1.
PART 1: DATA ANALYSIS
The table below shows how the Amounts of sweat and urine vary with external
temperature.
External temperature (oC)
0
5
10
15
20
25
30
35
(a)
(b)
(c)
(d)
(e)
2.
Urine (cm3/hr)
100
90
80
70
60
50
40
30
Sweat (cm3/hr)
5
6
10
20
30
60
120
200
Plot the amounts of urine and sweat produced against the external
temperature on the same axes.
(10 marks)
At what temperature is the amount of sweat and urine produced equal?
(01 mark)
(i)
What happens to the amount of sweat produced as the temperature
rises?
(01 mark)
(ii) Explain the observation in (c) (i) above.
(02 marks)
Explain the observation made on the amount of urine produced as
temperature increases?
(03 marks)
Explain any three ways in which the mammalian skin is adapted for
temperature regulation?
(03 marks)
The table below shows the blood glucose levels in a diabetic and non-diabetic
individual, after both individuals were given a sugar solution at 7.00 a.m. Study
the information and answer the questions that follow.
Time after glucose
ingestion
7.00 a.m
8.00 a.m
9.00 a.m
10.00 a.m
11.00 a.m
12.00 noon
1.00 p.m
Blood glucose concentration (mg/ 100 cm3)
Non-diabetic
Diabetic
90
160
150
260
120
330
90
250
90
200
90
160
90
150
1
(a)
(b)
(c)
(d)
(e)
3.
Plot a graph to represent the data.
(07 marks)
From the graph state the normal blood glucose concentration.
(01 mark)
State the similarities and differences between the variation of blood
glucose in the diabetic and non-diabetic individual.
(04 marks)
Explain the differences in (c) above.
(03 marks)
Describe the role of the liver and pancreas in regulating blood glucose
level.
(05 marks)
In trying to conserve fish stocks in a sea, the size of holes of fishing nets
(mesh size), was increased from 80 mm to 100 mm.
Table 1 shows the effect of increasing mesh size by comparing the mass of fish
caught during the year before and after the change mesh size, according the age
group of the fish.
Table 1
Age of fish (years)
2
3
4
5
6
7
(a)
(b)
(c)
(d)
(e)
Mass of fish caught (thousands of metric tonnes)
80 mm mesh size (before
100 mm mesh size (after
change)
change)
4.89
Nil
3.05
7.59
1.88
4.73
0.97
2.39
0.81
1.02
nil
0.92
What do you understand by the word conservation?
(02 marks)
Using the same axes, represent the information in table 1, in graphical
form.
(08 marks)
Calculate the total catch in metric tons, when the mesh size was
(i)
80 mm
(01 mark)
(ii) 100 mm
(01 mark)
From your graph, state four effects of increasing the mesh size on
catches of fish in the sea.
(04 marks)
Suggest a reason for each effect stated in (d)
(04 marks)
2
4.
In an experiment to investigate the rate of enzyme activity, three extracts of
fresh plant materials were mixed with a fixed concentration of hydrogen
peroxide solution in 10ml measuring cylinders, labeled 1, 2 and 3. The volume
of the mixtures including froth (foam) were read and recorded every 20 seconds
for 60 seconds.
The results obtained are as shown in the table below. The potato cylinders were
allowed to stand in the sucrose solutions for half an hour (30 minutes); after
which they were removed and re-measured.
The results obtained are shown in the table 1 below.
Time(s)
0
20
40
60
(a)
(b)
Volume of mixture
with extract 1 (cm3)
5.0
5.2
5.4
5.6
Volume of mixture
with extract 2(cm3)
5.0
5.3
5.6
6.0
Volume of mixture
with extract 3(cm3)
5.0
5.4
6.0
9.2
On the same axes, plot graphs on the graph paper provided for the
volume of mixtures 1, 2, 3 (on the y axis) with time (on the x-axis).
(09 marks)
Using your graph to calculate the rate of reaction (
) in
cm3 per second between 20 and 40 seconds for the reaction with each
extract.
(06 marks).
(i)
rate with extract 1.
(ii) rate with extract 2.
(iii) rate with extract 3.
c)
d)
e)
Explain the results for the rate of reaction in (b) above.
(03 marks)
Besides the factor being investigated in the experiment state any three
other factors that may affect an enzyme activity.
(1½ marks)
Suggest the identity of the enzyme whose action has been investigated in
the above experiment.
(½ mark)
3
5.
The graph below represents oxygen used and carbon dioxide released in an
aquatic plant under different conditions. The oxygen concentration as a
percentage was varied.
a)
b)
c)
d)
e)
From the diagram, which is the appropriate level of oxygen in water for
maximum rate of respiration.
(01 mark)
If the plant was terrestrial, explain with a reason what might be the
appropriate oxygen concentration
(02 marks)
i)
Why does the oxygen used increase with an increase in oxygen
concentration?
(02 marks)
ii)
Suggest the level of light intensity in which the experiment was
carried out.
(04 marks)
i)
In a graph representing respiration without oxygen; gaseous
exchange progressively decreases to zero. Explain this
observation
(03 marks)
ii)
What advantage would the experiment have if it was carried out
under light.
(04marks)
i)
State two advantages of having stomata on both sides of the leaf.
(02 marks)
ii)
What is the role of the vascular bundles in plant nutrition?
(03marks)
4
6.
Mammalian red blood cells are very sensitive to changes in salt concentrations
of the external solution. When placed in hypertonic solutions, they shrink and
crenate i.e. they become plasmolysed; and when placed in hypotonic solutions'
they swell and eventually burst i.e. they are haemolysed. In one experiment, the
percentage of red blood cells haemolysed at different concentration of salt
solutions were studied, and the results below were obtained.
Percentage of haemolysed
red blood cells(%)
Concentration of salt
solution (in g/1000ml)
(a)
7.
100
88
62
50
25
12.5
0.0
0.32
0.34
0.38
0.40
0.44
0.46
0.48
(i)
Plot a graph of the variation of the percentage of haemolysed red
blood cells with concentration of salt solution.
(7½ marks)
(ii) Describe the shape of the graph.
(1½ marks)
(b) Explain
(i)
what is meant by the term hypertenoic solution.
(02 marks)
(ii) why the red blood cells are heamolysed when placed in hypotonic
solutions.
(03 marks)
(c)
Explain how heamolysis of red blood cells is prevented in the
mammalian body.
(04 marks)
(d) Mention any two other aspects of the internal environment that the
mammalian body always maintains at relatively constant level.
(02 marks)
The graph below shows some changes in the dry weight of endosperms,
embryo and the total dry weight of germinating maize.
State what is generally happening to the dry weight of the following during the stated
time.
5
Endosperm from day 1 to day 9.
(½ mark)
Embryo from day 1 to day 9.
(½ mark)
Total dry weight from day 1 to day 6.
(½ mark)
Total dry weight after day 6.
(½ mark)
(b) Explain your answer to each of the following in (a) above respectively.
(i)……………………………………………………….
(03 marks)
(ii)……………………………………………………….
(03 marks)
(iii)………………………………………………………. (04 marks)
(iv)………………………………………………………. (03 marks)
(c)
(i)
What is meant by the phrase dry weight?
(01 mark)
(ii) State one disadvantage of using dry weight as a way of measuring
growth in a seedling.
(01 mark)
(d) Give three external environmental conditions that kept the maize grain
dormant before it germinated.
(03 marks)
8.
A biologist carried out an experiment to determine how auxins affect root and
shoot growth. Different amounts of auxins in (ppm) were supplied to roots and
shoots. The resulting growth responses of both shoot and roots are as follows in
the table below. (negative values are as a result of growth inhibition, while
positive value are as result of growth stimulation)
Concentration of
auxin /ppm
Percentage growth
response of shoots
Percentage of
growth
response of roots
10-6 10-5 10-4 10-3 10-2 10-l
100
101
102
103
0
0
0
0
20
100
200
100
0
-75
0
25
30
10
-20
-60
-80
-100 -100 -100
a)
Using an appropriate scale (s) and on the same graph, draw graphs to
represent the percentage growth response of shoots and roots with
varying auxin concentration.
(6½ marks)
b)
From your graphs, describe the growth response of shoots and roots at
different concentration of auxins.
(5marks)
c)
(i) How does light influence the distribution of auxins and what
effect does this induce in shoots and roots?
(5 marks)
Shoot: ………………………………………………………………. .
Root. ………………………………………………………………….
ii)
Give the significance of the plant responses you have stated in c(i)
above to plants
(2 marks)
d)
State any two properties of hormones?
(2marks)
6
9.
The following results were obtained from a study of the population growth of
fruit flies Drosophila.
Time
1
(weeks)
Number 20
of flies
(a)
(b)
10.
2
3
4
5
6
7
8
9
10
44
82
145
221
275
320
312
295
270
(i)
On the graph paper provided, plot the graph of Drosophila
population against time.
(09 marks)
(ii) Describe the trend of the graph during the 10 weeks. (03 marks)
(iii) Explain the trend of the graph.
(03 marks)
(vi) Give two reasons for the change which took place after seven
weeks.
(02 marks)
At the seventh week, it was observed that some of the flies were
red-eyed and others white eyed. In the previous generation, however, all
the flies were red-eyed.
(i)
If the two alternative eye colours are inherited according to
Mendelian laws, which one of them is recessive?
(01 mark)
(ii) How many of the flies counted at the seventh week were
red-eyed? (show your working)
(02 marks)
An experiment was carried out to investigate the variation in air temperature
and water temperature at a depth of 5 cm below the surface of a lake in the
same area, over a period of one day. The results are shown in the table below.
Temperature (oC)
Time (hours)
0600
0900
1200
1400
1800
2400
0600
Air
22
28
29
36
23
22
23
7
Water
24
24
25
26
24
24
24
(a)
(b)
(c)
(d)
(e)
Using the same axes, represent the information in the table graphically.
(07½ marks)
Using the graph in (a), describe the variation in air temperature between
0600 and 2400 hours.
(03½ marks)
Suggest an explanation for the variation of air temperature between
0600 and 2400 hours.
(03 marks)
(i)
Give the differences in variation in water and air temperature.
(02 marks)
(ii) Suggest an explanation for the observed differences in d (i) above.
(02 marks)
From the results of the experiment state an advantage aquatic mammals
have over terrestrial (land) mammals.
(02 marks)
11.
The table below shows the body volume and surface area of two human beings
A and B.
Human being
Body volume (m3)
Surface area (m2)
A
300
75
B
200
120
The graph below shows the body temperature of A during and after a cold bath.
(The temperature of the bath was 22oC)
8
(a)
(b)
(c)
Calculate the surface area to volume ratio of each person. (02 marks)
For how long was the person in the bath.
(01 mark)
Describe the variation in the person’s temperature with time.(03 marks)
(d)
Explain the variation in temperature of the subject with time between
(i)
10 and 30 minutes.
(03 marks)
(ii) 30 and 50 minutes
(05 marks)
On the same axes, sketch a graph to show how you would expect the
temperature of B to vary with time if B spends the same time in the bath
as A.
(02 marks)
Explain the difference between the graph for A and B.
(03 marks)
Explain what is meant by the term homeostasis.
(01 mark)
(e)
(f)
(g)
12.
(a)
Figures 4 (a), (b) and (c) show the variation of rate of photosynthesis
under different conditions. Study the figure and answer the questions
that follow.
(a)
(i)
(ii)
(b)
(c)
(d)
Describe the shape of curve 1 in figure 4 (a).
(02 marks)
Giving a reason, state why the rate of photosynthesis in curve 1
of figure 4 (a) remains constant at some stage.
(02 marks)
Giving a reason state two factors which might be the cause of a
constant rate of photosynthesis in figure 4 (b).
(03 marks)
Describe the shape of the curve in figure 4 (c).
(03 marks)
(i)
From figures (a), (b), and (c), state factors that affect the
rate of photosynthesis.
(03 marks)
(ii) Explain how each of the factors stated in d (i) affect the rate
of photosynthesis.
(07 marks)
9
13.
The table below shows the development of an infection with human-immuno
deficiency virus (HIV) over a period of 8 years in relation to changes in the
number of lymphocytes. Use it to answer the questions that follow.
Time/years
Average number of
lymphocytes in blood
Number of
HIV
particles
(a)
(b)
(c)
(d)
14.
0
1
2
3
4
5
6
7
27.1
28.0
20.2
10.1
4.9
3.0
2.1
1.2
0
33
40
50
70
10
16
19
Plot a suitable graph to illustrate the above data.
Use your graph to describe the changes in the number of HIV particles
over the 8 years period.
Describe two ways in which the curves for lymphocytes differ from that
of HIV particles.
Suggest an explanation for the description in (c) above.
In an experiment to investigate the effect of solute concentration of the
external solution on osmosis, fresh Irish potato cylinders were used. The potato
cylinders were trimmed to a uniform length and diameter of 30.00mm and
5.00mm respectively.
The potato cylinders were then placed in sucrose solutions of varying
concentration labeled as A, B, C, D and E in mol l-1. The potato cylinders were
allowed to stand in the sucrose solutions for half an hour; after which they were
removed and re-measured. The results obtained are shown in the table below:
Concentration
Diameter of
of sucrose
potato cylinders
-1
solutions(mol l ) after 30
minutes (mm)
Length of
potato cylinders
after 30
minutes (mm)
A
6.50
33.00
B
5.00
30.00
C
4.00
37.50
D
5.50
31.50
E
4.50
28.50
10
Volume of
potato cylinders
at the start of
the experiment
(mm3)
Volume of
potato cylinders
at the end of
the experiment
(mm)
(a)
(b)
(c)
(d)
(e)
15.
Calculate the volume of the potato cylinders at the s tart and end of the
experiment. Record your results in the table.
(Take volume of a cylinder = πr2h where π = )
Explain the difference in the volume of the potato cylinders at the end of
the experiment for each of the following:
(i)
Cylinders from solution A and D
(ii) Cylinders from solution C and E
Explain the result obtained for the cylinder from solution B.
State the biological importance of the results obtained in the experiment
above.
Apart from the tissue used in the experiment above, name any two other
tissues which can be used to obtain similar results.
The diagram below shows the growth curve of a maize seed measured
over a 15 week period. Examine it carefully and answer the questions that
follow:
(a)
(b)
(c)
(d)
Why is there negative growth initially during germination stage?
Describe the appearance of the seedling when positive growth occurs at
week 1
What process occurs at week 1 to account for this positive growth?
Why is the decrease in dry mass after the 12th week very sudden?
11
16.
(a)
(b)
(c)
(d)
17.
PART II: STRUCTURED AND ESSAY
The graph below shows results of the study that was carried out on the
relationship between the populations of wild rabbits and desert foxes in a
certain habit, with time in years. Study the graph and answer the questions that
follow.
State the name given to the relationship shown above.
State what happened to the:
(i)
population of desert fox up to the second year.
(ii) population of wild rabbits between the 2nd and 4th year.
Explain your answer in b(i) and (ii) above.
Mention any two ways by which
(i)
wild rabbits are able to avoid the desert fox.
(ii) the desert foxes are able to capture the wild rabbits.
(a)
(b)
(c)
(d)
(01 mark)
(01 mark)
(01 mark)
(03 marks)
(02 marks)
(02 marks)
Distinguish between the terms germination and seed dormancy.
(03 marks)
Give three roles of water to a germinating seed.
(03 marks)
Mention any two causes of seed dormancy.
(02 marks)
State how the causes of dormancy you have given in (c) above can be
broken.
(02 marks)
12
18.
The table below shows the composition of blood of three adult individuals.
One lives at a high altitude, another is anaemic and the other has an
infection. It also shows the average number of each blood component in an
adult human. Study the information in the table and answer the questions
that follow:
Average number
Components of blood
Person A Person B Person C in adult human.
Red blood cells per mm3
7,500,000 5,000,000 2,000,000 5,000,000
3
White blood cells per mm 6,000
8,000
12,000
5,000-10,000
3
Blood platelets per mm
250,000 255,000 100,000 250,000
(a)
(b)
19.
20.
Giving a reason, suggest the person,
(i)
who lives at high altitudes.
(03 marks)
(ii) who is anaemic
(02 marks)
(iii) who has an infection
(03 marks)
Suggest a likely effect of the observed number of blood platelets in
person C.
(02 marks)
Explain how each of the following features in a mammal affects body
temperature.
(a)
Size of the animal
(02 marks)
(b) Hair/fur on the skin
(02 marks)
(c)
Fat under the skin
(02 marks)
(d) Why is it important to maintain a constant body temperature?
(04 marks)
Figure 3 below represents blood vessels supplying selected organs. The arrows
show the direction of blood flow.
13
a)
b)
c)
21.
a)
b)
c)
22.
a)
b)
23
a)
b)
c)
Name the vessels labeled a to f
(03 marks)
State the differences in composition of blood in vessels;
i)
c and g
(02 marks)
ii)
a and b
(0l mark)
iii) d and f
(02 marks)
Explain the difference in blood pressure in blood vessels x and y.
(02 marks)
What is meant by the following terms as applied to wild life in a game
park?
i)
Game cropping
(01 mark)
ii)
Carrying capacity
(01 mark)
In an ecological study it was observed that organism A feeds on green
plants, while C feeds on A, B feeds C and that D feeds on .B. If all the
letters A, B, C and D represent living organisms in an ecosystem, which
organism is;
i)
Producer
(03 marks)
ii)
Secondary consumer
iii) Tertiary Consumer
iv)
Draw a pyramid of numbers using the data above. (01 mark)
In a practical experiment to determine the population of rats in the
neighbouring bush at Joll's schooL 75 rats were captured, marked and
released. After 2 days, a second capture of 200 rats was made. It was
observed that in the second capture 150 of them had not been captured
before.
i)
Identify the method used to determine the population of rats in
this experiment.
(01 mark)
ii)
Calculate the population of rats in the bush next to John's school.
(03 marks)
i)
What is meant by the term pollution?
(01 mark)
ii)
Outline any four common air pollutants.
(02 marks)
Describe the human activities that would lead to less production of
carbon dioxide into the atmosphere.
(12 marks)
(i)
What is meant by the term Mutation?
(01 mark)
(ii) Give any four agents of Mutations.
(02 marks)
How has the knowledge of genetics helped in improving plant breeds?
(04 marks)
Sickle cell anaemia is a condition in humans where red blood cells attain
sickleshapes. A normal man married a woman who is a carrier of sickle
cell-trait. Carry out test crosses to determine the genotypic ratio of the
likely off springs.
(08 marks)
14
24.
a)
b)
Outline the factors which affect the rate of photosynthesis. (05 marks)
Describe an experiment to show that light is necessary for
photosynthesis.
(10 marks)
25.
a)
b)
What is seed and fruit dispersal?
(02 marks)
Describe how seeds and fruits are adapted to their different methods of
dispersal.
(10 marks)
26.
(a)
(b)
What do you understand by the term pollution?
(02 marks)
(i)
Mention any five water pollutants you know
(2 ½ marks)
(ii) For each of the air pollutants mentioned, explain the effects it has
on living organisms.
(6 ½ marks)
Outline the ecological effects of wild fires on environment. (04 marks)
(a)
(i)
27.
(b)
How are flowering plants adapted to promoting self-pollination
(04 marks)
(ii) Outline the events that occur after fertilization of a flower
(06 marks)
Mention five advantages of vegetative propagation or reproduction in
plants.
(05 marks)
28.
(a)
(b)
Outline the functions of the mammalian ear.
(02 marks)
Explain how sound waves in the air are heard as a sound in your ear
(13 marks)
29.
(a)
Explain the roles played by different hormones in the female menstrual
cycle
(06 marks)
Explain the importance of the following in the development of
mammalian embryo during pregnancy:
(i)
Placenta
(05 marks)
(ii) Amniotic fluid
(03marks)
(b)
30.
(a)
(b)
Distinguish between complete and dominance and co-dominance.
(02 marks)
In an experiment, a variety of garden peas having a smooth seed coat
was crossed with a variety having a wrinkled seed coat. All the F1
generation had smooth seed coat. The F1 generation were selfed. The
total number of F2 generation was 7324. Using appropriate symbols,
workout the genotype of the F1 generation.
(03 marks)
15
31.
(c)
From the information above, workout the following for the F 2
generation.
(i)
Genotypic ratio.
(03marks)
(ii) phenotypic ratio.
(01 mark)
(iii) total number of wrinkled seeds.
(01 mark)
(a)
Outline four structural differences between arteries and veins.
(04marks)
As Jane was peeling matooke, she cut her finger and started bleeding.
Explain why the bleeding stops after a few minutes even before she had
had the wound dressed.
(11 marks)
(b)
32.
(a)
(b)
33.
(a)
(b)
(c)
34.
What are the problems encountered in wild life conservation.
(10 marks)
Why is it important to conserve wild life?
(05 marks)
A large area of forest was cut down and the land was cleared. Explain
how this might affect the carbon cycle.
(04 marks)
Explain how nitrogen in the muscle protein of a herbivore may be recycled to form protein in another herbivore some years later. [07 marks]
Explain how the activities of some bacteria form a part of both the
carbon and nitrogen cycles.
(04 marks)
Give biological explanations for the following observations.
(a)
Most insects have a small body size.
(b) Plants growing in arid areas have sunken stomata
(c)
Plants growing under forest have dark green leaves compared to those
growing in open areas.
(d) A baby breastfeeds several times a day while the mother eats few times a
day.
(e)
A seedling placed horizontally on a ground, its radicle bends towards the
ground surface while a plumule bends upwards after a few days.
(f)
Human drinks a lot in a single day while a bird takes less than 30mls of
water a day.
(g) Water logged soils are deficient in nitrates.
(h) The red pigment of red blood cells spread when a drop of blood is put in
a beaker of distilled water.
16
35.
(a)
(b)
Define:
(i)
Multiple alleles
(ii) Inbreeding
Ketty and John are both members of youth club. Betty whose blood
group is AB gets pregnant and produces a baby boy who is homozygous
for blood A. She claims John heterozygous for blood group A is
responsible for the child. As a U.C.E. candidate advise the court whether
John is guilty or innocent.
36.
(a)
(b)
Define the term heterodont.
A child ingested boiled meat and later took in some water. Describe the
changes that occurred in the child's alimentary canal.
37.
(a)
(b)
Define chemosynthesis.
With the aid of a well-labelled set up, describe an experiment you can
carry out in the laboratory to show that the rate photosynthesis is
affected by light of different intensities.
38.
Mutations can occur during the process of cell division.
(a)
Distinguish between a mutant and a mutagen.
(b) Describe the process of mitosis in an animal cell.
39.
(a)
(b)
Describe the events that result into the union of female and male
gametes in a flowering plant.
Suggest any three benefits of sexual reproduction over a sexual
reproduction.
40.
Outline the ecological effects of fires in an ecosystem.
41.
(a)
(b)
42.
(a)
(b)
43.
Describe the structure and distribution of xylem tissue in a
dicotyledonous stem.
State how the structures described in (a) are adapted to their functions.
Describe how the interaction of hormones control the human menstrual
cycle.
What changes occur if conception has occurred?
An athlete who lives at low altitude is trained at high altitude before major
competitions. Comment on the:
(a)
Respiratory changes that occur and
(b) The importance of the acquired changes.
17
44.
(a)
(b)
What is meant by a limiting factor?
Describe and explain how variations in
(i)
Light intensity
(ii) Temperature and
(iii) Carbon dioxide concentration may influence the rate of
photosynthesis.
45.
(a)
(b)
(c)
List four differences between blood and lymph.
Outline the transport of carbon dioxide by the mammalian blood. ·
Describe the cardiac cycle in a mammal.
47.
What is meant by:
(a)
(i)
Analogous structures
(ii) Homologous structures
(iii) Vestigial structures
(iv) Fossils
(b) For each of the structures in (a) above, say how they can be used as
evidence of evolution.
48.
(a)
(b)
(c)
What is respiration?
State three differences between aerobic respiration and anaerobic.
Describe gaseous exchange in a frog.
49.
a)
(i)
(ii)
(iii)
50
a)
b)
c)
What is meant by double circulation in the mammals? (3 marks)
Distinguish between double circulation and single circulation.
(4 marks)
Describe the sequence of events during one heart beat.
Draw and label a diagram illustrating the internal structure of a leaf.
(5 marks)
Describe the mechanism of how the active leaf cells obtain
carbon dioxide for photosynthesis.
(5 marks)
State other factors that determine the rate of photosynthesis.(5 marks)
18