B2 High Demand Application Questions
163 marks= 167 minutes
Q1.
Changing the conditions in which plants grow affects how fast they grow.
The diagram shows a propagator in which scientists can control temperature, light intensity
and carbon dioxide concentration.
The graph shows the effects of changing the temperature, light intensity and carbon dioxide
concentration on the growth of lettuce plants.
Page 1
(a)
Describe and explain the effect of increasing light intensity on the mean mass of
lettuce plants at 4% carbon dioxide and 15 °C.
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(3)
(b)
Growers wish to make maximum profits from their lettuces.
What do they need to consider before making decisions about the growing conditions
for their lettuces?
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....................................................................................................................................
....................................................................................................................................
(2)
(c)
The nutrient solution contains nitrate ions and magnesium ions.
Complete the table to show the functions of these ions in plants and their deficiency
symptoms.
Ion
Function in plants
Deficiency symptoms
.........................................................
........................................................
Nitrate .........................................................
........................................................
.........................................................
.........................................................
.........................................................
..........................................................
Magne
.........................................................
sium
.........................................................
.........................................................
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(4)
(Total 9 marks)
##
The following is adapted from an article which appeared in January 1994 in the Sunday
Times.
A woman gives birth at 59
Designer babies are just the first step in science’s ability to create a
super race.
Test-tube baby techniques give doctors an unprecedented degree of control
over the offspring produced. When eggs and sperms are donated they seek
to match the charactaristics of the donor whose role has been replaced. As
more is learned about the genetic contribution to charactaristics such as
intelligence, beauty or strength, this capacity to mix-and-match will increase.
Technological change frightens us when it is outside our control and when we
fear how it might be exploited by others. People wonder where the potential
Brave New World of “retirement births” and ‘designer’ babies will ultimately
lead us: cloning, genetic grading and even the introduction of animal genes
into humans. Unthinkable, perhaps, but entirely possible.
The techniques are there – in fact they have been for years. But who on earth
would want to use them, apart from some power mad politician?
Use information from the article and any of your own knowledge to discuss the arguments
for and against allowing doctors to experiment with human fertilisation techniques.
You will not receive marks for simply copying extracts from the article.
(Total 8 marks)
Q3.
(a)
During respiration, sugar is oxidised to release energy. Complete the equation
for respiration.
Sugar + ............................. = ............................. + ............................. + energy
(3)
Page 3
(b)
The photograph below shows an athlete using an exercise machine. The machine
can be adjusted to vary the rate at which the athlete is required to work.
The athlete’s heart rate and breathing rate were measured at different work rates.
The table below shows the results which were obtained.
WORK RATE
(J/s)
HEART RATE
(beats/min.)
BREATHING RATE
(breaths/min.)
0
86
9.6
60
106
10.0
80
112
10.4
100
122
10.4
120
135
11.4
140
143
14.5
160
156
15.8
200
174
30.5
Plot the data on the graph paper below.
Page 4
(3)
(c)
Explain, as fully as you can, the advantages to the body in the change in breathing
and heart rates.
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(6)
(d)
This increase in the rate of heart-beat is a response to a stimulus. For this response
suggest:
(i)
the stimulus;
..........................................................................................
(ii)
the co-ordinator;
..........................................................................................
(iii)
the effector.
..........................................................................................
(3)
(Total 15 marks)
Q4.
The graph shows the effect of temperature on photosynthesis.
Page 6
(a)
Between which temperatures is the rate of photosynthesis fastest?
............................... and .......................... °C
(1)
(b)
Suggest why the rate of photosynthesis stays the same between these two
temperatures.
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(2)
(c)
A greenhouse owner wants to grow lettuces as quickly and cheaply as possible in
winter.
At what temperature should he keep his greenhouse in order to grow the lettuces as
quickly and cheaply as possible?
.......................... °C
Page 7
Explain your answer.
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(3)
(Total 6 marks)
Q5.
The graph shows the mean light intensity at different times of the year in an oak wood.
(a)
(i)
In which month would you expect the rate of photosynthesis in the oak trees to
be greatest?
.........................................................................
(1)
(ii)
There are plants living on the ground in the wood. In which month would you
expect their rate of growth to be fastest?
...........................................................................................................................
Explain your answer.
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...........................................................................................................................
...........................................................................................................................
(3)
(b)
Name two factors, other than light intensity, that would affect the rate of
photosynthesis in the oak trees.
1 ..................................................................................................................................
2 ..................................................................................................................................
(2)
(Total 6 marks)
##
The passage below is an extract from an article in The Independent newspaper.
This Mouthwash could mean
a lot to your Children
A SIMPLE TEST SCREENS WOULD-BE PARENTS FOR THE
DEFECTIVE GENE THAT CAUSES
CYSTIC FIBROSIS
It is not every week that a university professor tells you to spit in front of him. But Bob
Williamson, professor of biochemistry and molecular genetics asked me to do just that.
In future, some people may choose their marriage partners on the basis of the contents
of their spit.
The professor handed me a sample bottle containing sterile salt solution.
I rinsed my mouth out and spat back into the tube. Incredible though it may sound, the
mouthwash now contained enough cells from the inner lining of my cheek for an
assistant to dissect my DNA and check whether I carry any of the mutations
responsible for cystic fibrosis.
Professor Williamson’s team can locate genetic markers, distinctive segments of DNA,
that are inherited along with the mutant genes in people affected with cistic fibrosis.
About 16 000 people who bought The Independent this morning unwittingly carry a
cystic fibrosis gene. The statistics indicate that 23 of the staff of this newspaper are
unknowing carriers. Carriers are normal healthy individuals who do not have the
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disease.
(a)
Describe, as fully as you can, where genes are located inside cheek cells.
.....................................................................................................................................
.....................................................................................................................................
(2)
(b)
The gene for cystic fibrosis has two forms called alleles. Only the recessive allele
causes cystic fibrosis.
Explain how two healthy carriers of the cystic fibrosis allele could produce a child with the
disease. Use the symbol A for the normal allele of the gene and a for the allele which
produces the disease. You may use a diagram if you wish.
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(4)
(d)
In the test used to identify the ‘genetic markers’, DNA is extracted from the cheek
cells. The DNA molecules are then made to produce hundreds of millions of copies of
themselves.
(i)
Explain, as fully as you can, how the structure of DNA molecules allows them to
replicate themselves.
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(6)
(ii)
Explain how DNA controls the structure of proteins.
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(3)
(Total 15 marks)
Q7.
(a)
Mice with black fur can have the genotype BB or Bb, whilst mice with brown fur
have the genotype bb.
(i)
Use a genetic diagram to show what fur colours you would predict in the F1
offspring produced by two mice who are both Bb.
(3)
(ii)
Why might your prediction of fur colour in the F1 generation not be proved
right?
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(1)
(b)
Using the example in part (a) to help:
(i)
describe the difference between dominant and recessive alleles;
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(2)
(ii)
describe the difference between alleles and genes;
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...........................................................................................................................
(2)
(iii)
describe the difference between homozygous and heterozygous
chromosomes.
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(2)
(Total 10 marks)
Q8.
Person A and Person B measured their pulse rates over a period of five minutes. For
one minute of this time they exercised by stepping on and off a box. At other times they sat
Page 12
still. The graph shows the results for Person A.
(i)
What does the graph tell you about the changes in the pulse rate of Person A within
the five minute period?
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(3)
(ii)
What was the pulse rate of Person A at the end of the five minute period?
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(1)
(iii)
The table shows the results obtained for Person B.
Time
in minutes
Pulse rate per
minute
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0
68
1
68
2
110
3
96
4
80
5
68
Plot these results on the graph.
(2)
(Total 6 marks)
Q9.
(a)
The volume of blood pumped out of the left ventricle at each beat was measured
for a person during six different activities. These activities showed an increasing
energy demand, with rest requiring the least energy and rowing a boat the most. The
results of these measurements are shown on the bar chart.
Page 14
(i)
The pulse rate was also measured for the person during the same activities.
The table shows the results that were obtained.
Activity
Pulse rate in
beats per minute
Rest
70
Writing
85
Cleaning the floor
100
Wallpapering
120
Walking fast
132
Rowing a boat
153
On the graph paper below draw a bar chart of the results obtained for the
measurements of the pulse rate.
(2)
(ii)
Undertaking activities with increasing energy demand has an effect on the
volume of blood pumped from the left ventricle (per beat) and on the pulse rate.
What do the bar charts show these effects to be? Use only information shown in
Page 15
the bar charts in your answer.
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(2)
(b)
The pulse rate changed when the activity changed. Explain the reason for this.
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(2)
(Total 6 marks)
Q10.
Photosynthesis takes place the leaves of green plants.
(a)
Write a balanced chemical equation for the formation of glucose by photosynthesis.
....................................................................................................................................
(3)
(b)
Describe two ways that the rate of photosynthesis can be decreased without lowering
the temperature.
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(2)
(c)
Some students decided to investigate the effect of temperature on the rate of
Page 16
photosynthesis in pond weed. They set up the apparatus and altered the temperature
using ice and hot water. The counted the number of bubbles given off in a minute at
different temperatures. They obtained the following results.
(i)
Plot the points on the graph.
(3)
(ii)
Use your graph to predict the number of bubbles per minute at 25 °C.
..........................................................................................................................
(1)
Page 17
(iii)
Suggest a reason why the rate of photosynthesis seems to decrease in this
pondweed after 40 °C.
..........................................................................................................................
..........................................................................................................................
(1)
(Total 10 marks)
Q11.
The diagram shows a human sperm. Inside the tail of the sperm is a filament
mechanism that causes the side to side movement of the tail, which moves the sperm.
(a)
Describe the function of the mitochondria and suggest a reason why they are
arranged around the filament near the tail of the sperm.
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(3)
(b)
Explain the significance of the nucleus in determining the characteristics of the
offspring.
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(2)
(Total 5 marks)
Q12.
Regular exercise is important, as it helps to maintain an efficient supply of blood to the
muscles, the heart and the lungs. This is helped by an increase in the heart rate during
exercise.
Explain why it is necessary for the heart rate to increase during exercise.
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(Total 4 marks)
Q13.
A student‘s breathing was monitored before and after vigorous exercise. The student
breathed in and out through a special apparatus. The graphs show the changes in the
volume of air inside the apparatus. Each time the student breathed in, the line on the graph
dropped. Each time the student breathed out, the line went up.
Page 19
(a)
How many times did the student breathe in per minute:
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before exercise; ...........................................................................................................
after exercise? .............................................................................................................
(1)
(b)
On each graph, the line A – B shows how much oxygen was used. The rate of oxygen
use before exercise was 0.5 dm3 per minute. Calculate the rate of oxygen use after
exercise.
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Rate of oxygen use after exercise = ................................................. dm3 per minute
(2)
(c)
The breathing rate and the amount of oxygen used were still higher after exercise,
even though the student sat down to rest. Why were they still higher?
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(4)
(Total 7 marks)
Q14.
The fruit fly, Drosophila, has either long wings or vestigial wings, as shown in the
diagram.
Page 21
Long-winged fly
Vestigial-winged fly
The size of the wings is determined by a pair of alleles: A and a.
Long-winged flies have one of two possible genotypes: AA or Aa.
Vestigial-winged flies have only one genotype: aa.
(a)
(i)
What is the genotype of a heterozygous fly?
...........................................................................................................................
(1)
(ii)
Why can vestigial-winged flies only have the genotype aa?
...........................................................................................................................
(1)
(b)
A male and a female long-winged fly were crossed. They produced 96 offspring.
72 of the offspring had long wings and 24 had vestigial wings.
Use a genetic diagram to explain this.
(4)
(Total 6 marks)
Page 22
Q15.
The diagram shows two patterns of cell division. Cell division type A is used in gamete
formation. Cell division type B is used in normal growth.
(a)
Name the two types of cell division, A and B, shown in the diagram.
Type A ........................................................................................................................
Type B ........................................................................................................................
(2)
(b)
Name the process in which an egg and sperm join together.
.............................................................................................................................
........
(1)
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(c)
Cell 1 contains 46 chromosomes. How many chromosomes will there be in:
(i)
cell 10; ..............................................................................................................
(1)
(ii)
cell 14?
.............................................................................................................
(1)
(Total 5 marks)
Q16.
The diagram shows the apparatus used to investigate the digestion of milk fat by an
enzyme. The reaction mixture contained milk, sodium carbonate solution (an alkali) and the
enzyme. In Experiment 1, bile was also added. In Experiment 2, an equal volume of water
replaced the bile. In each experiment, the pH was recorded at 2-minute intervals.
Either: Experiment 1
or:
milk (contains fat)
sodium carbonate solution
bile
enzyme
Experiment 2
milk (contains fat)
sodium carbonate solution
water
enzyme
The results of the two experiments are given in the table.
Page 24
(a)
Milk fat is a type of lipid. Give the name of an enzyme which catalyses the breakdown
of lipids.
.............................................................................................................................
......
(1)
(b)
What was produced in each experiment to cause the fall in pH?
.............................................................................................................................
......
(1)
(c)
(i)
For Experiment 1, calculate the average rate of fall in pH per minute, between
4 minutes and 8 minutes. Show clearly how you work out your final answer.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
............................................. pH units per minute
(2)
(ii)
Why was the fall in pH faster when bile was present?
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Page 25
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(1)
(Total 5 marks)
Q17.
The graph below shows the effect of a high carbohydrate diet on the stored
carbohydrate in the muscles.
Diet A
–
Diet B
Diet C
–
–
High carbohydrate diet, started after several days of eating a
diet without carbohydrate.
High carbohydrate diet, started after normal mixed diet.
Normal mixed diet.
What advice would you give the athlete about the best diet preparation for a long race?
Explain why you would give this advice.
Diet ......................................................................
Explanation
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(Total 2 marks)
Q18.
Changing the conditions in which plants grow affects how fast they grow.
The diagram shows a propagator in which scientists can control temperature, light intensity
and carbon dioxide concentration.
The graph shows the effects of changing the temperature, light intensity and carbon dioxide
concentration on the growth of lettuce plants.
Page 27
(a)
Describe and explain the effect of increasing light intensity on the mean mass of
lettuce plants at 4% carbon dioxide and 15 °C.
....................................................................................................................................
....................................................................................................................................
....................................................................................................................................
....................................................................................................................................
....................................................................................................................................
....................................................................................................................................
....................................................................................................................................
(3)
(b)
Growers wish to make maximum profits from their lettuces.
What do they need to consider before making decisions about the growing conditions
for their lettuces?
....................................................................................................................................
....................................................................................................................................
....................................................................................................................................
Page 28
....................................................................................................................................
(2)
(c)
The nutrient solution contains nitrate ions and magnesium ions.
Complete the table to show the functions of these ions in plants and their deficiency
symptoms.
Ion
Function in plants
Deficiency symptoms
.........................................................
........................................................
Nitrate .........................................................
........................................................
.........................................................
.........................................................
.........................................................
..........................................................
Magne
.........................................................
sium
.........................................................
.........................................................
.........................................................
(4)
(Total 9 marks)
Q19.
The diagram shows the apparatus used to investigate the digestion of milk fat by an
enzyme. The reaction mixture contained milk and the enzyme.
In Experiment 1, bile was also added.
In Experiment 2, an equal volume of water replaced the bile.
In each experiment, the pH was recorded at 2 minute intervals.
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The results of the two experiments are given in the table.
pH
Time in minutes
(a)
Experiment 1: with bile
Experiment 2: without bile
0
9.0
9.0
2
8.8
9.0
4
8.7
9.0
6
8.1
8.8
8
7.7
8.6
10
7.6
8.2
Milk fat is a type of lipid.
Explain why the pH changed in experiment 2.
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(2)
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(b)
(i)
For Experiment 1, calculate the average rate of fall in pH per minute, between
4 minutes and 8 minutes.
Show clearly how you work out your final answer.
...............................................................................................................
...............................................................................................................
................................. pH units per minute
(2)
(ii)
The average rate of fall in pH per minute for Experiment 2 was 0.1 units of pH
per minute.
Explain the difference in the rate of fall in pH when bile is present.
...............................................................................................................
...............................................................................................................
(1)
(Total 5 marks)
Q20.
DNA fingerprinting can be used to identify people. One example of the use of DNA
fingerprinting is to find out which man is the father of a child.
The diagram shows the DNA fingerprints of a child, the child’s mother and two men who
claim to be the child’s father.
The numbers refer to the bars on the DNA fingerprints.
Page 31
(a)
Only half the bars of the child’s DNA fingerprint match the mother’s DNA fingerprint.
Explain why.
........................................................................................................................
........................................................................................................................
(2)
(b)
Which man, A or B, is more likely to be the father of the child?
Use the numbers on the DNA fingerprints to explain your choice.
In your answer you should refer to all four people.
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(3)
(Total 5 marks)
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Q21.
The diagram shows a family tree in which some individuals have an inherited disorder,
which may cause serious long-term health problems.
(a)
What proportion of the children of A and B have the disorder?
.....................................................................................................................................
(1)
(b)
Explain the evidence from the diagram which shows that the allele for the disorder is
dominant.
Use the appropriate letters to identify individuals in your answer.
You may use genetic diagrams in your explanation. There is space for you to draw a
genetic diagram at the top of the facing page.
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(3)
(c)
(i)
What is meant by ‘embryo screening’?
...........................................................................................................................
...........................................................................................................................
(1)
(ii)
A doctor suggests that couple C and D should have their embryos screened but
that couple G and H do not need this procedure.
Explain the reasons for the doctor’s suggestions.
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(3)
(Total 8 marks)
Q22.
The dodo is an extinct bird. The drawing shows an artist’s impression of the bird.
Page 34
The dodo lived on a small island in the middle of the Indian Ocean. Its ancestors were
pigeon-like birds which flew to the island millions of years ago. There were no predators on
the island. There was a lot of fruit on the ground. This fruit became the main diet of the birds.
Gradually, the birds became much heavier, lost their ability to fly and evolved into the dodo.
(a)
Suggest an explanation for the evolution of the pigeon-like ancestor into the flightless
dodo.
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(4)
(b)
The dodo became extinct about 80 years after Dutch sailors first discovered the
island in the eighteenth century.
Scientists are uncertain about the reasons for the dodo’s extinction.
Suggest an explanation for this uncertainty.
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Page 35
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(1)
(Total 5 marks)
Q23.
Bile is produced in the liver, stored in the gall bladder, then released into the small
intestine.
(a)
Explain how bile affects the digestion of food in the small intestine.
.....................................................................................................................................
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.....................................................................................................................................
.....................................................................................................................................
(2)
(b)
Bile contains bile pigments and cholesterol.
If the diet contains too much cholesterol, some of it may form ‘gallstones’ in the bile.
These gallstones may prevent bile from moving out of the gall bladder into the small
intestine.
Bilirubin is a yellow-brown bile pigment. This pigment is produced by the liver from
haemoglobin released by broken-down red blood cells.
Suggest how gallstones may produce the following symptoms:
(i)
very pale faeces
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
(ii)
jaundice (a yellow tinge to the skin).
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...........................................................................................................................
(2)
(Total 6 marks)
Page 37
M1.
(a)
any three from:
•
((mean) mass) increases up to 7 / 8 units (of light) then levels off
•
light limiting factor up to 7 / 8 units
•
for photosynthesis
must be in correct context
•
other factor / temperature limiting above 7 / 8 units
3
(b)
any two from:
•
cost of providing conditions / heat / light / CO2
•
effect of treatment on profit
allow too much of factor is wasteful
•
relevant use of data from graph eg limiting factors
•
named other factors eg fertiliser / pest control / weeds /
density of planting
allow taste / appearance
2
(c)
nitrate function
produce amino acids / proteins / enzymes
ignore DNA
do not allow chlorophyll
1
nitrate deficiency
stunted growth
allow description
ignore plant dies
1
magnesium function
produce chlorophyll
ignore chloroplasts
1
magnesium deficiency
yellow leaves / plant
Page 38
ignore plant dies
1
[9]
M2.
Cogently argued based on biological principles, for and
against experimenting with human fertilisation techniques
max 4 pros e.g.
help for women who cannot conceive naturally
possibility of eliminating disease causing genes
possibility of inserting useful animal genes
max 4 cons e.g.
ethical objections
religious objections
social issues
any 6 for 1 mark each
6
cogently argued case gains up to 2 marks
2
[8]
M3.
(a)
oxygen;
)
carbon dioxide; ) allow symbols
water
)
each for 1 mark
3
(b)
graph with reasonable vertical scales;
accurate plotting of all points (ignore lines) and labelling lines
histogram – must be coded
gains 3 marks
3
(c)
6 of:
during exercise the level of CO2 (in the blood) rises;
Page 39
increased breathing to remove excess CO2;
increased oxygen supply to muscles;
or increased breathing takes in more O2
or increased heart rate takes more O2 to muscles;
increased supply of sugar to muscles;
increased respiration rate;
enable faster rate of energy release;
reference to lactic acid (allow even though not on syllabus)/O2 debt;
to avoid cramp;
anaerobic reference;
reference to removal of ‘heat’;
6
(d)
high carbon dioxide concentration;
brain/central nervous system;
heart muscles (both)
3
[15]
M4.
(a)
21.5 – 22 and 27 – 27.5
for 1 mark
1
(b)
ideas of
limiting factor / shortage of
e.g. light / carbon dioxide / water / chlorophyll
each for 1 mark
(allow 1 for ‘maximum / optimum rate of enzyme activity if no
reference to limiting factors) (ignore denaturation)
2
(c)
21.5 – 22° C
(allow first figure from answer to (i) so that no ‘double-penalty
but only if this first answer is 20 or greater)
maximum rate of photosynthesis / highest / fastest
but related to flat part of curve
most economical heating / cheapest related to heating
must relate to the temperature the candidate has given
each for 1 mark
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3
[6]
M5.
(a)
(i)
June
for 1 mark
1
(ii)
April
max. light
photosynthesis makes sugars/substances needed for growth
for 1 mark each
3
(b)
2 of:
temperature
carbon dioxide availability
water
chlorophyll
any 2 for 1 mark each
2
[6]
M6.
(a)
on chromosomes/DNA within the nucleus
each for 1 mark
2
(b)
parental genotypes correct i.e. Aa Aa;
gamete genotypes correct i.e. A or a A or a/correct lines;
F1 genotypes correct i.e.
AA Aa Aa aa;
aa recognised as child with cystic fibrosis
each for 1 mark
4
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(d)
(i)
molecule has two long strands/double helix;
idea of held together by (weak) bonds;
each strand has 4 different types of base;
)
which pair with specific bases in opposite strand; )
when strands separate;
) OWTTE
each strand acts as a ‘complementary’ template; )
makes 2 identical strands
)
each for 1 mark
6
(ii)
order of bases acts as a code;
which controls the order;
in which amino acids are assembled into protein;
read in triplet
each for 1 mark
3
[15]
M7.
(a)
(i)
gametes i.e. B b and B b
1
correct combination of genotypes i.e. BB, Bb, Bb, bb
1
correct analysis of phenotypes i.e. 3 black fur 1 with brown fur
1
(ii)
award one mark for the recognition
that it is down to chance (which two
gametes fuse) and not simply ‘because
it’s a prediction’
do not accept mutation
1
(b)
(i)
B is dominant/ an allele is dominant if it is expressed in the heterozygous
phenotype
candidates are likely to use a variety of ways of expressing
their ideas
Page 42
1
b is recessive/ a recessive allele is not expressed in the presence of its
contrasting allele
do not accept powerful
do not accept stronger
1
(ii)
alleles are different forms of a gene controlling a characteristic and
occupying the same site on homologous chromosomes (e.g. B or b)
1
genes are the units of DNA/sites on chromosomes carrying the information
that determines characteristics (e.g. bB)
1
(c)
homozygous: BB / bb / possessing a pair of identical alleles
for a character/true breeding
give credit to an explanation using a diagram
1
heterozygous: Bb / carrying a pair of contrasting/different alleles for a characteristic
do not accept references to xx, xy
do not accept gene by itself
1
[10]
M8.
(i)
with exercise rate rises;
accept between 1 – 2 minutes rate rises
1
(when exercise stops) rate falls slowly;
accept gentle fall or steady fall
for answers which just describe a rise then a fall allow one
mark only as an alternative to the first two points
1
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rate does not return to normal or to starting or to resting rate
accept rate returns to normal after five minutes or three
minutes of rest or after recording ended
1
(ii)
86 (per minute);
1
(iii)
plotting points;
deduct one mark for each error to max of two
if 68 wrongly plotted count as one error (ignore the quality of
the line)
2
[6]
M9.
(a)
(i)
plotting values for pulse rates;
2 marks- minus 1 mark for each error to a maximum of 2
Accept values if plotted on blood volume bar chart
Non-horizontal tops to bars producing variable values = 1
error
If drawn as a line graph =1 mark maximum
2
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(ii)
Either
volume of blood went up then fell;
Accept went to a maximum then fell
pulse rate increased (steadily);
Accept went up steadily or kept going up
2
Or
at first or with low activity or with moderate activity both pulse and
volume increased;
Accept activity up to wall- papering
with more activity pulse continued to increase but volume fell;
(b)
Any two of
Page 45
with increased activity greater muscle use or greater respiration;
need more glucose or oxygen;
Accept more sugar
heart beat faster;
Do not accept more air
Accept more blood needed or blood flows faster
If ‘more’ or equivalent stated once it can be accepted
elsewhere by implication
2
[6]
M10.
(a)
reactants: CO2 + H2O
1
products: C6H12O6 + O2
1
balance:
6CO2 + 6H2O → C6H12O6 + 6O2
1
(b)
1 mark each for any of the following
ideas:
lower CO2 concentration
lower light intensity
decrease water availability
alter light wavelength or colour
accept more green light
2
(c)
(i)
scales correctly constructed
i.e. equal intervals along each axis
1
points plotted correctly
1
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appropriate line correctly drawn
accept dot to dot or line of best fit
cancel if line extends through zero or beyond 50°C
1
(ii)
18 – 19 (bubbles per minute)
1
(iii)
heat denatures enzymes or destroys
membranes or ruptures cells or
destroys cells
do not accept kills enzymes
1
[10]
M11.
(a)
award one mark for each key idea
energy released or energy transferred or respiration
allow provides or gives
do not allow produces or makes
3
near to the site of movement or
energy available quickly or more
energy
accept allows more mitochondria to fit in
(mitochondria) packed (around
filament) or efficient arrangement or
spiral arrangement
(b)
contains chromosomes or genes or
DNA
not genetic material
1
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(which) contribute half (the genes) to
the fetus or offspring
23 chromosomes or half the genes
or reference to X,Y chromosome determining sex (if the
notion of halfness is there)
nucleus contains half genes for the offspring = 2 marks
1
[5]
M12.
any four from:
more energy / respiration required
accept it prevents / reduces anaerobic
respiration or less / no lactic acid
reference to increase must be made,
but only needed once, provided
inference is clear for remainder of points.
accept ‘delivered more quickly’ for ‘increase’
increase oxygen uptake into blood (in lungs)
increase oxygen delivery to muscles
increase glucose delivery to muscles
increase removal of heat from muscles or increase delivery of heat to skin
increase removal of carbon dioxide from muscles
increase removal of carbon dioxide from blood (in lungs)
[4]
M13.
(a)
(before exercise) – 9 to 11 and (after exercise) – 12 or 13
both correct
1
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(b)
0.75 to 0.90
ignore working or lack of working
eg. 2.35 – 1.55 or
for 1 mark
or other suitable figures
2
(c)
any four from:
still need to remove extra carbon dioxide
still need to remove heat / to cool
(some) anaerobic respiration (in exercise)
lactic acid made (in exercise)
oxygen needed to break down lactic acid or suitable reference to oxygen debt
lactic acid broken down to CO2 and water or lactic acid changed into glucose
4
[7]
M14.
(a)
(i)
Aa or aA
1
(ii)
allele / gene for vestigial wings / a is recessive
or vestigial is recessive or A is dominant or
A would override the effect of a or A present gives long wings
1
(b)
parental genotypes correct – both Aa
NB can pick up chain of logic at any point correctly
derived from candidate’s previous point
1
gametes correctly derived from P genotypes
1
offspring genotypes correctly derived from gametes
1
3:1 ratio recognised
wrong cross and not 3:1 ratio = max 2
Page 49
1
[6]
M15.
(a)
A = meiosis
accept ‘mieosis’
do not accept ‘miosis’
1
B = mitosis
do not accept ‘meitosis’ etc
1
(b)
fertilisation allow conception
1
(c)
(i)
23
1
(ii)
46
1
[5]
M16.
(a)
lipase
1
(b)
fatty acid
ignore glycerol
1
(c)
(i)
0.25 or
if correct answer ignore working or lack of working
Page 50
for 1 mark
2
(ii)
fats emulsified or described re. Small droplets or large S.A.
(for enzyme action) or fats ‘mix’ better with water
do not allow breakdown / breakup unqualified
1
[5]
M17.
follow diet A because it gives the highest proportion of stored sugar in the muscles
for 1 mark each
[2]
M18.
(a)
any three from:
•
((mean) mass) increases up to 7 / 8 units (of light) then levels off
•
light limiting factor up to 7 / 8 units
•
for photosynthesis
must be in correct context
•
other factor / temperature limiting above 7 / 8 units
3
(b)
any two from:
•
cost of providing conditions / heat / light / CO2
•
effect of treatment on profit
allow too much of factor is wasteful
•
relevant use of data from graph eg limiting factors
Page 51
•
named other factors eg fertiliser / pest control / weeds /
density of planting
allow taste / appearance
2
(c)
nitrate function
produce amino acids / proteins / enzymes
ignore DNA
do not allow chlorophyll
1
nitrate deficiency
stunted growth
allow description
ignore plant dies
1
magnesium function
produce chlorophyll
ignore chloroplasts
1
magnesium deficiency
yellow leaves / plant
ignore plant dies
1
[9]
M19.
(a)
the enzyme must be lipase
1
since fatty acid produced, which lowered the pH
1
(b)
(i)
0.25 or
correct answer with / without working
Page 52
if answer incorrect / missing, then evidence of
gains 1 mark
2
(ii)
bile provides optimum / suitable / best pH for enzyme action
therefore the rate of the reaction increased
1
[5]
M20.
(a)
eggs produced by meiosis
1
therefore contain only half of mother’s DNA
1
(b)
(man B)
no marks
(child has) mother’s 25 / 28 / 30 / 31
or
child gets 17 / 19 / 22 / 24 from mother
1
(child has) man B’s 10 / 12 / 13 / 14
or
child gets 18 / 20 / 21 / 23 from B
1
no bars / DNA / lines from man A correspond to child
1
[5]
M21.
(a)
1 in 4 / 1/4 / 1: 3 / 25% / 0.25
do not accept 3:1 / 1:4 / 2:6
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1
(b)
either from C and D
accept synonyms for dominant / recessive eg
Normal / faulty
accept genetic diagram if clearly referring to correct
individuals or genotypes on family tree
allow ‘gene’ for ‘allele’
any three from:
•
C and D have disorder
ignore ‘C & D are carriers’
•
I/J don’t have disorder
•
C and D have dominant and
recessive alleles
•
recessive alleles from C and D passed to I/J
or I/J have two recessive alleles
NB if allele was recessive then all offspring of C and D would
have the disorder = 3 marks
or from A and B
assume response refers to A + B unless contradicted
•
A is homozygous recessive / rr, and B is heterozygous / Rr can be shown
in words or symbols
allow any symbol
•
offspring can be rr or Rr described
allow without key
3
(c)
(i)
(embryos) checked for inherited / genetic disorders / conditions
accept diseases for disorders
1
(ii)
any three from:
•
C/D have disorder / have dominant allele
accept disease / condition
accept ‘gene’ for ‘allele’
ignore reference to ‘carriers’
•
chance of embryo / foetus / child having disorder
or may pass on alleles for disorder to their offspring
Page 54
•
C/D might want to decide on termination or prepare
for child with disorder
•
G and H don.t have disorder / both homozygous
recessive / have no dominant alleles (for this disorder)
•
so offspring (of G and H) cannot / don.t have disorder
3
[8]
M22.
(a)
any four from:
•
mutation / variation
•
produces smaller wings / fatter body
must be linked to mutation / variation
•
wings no longer an advantage since no predators
allow wings / flight not needed as no predators
•
wings no longer an advantage since food on ground
allow wings / flight not needed as food on ground
•
fatter body can store more energy when fruit scarce
•
successful birds breed / pass on genes
4
(b)
any one from:
•
evidence has all gone
•
no scientists on island at time to record evidence
•
no records (from sailors)
1
[5]
Page 55
M23.
(a)
any two from:
•
neutralises acid / makes conditions alkaline / raises pH
•
enzymes (in small intestine) work (more/most effectively)
or stop/prevents enzymes being denatured
•
emulsifies fats/lipids or description of emulsification
do not accept breakdown unqualified
•
larger surface area
2
(b)
(i)
bile / bilirubin / pigment / broken down haemoglobin /
substance / cholesterol linked to movement or effect
1
does not get to the intestine / food / faeces
or cannot leave liver or effect not happening (in intestine)
1
(ii)
bilirubin / pigment / broken down haemoglobin
not ‘bile’ alone
1
(deposited) in skin
only award if bilirubin / pigment / broken down haemoglobin
given
allow carried in the blood
1
[6]
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