YEAR 12 BIOLOGY: HEART STRUCTRE Name
1. On the diagram below: i) put heads on the arrows to show the direction of blood flow ii)
name the numbered parts of the heart iii) colour the right side of the heart blue and the
left side red. [4marks]
1.
2.
3.
4.
5.
6.
7.
2. Which chambers of the heart have the thicker walls? [1mark]
3. Relate the thickness of the chambers to their functions. [2marks]
4. What is the function of the valves? Label the valves on the diagram above [2 marks]
5. What is the type of muscle that makes up the walls of the heart? Why is it so special, and
how does it maintain a constant blood supply? [3 marks]
6. Trace the pathway a drop of blood would take from the time it leaves the aorta, to the
time it returns to the left ventricle ready to leave the aorta again, describing the
chambers and vessels [4marks]
The Heart
The human heart has four chambers: two thin-walled atria on top, which receive blood, and
two thick-walled ventricles underneath, which pump blood. Veins carry blood into the atria
and arteries carry blood away from the ventricles. Between the atria and the ventricles are
atrioventricular valves, which prevent back-flow of blood from the ventricles to the atria. The
left valve has two flaps and is called the bicuspid (or mitral) valve, while the right valve has
3 flaps and is called the tricuspid valve. The valves are held in place by valve tendons
(“heart strings”) attached to papillary muscles, which contract at the same time as the
ventricles, holding the vales closed. There are also two semi-lunar valves in the arteries (the
only examples of valves in arteries) called the pulmonary and aortic valves.
The left and right halves of the heart are separated by the inter-ventricular septum. The
walls of the right ventricle are 3 times thinner than on the left and it produces less force and
pressure in the blood. This is partly because the blood has less far to go (the lungs are right
next to the heart), but also because a lower pressure in the pulmonary circulation means
that less fluid passes from the capillaries to the alveoli.
The heart is made of cardiac muscle, composed of cells called myocytes. When myocytes
receive an electrical impulse they contract together, causing a heartbeat. Since myocytes
are constantly active, they have a great requirement for oxygen, so are fed by numerous
capillaries from two coronary arteries. These arise from the aorta as it leaves the heart.
Blood returns via the coronary sinus, which drains directly into the right atrium.
PLASMA MEMBRANE
Phospholipid bilayer:
Periperal protein on the inner surface:
Peripheral protein on the outer surface:
Integral protein:
Glycoprotein:
Cytoskeleton:
AS Biology:
UNIT 1 Biology and Disease
1.
2.
3.
4.
5.
6.
CAUSES OF DISEASE.
ENZYMES AND THE DIGESTIVE SYSTEM.
CELLS AND THE MOVEMENT IN AND OUT OF THEM.
LUNGS AND LUNG DISEASES.
THE HEART AND HEART DISEASE .
IMMUNITY.
TOPIC 1 CAUSES OF DISEASE :
1.
Smoking is a risk factor associated with coronary heart disease. Smoking is known to raise
the concentration of fibrinogen in the blood, promote the aggregation of platelets and reduce
the ability of arteries to dilate.
Use this information to:
(a)
explain the effect of smoking on blood pressure;
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
(b)
explain how smoking might lead to the formation of a blood clot.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(3)
Total 5 marks)
Ans1 (a)
(b)
Because arteries cannot dilate / dilate less;
Heart must work harder to force blood through;
Increases blood pressure;
max 2
Higher blood pressure causes damage to blood vessel lining / endothelium
/ collagen;
Platelets stick together / form a plug / adhere to collagen fibres;
Release of thromboplastin / thrombokinase;
Fibrinogen converted to insoluble fibrin;
Platelet plug trapped by fibrin mesh;
max 3
[5]
2.
Melanoma is a malignant skin cancer. The graph shows the incidence of melanoma in the
UK between 1970 and 1990.
10
Females
8
Males
6
Incidence
per 100 000 of
population 4
2
0
1970
(a)
1980
Year
1990
Explain what is meant by malignant.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
(b)
(i)
Over the period shown, the incidence of melanoma has increased. Give two
other conclusions that can be drawn from the graph, about the incidence of
melanoma.
.............................................................................................................
.............................................................................................................
.............................................................................................................
.............................................................................................................
(2)
(ii)
In a population of 1 million people where half were male and half were female,
how many people developed melanoma in 1980? Show your working.
Answer = ...................................
(2)
(iii)
Melanoma is more common in fair-skinned people living in sunny parts of the
world than in the UK. Explain why.
.............................................................................................................
.............................................................................................................
.............................................................................................................
.............................................................................................................
.............................................................................................................
(2)
Total 8 marks)
Ans 2 (a)
(b)
(Cancer = ) mass of cells that divide continuously / uncontrolled / faster;
(Malignant = ) can spread (to other body parts);
(i)
(ii)
(iii)
2
Higher incidence in females than males / females have higher risk;
Correlation between changes in males and females / changes in both
occur at same times;
Change in rate between c1981-1986 / larger increase then;
2
Male = 3 (per 100,000) and female = 5 (per 100,000);
(5 x 3) + (5 x 5) = 40;
Reject correct answer based on wrong readings
2
Fair-skinned people contain less pigment / melanin / melanocytes;
More UV light in sunny parts;
Reject lifestyle argument
[8]
3.
2
The bar chart shows the effects of smoking and alcoholic drinks on the risk of developing
mouth cancer.
40
35
No alcoholic
drinks
30
Risk of
25
developing mouth
cancer / arbitrary 20
units
15
1 to 3 alcoholic
drinks per day
4 or more alcoholic
drinks per day
10
5
0
Non-smokers
(i)
20-40
cigarettes
per day
Over 40
cigarettes
per day
Describe the effects of smoking and drinking on the risk of developing mouth cancer.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(3)
(ii)
Suggest one reason why people who neither drink nor smoke sometimes develop
mouth cancer.
........................................................................................................................
........................................................................................................................
(1)
(Total 4 marks)
Ans 3.
(i)smoking and drinking increase risk;
risk increases for nonsmokers with more alcohol;
20-40 cigarettes increases risk;
at all levels of alcohol consumption;
4 or more drinks increase risk in all groups;
worst risk with combination of 40+ cigarettes and 4 or more drinks;
smoking and drinking together have a greater effect than either
on its own;
over 40 cigarettes and no alcohol greater than 1 or 2 alcoholic
drinks/valid comment about anomaly;
3 max
(ii)
other environmental factor/e.g. passive smoking;
genetic predisposition / inherited from parents;
mutation;
4.
The table shows some information about the incidence of high blood pressure and heart
attacks in the UK.
Sex
Male
Female
(a)
Condition
high blood pressure
heart attack
high blood pressure
heart attack
Percentage of people affected in each age group
16-24 25-34 34-44 45-54 55-64 65-74 74-80
years years years years years years years
0.5
1.5
0.7
1.6
3.5
0.1
3.8
0.1
6.0
0.2
7.8
0.3
17.0 22.5 18.5
1.1 2.4 3.2
20.5 27.9 26.9
0.6 0.7 1.8
Use the pattern of data in the table to describe:
(i)
two similarities between males and females;
1 ...................................................................................................
.............................................................................................................
2 ...................................................................................................
.............................................................................................................
(ii)
two differences between males and females.
1 ...................................................................................................
.............................................................................................................
2 ...................................................................................................
.............................................................................................................
(4)
(b)
People have been advised to reduce their cholesterol intake as a part of a healthy life
style. The graph shows information about mean daily intake of cholesterol.
700
700
600
500
480
Key
Male
Female
378
Cholesterol 400
intake/mg day–1 300
252
200
100
0
1960
Year
1995
Calculate which group, male or female, shows the greater percentage reduction in
cholesterol intake between 1960 and 1995. Show your working.
(2)
(c)
Explain how smoking and a high blood cholesterol concentration increase the risk of
developing coronary heart disease.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(6)
(Total 12 marks)
Ans4. (a)
(i)
(ii)
(b)
(c)
(Risk of):High blood pressure increases with age;
Heart attack increases with age / no heart attacks before 35 years;
2
Females (or reverse argument for males):
More likely to develop high blood pressure;
Have lower risk of heart attack (as they get older / post-55);
2
Male is (700 – 378 = 322, 322 / 700 = ) 46%;
Female because (480 – 252 = 228 / 480 = ) 47.5%;
2
Principle:
CHD = heart muscle receives inadequate amount of blood
or oxygen / (coronary) blood supply reduced;
Smoking:
Raises concentration of fibrinogen (in blood) / increased risk of
clotting;
Increases viscosity of blood;
(Nicotine) causes platelets to stick together / causes vasoconstriction;
Carbon monoxide associated with plaque formation;
Reduces ability of arteries to dilate / reduces elasticity;
Cholesterol:
Fatty streaks / deposits adhere to wall of arteries;
Atheroma / atherosclerosis / plaque;
Narrows lumen of artery;
Damages endothelium;
Can lead to formation of thrombus / blood clot;
Clots need to be in context
6 max
[12]
TOPIC 2 ENZYMES AND THE DIGESTIVE SYSTEM
1.
Sucrose is a disaccharide. It is also a non-reducing sugar.
(a)
Benedict’s solution is used to identify non-reducing sugars.
Complete the flow chart to show the steps you would carry out in order to get a
positive result.
Add (i) ....................................................................................................
(ii) ...................................................................................................
Add Benedict's solution then heat in a water bath
Red-brown precipitate indicates a non-reducing sugar
(2)
Ans 1.
2.
(a)
Neutralise/Add alkali/named alkali
Hydrochloric acid;
2
PrP is a protein normally found in brain tissue. The diagram shows part of the structure of a
PrP molecule. The dotted line represents the middle part of the molecule which has been left
out of this diagram.
Position X
C
O
(a)
(i)
OH
Name the monomers which make up this molecule.
.............................................................................................................
(1)
(ii)
Name one chemical element which would be found in this molecule but not in a
polysaccharide molecule.
........................................................................................................
(1)
(iii)
Give the formula of the chemical group that would be found at position X on
the molecule.
......................................................................................................
(1)
PrP molecules are found on the outside of the cell surface membranes of nerve cells. The
precise function of PrP is still unknown but it is thought that its tertiary structure enables it to
act as a receptor molecule.
(b)
Describe:
(i)
the secondary structure of a protein,
...................................................................................................
..................................................................................................
(1)
(ii)
the tertiary structure of a protein.
................................................................................................................................
................................................................................
(1)
(c)
(i)
What is meant by a receptor molecule?
.........................................................................................................
......................................................................................................
(1)
(ii)
Explain how its tertiary structure might allow a protein molecule to act as a
receptor molecule.
........................................................................................................
.......................................................................................................
.........................................................................................................
......................................................................................................
(2)
(d)
It appears that when a cow gets BSE something causes the PrP molecules to become
sticky so that they clump together. With an electron microscope, string-like fibrils
composed of clumps of PrP can be seen in the brain tissue of cattle affected by BSE.
Explain why the string-like fibrils of PrP can be seen in the brain tissue of cattle with
an electron microscope but not with a light microscope.
.................................................................................................................
..................................................................................................................
..................................................................................................................
...................................................................................................................
(2)
(e)
It is not known what makes the PrP molecules stick together. One hypothesis is that an
unknown infectious agent may bring about a change in the secondary structure of the
PrP molecule. This could explain the fact that the PrP molecules in fibrils are resistant
to the action of protein-digesting enzymes which bring about the hydrolysis of PrP
from healthy animals.
(i)
Describe what happens during hydrolysis of PrP.
........................................................................................................
............................................................................................................
.......................................................................................................
..........................................................................................................
(2)
(ii)
Suggest how a change in the secondary structure of the PrP molecule could
explain the fact that PrP in fibres is resistant to the action of protein-digesting
enzymes.
......................................................................................................
......................................................................................................
..........................................................................................................
.......................................................................................................
..................................................................................................
(2)
(Total 14 marks)
Ans 2.
Quality of Written Communication
The parts to many of the answers to this question require continuous prose. To gain one mark
for Quality of Written Communication these answers should be presented in clear, scientific
English. Technical terminology should have been used effectively and should usually be
accurate
(a)
(i)
Amino acids
1
(ii)
Nitrogen / sulphur
1
(iii)
NH2
1
(b)
(c)
(d)
(e)
(i)
Amino acid chain coiled / pleated / helix
1
(ii)
Further folding / secondary structure folded / globular shape
1
(i)
One into which other molecules/ hormones/ fit
1
(ii)
Tertiary structure gives receptor particular shape; Provides sites into which
hormone fits
2
Fibrils thin / close together;
Electron microscope has greater resolution /
can distinguish between objects close together;
because wavelength of electron beam smaller;
(i)
(ii)
Max 2 marks
Breakdown into amino acids;
involving the addition of water;
2
Change in secondary structure would change the shape of
PrP molecule; No longer fits/binds with / forms enzyme-substrate
complexes with; active site of enzyme/endopeptidase;
3
[l5]
3.
(a)
Diagram A shows an enzyme, and B is the substrate of this enzyme.
A
B
By drawing on this diagram, show how a competitive inhibitor would affect the
activity of the enzyme.
(2)
(b)
The graph shows the effect of changing substrate concentration on the rate of an
enzyme controlled reaction.
Rate
of
reaction
X
Substrate concentration
Explain why increasing substrate concentration above the value shown at X fails to
increase the rate of reaction further.
.......................................................................................................................
.......................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
(c)
Explain how adding excess substrate could overcome the effect of a competitive
inhibitor.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
(Total 6 marks)
Ans 3.
(a)
(b)
(c)
Similar shaped but not identical molecule drawn;
occupying active site
2
Substrate concentration now not limiting /
enzyme concentration now limiting factor;
Substrate more likely to form enzyme substrate complex /
active sites all occupied;
2
More / higher ratio of substrate molecules than inhibitor molecules;
therefore more likely to occupy actives sites than substrate will occupy;
more likely to collide with active sites / displace inhibitor
max 2
[6]
4.
The diagram shows the structure of the amino acid seine.
OH
H
C
H
H
O
N
C
H
C
OH
H
(a)
(i)
Draw a box on the diagram around the R group of serine and label the box with
the letter R.
(1)
(ii)
Draw a circle around each of the parts of the serine molecule which would be
removed when two other amino acid molecules join directly to it.
(1)
(b)
(i)
Which two substances are formed when two amino acid molecules join
together?
1 .........................................................................................................
2 .......................................................................................................
(1)
(ii)
Name the type of bond formed between the joined pair of amino acid molecules.
.............................................................................................................
(1)
(c)
Explain how a change in the primary structure of a globular protein may result in a
different three-dimensional structure.
.......................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(3)
(Total 7 marks)
Ans4. (a)
(b)
(c)
(i)
box drawn around R group (i.e. CH2OH group)
(allow circle if labelled R);
(ii)
circle drawn around either of the Hs on NH2 group and circle drawn
around the OH;
1
(i)
(di)peptide and water;
1
(ii)
peptide;
1
sequence of amino acids changes;
tertiary structure changes/folds in a different way;
bonds form in different places;
(Reject peptide bonds)
1
3
[7]
TOPIC 3: CELLS AND MOVEMENT IN AND OUT OF THEM
1.
The diagram shows part of an animal cell as seen through an electron microscope.
(a)
Name the organelles labelled A and B.
A ..............................................................................................................
B .............................................................................................................
(2)
(b)
Explain why the shapes of the two organelles labelled A appear different.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
(c)
Give the function of organelle B.
........................................................................................................................
........................................................................................................................
(1)
(d)
The epithelial cells of the small intestine have large numbers of organelle A.
Explain how this is an adaptation for the function of these cells.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(3)
(Total 8 marks)
Ans 1.
(b)
(a)
B ribosomes (accept ribosomes and rER);
A mitochondria;
2
idea of sections or cuts;
idea of mitochondria orientated differently or in different positions /
description of 3D structure of mitochondria, e.g. sausage-shaped;
2
(c)
translation / protein/polypeptide synthesis;
1
(d)
provide/produce energy or ATP (reject create energy);
(disqualify first mark if ‘for respiration’)
high respiration (rate) (accept lots);
for active uptake / transport (accept description);
absorption of digested food/substances/products/correctly named product
(only accept monosaccharides, amino acids, dipeptides);
3 max
[8]
2.
The diagram shows part of a plasma membrane.
(a)
Describe two functions of the structure made from the parts labelled X.
1 ..............................................................................................................
........................................................................................................................
2 .............................................................................................................
........................................................................................................................
(2)
(b)
Give one function of the molecule labelled Y.
........................................................................................................................
........................................................................................................................
(1)
(c)
The part labelled Z is involved in facilitated diffusion of substances across the
membrane.
(i)
Give one similarity in the way in which active transport and facilitated diffusion
transport substances across the membrane.
.............................................................................................................
.............................................................................................................
(ii)
Give one way in which active transport differs from facilitated diffusion.
.............................................................................................................
.............................................................................................................
(2)
(iii)
The graph shows the relationship between the concentration of a substance
outside a cell and the rate of entry of this substance into the cell.
Rate of entry
of substance
into cell
External concentration of substance
Explain the evidence from the graph that this substance is entering the cell by
facilitated diffusion and not by simple diffusion.
.............................................................................................................
.............................................................................................................
(2)
(Total 7 marks)
Ans 2.
(b)
(c)
(a)
two of the following:
form(water) impermeable barrier to water-soluble substances / selectively
permeable / allows non-polar molecules to pass through;
allows cell to maintain different concentrations either side;
makes membranes self-sealing/able to fuse with other
membranes/able to form
vesicles / gives flexibility/fluidity;
2 max
(surface/extrinsic protein) for cell recognition / binding to
hormones/identification
1
(i)
involves carrier/transmembrane/transport proteins;
(reject channel proteins)
1
(ii)
requires energy/requires use of ATP / moves substances/ions/molecules
against a concentration gradient;
1
the curve levels off above a certain external concentration of substance;
as channel proteins are saturated with molecules
(and no more can be carried);
2
(iii)
[7]
3. Protein molecules in the cell surface membrane are involved in the active transport of glucose
molecules into the cell.
(a)
The graph shows how the uptake of glucose by red blood cells varies with the glucose
concentration of the surrounding medium.
Rate of
uptake
glucose
Concentration of glucose
in surrounding medium
Explain the shape of the curve.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(3)
(b)
The table shows the results of an investigation into differences in the rates of uptake of
different sugars by red blood cells.
Sugar
(i)
Relative rate of uptake
Glucose
100
Galactose
13
Xylose
7
Give one factor, other than the concentration of sugar in the surrounding
medium, which should have been standardised in this investigation. Describe
and explain how variation in this factor would affect the rate of uptake.
Factor...................................................................................................
Explanation..........................................................................................
.............................................................................................................
.............................................................................................................
.............................................................................................................
(2)
(ii)
Use your knowledge of protein molecules in cell surface membranes to suggest
why the rate of uptake of these sugars differs.
.............................................................................................................
.............................................................................................................
.............................................................................................................
(2)
(Total 7 marks)
Ans3 .
(b)
(a)
In first part of the curve concentration of glucose in surrounding
medium limiting/rate of uptake dependent on glucose;
More glucose molecules, more protein carriers occupied;
In second part number of proteins/carriers limiting/working at full capacity;
All carriers occupied;
max 3
(i)
(ii)
Temperature;
Would increase the rate of movement/kinetic energy of molecules/
gives more chance of colliding with carrier;
or
Temperature/pH;
Denature protein carriers;
or
Number of red blood cells;
More uptake because greater surface area/more carriers;
or
Oxygen;
Linked to ATP/energy/respiration and active transport;
Concept of shape of different molecules/receptor site;
Concept of fit determining specificity;
More carriers for glucose;
2
max 2
[7]
4.
The diagram shows part of a plant cell as seen through an electron microscope.
(
a)
Name organelles
A
..........
..........
..........
..........
..........
..........
.......
B
..........
..........
..........
.....................................
C ...................................................................
(3)
(b)
Give the function of
(i)
structure X;
.............................................................................................................
.............................................................................................................
(ii)
structure Y.
.............................................................................................................
.............................................................................................................
(2)
(c)
Calculate the width of the structure labelled X in micrometres.
Show your working.
Width ............................ micrometres (µm)
(2)
(Total 7 marks)
Ans4 (a)
(b)
A ribosome (RER neutral);
1
B vacuole;
1
C smooth ER / SER;
1
(i)
(ii)
(c)
support / strength / shape / prevents osmotic lysis;
(protection, permeability neutral)
1
photosynthesis / light energy  chemical energy;
(makes food/sugar neutral)
1
0.2 – 0.24 gains 2 marks;
ELSE evidence of observed measurement
(5 – 6 mm / 0.5 – 0.6 cm) ÷ 25 000
gains one mark;
2
[7]
5.
Cholera is a water-borne disease caused by the intestinal pathogen, Vibrio cholerae. The
pathogen produces an exotoxin which acts specifically on the epithelial cells of the small
intestine causing changes in membrane permeability. Individuals with cholera suffer from
severe diarrhoea which may result in death.
(a)
Suggest two precautions which could be used to prevent the transmission of cholera.
1 ....................................................................................................................
2 .............................................................................................................
(1)
(b)
Explain how the effects of diarrhoea on the body can be treated.
........................................................................................................................
........................................................................................................................
........................................................................................................................
(c)
........................................................................................................................
(i)
What is an exotoxin?
(2)
.............................................................................................................
.............................................................................................................
(1)
S
(ii)
Suggest why the cholera exotoxin is specific to the epithelial cells of the small
intestine.
.............................................................................................................
.............................................................................................................
.............................................................................................................
.............................................................................................................
(2)
S
(d)
The cholera exotoxin affects the movement of ions through the intestinal wall. It
causes the loss of chloride ions from the blood into the lumen of the small intestine.
This prevents the movement of sodium ions from the lumen of the small intestine into
the blood.
(i)
Describe how sodium ions normally enter the blood from the cells of the
intestinal wall against a concentration gradient.
.............................................................................................................
.............................................................................................................
.............................................................................................................
(2)
(ii)
Use the information provided to explain why individuals with cholera have
diarrhoea.
.............................................................................................................
.............................................................................................................
.............................................................................................................
.............................................................................................................
(2)
(Total 10 marks)
Ans5. (a)
(b)
(c)
effective water / sewage treatment / prevent water contamination /
improved hygiene / vaccination / quarantining of affected area; (any two)
1
oral rehydration therapy/ORT;
replaces lost water and salts;
OR
drinking large amounts of water;
with salts/minerals;
(i)
(protein/poison) excreted / secreted by bacteria;
2
1
(ii)
(d)
(i)
(ii)
receptor / proteins on membrane;
complementary shape of exotoxin;
2
active transport;
using ATP / carrier proteins;
2
higher solute concentration / water potential lowered in small intestine;
osmotic loss of water;
2
[10]
Topic 4 : Lungs and Lung disease
1.
(a)
Figure 1 shows the change in lung volume during inspiration.
Change
in lung
volume
/dm 3
0.5
0
Time
Figure 1
Sketch a curve on the axes in Figure 2 to show the expected change in alveolar
pressure during inspiration.
increase
Change in
alveolar
0
pressure
Time
decrease
Figure 2
(1)
(b)
Breathing rate changes as the concentration of carbon dioxide and of oxygen in
inspired air, and the pH of arterial blood, change. This is shown in Figure 3.
Figure 3
80
Carbon
dioxide
concentration
60
Breathing rate
/dm 3 minute –1
40
Oxygen
concentration
pH
20
0
Carbon dioxide
concentration HIGH
Oxygen
concentration
LOW
pH
(i)
ALKALINE
HIGH
LOW
ACID
Which factor has the greatest effect on breathing rate? Give evidence from the
graph to support your answer.
.............................................................................................................
.............................................................................................................
.............................................................................................................
(1)
(ii)
Divers who do not use air tanks may inhale and exhale deeply several times in
quick succession before diving. As a result, they may lose consciousness and
drown. Using information in the graph, explain why they may lose
consciousness.
.............................................................................................................
.............................................................................................................
.............................................................................................................
.............................................................................................................
(3)
(c)
The diagram shows how the ventilation cycle is controlled.
Inspiratory cells in
medulla oblongata
of the brain
Stimulation
Diaphragm and
external intercostal
muscles contract
Inhibition
Lungs expand
Stretch receptors
in air passages
Explain how the stretch receptors are involved in controlling the ventilation cycle
through negative feedback.
.......................................................................................................................
.......................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(3)
(Total 8 marks)
Ans1. (a)
(b)
Decreasing line / initial drop followed by increasing line (‘U’ shape);
(i)
(ii)
(c)
1
CO2 concentration as most marked response /
covers biggest range / greatest increase;
1
Decreased CO2 concentration in blood;
breathing centre no longer stimulated;
lack of O2 causes unconsciousness;
3
Stimulus
Action
Response
-Lung expansion causes activation of stretch receptors;
-which prevent the inspiratory / medulla / brain cells from
generating impulses;
-so the diaphragm and intercostal muscles are unable to contract;
causing the stretch receptors to be no longer stimulated;
so nerve impulses are generated again by the medulla;
leading to lung expansion;
3
[8]
2.
The diagram shows some of the nerve pathways involved in the control of ventilation in
humans.
Chemoreceptors sensitive
to carbon dioxide
Respiratory
centre in
medulla
Key
Nerves
Stretch receptors
in lungs
(a)
Give one place where chemoreceptors sensitive to carbon dioxide are found.
........................................................................................................................
(1)
(b)
Describe the role of the stretch receptors in the lungs in the maintenance of breathing.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
(c)
A person was asked to hyperventilate while his pattern of breathing was being
recorded. The trace shows the changes in the pattern of breathing before, during and
after hyperventilation.
Breathing
movements
Normal
Hyperventilation
Time
Recovery
(i)
Describe how the pattern of breathing changed when the person was
hyperventilating.
.............................................................................................................
.............................................................................................................
(1)
(ii)
Suggest an explanation for the long delay after hyperventilation before
breathing started again.
.............................................................................................................
.............................................................................................................
.............................................................................................................
.............................................................................................................
(2)
(Total 6 marks)
Ans2. (a)
(b)
(c)
Carotid body / aortic body / medulla
1
Inflation of the lungs stimulates these receptors which transmit impulses;
to respiratory centre / medulla inhibiting inspiration and allowing
expiration.
2
(i)
Rate and depth of breathing increased
1
(ii)
(Hyperventilation) removes carbon dioxide;
Time required for carbon dioxide concentration to increase in blood.
2
[6]
3.
The table shows the number of deaths from various causes in a group of individuals of the
same age. Individuals were identified as smokers or non-smokers.
Cause of Death
Number of deaths among
smokers
Number of deaths among
non-smokers
Total deaths (all causes)
7316
4651
Coronary artery disease
3361
1973
556
428
86
29
Lung cancer
397
37
Other causes
2916
2184
Strokes
Aneurysm
(a)
Why was it necessary for the smokers and the non-smokers to be the same age?
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
(b)
Do the figures in the table show that smokers were more likely to have died from a
stroke than non-smokers? Use suitable calculations to support your answer.
(3)
(c)
The bar chart shows the risk of developing lung cancer in relation to the number of
cigarettes smoked per day before stopping, and the number of years since giving up
smoking.
×40
×35
Key
Relative ×30
risk of lung
cancer
×25
Years since giving
up smoking
1–4
30+
×20
×15
×10
×5
×0
1–10
11–20
21–30
31–40
41+
Cigarettes smoked per day before giving up smoking
(i)
Give two conclusions that can be drawn from the information in the bar chart.
1 ...................................................................................................
.............................................................................................................
2 ...................................................................................................
.............................................................................................................
(2)
(ii)
Explain what is meant by “relative risk” on the y-axis of the bar chart.
.............................................................................................................
.............................................................................................................
.............................................................................................................
.............................................................................................................
(2)
(d)
Explain what is meant by a malignant tumour and describe how exposure to cigarette
smoke may result in the formation of a malignant tumour.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(6)
(Total 15 marks)
Ans3. (a)
Enables comparison to be made;
Since increase in incidence with age/ older people have had more
exposure to cigarettes;
2
(b)
(c)
No/ incorrect response with some attempt at calculation based on 556
and 428 as numerators; = 1 mark
No/ incorrect response with correct calculation; = 2 marks
Correct response (non-smokers have greater risk than smokers)
with calculation of 556/7316 × 100 = 7.6% and 428/4651 × 100 =
9.2% for smokers and non-smokers respectively; = 3 marks
3
(i)
2
(ii)
(Relative risk of) lung cancer decreases the longer it is since
giving up smoking;
(Relative risk of) lung cancer increases with the number of
cigarettes smoked per day;
1.
2.
3.
4.
5.
6.
7.
8.
9.
Mass of abnormal cells;
Idea of spread/ metastasis;
Altered DNA/ biochemical differences;
Rapid rate of cell division/ uncontrolled cell division;
Cigarette smoke contains carcinogens/ mutagens/
cancer-causing chemicals;
Causes changes in DNA;
Of genes that control cell division;
Reference to oncogenes;
Reference to tumour suppresser genes;
2
max 6
[15]
4.
Read the following passage.
When a person breathes in, the diaphragm muscle contracts and the diaphragm
flattens. This, together with movement of the ribs, leads to air being drawn into the
lungs. Breathing out is generally passive and results from the relaxation of the
diaphragm muscle and the elastic recoil of the lung tissue.
5
10
Two sets of intercostal muscles also play an important part in breathing in humans.
Contraction of the external intercostal muscles is associated with breathing in. During
strenuous exercise, contraction of the internal intercostal muscles helps force air out of
the lungs. In this case, breathing out is active.
Crocodiles also have lungs and breathe air. They have well developed intercostal
muscles
but do not appear to use these during breathing. They also lack a diaphragm.
Breathing in, in crocodiles, is brought about by contraction of muscles attaching the
liver to the hip bones (see diagram). This pulls the liver back and causes air to enter
the lungs.
Breathing out results from the contraction of abdominal muscles which move the liver
forwards.
Lungs
Liver
Muscles
Hip bone
Use information in the passage and your own knowledge to answer the questions.
(a) Describe the movement of the ribs when a person breathes in (line 2).
.....................................................................................................................................
.....................................................................................................................................
(1)
(b)
(i)
Explain what is meant by passive (line 3).
.............................................................................................................
.............................................................................................................
(1)
(ii)
Is breathing out in crocodiles active or passive? Explain your answer.
.............................................................................................................
.............................................................................................................
(1)
(c) Explain how movement of the liver causes air to enter a crocodile’s lungs.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(3)
(d)
Describe the difference in the composition of gases in inhaled and exhaled air. Explain
how these differences are caused.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(6)
(Total 12 marks)
Ans4. (a)
(b)
(ii)
(c)
(d)
up and out;
(i)
1
does not require work/effort / involve muscle contraction/energy
expenditure;
1
active as it involves contraction of muscles;
1
liver moves back;
increases volume of lungs;
pressure lower (in lungs than outside);
maximum of three marks for description, points 1 to 4
1 inhaled air contains more oxygen than exhaled air;
2 inhaled air contains less carbon dioxide than exhaled air;
3 inhaled air contains less water (vapour);
3 max
4
5
6
7
8
relative amount/percentage of nitrogen also changes;
respiration results in lower blood oxygen / higher blood carbon dioxide;
oxygen enters blood / carbon dioxide leaves blood in alveoli;
by diffusion;
water vapour diffuses from moist surface;
6 max
[12]
TOPIC 5: THE HEART AND HEART DISEASE
1.
(a)
The diagram shows a human heart.
Left atrium
Coronary artery
(i)
Use a guideline and label to show the position of the sinoatrial node (SAN).
(1)
(ii)
What is the function of the coronary artery?
.............................................................................................................
.............................................................................................................
(1)
(b)
Impulses spread through the walls of the heart from the SAN. The table shows the rate
of conduction of impulses through various parts of the conducting tissues.
Rate of conduction / m s–1
Mean distance / mm
From SAN to
atrioventricular node
(AVN) across atrium
1.0
40
Through AVN
0.05
5
From AVN to lower end
of bundle of His
1.0
10
Along Purkyne fibres
in ventricle walls
4.0
–
Part of pathway
(i)
Calculate the mean time taken for an impulse to pass from the SAN to the lower
end of the bundle of His. Show your working.
................................... s
(2)
(ii)
Explain the advantage of the slow rate of conduction through the AVN.
.............................................................................................................
.............................................................................................................
.............................................................................................................
.............................................................................................................
(2)
(iii)
Suggest one advantage of the high rate of conduction in the Purkyne fibres
which carry impulses through the walls of the ventricles.
.............................................................................................................
.............................................................................................................
(1)
(c)
How would cutting the nerve connections from the brain to the SAN affect the beating
of the heart?
........................................................................................................................
........................................................................................................................
(1)
(Total 8 marks)
Ans 1 (a) (i)
(b)
guideline to upper part of right atrium;
1
(ii)
supply oxygen / nutrients to heart muscle / for contraction;
1
(i)
0.15s = 2 marks;
(working 0.04 + 0.10 + 0.01 = 1 mark)
(allow 1 mark for correct method dividing each distance by rate)
2
delays contraction of ventricles;
until after atria have contracted / ventricles filled;
2
rapid contraction of ventricles / both ventricles contract
together / rapid transmission to tip so contraction starts at
bottom of ventricles;
(reject strong contraction)
1
(ii)
(iii)
(c)
rate of heart beat not adjusted to activity / carries on beating at
constant rate / myogenic, so no effect;
(Accept: rate would increase because parasympathetic normally inhibits)
1
[8]
2.
The diagram shows a human heart
(a)
On the diagram, label the position of the atrioventricular node.
(1)
An electro-cardiogram (ECG) is produced by placing electrodes on the chest to detect
electrical changes in the heart.
The diagram shows an ECG and the pressure changes during a human cardiac cycle.
Pressure
in aorta
Blood
pressure
Pressure in
left ventricle
R
T
P
P
ECG
Q
0
(b)
(i)
0.1
S
0.2
0.3
0.4
Time/seconds
0.5
0.6
0.7
0.8
The QRS wave is associated with the spread of electrical activity over the
ventricle. Explain the evidence in the graph which supports this.
.............................................................................................................
.............................................................................................................
.............................................................................................................
.............................................................................................................
(2)
(ii)
Explain why there is no change in the electrical activity between 0.31s and
0.77s.
.............................................................................................................
.............................................................................................................
(1)
(c)
(i)
At what time in the cardiac cycle does the aortic semilunar valve open?
.............................................................................................................
(1)
(ii)
The pressure changes shown in the diagram are on the left side of the heart.
Sketch a curve on the graph to show the pressure changes in the right ventricle.
(2)
(Total 7 marks)
Ans2 (a)
(b)
correct position of AVN; (at the top of Purkyne tissue)
(i)
pressure in ventricles increasing (so ventricle contracting);
QRS occurs before pressure increase/ventricle contraction/
contracts after S / 0.14s;
2
corresponds to time when heart is relaxed/filling with blood/
diastole / not contracting;
1
(i)
0.2s ;
1
(ii)
line below left ventricle;
in phase with left ventricle;
2
(ii)
(c)
1
[7]
3.
(a)
What is atheroma?
........................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
(b)
Describe how atheroma can lead to an aneurysm.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
(Total 4 marks)
Ans 3.
(b)
(a)Plaque/ fatty material/ cholesterol/ foam cells/ lipoprotein build up;
In artery/ blood vessel wall;
2
Weakens artery wall;
So that it swells/ bursts;
2
[4]
4.
Figure 1
(a)
Figure 1 shows a section through a healthy coronary artery. The actual diameter of the
lumen of the artery along line AB is 1.94 mm. Explain how you would calculate the
magnification of this drawing.
........................................................................................................................
........................................................................................................................
........................................................................................................................
(1)
(b)
Figure 2 shows a section through a coronary artery from a person with atheroma.
Figure 2
(i)
Give two ways in which the artery of the person with atheroma differs from the
artery of the healthy person.
1 ...................................................................................................
.............................................................................................................
2 ...................................................................................................
.............................................................................................................
(2)
(ii)
Describe and explain how atheroma can lead to myocardial infarction.
.............................................................................................................
.............................................................................................................
.............................................................................................................
.............................................................................................................
.............................................................................................................
(3)
(Total 6 marks)
Ans4. (a)
(b)
measured diameter (mm)
 magnificat ion;
1.94
[Note: marks in this answer are awarded for explanation.
The answer gains no marks]
1
(i)
Lumen narrower (in diseased artery);
Wall thicker (in diseased artery);
Cholesterol/fatty tissue/plaque/lipids/atheroma/foam cells invading
wall/in wall(i.e. not on endothelium);
max 2
[Note: If answers start “it” assume this refers to the diseased artery]
(ii)
Atheroma/fatty material deposited in wall of artery;
Causes turbulence/damage to endothelium/raises blood pressure;
Blood clot formation;
Atheroma/blood clot lodges in narrowed blood vessel/coronary artery;
Reduces oxygen (supply) to (region of) heart muscle/heart cells;
max 3
[6]
TOPIC 6: IMMUNITY
1.
(a)
Describe the methods of transmission and the symptoms of Salmonella food
poisoning.
Explain the methods by which its incidence might be reduced.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(5)
(b)
Antibodies can be used to give protection against infection by some pathogenic
microbes. Explain how a bacterium could be genetically engineered to produce an
antibody.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(5)
(Total 10 marks)
Ans1. (a)
(b)
Bacterium transmitted in infected faeces;
or from undercooked food;
causes vomiting and diarrhoea;
Correct cooking of meat ensures that temperatures reached kill bacteria;
Correct storage avoiding risk of cross-infection;
Personal hygiene avoiding contaminated food
max 5
Determine nucleotide sequence for antibody;
extract genetic material from lymphocyte;
use restriction endonuclease to remove nucleotide sequence;
cut bacterial plasmid with same endonuclease;
use ligase to splice sequence into plasmid;
detail, e.g. reference to sticky ends
max 5
[10]
2.
Haemophilus influenza type b (Hib) is the bacterium which causes Hib meningitis.
A carbohydrate from the bacterial coat was used to prepare a vaccine against the disease.
However, this vaccine was not effective in children under two years of age because they
produced very few antibodies and were unable to produce the necessary memory cells. When
the carbohydrate was combined with a protein from the bacterial coat, a vaccine effective in
children less than a year old was produced. This vaccine was introduced into the UK in
October 1992. In 1993 the number of cases of Hib meningitis occurring in children under
one year old was only 25% of that predicted. All of these occurred in unvaccinated children.
The goal is now the elimination of Hib meningitis from the UK by vaccinating at least 90%
of the children under 2 years of age.
(a)
Explain the function of the protein from the bacterial coat when the vaccine is injected
into a child.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
(b)
Explain how Hib meningitis may be eliminated even though every child is not
vaccinated.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
(c)
Using the information in the passage. explain why the vaccine containing only
carbohydrate did not provide effective protection against Hib meningitis.
........................................................................................................................
........................................................................................................................
(1)
(d)
Give two other methods used to prepare vaccines.
1. .............................................................................................................
2. .............................................................................................................
(2)
(Total 7 marks)
Ans2. (a)
(b)
acts as an antigen;
stimulates immune response/production of antibodies;
production of memory cells;
which rapidly produce antibodies when individual infected by Hib;
herd effect/high percentage cover;
only unvaccinated individuals likely to catch disease;
max 2
small chance of infected individual meeting unvaccinated individual;
(c)
(d)
carbohydrate in bacterial coat not very effective in stimulating immune
response/insufficient antibodies to destroy Hib bacteria/
carbohydrate does not stimulate production of memory cells;
killed microorganism;
modified toxin;
attenuated/heat treated/UV treated microorganism;
genetically engineered antigens;
isolated antigen;
max 2
1
max 2
[7]
3.
Describe how each of the following prevents infection by microorganisms.
(a)
skin
........................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
(b)
tears
........................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
(c)
cilia
........................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
(d)
phagocytic cells
........................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
(Total 8 marks)
Ans3. (a)
(b)
(c)
(d)
barrier to microorganisms/bacteria/pathogens;
layer of dead cells;
impregnated with keratin/cornified;
fatty acids in sebum inhibit growth of microorganisms;
commensal bacteria compete with other microorganisms;
max 2
contain lysozyme/enzyme;
capable of digesting bacterial cell walls/killing bacteria;
physical washing away;
max 2
transport mucus;
mucus contains trapped bacteria/microorganisms;
microorganisms are moved up the respiratory tract and are swallowed;
killed by acid in the stomach;
max 2
engulf microorganisms;
digested/destroyed by enzymes;
released from lysosomes;
role of macrophages in the immune response;
max 2
[8]
4.
(a)
Describe how each of the following parts of the body is protected to prevent
microorganisms entering living cells.
(i)
Skin
.............................................................................................................
.............................................................................................................
(1)
(ii)
Lungs
.............................................................................................................
.............................................................................................................
(1)
(iii)
Eyes
.............................................................................................................
.............................................................................................................
(1)
(b)
Describe how macrophages help to prevent the spread of microorganisms that enter
the blood and other tissues.
........................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
(Total 5 marks)
Ans4. (a)
(b)
(i)
dead cells/keratin as barrier;
(sweat and sebum neutral)
(accept (commensal) skin flora kill/compete with microbe)
(accept skin acidity kills microbes)
1
(ii)
mucus traps microorganisms;
(cilia neutral)
1
(iii)
tears contain lysozyme/contain enzymes which kill microbes;
(accept bactericide)
1
move to site of infection;
phagocytosis/engulf bacteria;
(digest neutral)
stimulate (T)-lymphocytes/B cells/T cells;
2 max
[5]
5.
Answers should be written in continuous prose. Credit will be given for biological accuracy,
the organisation and presentation of the information and the way in which the answer is
expressed.
Read the following passage.
A potential new cancer treatment involves what are known as magic bullets. Cancer cells
have cell-surface antigens which are not found on normal cells. Antibodies are produced to
one of these antigens by the monoclonal antibody technique. Once the antibody molecules
have been made, an enzyme is attached to them and the antibody-enzyme complex is
injected into the patient. A drug, which causes cell lysis, is then injected in an inactive form.
(a)
Use the information in the passage to suggest how the drug kills only cancer cells.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(3)
(b)
Explain the role of B-lymphocytes and T-lymphocytes in the defence of the body
against a virus infection.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(6)
(c)
Immunisation programmes may use either attenuated or dead microorganisms.
Suggest why there might be problems for the patient when using these vaccines.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(3)
(Total 12 marks)
Ans5. (a)
Antibody binds/eq/recognises only to cancer cells;
because of antibody-antigen binding/eg;
enzyme activates the drug;
at cancer cells only;
max 3
(b)
(c)
B lymphocytes produce antibodies/involved in humoral response;
T lymphocytes involved in cell mediated immunity;
Macrophages present antigens;
(specific) B lymphocytes recognise/bind to antigen;
increase in numbers by mitosis;
produce plasma cells (which make antibodies);
antibodies bind to and clump/ agglutinate virus;
memory cells produced by 1st exposure/cloned on 2nd exposure;
T lymphocytes(helpers) produce lymphokines/chemicals;
which aid B lymphocyte cloning;
encourages phagocytes to engulf clumped virus;
killer T cells kill virus infected cells;
max. 6
Process of killing organisms might not be 100% efficient;
live organisms might give rise to full-blown disease;
attenuated organisms are non-virulent;
but might mutate to virulent forms;
immunity can decline - booster injections required;
named side effects, eg allergies;
less effective due to changed antigens;
max. 3
[12]