Biology Revision Unit 1

Front 1

Protein synthesis involves transcription and translation. Describe the process of
transcription.

Back 1

1. DNA molecule unwinds, hydrogen bonds break and DNA strands separate;
2. one strand acts as a template ;
3. free nucleotides line up against DNA ;
4. RNA polymerase ;
5. nucleotides joining together by phosphodiester bonds to form mRNA ;
6. movement to ribosomes ;

Front 2

DNA and messenger RNA (mRNA) have different properties. DNA is very stable
but mRNA breaks down quickly and most of it will be broken down within a day
of it being produced. Suggest why it is important for DNA to be more stable than
mRNA.

Back 2

1. DNA contains genetic information ;
2. DNA codes for protein ;
3. a change in DNA could produce a different protein / mRNA;
4. it is required throughout life or cell / organism ;
5. it is needed to pass on to next generation of cell / organism ;

Front 3

Suggest why the initial rate of reaction was measured in this investigation.

Back 3

1. it allows a comparison to be made (with and without copper ions) ;
2. substrate concentration being the same (with and without copper ions) ;
3. the rate of reaction changes with time ;
4. because substrate is being used up ;

Front 4

The student suggested that the copper ions were acting as an active site-directed
inhibitor at concentrations above 4 arbitrary units. Explain what is meant by the term
active site-directed inhibition.

Back 4

1. inhibitor block the active site ;
2. inhibitor is the same shape as substrate ;
3. preventing substrate binding with enzyme ;
4. the more inhibitor the more active sites are blocked ;
5. reduces enzyme activity ;

Front 5

Describe a test that could be used to show that starch has been broken down.

Back 5

1. use of iodine solution ;
2. observation / colour change;
3. credit any valid experimental details ;

Front 6

Suggest one reason why the double membrane is not clearly visible all around the
mitochondrion labelled A.

Back 6

1, resolution not high enough
2, damage
3, angle of section
4, poor printing of photograph

Front 7

draw and label a diagram to show the structure of a chloroplast

Back 7

1. {envelope / double membrane} clearly shown ;
2. granum clearly shown ;
3. {granum / thylakoid(s)} labelled ;
4. {stroma / ribosomes / starch grain / DNA / lipid droplet / {double
/ inner / outer} membrane / envelope / intergranal lamellae}
correctly labelled ;

Front 8

Give an account of the events that take place during prophase and metaphase of mitosis.

Back 8

1. during prophase chromosomes becoming visible ;
2. centrioles move to opposite poles ;
3. formation of spindle ;
4. disappearance of nucleolus;
5. breaking down of nuclear membrane in prophase or
nuclear envelope is broken down by metaphase ;
6. at metaphase chromosomes attached to spindle fibres ;
7. chromosomes lined up at equator ;

Front 9

Explain what is meant by the term tissue.

Back 9

same cells of similar function

Front 10

Some polar molecules cross the membrane by combining
with transport proteins which can change their shape. When this movement occurs
down a concentration gradient, the process is called ...............................................
and when it occurs against a concentration gradient the process is called
................................................

Back 10

facilitated diffusion, active transport

Front 11

which is structural carbohydrate? Glycogen or Cellulose

Back 11

cellulose

Front 12

DNA structure. suger and phosphate join by what bond?

Back 12

phosphodiester bond

Front 13

Protein synthesis. it involves two stages. the first stage is what? and what happened?
second stage? what happened?

Back 13

1, the first stage is transcription.
2, it takes place in the nucleus of the cell.
3, During this stage, a molecule called mRNA is made using the antisense DNA strand as a template.

1, The second stage known as translation,
2, takes place in the cytoplasm of the cell on ribosomes.
3, During this stage, tRNA molecules enable the amino acids attached to them to line up in the correct order. The amino acids are joined together by the formation of peptide bonds.

Front 14

using the information in the graph, compare the uptake of substance A with the uptake of substance B during the period of 5 hours. (A直线上升，B30分钟一样，之后比A慢， 2小时开始平)

Back 14

1. rate is same for up to 30 minutes;
2. faster uptake for A than B;
3. uptake of A is linear throughout whereas uptake of B is not ;
4. uptake of substance B levels off at 2 hours whereas uptake of A does not ;
5. credit correct manipulation of comparative figures ;

Front 15

substance B enters te cells by diffusion. describe and explain how the results of this experiment support this statement

Back 15

1. diffusion of substance B occurring due to concentration difference
2. rate of uptake decreases as the concentration gradient decreases ;
3. net uptake stops when concentration inside cell equals that outside the cell

Front 16

differences between active transport and diffusion

Back 16

1. active transport is against concentration gradient ;
2. active transport requires ATP ;
3. involvement of membrane proteins in active transport ;

Front 17

describe the circulation of blood in a fish

Back 17

1. blood flows from heart to gills ;
2. from gills to rest of body
3. from body back to heart ;
4. single circulation ;

Front 18

advantages of human circulatory system compared with that of a fish

Back 18

1. blood flows at higher pressure to the body, thus faster, more efficient exchange of gases;
2. blood flows at lower pressure to the lung, thus slower, this reduces risk of damage to lungs

Front 19

suggest why the insect does not need blood vessels to transport its blood around the body

Back 19

1. large surface area to volume ratios ;
2. all cells are very close to the blood / heart ;
3. diffusion is fast enough for exchange of nutrients / gases / waste} ;
4. low metabolism ;
5. movement of blood back into the heart is fast enough

Front 20

describe blood clotting process

Back 20

1. there is a cascade of events leading to blood clotting ;
2. thromboplastin starting the cascade ; conversion of prothrombin into thrombin ;
3. thromboplastin /thrombin is an enzyme ;
4. conversion of fibrinogen into fibrin ;
5. formation of mesh of fibres;
6. ref to requirement of calcium ions;
7. platelets getting trapped in the mesh;

Front 21

suggest why the clotting time of the human blood with snake venom added was compared with the clotting time in the presence of Factor Xa

Back 21

1, if the snake venom has similar effects as a known
clotting factor, an idea of its mode of action can be
worked out
2, we can see how deadly the snake is
3, compare to normal clotting process
4, possible use as medication
5, for research into antidotes

Front 22

describe the structure of enzyme

Back 22

1. an enzyme is a protein ;
2. they have 3D / tertiary / globular structure ;
3. intramolecular bonds holding structure in place ;
4. between the R groups ;
5. active site ;
6. specificity of active site ;

Front 23

how the enzyme in the snake venom could be involved in the blood clotting process

Back 23

1. it is one of the enzymes in the clotting process has active site complementary to one of the substrates ;
2. it activating other enzymes ;
3. effect on platelets ;
4. it triggers the clotting process ;

Front 24

describe an experiment that the student could perform, using Daphnia, to confirm that herbal tea has the lowest caffeine content

Back 24

1. heart rate determined before treatment ;
2. daphnia need to be put into tea and allowed to acclimatise ;
3. practical detail e.g. use of microscope ;
4. details of determining heart rate described;
5. named controlled variable ;
6. repeats /replicates ;
7. thus heart rate of daphnia determined in white tea;

Front 25

one ethical reason for the use of invertebrates and one ethical reason against the use of invertebrates in experiments

Back 25

For:
1. Daphnia are very simple organisms / Daphnia
have basic nervous system / eq ;
Against:
1. use of (any) animal is wrong / how can we be
sure what the Daphnia can feel / ref. to possibility that the Daphnia could die / eq ;

Front 26

suggest why cells from mouth swabs or blood samples are used rather than gametes

Back 26

1. these cells are easy to collect ;
2. a relatively large amount of DNA can be collected ;
3. they contain diploid cells;
4. cells have same alleles;
5. any recessive allele will be present in them ;
6. if the gametes were tested they may not contain the recessive allele as they are haploid;

Front 27

explain why it is necessary to test for several different recessive alleles in the screening for cystic fibrosis

Back 27

1. cystic fibrosis results from one of a number of
possible mutations of this gene ;
2. testing for only one will miss other recessive alleles ;

Front 28

in the risk analysis shown, if neither partner is a carrier then it is considered that the chance of having a child with cystic fibrosis is low. explain why the probability of having a child with cystic fibrosis is low and not zero.

Back 28

1. false negatives ;
2. the screening programme does not test for all the possible mutations that can cause cystic fibrosis ;
3. mutation may occur in the formation of the gametes ;
4. mutation in both gametes ;
5. mutation may occur after fertilisation ;

Front 29

in the risk analysis shown, if one of the partners is found to be a carrier then screening for cystic fibrosis may be offered to other family members. explain why this screening is offered to other family members.

Back 29

1. idea that any other family member could be a
carrier ;
2. idea that informed choices can be made
about having children (if they know that they are carriers) ;

Front 30

describe two changes that this woman maybe able to make to her lifestyle, to reduce her risk of dying from CVD, explain how each change would reduce the risk

Back 30

1. the woman could reduce her energy intake ; weight/ BMI decreases if her energy expenditure greater than intake;

2. diet should have reduced cholesterol levels. cholesterol has been associated with high blood pressure / atherosclerosis; diet should have reduced saturated fat; reduces blood cholesterol /LDL ;

3. idea that the woman could increase the amount of exercise she took ; weight decreases if energy expenditure is
greater than her intake / exercise helps maintain a healthy heart /reduces blood pressure ;

4. idea that if the woman smoked she should reduce it ; smoking reduces oxygen uptake / increases stickiness of platelets / increases blood pressure / increases risk of atheroma ;

5. idea that diet should have reduced salt; high salt associated with high blood pressure ;

6. idea of moderate alcohol intake ; high alcohol associated with high blood pressure ;

Front 31

explain how a gene mutation may result in a protein that does not function normally.

Back 31

1, mutations are changes in the arrangement of bases in an individual gene. The genetic code carried on the DNA is translated into living cellular material during protein synthesis.
2, If a single codon is changed or misread during the process, then the amino acid for which it codes may be different.
3, different sequence of amino acid may cause different primary structure of protein.
4, It changes R groups and bonding in protein, thus protein forms different structure, thus it appeared a different 3D shape.

Front 32

mammalian gametes are formed by meiosis and have the ability to fuse to form a zygote. explain why it is important that gametes are produced by meiosis.

Back 32

1, halves the chromosome number to make it haploid cells
2, randomly assorts the chromosomes to provide genetic variation
3, the diploid number is maintained in the zygote

Front 33

explain how the genetic material from a mammalian sperm cell is able to enter an ovum to bring about the process of fertilisation

Back 33

1, acrosome
2, digestive enzymes
3, break down jelly surrounding ovum and allow head to reach the ovum membrane
4, genetic material passing through ovum membrane

Front 34

calculate the number of cells that will be present in the embryo after the first four mitotic divisions of the zygote

Back 34

16

Front 35

suggest why during the first four mitotic divisions, the embryo does not increase in volume even though the total number of cells increases.

Back 35

because no new cytoplasm is produced

Front 36

outline the events that occur in mitosis from the start of prophase up to the end of metaphase

Back 36

1, chromosomes shorten, coil and condense, thus each chromosome become visible as two chromatids
2, nuclear membrane breaks down
3, centrioles position themselves at the opposite end of the cell
4, spindles formed from microbubules between centrioles
5, chromosomes line up on the equator and attached by centromeres

Front 37

name the structure that initiates electrical activity in the heart

Back 37

pace maker

Front 38

explain what is meant by the term cardiac cycle

Back 38

1. cardiac cycle is the sequence of events from one beat to the next beat ;
2. the heart contract during systole and relaxs during diastole;
3. atrial systole → ventricular
systole → diastole / approx 30% of time spent in systole
and 70% in diastole ;
4. correct detail of electrical regulation of cardiac cycle;

Front 39

explain why the maximum blood pressure is higher in the left ventricle than in the right ventricle

Back 39

1. left ventricle has thicker muscle
2. blood from left ventricle has to divide between more
capillaries;
3. left ventricle has to pump blood further;

Front 40

explain why blood pressure varies in a ventricle during the cardiac cycle

Back 40

1. pressure increases during atrial systole as blood forced into ventricle;
2. pressure increases during initial ventricular systole due to reducing volume of ventricle;
3. pressure starts to decrease due to blood into artery / loss
of blood from ventricle ;
4. pressure decreases during diastole due to increasing volume of chamber ;

Front 41

other risk factors for heart disease

Back 41

1. gender
2. smoking
3. genes / inheritance
4. stress
5. high LDL level / LDL to HDL ratio / high blood cholesterol
6. inappropriate diet such as high salt / fat / cholesterol / calorie intake
7. high alcohol intake
8. obesity
9. lack of exercise

Front 42

suggest reasons why a range of blood LDL is given in the table rather tan a single level

Back 42

1, because LDL levels vary before and after a meal
2, differences in age, gender and genetics
3, accuracy of test and measuring equipment
4, variation within a population

Front 43

explain how a deletion in the DNA base sequence that codes for the LDL receptor protein can make a receptor protein that is non-functional

Back 43

1, deletion can lead to change of amino acid, thus the sequence of amino acid and the primary/tertiary structure of protein will change
2, the shape of protein is important in the protein's function, which is bindingof LDL, thus it became non-functional
3, frameshift

Front 44

why sample 3 is with the HH genotype?

Back 44

1, it has a lighter fragment of DNA because it is a deletion
2, therefore it moves faster towards the positive terminal
3, line is twice as thick meaning that it is homozygous

Front 45

suggest why the waxy surface of orange is removed before they are submerged in pectinase

Back 45

1. waxy layer is waterproof ;
2. enzyme in aqueous solution, therefore enzyme unable to pass through waxy layer;
3. pectinase is specific and will not digest lipid / waxy surface ;

Front 46

explain why pectinase does not hydrolyse the cellulose found in the orange peel cell walls

Back 46

shape of enzyme active site fits pectin / does not fit cellulose /

reference to specificity of enzymes ;

Front 47

suggest why chopping up the oranges could speed up hydrolysis

Back 47

1. increases the surface area ;
2. more substrate available / increases the number
of enzyme-substrate complexes / collisions between enzyme and substrate

Front 48

the pectinase shows a small increase in concentration over the 12 hours of the hydrolysis. suggest why the concentration of the pectinase increases slightly

Back 48

1. hydrolysis uses up water ;
2. evaporation of water ;
3, osmosis into orange ; so same number of the enzyme molecules but in less solvent, thus concentration of the pectinase increases;
4. pectinase released from orange tissues;

Front 49

how the cell differ when it is in anaphase

Back 49

1, centromeres have separated
2, spindle fibres visible between chromosomes
3, chromosomes are shorter/ longer in late anaphase
4, groups of chromosomes pulled toward each pole of cell

Front 50

what is meant by stem cell

Back 50

a cell which can divide and can differentiate into different types of cell

Front 51

describe how adult stem cells differ from embryonic stem cells

Back 51

1. adult stem cells are pluripotent whereas embryonic cells are totipotent ;
3. adult stem cells can only develop into certain cells whereas embryonic stem cells can develop into any kind of cell ;

Front 52

advantages of using adult stem cells rather than embryonic stem cells

Back 52

1. does not involve the ethical issues associated with embryonic stem cells;
2. can use patients own stem cells therefore no immunity problem ;
3. easier to obtain ;

Front 53

advantages of using stem cells as an alternative to organ transplants

Back 53

1. overcomes problem of shortage of donors ;
2. can use patients own stem cells therefore no immunity problem ;
3. necessary surgery less invasive / drastic / life threatening / recovery time ;
4. (probably) less expensive ;

Front 54

explain how the embryoinc stem cells used in some types of medical research are produced and obtained

Back 54

1. by fertilisation of ova by sperm ;
2. in vitro / in a test tube / ova removed from woman’s body ;
3. usually surplus /spare fertilised ova from IVF treatment ;

Front 55

explain how acrosome 's structures helps to bring about fertilisation

Back 55

releases digestive enzyme and dissolves through jelly-like layer of zona pellucida

Front 56

explain how mitochondria 's structures helps to bring about fertilisation

Back 56

provide energy to enable sperm to reach ovum

Front 57

where do unsaturated lipids have their double bonds?

Back 57

have double bonds between carbon atoms and between carbon and oxygen atoms

Front 58

name methods of prenatal testing and explain how it can be used to detect cystic fibrosis (A**)

Back 58

1, amniocentesis
2, amniotic fluid removed from amniotic sac of mother
3, embryonic cells present in amniotic fluid
4, DNA can be analysed to detect defetive genes

Front 59

name methods of prenatal testing and explain how it can be used to detect cystic fibrosis (CVS)

Back 59

1, chorionic villus sampling
2, placental tissue removed from womb of mother
3, fetal cells present in placenta tissue
4, DNA can be analysed to detect defective genes

Front 60

benefit and risk to pregnant women of prenatal testing

Back 60

Benifit:
1, gives information about possible abnormalities
2, consider termination, opportunity for choice, peace of mind

Risk:
1, possibility of miscarriage, risk of lossing babe
2, potential for incorrect result, wrong decision can be made
3, potential for harm to fetus, subsequent health issues or miscarriage

Front 61

describe the roles of the atrioventricular (bicuspid and tricuspid) valves during the cardiac cycle

Back 61

1. valves separate atria from ventricles ;
2. open during atrial systole so that blood can pass through to ventricles;
3. closed during ventricular systole to prevent backflow up into atria;
4. open during diastole so that ventricles can start to fill up as atria are filling;

Front 62

suggest reasons for the difference between pressure in the right ventricle and the pressure in the left ventricle

Back 62

1. pressure in the left ventricle is higher than that in the right ventricle;
2. left ventricle pumps blood all around body;
3. right ventricle pumps blood to lungs; if blood under high pressure there would be damage to lungs ;
4. thick wall of left ventricle ;

Front 63

distinguish between causation and correlation

Back 63

Causation:
when a change in one variable is responsible for a change in another variable ;

Correlation:
relationship between two variables such that a change in one of the variables is reflected by a change in the other variable ;

Front 64

a student concluded from the results for gender, shown in the table below (slightly difference) that higher cholesterol levels cause lower blood pressure

Back 64

1. other variables need considering for a causal relationship ;

2. named variable (e.g. genetics, ethnic group, mass of individuals, age of individuals, diet, smoking, exercise) ;

3. cholesterol level of 204 mg dm-3 may not be significantly lower than 207 mg dm-3 ;

4. 30% may not be significantly different from 26% / two values are not very different;

5. no information on how many tested / survey not repeated elsewhere ;

Front 65

reasons for drop of heart disease data

Back 65

1. people more aware of the dangers / better health education;
2. less stress ;
3. more screening ;
4. better treatments ;
5. more exercise being taken;
6. changed diet / less obesity ;
7. less alcohol intake ;
8. decrease in smoking ;
9. change in population genetics ;

Front 66

how atherosclerosis develops?

Back 66

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

Front 67

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

Back 67

1. DCPIP ;
2. use of juice ;
3. titrating juice with DCPIP ;
4. colour change e.g. from blue to colourless / pink ;
5. use calibration curve to determine vitamin C concentration / comparison with standard vitamin C ;
6. procedure being repeated at regular time intervals e.g. everyday ;
7. replication ;
8. description of one controlled variable ;
9. drawing graph of both sets of results ;

Front 68

allele?

Back 68

an allele is the different form of a gene ;

Front 69

gene?

Back 69

a gene is a section of DNA that codes for a polypeptide on a chromosome ;

Front 70

recessive allele?

Back 70

allele that is only expressed in the phenotype of an organism if the dominant allele is not present ;

Front 71

homozygous?

Back 71

alleles of a particular gene are the same

Front 72

osmosis?

Back 72

1. movement of water through a partially permeable membrane ;
2, down water concentration gradient ;

Front 73

the student concluded that there was a difference in water content of the two potatoes. suggest reasons for this difference in water content

Back 73

age, type / variety / genotypes / country of origin, storage time,
growth conditions,
part of potato used,
damage,
sprouting,
{storage conditions / temperature / humidity / light;

Front 74

suggest reasons why measuring the change in length would not be as accurate as weighing the potato pieces

Back 74

Any two from:
potato pieces are not straight,
potato widths are different,
edges may not be cut straight,
rulers are {subjective / analogues},
change in length is small,
only measuring changes in one plane

Front 75

number of stands in the nucleic acid for DNA and mRNA?

Back 75

two and one

Front 76

name of base complementary to adenine for DNA and mRNA?

Back 76

thymine and uracil

Front 77

if a protein formed at a ribosome is 300 amino acids long, state how many water molecules would be released during its synthesis?

Back 77

299

Front 78

assuming that the start codon on mRNA is three bases long and the stop condon is also three bases long, calculate the minimum number of bases in the mRNA needed o code for a protein that is 300 amino acids long

Back 78

906

Front 79

name mechanisms by which amino acids can move trough the cell surface membrane

Back 79

1, active transport/uptake
2, facilitated diffusion
3, endocytosis/pinocytosis/endopinocytosis

Front 80

describe how blood is moved through veins?

Back 80

1, skelatal muscle contracts and squeeze vein
2, blood is forced in both directions
3, in one way, valves present thus prevent backflow
4, role of thorax
5, lower pressure in heart during diastole

Front 81

structural features of a capillary that enable it to exchange materials rapidly between the blood and the surrounding body tissues

Back 81

1, walls of a capillary is only one cell think
2, small lumen
3, pores present

Front 82

variables that the student controlled by using the same Daphnia

Back 82

genotype, age, size, gender, physiological state, pre-treatment, absorption rate

Front 83

suggest why the Daphnia heart rate was higher at the end of the investigation compared to the 180 beats per minute at the start

Back 83

1, variation due to chance
2, still some caffeine present within the organism
3, time to recover from effect of caffeine
4, inaccuracy of measurements

Front 84

primary structure of a protein?

Back 84

linear sequence of amino acids joined by peptide bonds

Front 85

the investigation was repeated using DNA polymerase and starch solution but no reaction took place. explain why no reaction took place.

Back 85

1, DNA polymerase has a different shaped active site
2, so starch cannot bind
3, enzyme-substrate complexes cannot form
4, enzyme specificity

Front 86

explain fluid and mosaic

Back 86

fluid: phospholipid molecules can move within phospholipid monolayer

mosaic: proteins dotted throughout the bilayer membrane

Front 87

glycoproteins and phospholipids are molecules found in cell surface membranes. give one function of a glycoprotein.

Back 87

act as receptors

Front 88

describe the structure of a phospholipid molecule

Back 88

1. two fatty acid ‘tails’ ;
2. glycerol ;
3. phosphate ;

Front 89

how different types of lipoproteins can affect the health of the body

Back 89

1. LDLs carry most cholesterol ; LDLs bind to receptors on cell membranes ; if in high concentration, they overload receptors. results in high blood cholesterol ;thus high risk of atherosclerosis ;

2. HDLs transport cholesterol to liver ; cholesterol broken down therefore less risk of
atherosclerosis ;

Front 90

three steps to destroy a tumour

Back 90

1, stop oxygenated blood reaching tumour
2, anaerobic respiration to tumour tissue
3, build-up of lactic acid

Front 91

describe the effect of cystic fibrosis on the male reproductive system

Back 91

1, impairs functioning of male reproductive system
2, commonly causes a lack of vas deferens/sperm ducts
3, therefore no sperm released
4, if vas deferens present, lumen narrowed
5, so fewer than normal sperm released

Front 92

explain how a cornonary bypass could restore normal heart function

Back 92

1, allow oxygenated blood to reach cardiac muscle tissues
2, heart muscle beyond block able to work more efficiently
3, enables aerobic respiration
4, removal of lactic acid

Front 93

describe how ions such as Ca2+ pass through the cell surface membrane by facilitated diffusion

Back 93

1. ion binds to carrier protein in membrane
2. specificity of protein to ion
3. protein spans the membrane;
4. protein changes shape
5. ion moves down a concentration gradient;
6. until both sides are equal ;

Front 94

disaccharides can be split by what bonds?

Back 94

hydrolysis of glycosidic bonds

Front 95

amylose is an example of a ?saccharide?

Back 95

polysaccharide

Front 96

the role of starch is to?

Back 96

store energy in plants

Front 97

proteins are polymers of amino acids joined by peptide bonds formed between the?

Back 97

carboxyl group and amino group

Front 98

the 3D structure of a protein is held together by?

Back 98

disulphide bridges, hydrogen and ionic bonds

Front 99

pulmonary artery carries deoxygenated blood to the lungs. the ? returns deoxygenated blood back to the heart from the body.

Back 99

vena cava

Front 100

suggest which stage of the cardiac cycle is shown in the diagram and give a reason for your answer

Back 100

1. diastole or atrial systole ;
2. the atrioventricular valves are open / semi-lunar valves are closed ;

Front 101

describe the structure of phospholipid

Back 101

1. phosphate head ;
2. two fatty acid tails ;
4. location of glycerol ;
5. ester bonds ;

Front 102

explain how the properties of phospholipid contribute to the structure of the cell membrane?

Back 102

1. hydrophilic part, polar, charged ;
2. hydrophobic part, non polar, uncharged ;
3. orientation of molecule in
relation to water;
4. aqueous environment is on two sides

Front 103

describe the role of proteins in active transport

Back 103

1. molecule binds carrier proteins;
2. carrier protein changes shape ;
3. molecules move against a concentration gradient;
4. use of ATP / energy ;

Front 104

describe the role of proteins in facilitated diffusion

Back 104

1. proteins as channels ;
2. channels can open or close /carriers change shape ;
3. for large, polar, charged molecules to pass through membrane ;
4. molecules move down a concentration gradient

Front 105

describe the distribution of the proteins in this single cell after fusion

Back 105

1. both types of protein in fused cell in correct context ;
2. the proteins are mixed
3. same original number of protein ;

Front 106

describe how the results of "a single cell after fusion" can be explained by the fluid mosaic model

Back 106

1. phospholipids allow fluidity;
2. fluidity allow membranes to fuse;
3. fluidity allows protein to move;

Front 107

describe the effects of frequent and occasional cocaine use on the mean concentrations of von Willebrand factor and fibrinogen in the blood

Back 107

1. frequent cocaine use results in higher levels in both
blood components compared to occasional use ;
2. correct manipulation of figures to approximate the increase in levels of one of
the blood components ;
3. frequent use increases fibrinogen beyond
normal range ;
4. the levels of both the blood
components are within the range for normal levels in occasional users ;

Front 108

using information given, explain why conclusions cannot be made about the effect of occaional cocaine use on the concentrations of these blood components

Back 108

1. blood components within normal level range
2. no indication of data analysis e.g. spread of
data, statistics
3. no indication of number in samples
4. no indication of other variables

Front 109

using the information in this diagram and your own knowledge of the blood clotting process, suggest why frequent cocaine use could increase the risk of a blood clot forming

Back 109

1. von Willebrand factor results in platelets sticking to the endothelium and each
other;
2. release of thromboplastin from platelets ;
3. as a result the blood clotting process is
triggered ;
4. detail of clotting process ;
5. more fibrinogen resulting in the clot growing faster ;
6. von Willebrand factor making the platelets stickier ;
7. as a result of platelets
sticking together the clot grows faster ;
8. If the blood is flowing slower then there is an increased chance of blood clotting

Front 110

it has been suggested that there is a correlation between the cahnge in the concentration of fibrinogen in the blood and the increased risk of heart disease due to cocaine use. explain why this suggestion is valid

Back 110

1. a correlation is a relationship between two factors, when one factor
changes another factor changes ;
2. fibrinogen increases with cocaine use ;
3. heart attacks increase with cocaine use ;
4. increased fibrinogen levels have not been shown to result in the increase in heart
disease ;

Front 111

explain how a gene mutation causes a build up of mucus in the respiratory system of a person with cystic fibrosis

Back 111

1. CFTR protein;
2. a different sequence of amino acids on defective CFTR protein ;
3. change in protein ;
4. role of protein in transporting chloride ions ;
5. chloride ions not going into mucus;
6. sodium ions moving in ;
7. water does not move out of cells by osmosis ;
8. mucus on cell surface becomes thicker
9. thickened mucus cannot be moved by cilia / coughing ;

Front 112

suggest why people with cystic fibrosis are more likely to suffer from these lung infections than people without cystic fibrosis

Back 112

1. mucus traps bacteria and pathogens;
2. mucus containing the bacteria cannot be removed by cilia;
3. mucus provides conditions for bacteria to grow;
4. antibodies not being effective ;
5. trauma caused by coughing ;
6. resident phagocytes /
macrophages cannot destroy bacteria ;

Front 113

explain what is biological catalyst

Back 113

produced by cells,speeds up rate of reactions

Front 114

activation energy

Back 114

energy needed for a reaction to occur by increasing the number of collisions;

Front 115

explain why it is necessary to measure the initial rate of reaction when investigating the effect of enzyme concentration on the rate of reaction

Back 115

1. there should be enough substrate molecules to saturate the enzyme ;
2. to ensure that substrate is not a limiting factor;
3. highest rate / decreases after initial rate ;
4. as reaction proceeds substrate concentration
decreases ;
5. as substrate gets used up by enzyme
6. substrate concentration should be constant in each test;

Front 116

in this investigation, the substrate concentration was a factor that was kept constant, suggest other factors thatshould be kept constant. for each factor, state how it can be kept constant

Back 116

pH ;
buffer ;

temperature ;
water bath ; not room temperature

time of reaction ;
stopwatch ;

volume of {enzyme / substrate} ; not amount
measuring cylinder / pipette ;

type of enzyme ;
same batch of enzyme ;

Front 117

factors that increase the risk of CVD?

Back 117

genetic, diet qualified, increasing age, male,
high blood pressure, smoking, inactivity / lack of exercise

Front 118

suggest why it is necessary to have so many people involved in this study?

Back 118

1, it makes the results / data / study representative / reliable;
2. there are many potential risk
factors / large variation between individuals;
3. side effects more likely to show up ;

Front 119

suggest what the placebo could be in this study?

Back 119

solvent used for drug S / saline / water / sugar
tablet / empty capsule

Front 120

suggest why this study had to run for a number of years?

Back 120

1, CVD is not an immediate disease
2, side effects may take time to become apparent
3, need to see if drug works over a long time

Front 121

explain why drug S could be a potential statin

Back 121

it has been shown to reduce {CVD / stroke}

Front 122

using the information shown in the photographs and in the graph, describe the effects of gene therapy on these rats

Back 122

1. tumour has decreased in size
2. decrease in size quantified ;
3. rats survive longer ;
4. more rats survive / higher survival rate / lower death rate ;
5. 80% ;

Front 123

describe the role of the viruses in this investigation

Back 123

1, virus acting as a vector ;
2. virus is used to get the gene / DNA into the cells

Front 124

suggest why the injection was made into the spinal cord

Back 124

neurones in spinal cord / endorphins being made in spinal cord / spinal cord connects to brain

Front 125

compare the levels of tolerance to pain in the rats given gene therapy with the control group

Back 125

1. little change in control but treated rats rise and fall ;
2. in first 2 weeks / ½ month level of tolerance is almost the same in both groups / slightly higher in control group;
3. after the first 2 weeks the level of tolerance is higher in the rats given gene therapy
4. between 2 weeks and 2 months there is an increase in tolerance in rats given gene
therapy but control group remains the same
/ drops slightly ;
5. decrease in tolerance in group given gene therapy in last month / after two
months and slight increase in control group
6. credit correct comparative manipulation of figures ;