Feversham College
A-level Biology (7401/7402)
Name:
Class:
Section 6 Practical Skills
Author:
Date:
Time:
70
Marks:
56
Comments:
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Q1.
(a)
Describe how insulin reduces the concentration of glucose in the blood.
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(3)
Some people produce no insulin. As a result they have a condition called diabetes. In an
investigation, a man with diabetes drank a glucose solution. The concentration of glucose in his
blood was measured at regular intervals. The results are shown in the graph.
(b)
Suggest two reasons why the concentration of glucose decreased after 1 hour even
though this man’s blood contained no insulin.
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(2)
(c)
The investigation was repeated on a man who did not have diabetes. The concentration of
glucose in his blood before drinking the glucose solution was 80 mg per 100 cm3. Sketch a
curve on the graph to show the results you would expect.
(1)
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(d)
The diabetic man adopted a daily routine to stabilise his blood glucose concentration within
narrow limits. He ate three meals a day: breakfast, a midday meal and an evening meal. He
injected insulin once before breakfast and once before the evening meal.
The injection he used before breakfast was a mixture of two types of insulin. The mixture
contained slow-acting insulin and fast-acting insulin.
(i)
Explain the advantage of injecting both types of insulin before breakfast.
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(2)
(ii)
One day, the man did not eat a midday meal. Suggest one reason why his blood
glucose concentration did not fall dangerously low even though he had injected
himself with the mixture of insulin before breakfast.
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(1)
(Total 9 marks)
Q2.
S
In an investigation by a student into the responses of maggots, the bottom of a large
box was marked with six coloured segments, as shown in the diagram.
30 maggots were placed on each segment in the box. A transparent cover was put on the
box and light bulbs were positioned so that the segments were evenly illuminated. The
positions of the maggots were recorded after one hour. The intensity of the light reflected by
each segment was measured.
The experiment was repeated three more times. The total number of maggots in each
segment from the four experiments is shown in the table.
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Colour of
segment
Intensity of reflected light /
arbitrary units
Total number of maggots
Black
4
154
Red
25
229
Blue
10
178
White
44
47
Green
25
48
Yellow
40
64
(a)
Give one conclusion about the responses of maggots which is supported by these results.
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Give the evidence from the table for your conclusion.
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(2)
(b)
The chi-squared test was used to analyse the data. For the results obtained, suggest one
null hypothesis which might be analysed by a chi-squared test.
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(1)
(c)
It was suggested that the movement of the maggots might have been influenced by the
Earth’s magnetic field. Suggest one simple way of repeating the investigation which would
avoid this possibility.
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(1)
(Total 4 marks)
Q3.
S
A large number of roots from
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many genetically identical bean plants were
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cut into short pieces. The pieces were sorted into groups, depending upon their distance
from the root tip. Some pieces from each group were used to find the mean dry mass of
their cells. Thin sections cut from other pieces were examined with a light microscope to
find the proportion of dividing cells and the mean volume of the cells.
The graph shows the results. The diagrams below the graph show the appearance of cells
in light microscope sections at different distances from the root tip.
(a)
Suggest two variables, other than genotype, which need to be controlled to ensure similar
root growth in different plants. In each case give the reason for your answer.
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(2)
(b)
Suggest how the proportion of dividing cells in a thin section could be determined.
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(2)
(c)
Explain the change in the proportion of dividing cells with increasing distance from the root
tip.
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(2)
(d)
Using the graph and diagrams, suggest how a root tip gets longer.
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(3)
(Total 9 marks)
Q4.Researchers investigated whether the blood supply to slow and fast muscle fibres in a muscle
changes with age. They used diaphragms taken from hamsters (Mesocricetus auratus). The
diaphragm is in constant use for breathing. They took diaphragms from groups of young, adult
and old hamsters.
They removed the diaphragm from each animal and took a sample of muscle tissue.They
examined it under an optical (light) microscope. For each sample they selected several fields of
view at random. In each field of view, they then counted the number of capillaries associated with
each type of muscle fibre.
This allowed the researchers to calculate the mean number of capillaries for each type of muscle
fibre, for each age group.
The table below shows the researchers’ results which include standard deviation (SD).
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Hamster
age group
(a)
Number of
hamsters in
group
Mean number of capillaries associated
with each type of muscle fibre
Slow fibres
(± SD)
Fast fibres
(± SD)
Young
9
3.4
(±0.8)
4.0
(±0.8)
Adult
10
4.7
(±0.2)
6.3
(±0.4)
Old
8
4.6
(±0.9)
6.8
(±0.6)
Give four precautions that the researchers took to make their calculations of mean number
of capillaries per fibre reliable.
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(4)
(b)
The researchers examined the muscle of an animal in the old age group. They found one
field of view containing only slow muscle fibres. They counted 69 capillaries in this field of
view.
(i)
Use a calculation to estimate how many slow muscle fibres were visible in this field of
view. Show your working.
Number of slow muscle fibres = ..........................................................
(2)
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(ii)
The actual number of slow muscle fibres in the field of view was not the same as the
number you calculated in question (i).
Give one reason why.
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(1)
(c)
A student read the report of the researchers’ investigation. She thought that the
investigation was unethical but that a conclusion could still be made.
(i)
Suggest why she thought the investigation was unethical.
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(1)
(ii)
She concluded that age had a significant effect on the mean number of capillaries
per fibre.
Evaluate this conclusion.
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(4)
(Total 12 marks)
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Q5.
A flatworm is a simple soft-bodied animal. The diagram shows the movements of an aquatic
flatworm in light and in shade. The path followed by the flatworm over a period of three minutes
was traced on the side of a tank.
(i)
Name the type of behaviour shown. Give a reason for your answer.
Type of behaviour .........................................................................................
Reason .........................................................................................................
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(2)
(ii)
Suggest one advantage of the behaviour shown in the diagram.
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(1)
(Total 3 marks)
Q6.Some mice have diabetes. The diabetes causes the blood glucose concentration to become very
high after a meal. Scientists investigated the use of an inhibitor of amylase to treat diabetes.
The scientists took 30 mice with diabetes and divided them into two groups, A and B.
•
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Group A was given yoghurt without the inhibitor of amylase each day.
Group B was given yoghurt with the inhibitor of amylase each day.
Apart from the yoghurt, all of the mice were given the same food each day.
The scientists measured the blood glucose concentration of each mouse, 1 hour after it had
eaten. This was done on days 1, 10 and 20 after the investigation started.
The following figure shows the scientists’ results.
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Days after the investigation started
(a)
Group A acted as a control in this investigation.
Explain the purpose of this group.
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(2)
(b)
Apart from the yoghurt, it was important that all of the mice were given the same food each
day.
Give two reasons why it was important that all of the mice were given the same food each
day.
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(2)
(c)
The scientists’ hypothesis was that adding the inhibitor of amylase to the food would lead
to a lower blood glucose concentration.
Use your knowledge of digestion to suggest how the addition of the inhibitor could lead to a
lower blood glucose concentration.
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(2)
(d)
Give one reason why these results may not support the use of the inhibitor of amylase to
treat diabetes in mice.
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(2)
(Total 8 marks)
Q7.
The human body-louse is an insect which lives and feeds on the surface of the skin. A louse
was placed in a chamber, half of which was kept at 35 °C and half at 30 °C. The diagram shows
the pattern of movement of the louse.
(a)
Name the type of behavioural response shown by the body-louse in this investigation.
Give evidence for your answer.
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(b)
Suggest and explain one advantage of this behaviour to the human body-louse.
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(2)
(Total 4 marks)
Q8.
Termites are insects. Some species live in colonies in the soil. Although most termites are
wingless, winged termites are sometimes produced. The winged termites fly from the soil, mate
and start new colonies.
A scientist studied the behaviour of winged termites. He divided these termites into three groups.
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Group A had their eyes covered.
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Group B had their antennae removed.
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Group C was the control group.
He put individual winged termites on a sloping board that was illuminated from one side. The
diagram shows the direction of movement of a typical termite from each of the three groups.
(a)
(i)
What type of behaviour was shown by the termite from group B?
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(1)
(ii)
Give the evidence for your answer.
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(1)
(b)
Explain what the results from group A suggest about the factors controlling the behaviour
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of winged termites.
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(3)
(c)
Suggest one advantage to the termites from group C of the behaviour shown in the
investigation.
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(2)
(Total 7 marks)
Q9.The diagram shows a mitochondrion.
(a)
Name the parts labelled X and Y.
(i)
X .............................................................
(ii)
Y ..............................................................
(2)
Scientists isolated mitochondria from liver cells. They broke the cells open in an ice-cold,
isotonic solution. They then used a centrifuge to separate the cell organelles. The diagram
shows some of the steps in the process of centrifugation.
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(b)
Suggest which pellet, A, B or C contained the mitochondria.
(1)
(c)
Explain why the solution used was
(i)
ice-cold
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(1)
(ii)
isotonic.
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(2)
(d)
People with mitochondrial disease have mitochondria that do not function properly.
Some people with mitochondrial disease can only exercise for a short time. Explain why a
person with mitochondrial disease can only exercise for a short time.
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(2)
(Total 8 marks)
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