1920-AS Biology Top Questions
Q.1
ID: 21
Topic: Cell and Nuclear Division
Question description: The mitotic cell cycle
Fig. 1.1 shows drawings of a cell at various stages in the mitotic cell cycle.
Date 21-08-19 | Level M | 1
Fig. 1.1
a.
List the letters shown in Fig. 1.1 in the order in which these stages occur during a mitotic cell cycle.
The first stage has been entered for you.
A
…..… …..… …..… …..…
[1]
b.
Explain what is happening in stage D in Fig. 1.1.
[2]
c.
Describe in outline what happens to the DNA in the nucleus during stage A in Fig. 1.1.
[3]
d.
State the importance of mitosis in the growth of a multicellular organism, such as a flowering
plant or a mammal.
[1]
[Total : 7]
Q.2
ID: 29
Topic: Transport
Question description: The haemoglobin and myoglobin molecule structures and functions
Haemoglobin is a globular protein with quaternary structure.
Fig. 5.1 is a diagram of the haemoglobin molecule.
a.
With reference to Fig. 5.1,
i.
name X and state its function;
ii.
explain why haemoglobin is described as a globular protein with quaternary structure.
[2]
[2]
b.
Explain why people who have a deficiency of iron in their diet are often lacking in energy and feel
tired.
[3]
Date 21-08-19 | Level M | 2
Fig. 5.2 shows the oxygen dissociation curves for myoglobin, M, and haemoglobin, H.
c.
State the tissue where myoglobin is found.
d.
With reference to Fig. 5.2,
[1]
i.
e.
state the percentage saturation of myoglobin and haemoglobin when the partial pressure of
oxygen is 2 kPa;
[1]
ii.
explain the significance of the difference in percentage saturation that you have shown in (i).
[3]
When a person exercises vigorously, the partial pressure of carbon dioxide in the blood increases.
Draw on Fig. 5.2 a dissociation curve for haemoglobin when the partial pressure of carbon dioxide
has increased.
[1]
[Total: 13]
Date 21-08-19 | Level M | 3
Q.3
ID: 41
Topic: Biological Molecules
Question description: The roles of water in living and non-living organisms
a.
The table below includes statements about the roles of water
• in living organisms
• as an environment for living organisms.
Complete the table by indicating with a tick (✓) which one of the properties of water is responsible
for each role.
You should put only one tick in each row.
Date 21-08-19 | Level M | 4
Fig. 3.1 shows a potometer that is used for measuring rates of water uptake by leafy shoots.
A student used the potometer shown in Fig. 3.1 to investigate the rate of water uptake of a leafy shoot
under six different sets of conditions. The student changed two environmental conditions around the plant:
• temperature
• wind speed.
For each experiment, the apparatus was left in the conditions until the rate of water uptake by the leafy shoot
became constant. The student took several measurements during each experiment and calculated the mean
rate of movement of the gas bubble. The results are recorded in Table 3.1.
Date 21-08-19 | Level M | 5
a.
Using the data in Table 3.1, describe and explain the effect of the two conditions that the student
changed during the investigation on the rate of water uptake.
[4]
The rate of water movement up the leafy shoot was measured before it was cut from the plant. The rate
was found to be less than the rate of water uptake from the potometer when kept in the same
temperature and wind speed conditions.
b.
Suggest why the rate of water movement in an intact shoot is less than that measured in the potometer.
[2]
[Total:11]
Date 21-08-19 | Level M | 6
Q.4
ID: 43
Topic: Cell Structure
Question description: The structure of a mesophyll cell from a leaf
Fig. 4.1 is an electron micrograph of a mesophyll cell from a leaf.
Date 21-08-19 | Level M | 7
a.
Calculate the magnification of Fig. 4.1. Show your working and express your answer to
the nearest whole number.
Answer : ... ...
..................................................................................................................... [2]
Date 21-08-19 | Level M | 8
b.
Identify, by using the letters A to F, a part of the cell shown in Fig. 4.1 where the
following substances are located.
- chlorophyll
- cellulose
- DNA
- phospholipid
[4]
c.
State three ways in which the structure of a red blood cell differs from the structure of
the cell shown in Fig. 4.1.
[3]
Table 4.1 shows the red blood cell counts for two people from Peru - one who lived at
sea level and the other who lived at 5 000 metres above sea level.
Table 4.1
red blood cell count / cells mm-3
d.
sea level
5.0 × 106
5000 metres above sea level
6.3 × 106
Explain why the red blood cell count is much higher in the person who lived at high
altitude.
..[2]
[Total:11]
Date 21-08-19 | Level M | 9
Q.5
ID: 92
Topic: Cell Membranes and Transport
Question description: Cell surface membrane components and characteristics
Fig. 6.1 shows a diagram of a plasma (cell surface) membrane.
a.
b.
Indicate, by putting a circle, ,
membrane shown in Fig. 6.1.
around one of the following, the width of the
0.7 nm 7.0 nm 70 nm 7  10-5 m
700 µm
7.0 µm
[1]
Outline the functions of the following components of the plasma membrane.
K
L
M
N
[4]
c.
Some substances may cross plasma membranes by simple diffusion. Glucose, however, does not.
Explain why glucose cannot pass across membranes by simple diffusion.
[2]
Date 21-08-19 | Level M | 10
d.
e.
In an investigation, animal cells were exposed to different concentrations of glucose. The rate of
uptake of glucose into the cells across the plasma membrane was determined for each concentration.
Fig. 6.2 shows the results.
Using the information in Fig. 6.2, explain how the results of the investigation support the idea that
glucose enters cells by facilitated diffusion.
[2]
State how active transport differs from facilitated diffusion.
[1]
[Total : 10]
Date 21-08-19 | Level M | 11
Q.6
ID: 100
Topic: Cell Structure
Question description: Animal cell structure
Fig. 2.1 is an electron micrograph of part of an animal cell. A centriole is labelled.
a.
Name the structures labelled A to C.
A
B
C
[3]
Date 21-08-19 | Level M | 12
b.
Describe the roles of centrioles in animal cells.
c.
[3]
Explain why it is possible to see the internal membranes of a cell in electron micrographs, such as Fig.
2.1, but it is not possible to see them when using the light microscope.
d.
A student investigated the effect of temperature on beetroot tissue. Beetroot cells contain a dark red
pigment known as betalain, which is stored inside their vacuoles.
The student
• cut the beetroot tissue into cubes of the same size
• washed the cubes thoroughly in distilled water
• placed the same number of cubes into distilled water at seven different temperatures.
After 30 minutes, samples of the water were removed and placed in a colorimeter to measure the
transmission of light. The lower the percentage transmission the more betalain is present in the
water.
The results are shown in Fig. 2.2.
Date 21-08-19 | Level M | 13
Using the information in Fig. 2.2,
i.
describe the student's results;
[3]
ii.
explain the effect of increasing temperature on the beetroot tissue.
[3]
[Total : 15]
Q.7
ID: 124
Topic: Cell and Nuclear Division
Question description: Cancer cell in the process of dividing by mitosis
Fig. 6.1 is an electron micrograph of a cancer cell in the process of dividing by mitosis.
a.
The stage of mitosis visible in Fig. 6.1 is metaphase.
State which features of the cell shown in Fig. 6.1 indicate that it is at metaphase and not at anaphase.
[2]
b.
c.
People who have smoked cigarettes for many years are at risk of developing lung cancer.
Describe how cigarette smoke is responsible for the development of lung cancer.
[4]
Fig. 6.2 shows the change in the percentage of smokers in the male population of the UK between
1950 and 2005.
Date 21-08-19 | Level M | 14
Fig. 6.3 shows the change in mortality rate in the UK in men aged 75 to 84 between 1950 and
2005.
Date 21-08-19 | Level M | 15
Fig. 6.2 and Fig. 6.3 appear to show that there is no link between the percentage of the population that
smoke and the death rate from lung cancer.
Explain why the mortality rate from lung cancer among men increased and then decreased over the
period shown in Fig. 6.3, even though the percentage of smokers decreased over the same period of
time.
[3]
[Total : 9]
Q.8
ID: 141
Topic: Gas Exchange
Question description: Alveolus and surrounding tissues
Fig. 2.1 is a section of an alveolus and surrounding tissue.
Date 21-08-19 | Level M | 16
a.
Calculate the actual diameter of the alveolus along the line X-Y.
Show your working and give your answer to the nearest micrometre.
Answer = ______ µm
[2]
b.
i.
Describe the role of elastic fibres in the wall of the alveolus.
ii.
With reference to Fig. 2.1, explain how alveoli are adapted for gas exchange.
[2]
c.
[4]
Chronic obstructive pulmonary disease (COPD) is a progressive disease that develops in many
smokers. COPD refers to two conditions:
•
chronic bronchitis
•
emphysema.
i.
State two ways in which the lung tissue of someone with emphysema differs from the lung
tissue of someone with healthy lungs.
Date 21-08-19 | Level M | 17
[2]
ii.
State two symptoms of emphysema.
[2]
[Total : 12]
Q.9
ID: 142
Topic: Transport
Question description: A cross-section of the heart at the level of the valves
a.
Fig. 3.1 shows a cross-section of the heart at the level of the valves.
i.
Complete the following flow chart to show the pathway of blood through the heart.
ii.
Explain how the valves P and Q ensure one-way flow of blood through the heart.
[2]
Date 21-08-19 | Level M | 18
b.
The cardiac cycle describes the events that occur during one heartbeat.
Fig. 3.2 shows the changes in blood pressure that occur within the left atrium, left ventricle and
aorta during one heartbeat.
Date 21-08-19 | Level M | 19
In the table below, match up each event during the cardiac cycle with an appropriate number 1 to 7
on Fig. 3.2.
You should put only one number in each box. You may use each number once, more than once or
not at all.
The first answer has been completed for you.
event during the cardiac cycle
number
atrioventricular (bicuspid) valve opens
6
ventricular systole
semilunar (aortic) valve closes
left ventricle and left atrium both
relaxing
semilunar (aortic) valve opens
c.
[4]
Explain the roles of the sinoatrial node (SAN), atrioventricular node (AVN) and the Purkyne
tissue during one heartbeat.
[5]
[Total : 13]
Date 21-08-19 | Level M | 20
Q.10
ID: 144
Topic: Genetic Control
Question description: DNA replication
a.
Name the stage during the mitotic cell cycle when replication of DNA occurs.
b.
Fig. 5.1 shows details of DNA replication.
[1]
i.
Name the bonds shown by the dashed lines on Fig. 5.1.
ii.
Name the nitrogenous bases, M and O.
[1]
[1]
c.
d.
Explain why DNA replication is described as semi-conservative.
[2]
The enzyme that catalyzes the replication of DNA checks for errors in the process and corrects
them. This makes sure that the cells produced in mitosis are genetically identical.
[2]
Date 21-08-19 | Level M | 21
[Total : 7]
Q.11
ID: 181
Topic: Enzymes
Question description: The enzyme sucrase structure
The enzyme sucrase catalyzes the breakdown of the glycosidic bond in sucrose.
A student investigated the effect of increasing the concentration of sucrose on the rate of activity of sucrase.
Ten test-tubes were set up with each containing 5 cm3 of different concentrations of a sucrose solution.
The test-tubes were placed in a water bath at 40 °C for ten minutes. A flask containing a sucrase solution was
also put into the water bath.
After ten minutes, 1 cm3 of the sucrase solution was added to each test-tube. The reaction mixtures were
kept at 40 °C for a further ten minutes.
After ten minutes, the temperature of the water bath was raised to boiling point. Benedict’s solution was
added to each test-tube. The time taken for a color change was recorded and used to calculate rates of enzyme
activity.
The results are shown in Fig. 4.1.
a.
i.
Name the type of reaction catalysed by sucrase.
ii.
Explain why the temperature of the water was raised to boiling point.
[1]
[1]
b.
Describe and explain the results shown in Fig. 4.1.
[5]
[Total : 8]
Date 21-08-19 | Level M | 22
Q.12
ID: 187
Topic: Biological Molecules
Question description: A molecule of a triglyceride structure and function
a.
Fig. 5.1 represents a molecule of a triglyceride.
Name the components A and C and name the bond B.
Write your answers on the dotted lines provided in Fig. 5.1.
[3]
b.
A phospholipid is sometimes described as a modified triglyceride.
i.
State how the structure of a phospholipid differs from a triglyceride.
ii.
Explain how a phospholipid is suited to its role in cell membranes.
[2]
[3]
A student carried out an investigation into the digestion of triglycerides using lipase.
Ten cm3 of olive oil, adjusted to pH 8.0, was added to a test-tube, which was then put in a
water bath at 37 °C for ten minutes.
One cm3 of lipase solution was incubated at the same temperature in a separate test-tube
before being added to the olive oil.
Date 21-08-19 | Level M | 23
The initial pH of the reaction mixture was measured using a pH meter. The pH was recorded at
five minute intervals for 60 minutes.
c.
Suggest why the olive oil was adjusted to pH 8.0 before the lipase was added.
[1]
d.
Fig. 5.2 shows the results of the investigation.
With reference to Fig. 5.2,
i.
describe the results of the investigation
[2]
ii.
explain the results of the investigation.
[4]
Q.13
ID: 190
Topic: Genetic Control
Question description: The difference between DNA and RNA
a.
Complete the table to show three ways in which the structure of DNA differs from RNA.
Date 21-08-19 | Level M | 24
b.
Table 2.1 shows two messenger RNA (mRNA) codons. Fill in the complementary transfer RNA
(tRNA) anticodons in the spaces provided.
c.
Calculate the minimum number of DNA nucleotides necessary to code for a polypeptide with 238
amino acids.
Show your working.
answer ...
... nucleotides
[2]
Describe the role played by tRNA in polypeptide synthesis.
[4]
[Total: 11]
d.
Q.14
ID: 281
Topic: Enzymes
Question description: The effect of the three enzyme concentrations on the starch suspension
Starch is a storage product found in many plant cells.
It contains a carbohydrate called amylose that stains blue / black in the presence of iodine in potassium
iodide solution.
You are provided with three solutions of the enzyme amylase, of different concentrations, labeled A1,
A2 and A3. Do not assume that they are in the correct order of concentration.
You are also provided with a suspension of starch.
Date 21-08-19 | Level M | 25
You are required to investigate the effect of the three enzyme concentrations on the starch suspension.
Place three rows of five separate drops of iodine solution onto a dry tile. Label the rows A1, A2 and A3, as
shown in Fig. 1.1.
a.
i.
Use the prepared tile to investigate the effect of enzyme concentration on the starch
suspension.
Take no more than ten minutes to complete your investigation. Record your observations in
Table 1.1.
ii.
Explain your procedure.
[3]
Date 21-08-19 | Level M | 26
b.
A student carried out a similar experiment and obtained the results shown in Table 1.2.
1
time/minute
Complete the table to show the rate for 2.0% amylase concentration.
Rate can be calculated by using the formula; rate =
i.
ii.
[1]
Use the data in Table 1.2 to plot a graph of amylase concentration against one of the other
variables, on the grid below.
[4]
iii.
Explain these results.
[2]
Date 21-08-19 | Level M | 27
c.
Explain how the experiment could be modified to investigate the effect of temperature on the rate of
reaction.
[3]
[Total : 15]
Q.15
ID: 320
Topic: Transport
Question description: The changes in blood pressure in the left atrium, left ventricle and aorta during
one complete contraction of the heart
Fig. 4.1 shows the changes in blood pressure in the left atrium, left ventricle and aorta during one
complete contraction of the heart. It also shows a recording of the electrical activity of the heart.
a.
Name the source of the electrical activity in the heart.
b.
Explain how the heart is coordinated so that the ventricle contracts after the atrium has contracted.
[1]
[4]
Date 21-08-19 | Level M | 28
c.
d.
With reference to Fig. 4.1, calculate the heart rate in beats per minute. Show your working and
express your answer to the nearest whole number.
[2]
The pressure in the right ventricle is rarely higher than 4.0 kPa.
Explain why the pressure in the right ventricle is much lower than that in the left ventricle.
[2]
[Total : 9]
Q.16
ID: 341
Topic: Enzymes
Question description: The effect of substrate concentration on the activity of trypsin
Trypsin is a protease enzyme, which hydrolyses protein molecules, such as albumen, to amino acids.
A student investigated the effect of substrate concentration on the activity of trypsin. Six different
concentrations of albumen were prepared and trypsin was added to each in turn.
The student measured the time for albumen to break down and then calculated the rate of reaction. The
investigation was carried out at 35 °C.
The student’s results are shown in Fig. 3.1.
Date 21-08-19 | Level M | 29
a.
Explain the results shown in Fig. 3.1.
b.
The student repeated the investigation at 25 °C.
Draw on Fig. 3.1 a curve to show the results that you would expect.
[3]
[2]
During infections of the lungs, phagocytes move from the blood to the lining of the alveoli.
Phagocytes release the enzyme elastase (a protease) in order to digest a pathway through the alveolar wall.
Most people produce a glycoprotein, alpha 1-antitrypsin (AAT), in the lung which inhibits elastase and so
prevents widespread breakdown of alveoli. The inhibitory action of AAT was investigated using the
enzyme trypsin.
c.
d.
Describe one way in which AAT may act to inhibit the enzyme elastase.
[3]
Explain how you would adapt the student’s investigation with trypsin to find out how AAT acts as an
inhibitor.
You may use the space below to sketch the graph of the results that you might expect.
[4]
e.
f.
Elastase breaks down the protein elastin. Describe the function of elastin in the lungs.
[2]
Tobacco smoke inactivates AAT. In long-term smokers this can result in the breakdown of much of
the elastin in the lungs.
State the name of the condition that results from breakdown of elastin that occurs in some longterm smokers.
[1]
[Total : 15]
Date 21-08-19 | Level M | 30
Q.17
ID: 357
Topic: Enzymes
Question description: The effect of pH on the activity of the enzyme
Amylase is an enzyme that catalyzes the hydrolysis of starch. A student investigated the effect of pH
on the activity of the enzyme.
Eight test-tubes were set up each containing 5 cm3 of the same concentration of amylase solution but in
buffer solutions of different pH values. The test-tubes were left in a water-bath at 30 °C for 10 minutes.
After 10 minutes, 5 cm3 of a starch suspension at 30 °C was added to each test-tube.
Immediately, the student took a sample from each test-tube and tested the reaction mixture for the
presence of starch. Samples were then taken every minute for 10 minutes and tested in the same way.
The student’s results are shown in Table 2.1.
a.
Describe how the student would test for the presence of starch.
[2]
Date 21-08-19 | Level M | 31
b.
c.
Use the axes below to sketch a graph to show the effect of pH on the rate of hydrolysis of starch by
amylase.
[2]
With reference to the student’s results, describe and explain the effect of pH on the rate of hydrolysis
of starch by amylase.
[5]
[Total : 9]
Date 21-08-19 | Level M | 32
Q.18
ID: 359
Topic: Transport
Question description: The rates of transpiration of plants of two species
a.
Explain what is meant by the term transpiration.
[2]
The rates of transpiration of plants of two species, A and B, were measured over a period of seven hours. The
results are shown in Fig. 4.1.
b.
c.
With reference to Fig. 4.1, compare the rates of transpiration of the two species over the seven hour
period.
[4]
State two possible features of the leaves of species B that could explain the different rates of
transpiration in comparison with species A.
Explain how each feature acts to reduce transpiration.
[4]
[Total : 10]
Date 21-08-19 | Level M | 33
Q.19
ID: 389
Topic: Transport
Question description: Red blood cells
Red blood cells are suspended in plasma which has a concentration equivalent to that of 0.9% sodium
chloride (NaCl ) solution.
A student investigated what happens to red blood cells when placed into sodium chloride
solutions of different concentration.
A small drop of blood was added to 10 cm3 of each sodium chloride solution. Samples were
taken from each mixture and observed under the microscope. The number of red blood cells
remaining in each sample was calculated as a percentage of the number in the 0.9% solution. The
results are shown in Fig. 3.1.
a.
With reference to Fig. 3.1, describe the student’s results.
[3]
Date 21-08-19 | Level M | 34
The student also measured the cell volumes of the red blood cells in three of the sodium chloride solutions.
The results are shown in Table 3.1.
Fig. 3.2 shows the appearance of some red blood cells removed from the 1.5% sodium chloride solution.
b.
Explain the results shown in Fig. 3.1, Table 3.1 and Fig. 3.2, in terms of water potential.
0% NaCl solution ...
0.7% NaCl solution ...
1.5% NaCl solution ...
[6]
Red blood cells each contain about 240 million molecules of haemoglobin that transport oxygen and
carbon dioxide.
c.
d.
Describe the role of haemoglobin in the transport of oxygen and carbon dioxide.
[4]
The haematocrit is the proportion of the blood that is composed of red blood cells.
Samples of blood were taken from an athlete who lived at sea level since birth and moved to live
and train at an altitude of 5000 m for three weeks. The haematocrit and the number of red blood cells
per mm3 were determined before moving to high altitude and after three weeks at that altitude. The
results are shown in Table 3.2.
Date 21-08-19 | Level M | 35
i.
ii.
Calculate the percentage increase in the number of red blood cells per mm3 after three weeks
at 5000 m. Show your working.
Answer = ... %
[2]
Explain why the haematocrit increases at altitude.
[3]
[Total : 18]
Q.20
ID: 390
Topic: Infectious Disease
Question description: Cholera bacteria
Cholera bacteria release the enzyme neuraminidase which alters some of the surface proteins on the
membranes of epithelial cells in the small intestine.
These surface molecules become receptors for the toxin, choleragen, released by cholera bacteria. The toxin
stimulates the cells to secrete large quantities of chloride ions into the lumen of the small intestine. Sodium
ions and water follow the loss of chloride ions.
a.
i.
Name the pathogen that causes cholera.
[1]
ii.
Suggest how chloride ions are moved from the epithelial cells into the lumen of the small
intestine.
[1]
iii.
Explain how cholera bacteria are transmitted from one person to another.
[3]
A potential vaccine for choleragen was trialled on volunteers. Fig. 4.1 shows the concentration of antibodies
against choleragen in the blood of a volunteer who received a first injection at week 0, followed by a booster
injection at week 15.
Date 21-08-19 | Level M | 36
b.
c.
Using the information in Fig. 4.1, explain the differences between the responses to the first injection
and the booster injection.
[4]
Discuss the problems involved in preventing the spread of cholera.
[4]
[Total : 13]
Date 21-08-19 | Level M | 37
Q.21
ID: 401
Topic: Immunity
Question description: The concentration of antibody in blood plasma changes during the response to
an antigen which is injected at day 0
a.
Outline the roles of the T-lymphocytes and B-lymphocytes in a primary immune response
T-lymphocytes
B-lymphocytes
[4]
Fig. 4.1 shows how the concentration of antibody in blood plasma changes during the response to an
antigen which is injected at day 0.
b.
c.
Explain why the concentration of antibody falls as shown in Fig. 4.1.
[3]
Draw on Fig. 4.1 how the antibody concentration would change if the same antigen entered the
blood plasma on day 40.
[3]
[Total : 10]
Date 21-08-19 | Level M | 38
Q.22
ID: 420
Topic: Transport
Question description: Phloem transfer cell
Phloem transfer cells are modified companion cells that move sucrose and other assimilates from mesophyll
tissue into phloem sieve tube elements.
Fig. 5.1 is an electron micrograph of a phloem transfer cell.
a.
Fig. 5.1
Calculate the actual distance across the transfer cell from X to Y.
Show your working and express your answer to the nearest micrometre.
answer ...
µm
[2]
Date 21-08-19 | Level M | 39
b.
c.
With reference to Fig. 5.1, explain how phloem transfer cells help in the movement of sucrose from
the mesophyll of a leaf into a phloem sieve tube element.
[5]
Explain how sucrose in the phloem sap is moved from sieve tube elements in leaves to cells in a sink,
such as a root.
[4]
[Total : 11]
Q.23
ID: 257
Topic: Transport
Question description: Artery and a vein from a mammal
Fig. 1.1 is a photomicrograph of a transverse section of an artery and a vein from a mammal.
a.
State three ways, visible in Fig. 1.1, in which the artery differs from the vein.
1.
2.
3.
[3]
b.
The lungs contain arteries, veins and capillaries. Explain the role of capillaries in the lungs.
[3]
c.
Describe the effect of tar from cigarettes on the lining of the gaseous exchange system.
Date 21-08-19 | Level M | 40
[3]
[Total : 9]
Q.24
ID: 98
Topic: Transport
Question description: The heart and associated blood vessels
Fig. 1.1 shows the heart and associated blood vessels.
a.
Fig.1.1
On Fig. 1.1, draw label lines and use the letters P, Q and R to indicate the following structures:
P
Q
R
b.
c.
a blood vessel that carries deoxygenated blood
a structure that prevents backflow into a ventricle
a blood vessel that carries blood at high pressure
[3]
The changes in blood pressure in the right atrium are the same as those in the left atrium. The
changes in blood pressure in the right ventricle are different from those in the left ventricle. Explain
why this is so.
[4]
Some components of tobacco smoke are absorbed into the blood stream and affect the cardiovascular
system. Describe the effects of nicotine and carbon monoxide on the cardiovascular system.
nicotine ...
carbon monoxide ...
[4]
[Total : 11]
Date 21-08-19 | Level M | 41
Q.25
ID: 157
Topic: Gas Exchange
Question description: The human gas exchange system
Various structures in the human gas exchange system are adapted in different ways to
perform their specific functions.
a.
Complete the table below using a tick ✓ or cross ✗ in each box to show whether or not the
structure shows the particular feature.
Two boxes have been completed for you.
lined with cilia
reinforced with
cartilage
trachea
site of
gas exchange
contains smooth
muscle
✗
bronchus
bronchiole
✓
alveolus
b.
[4]
State the two ways in which the concentration gradients of oxygen and carbon dioxide are
maintained for efficient gas exchange.
1.
2.
[2]
c.
The alveoli in the lungs have elastic fibres in their walls.
i.
State one function of the elastic fibres.
ii.
Name the medical condition caused by breakdown of the elastic fibres.
[1]
d.
[1]
Cigarette smoke contains tar, a substance which has several harmful effects on the cells lining the
gas exchange system.
Outline three of these effects.
1.
2.
3.
[3]
[Total : 11]
Date 21-08-19 | Level M | 42
Q.26
ID: 321
Topic: Infectious disease
Question description: Tuberculosis (TB)
a.
i.
Name the organism that causes tuberculosis (TB).
[1]
ii.
Explain how TB is transmitted from an infected person to an uninfected person.
[2]
The World Health Organisation (WHO) collects data on TB from its six different regions as shown in Table
5.1. In 2003, it used these figures to estimate
•
•
the total number of people with the disease in each region
the number of deaths from TB.
Many of those who died from TB were also infected with HIV.
Table 5.1
b.
c.
d.
Explain the advantage of expressing the number of cases and the number of deaths as per 100 000
population’.
[2]
Using the information in Table 5.1, outline the reasons why TB has a greater impact on he health of
people in some regions rather than others.
[3]
th
The number of cases of TB decreased considerably in many countries during the 20 century. Over
the past 20 years, the number of cases worldwide has increased very steeply. A vaccine against TB
has existed since 1921.
Explain why TB has not been eradicated even though a vaccine has existed since 1921.
[3]
[Total : 11]
Date 21-08-19 | Level M | 43
Q.27
ID: 393
Topic: Infectious Disease
Question description: Malaria
Malaria is an infectious disease that is considered by the World Health Organization to be a disease of
worldwide importance.
a.
Explain what is meant by the term infectious.
b.
Name one species of organism that causes malaria.
c.
Explain the significance of the following statements in the control of malaria.
[2]
[1]
i.
d.
The female Anopheles mosquito has been more closely studied with regard to malaria
than the male Anopheles mosquito.
[1]
ii.
The infective stages of the malarial organism are present in anti-coagulant produced by the
mosquito.
[1]
iii.
After circulating in the blood for a short time, the pathogen enters liver cells of the newly
infected person and then enters red blood cells.
[2]
Discuss the factors that determine the distribution of malaria worldwide.
[4]
[Total : 11]
Date 21-08-19 | Level M | 44