ;

Question 16

reasons why Daphnia is a suitable organism for investigating the
effect of chemicals on heart rate.

Answer 16

idea that you can see the { heart / internal organs / eq} ;

2. Daphnia {are simple organisms / have less developed nervous system / can’t feel pain / eq} ;
3. idea that there are fewer ethical concerns because it is an { invertebrate / eq} ;
4. idea that they are abundant / used as fish food / eq ;
5. idea that they can absorb chemicals from the surrounding solution quickly ;

Question 17

suitable control method for daphnia experiment

Answer 17

; Examples:
• temperature ; heat shield ;
• volume of caffeine (solution) ; (use pipette to measure) stated volume e.g. 2 cm3 ;
• { age / species / source /size / gender } of Daphnia ; hatched from eggs at the same time ;
• pre-treatment / acclimatisation ; same time ;
• reduce movement of Daphnia ; use of cotton wool
strands ;
• method of measuring heart rate ; count number of
heartbeats in 30 seconds / eq ;
• {concentration / source} of caffeine ; one caffeine
tablet in 10 cm3 of water

Question 18

Explain why many small animals, such as Daphnia, have a heart.

Answer 18

1. reference to mass flow ;
2. name a suitable substance transported e.g. oxygen ;
3. comment on {blood pressure / fast movement of blood to cells /eq} ;
4. idea of increased concentration gradient of solutes e.g. oxygen ;
5. idea that diffusion alone would be too slow ;
6. has high metabolic rate / eq ;

Question 19

Explain why people with cystic fibrosis can have breathing difficulties.

Answer 19

1. produces {thicker / stickier / more viscous / eq} mucus ;
2. blocking { trachea / bronchi / bronchioles / airway / eq} / eq ;
3. cilia are unable to move mucus out of lungs / eq ;
4. idea of reduced flow of {air / oxygen } to alveoli ;
5. idea of reduced concentration gradient for {oxygen / carbon dioxide} (in alveoli) ;
6. idea of loss of surface area / elasticity / eq ;
7. idea of reduced gaseous exchange ;
8. trapped bacteria may result in more respiratory infections / eq ;

Question 20

Explain either one ethical issue or one social issue relating to the use of prenatal genetic testing.

Answer 20

1. idea that it may result in a miscarriage / choice of an abortion ;
2. {killing / eq} is {wrong / unethical / eq};
   OR
3. idea of risk of false {positive / negative} ;
4. comment on consequence e.g. healthy fetus may be aborted / parents not prepared for child with cystic fibrosis / eq ;
   OR
5. if cystic fibrosis or some other abnormality may be found ;
6. comment on possible problems with {future employment / insurance / what constitutes a serious condition} / eq ;
   OR
7. who has right to decide if tests should be performed / eq ;
8. {implications of medical costs / disagreements over next step} ;
   OR
9. issues relating to confidentiality of {parents / child} / eq ;
10. idea that {some other abnormality may be found / paternal DNA does not match / other family members have right to know results} ;

Question 21

Suggest one piece of medical advice that could be given to someone who does not have high blood pressure but who is obese.

Answer 21

1. reduce energy intake / increase activity / follow calorie controlled diet / eq ;
2. idea of change in balance of energy budget ;
3. lower {weight / BMI / obesity level / eq} / reduce risk of {atherosclerosis / diabetes / eq} ;
   OR
4. statins / sterols / reduce { cholesterol
   / saturated fats / eq} in diet / eq ;
5. reduce blood cholesterol levels ;
6. idea of reducing risk of atherosclerosis / eq ;
   OR
7. eat more fruit / vegetable / vitamins /
   moderate alcohol intake / eq ;
8. reference to antioxidants ;
9. they protect against free radical damage / reduce damage to cells / eq ;
   OR
10. anticoagulants / platelet inhibitory
    drugs / warfarin / aspirin / eq ;
11. prevent blood clot formation / eq ; 12.reduces risk of blocking artery / eq

Question 22

Amino acids chain

Answer 22

R groups bond to form secondary and tertiary structure

Question 23

Explain how the dipolar nature of water is essential for living organisms.

Answer 23

1. idea that water can form {hydrogen bonds / eq} ;
   and any one from
2. water is a solvent / {ions / polar molecules / eq } can {dissolve / be transported / eq } in water
3. reference to cohesion/adhesion
4. idea of hydrogen bonds holding water together as a liquid, so that it can move in mass flow systems
5. suitable ref. to specific heat capacity
6. idea of distribution of thermal energy around body
7. reference to high latent heat of vaporisation

Question 24

During this cardiac cycle, the changes in pressure that occur in the left atrium and in the left ventricle are different.

Answer 24

1. {pressure changes / maximum pressures} are smaller in the atrium than the ventricle / eq ;
2. the atrium has less (cardiac) muscle than the ventricle ;
3. the atrium does not have to push the blood as far as the ventricle has to / eq ;
4. the increase in pressure happens in the atrium before the ventricle / eq ;
5. idea that atrial systole has to happen before ventricular systole in order for the ventricle to fill with blood ;
6. idea that increase in atrial pressure causes increase in {pressure / volume } in ventricles ;
7. appropriate reference to effect of atrioventricular valve (AV) (on pressure) ;

Question 25

Describe the role of each of the following in protein synthesis.

Answer 25

mRNA
1. idea of mRNA being a copy of the { antisense DNA strand / template DNA strand / coding DNA strand / gene / allele / part of DNA / eq } ;
2. idea that mRNA {made up of codons / codes for specific amino acids / code for amino acid sequence / eq} ;
3. idea of mRNA being taken {into the cytoplasm / to the ribosomes / out of the nucleus / eq} ;
4. used in translation ;
5. binds to ribosome ;
tRNA
6. (tRNA) {attaches to / transports / eq } (specific) amino acid / eq ;
7. idea that tRNA binds to mRNA / reference to anticodon codon interaction ;
8. idea that two tRNA bring amino acids together (for peptide bonds to be formed) ;

Question 26

general formula

Answer 26

general formula for a monosaccharide is CnH2nOn whereas formula for disaccharide is CnH2n-2On-1

Question 27

Explain why a diet consisting of a high proportion of carbohydrates could lead to obesity.

Answer 27

1. idea of carbohydrates providing a source of energy ;
2. if the {energy / carbohydrate / eq} input is greater than the {energy output / carbohydrate use / eq} (weight will be gained) / eq ;
3. idea of excess carbohydrate converted to fat

Question 28

*(a) Describe the structure of the mammalian heart.

Answer 28

1. idea that there are four chambers ;
2. correct reference to relative position of atria
   and ventricles ;
3. idea of left and right sides separate / septum
   ;
4. reference to muscular nature of walls ;
5. reference to cardiac muscle ;
6. idea of relative thickness of ventricle (walls) ;
7. correct reference to position of {atrioventricular valves / eq} ;
8. correct reference to position of semilunar valves ;
   10.correct reference to position of {aorta / pulmonary artery} ;
9. correct reference to position of {vena cava / pulmonary vein} ;
10. correct reference to coronary arteries ;

Question 29

xplain the importance of the heart and circulation to a large mammal

Answer 29

1. idea that the heart has to pump blood a long way around the body of the giraffe ;
2. (therefore) blood needs to be (pumped) at high pressure / eq;
3. blood vessels are needed to contain the blood / reference to closed circulation / eq ;
4. idea of double circulatory system ;
5. capillaries needed to ensure that all parts of giraffe are close to blood supply/ eq ;
6. idea of need for a circulation to {provide oxygen / remove carbon dioxide / other correct named substance} ;
7. idea of {oxygen / glucose} needed as {high metabolic rate / high rate of respiration / eq} ;
8. idea of diffusion not meeting the requirements of the giraffe ;
9. reference to low surface area to volume ratio ;
10. idea that circulatory system helps regulation of body temperature ;

Question 30

Suggest why there are changes to the available energy (ATP) in the heart muscle cells following the loss of blood flow.

Answer 30

1. idea of {less / no /eq } oxygen (available) ;
2. idea of {less / no / eq} {respiratory substrate / glucose / eq} ;
3. {less / no/ eq} (cellular/ aerobic) respiration / eq ;

Question 31

Calculate beats per minute

Answer 31

60/ seconds for one cycle