Biology Revision Unit 1 May 13

Front 1

Proteins are made of monomers called ............................................................................................. . These monomers
are joined together by ............................................................................................. bonds,

Back 1

1. amino acids ;
2. peptide ;

Front 2

Describe the three-dimensional (tertiary) structure of an enzyme.

Back 2

1. globular ;
2. active site ;
3. specific shape of active site ;
4. bonds /named bond / interaction between R groups ;
5. named bond/interaction e.g. disulphide bond, hydrogen bonds, hydrophobic interactions between R groups;

Front 3

Explain how the primary structure of an enzyme determines its three-dimensional
(tertiary) structure and its properties.

Back 3

1. primary structure position / sequence of the amino acids / R groups ;
2. determines the positioning and type of the bonds;
3. determining the shape and properties of the active site;
4. interaction of active sites and substrates ;
5. polar / hydrophilic on the outside of enzymes / non polar / hydrophobic on the inside;
6. solubility ;

Front 4

Using the information shown in the photograph and your own knowledge,
suggest how gas exchange occurs in an amoeba.

Back 4

1. gas exchange occurs through the cell membrane / phospholipid bilayer ;
2. the membrane is thin ;
3. oxygen enters cell from water;
4. carbon dioxide leaves cell into water;
5. O2 / oxygen / CO2 / carbon dioxide are small / non-polar molecules;
6. diffusion ;
7. description suitable concentration gradient ;
8. large surface area to volume ratio ;

Front 5

Suggest how oxygen passes from the cell membrane into the centre of an
amoeba.

Back 5

1. diffusion in the cytoplasm ;
2. through the cytoplasm / description of part of cytoplasm ;
3. down a concentration gradient in the cytoplasm ;

Front 6

The fluidity of the membrane is determined by the proportion of

Back 6

cholesterol

Front 7

State two variables that both of these students must keep the same if their
results are to be compared.

Back 7

1. pre-treatment e.g. rinsing method ;
2. size / mass / surface area / volume / shape of beetroot ;
3. beetroot storage conditions ;
4. same / type / species beetroot ;
5. age of beetroot / storage time ;
6. incubation time;
7. volume / concentration of water / solution added to beetroot;
8. pH ;

Front 8

Give two reasons why the results obtained by the second student are more
reliable than those of the first student.

Back 8

1. repeats / replicates ;
2. colorimeter / readings are objective / quantitative / not qualitative / more accurate / provide numbers / more precise / measured not judged

Front 9

In the first student’s experiment at 5 °C, the fluid was pale pink but the fluid
in the second student’s experiment was colourless.
Suggest an explanation for this difference.

Back 9

pink colour due to pigment is released when cells / vacuoles/ membranes are damaged and had not been washed off

Front 10

Each of the students used their own results to describe the effect of
temperature on the permeability of the membranes of the beetroot cells.
Suggest one way in which these two descriptions might differ.

Back 10

idea that the second experiment shows that the permeability increases between {5 / 22} oC and 42 oC / in first experiment 5 oC has an effect
OR
idea that the second experiment’s results are
quantified ;

Front 11

Describe the structure of glycogen and explain why it is a suitable molecule for
storing energy.

Back 11

Any 3 of the following:
1. consists of (α) glucose ;
2. joined by 1,4 / 1,6 glycosidic bonds ;
3. branched structure;
4. compact structure ;

Any 3 of the following:
5. it is easily / rapidly / hydrolysed ;
6. leading to more glucose in a smaller space in a cell;
7. low solubility ;it does not diffuse out of cells ;
8. it has no osmotic effect

Front 12

Using the information in the graph, describe how the source of energy used
depends on the intensity of exercise.

Back 12

1. increasing intensity increases carbohydrate use / decreases fat use;
2. low intensity exercise / intensity below {39 / 40} au} uses more energy derived from fats;
OR {high intensity exercise / intensity above
{39 / 40} au uses more energy derived from
carbohydrates ;
3. at {39 / 40} au both sources of energy used equally;
4. credit correct manipulation of figures to compare energy usage ;

Front 13

Using the information in the graph and your knowledge of glycogen, explain what
type of athletic event could be prepared for using a carbohydrate-loading diet.

Back 13

1.this diet is suitable for a high intensity event ;
2. credit suitable example of athletic event ;
3. more carbohydrate being used (than fat) above {39 / 40} a.u. ;
4. carbohydrate being stored as glycogen ;
5. maximum / more / lots of glycogen stored;
6. breakdown of glycogen provides energy for the event ;

Front 14

Discuss either one ethical issue or one social issue relating to the use of this
method of prenatal genetic screening.

Back 14

1. some people think fetus has right to life ; abortion is murder
2, there is risk of miscarriage for the mother;
Or:
3. false positive and false negative results are possible; if so, consequences of false result e.g. abortion of healthy fetus ;
Or:
5. it's difficult to say who has right to decide if tests should be performed;
6. there are implications of medical costs / parents have a right to know, so that they can prepare early treatment if they choose to give birth to a child with genetic conditions
Or:
7. issues relating to confidentiality of {parents / child;
8. idea that {some other abnormality may be found / paternal DNA does NOT match / other family members have right to know results} ;
Or:
9. if abnormality found ;
10. consequence of abnormality found e.g. abortion, comment on possible problems with {future employment / insurance / what constitutes a serious condition} / eq ;
Or:
11. damage to fetus / risk of miscarriage ;
12. loss of fetus / risk to mother / eq ;
Or:
13. ref. to stress to parents /eq ;
14. consequences of stress e.g. increased risk of miscarriage ;

Front 15

Explain why gene therapy has the potential to treat some genetic disorders.

Back 15

1. faulty alleles / genes /DNA ;
2. gene therapy uses normal / functioning / healthy alleles / genes ;
3. so the normal protein / gene product / RNA is produced by the cells ;

Front 16

Suggest how patients with cystic fibrosis could be treated using gene therapy.

Back 16

1. using alleles /genes /coding for the CFTR protein /channel ;
2. introducing the {alleles / genes into the cells ;
3. of the lungs / pancreas / reproductive tracts ;
4. that produce mucus ;
5. using a vector
6. credit suitable delivery mechanism e.g. nebuliser, injection ;
7. treatment needs to be repeated due to cell replacement ;

Front 17

Describe how this apparatus could be used to compare the catalase activity in
two different types of mussel.

Back 17

1. measuring volume of oxygen ;
2. time e.g. oxygen produced in unit time, time taken to produce same volume of oxygen ;
3.measuring the initial rate of reaction ;
4. controlled variable in relation to the mussel e.g. age, part of mussel, mass, surface area ;
5. a controlled variable in relation to the experiment e.g. volume of hydrogen peroxide, temperature, concentration, pH ;
6. repeats ;

Front 18

Describe how atherosclerosis develops.

Back 18

1. damage to endothelial cells/ epithelial cells / lining of artery ;
2. inflammatory response ;
3. migration of white blood cells into area ;
4. build up of cholesterol;
5. formation of atheroma / plaque ;
6. calcium salts / fibrous tissue;
7. loss of elasticity of artery/ narrowing of lumen
8. this process is self–perpetuating ;

Front 19

Explain the meaning of the term genotype.

Back 19

the alleles present in an organism

Front 20

Give two factors, other than genetic factors, that increase the risk of developing
CVD.

Back 20

More saturated fat / more cholesterol / more salt /obesity / more alcohol / more age / male / post-menopausal women / high blood pressure / smoking / diabetes / less activity / stress ;

Front 21

Describe the risks of using plant statins to treat CVD.

Back 21

1. muscle inflammation / pain;
2. liver damage / failure ;
3. joint aches / pains ;
4.nausea/constipation/diarrhoea ;
5. kidney damage / failure ;
6. cataracts ;
7. diabetes ;
8. allergies / skin inflammation / skin rash;
9. respiratory problems / persistent cough;
10. headaches / dizziness / depression ;

Front 22

Explain why it would be incorrect to conclude that, in Japan, the same number of
males as females are obese.

Back 22

1. graph shows percentages ;
2. population size is not known e.g. sample size not known / the actual number of males and females who are obese will depend on the population size of each gender;
3. there may be a different number of males to females

Front 23

Using the information in part (d), describe the evidence that suggests there is
a correlation between the consumption of corn syrup and obesity.

Back 23

1. the consumption of corn syrup goes up ;
2. this is before the increase in obesity ;
3. the consumption of dextrose falling with time e.g. during the 1970s ;
4. the consumption of glucose staying fairly constant ;

Front 24

Suggest one possible source of error in the student’s procedure that could
make this value for the percentage decrease in the mass of the strawberries
inaccurate.
Explain how this source of error would affect the value for the percentage
decrease in the mass of the strawberries.

Back 24

1. idea that not all of the {juice / sugar} washed off / idea that the strawberries were not dried after rinsing properly / idea that some water reabsorbed (during washing) ;
2. loss of mass of strawberries not as high as it should have been ;
3. (%) value too small ;
OR
1. idea that strawberry {tissue / juice} lost because {washing too vigorous / tissue stuck to towel when drying / squeezing strawberries / juice absorbed from strawberries} / water lost through evaporation ;
2. loss of mass of strawberries higher than it should have been;
3. (%) value too high;

Front 25

Using your knowledge of cell transport mechanisms and the properties of
water, explain how the juice is formed from the water that came from the
fruit.

Back 25

1. water gradient between sugar and strawberries ;
2. osmosis of water from inside of strawberry to outside;
3. water is found in cytoplasm / vacuoles of strawberry ;
4. water as a solvent for the sugar ;
5. dipolar nature of water

Front 26

Explain how cystic fibrosis affects the digestive system.

Back 26

1. CFTR channel not functioning properly ;
2. thicker mucus ;
3. mucus blocks pancreatic ducts ;
4. in the pancreas ;
5. enzymes cannot reach small intestine ;
6. reduced digestion of food ;
7. reduced absorption;
8. malnutrition / weight loss ;
9. self-digestion of pancreatic cells / problems controlling blood sugar levels / cysts / fibroids;

Front 27

Explain how preimplantation genetic diagnosis is performed to detect cystic
fibrosis.

Back 27

1. IVF / description of preimplantation ;
2. embryo DNA analysed
3. presence of CFTR gene mutation / faulty allele tested for

Front 28

Discuss either one ethical issue or one social issue relating to the use of
preimplantation genetic diagnosis.

Back 28

1. who has right to decide if tests should be
performed / eq ;
2. {implications of medical costs / disagreements
over next step / embryo has rights} ;
OR
3. issues relating to confidentiality of {parents /
child} / eq ;
4. idea that {some other abnormality may be found /
paternal DNA does not match / other family
members have right to know results} ;
OR
5. idea some other abnormality may be found / false negative ;
6. comment on possible problems with e.g. future
employment / insurance / what constitutes a
serious condition / eq ;
OR
7. idea that embryo could be {damaged / destroyed / discarded / eq} / false positive ;
8. embryo {is a potential life / has rights} /destroying embryo is {wrong / unethical / murder / eq} ;

Front 29

Explain how lowering blood cholesterol levels can reduce the risk of CVD.

Back 29

1. less cholesterol in blood to build up on artery wall ;
2. less likely to develop atherosclerosis ;
3. subsequent consequence of atherosclerosis e.g. narrowing of arteries, ischaemia, decrease in flow of blood to heart ;

Front 30

giving three other ways in which the risk of
CVD may be reduced.

Back 30

1. decrease in smoking / not smoking / eq ;
2. reference to {increase / regular / eq} exercise ;
3. improvements to diet qualified, e.g. reduce salt, reduce saturated fat, increase fibre ;
4. maintaining appropriate weight / eq ;
5. {moderate / reduced} alcohol consumption / eq ;
6. reducing stress / eq ;
7. use of medication e.g. statins, antihypertensives, warfarin ;

Front 31

Risk calculators can be used to estimate the probability that a person will develop
CVD. Many of these calculators start by asking for the age and gender of the
person using them. Explain why information about age and gender is important
in estimating the risk of developing CVD.

Back 31

1. age effect qualified e.g. older increases risk, {arteries {become less elastic / more easily damaged / blood pressure increases} with (increase in) age ;
2. gender effect qualified e.g. {women less likely to develop CVD than men / oestrogen offers some protection to women against CVD } (pre menopause)

Front 32

Describe two differences between the data presented in the map and the
data shown in the graph.

Back 32

1. Finland {highest on graph / not highest on map} Germany and UK have the highest on the map / eq ;
2. idea that a number ( 3 or more) of countries are the same on the map ;
3. France does not have the lowest number of deaths / eq ;
4. Credit any other correct comparison ;
5. {map shows number of deaths and graph shows relative death rate / map gives the results grouped together but graph shows individual values / map does not allow for population size} ;

Front 33

Suggest one reason for the differences between the data presented in the
map and the data shown in the graph.

Back 33

1. the data on the map is shown in groups;
2. the data might come from a different year / different time / no information given on the year ;
3. different groups of people were surveyed;
4. idea that bar graph shows number of deaths relative to population / the map does not take into account the population of the country

Front 34

Describe the structure of an amino acid.

Back 34

1. presence of amine group /eq ;
2. presence of carboxyl group / eq ;
3. reference to R group ;
4. reference to central carbon atom ;
[award marks on correctly drawn diagram]

Front 35

Describe how mRNA is synthesised.

Back 35

1. transcription ;
2. DNA unwinds / strands separate ;
3. (RNA) (mono)nucleotides {line up against / attach / eq} to one (DNA) { strand / template ;
4. complementary base pairing between DNA and (mono)nucleotides;
5. mononucleotides joining together / formation of phosphodiester bonds ;
6. condensation reaction ;
7. named enzymes involved;
8. mRNA detaches (from DNA)

Front 36

Describe an investigation that the student could carry out to compare these two
methods of cooking on the vitamin C content of carrots.

Back 36

1. idea that some carrots need to be boiled in water and some cooked in microwave ;
2. reference to control of appropriate variable;
3. reference to {juice / cooking water} being used ;
4. reference to DCPIP ;
5. {reference to titration / description of titration} (of juice) ;
6. colour change of DCPIP e.g. from blue to {colourless / pink} as juice added / until stays blue as DCPIP added ;
7. reference to {comparison of volumes of DCPIP added to each / use of calibration curve / calculation of vitamin C concentration against known vitamin C solution} ;
8. reference to repeats ;

Front 37

Suggest why there was an increase in the mean mass of the volunteers on
both diets between 6 months and 12 months.

Back 37

not following the diet {anymore / so strictly} / not doing so much exercise

Front 38

State two variables that the scientist needed to control in this investigation.

Back 38

1. gender / eq ;
2. age / eq ;
3. extent to which individuals were over-weight / eq ;
4. occupation / eq ;
5. alcohol intake / eq ;
6. standardised exercise programme / amount of exercise taken eq ;
7. health / disability / stress / eq ;
8. timing of meals / eq ;
9. time of weighing / eq ;

Front 39

suggest why exercise is usually included as part of a weight loss programme.

Back 39

1. idea that exercise uses energy ;
2. the {longer / more intense} the exercise, the more {energy used / weight loss} / eq ;
3. idea of {mass / weight} loss depends on energy input lower than energy output ;
4. idea that exercise increases metabolism / muscles use more energy than fat ;