PAPER ONE.

1. In the body, proteins may combine with acids or bases depending on the
a. Temperature of the medium
b. Hydrogen ion concentration in the medium
c. Number of solvent molecules present in the medium
d. Number of amino acid molecules in the protein.

2. The epithelia type lining the mammalian alveoli is
a. Columnar
b. Cuboid
c. Stratified
d. squamous

3. Which one of the following is correct about the first division of meiosis but not that of mitosis?
a. Nucleolus disappears
b. Spindle is formed
c. Centrioles move to opposite poles of the nucleus
d. Homologous chromosomes associate to form bivalents.

4. Worker bees and the queen are bee are polymorphic forms which differ in their fertility as a result of
a. Feeding on different diets
b. Worker’s eggs not being fertilized
c. W+orkers being produced parthenogenetically
d. The queen having diploid cells while the workers have haploid cells.

5. Which of the following ions move from the plasma into the red blood cells to maintain electro-neutrality during the uptake of carbondioxide by the blood in the tissues?
a. CI
b. CO
c. K
d. HCO

6. Which one of the following is not a correct statement about nastic response?
a. The response may be a growth movement
b. The direction of movement of a plant is always related to the direction of the stimulus
c. It is a response from a non-directional stimuli
d. The light period is interrupted with short dark period.

7. Long-day plants may be stimulated to flower if
a. The period of darkness is interrupted with flashes of light
b. Provided with more than 10 hours of light
c. Provided with 12 hours of complete darkness
d. The light period is interrupted with short dark period

8. Wearing a coarse shirt causes unpleasant sensation at first but later the discomfort disappears because
a. With continued stimulus, generator potential falls below threshold value
b. The post-synaptic surfaces fail to release the transmitter substance
c. Nervous system stops carrying sensory impulses
d. Continued stimulation leads to fusion of generator potentials.

9. Which one of the following is the correct shape in the region of the body of an earth worm where its circular muscles are contracted?
a. Short and thick
b. Long and thin
c. Short and thin
d. Long and thick

10. Chiroleples, the desert frog flourishes in the desert because it
a. Has a water proof skin
b. Is nocturnal
c. Has few and small glomeruli
d. Reabsorbs metabolic water.

11. Which one of the following is the ultimate hydrogen acceptor during an anaerobic respiration in animals?
a. Lactic acid
b. NAD
c. Pyruvic acid
d. Acetyladehyde

12. Which one of the following is unlikely to be found in the body cells of obligate anaerobes?
a. Glycolytic enzymes
b. ATP
c. Mitochondria
d. Sugars

13. Which one of the following is illustrated in figure 1?

a. Which increases in light intensity, the rate of photosynthesis increases until temperature becomes a limiting factor.
b. Rate of photosynthesis increases with an increase in the carbondioxide concentration.
c. With increase in light intensity, the rate of photosynthesis increase indefinitely.
d. Rate of photosynthesis increases with an increase in light intensity until carbondioxide concentration becomes a limiting factor.

14. Which one of the following is not a fibrous protein?
a. Keratin
b. Globulin
c. Elastin
d. Collagen

15. Which one of the following activities would result into a low respiratory quotient?
a. Respiration in muscles during heavy exercise
b. Formation of calcareous shells
c. Preparation for hibernation in a mammal

16. A probable function of the endoplasmic reticulum is to
a. Control the entry and exit of materials in cells
b. Facilitate intracellular transport of materials
c. Act as template in protein synthesis
d. Enable substances diffuse against concentration gradient.

17. The rapid stomatal closure during wilting is due to
a. Increase in abscisic acid
b. Rapid conversion of sugar to starch
c. Rapid accumulation of carbondioxide in the guard cells
d. Reduction in the level of mineral ions in the guard cells

18. Cartilaginous fish retain urea In the blood in order to
a. Avoid dehydration
b. Reduce entry of salts into the tissues
c. Avoid loss of excess water by excreting it
d. Maintain an internal ionic concentration in balance with the external medium

19. Which one of the following organisms does not belong to the same phylum as the reset?
a. Tape worms
b. Liver fluke
c. Planaria
d. Leech.

20. A cockroach has a respiratory system while an earth worm does not because
a. Earthworms do not need much oxygen
b. The surface volume ratio in a cockroach is small
c. Earthworms can be parasitic
d. The respiratory system provides shape in a cockroach

21. Which one of the following structures is not homologous with the rest?
a. Bat wing
b. Human fore arm
c. Insect wing
d. Bird wing

22. Which one of the following has the greatest biomass in an ecosystem?
a. Tertiary consumers
b. Primary producers
c. Secondary consumers
d. Primary consumers

23. Which one of the following is an effect of the luteinizing hormone?
a. Development of the graafian follicles.
b. Ovulation
c. Stimulation of sperm production
d. Repair of the uterine wall

24. Which one of the following is a correct statement about a neurone membrane during resting potential?
a. The inside of the neurone membrane is negatively charged.
b. The Na, K and CI ions are evenely distributed on either side of the membrane.
c. The concentration of Na ions is greater inside the membrane
d. The concentration of K ions is greater outside the membrane.

25. Which one of the following statements is not correct about a test cross?
a. It is carried out on an organism with a dominant phenotype
b. The offspring of the cross may all have dominant phenotype
c. The organism of the unknown genotype is crossed with a homozygous dominant individual
d. The offspring of the cross may have the ratio of 1 dominant phenotype: 1 recessive phenotype.

26. Which of the following conditions result from gene mutation?
a. Klinefelter’s syndrome
b. Turner’s syndrome
c. Sickle cell anaemia
d. Down’s syndrome

27. If the triplet of mRNA is AAG what is the complementary triplet of the bases on the tRNA molecule?
a. TTC
b. UUC
c. CCT
d. CCU

28. Which one of the following factors does not increase the chances of fertilization in mammals?
a. Seasonal breeding cycles.
b. Female receptiveness to the male only during ovulation
c. Internal fertilization
d. Development of secondary sex characteristics

29. Which one of the following is not a problem that endoparasites face in their transmission?
a. Leaving the host
b. Entering the host
c. Leaving away from the host
d. Identifying the host

30. Which one of the following statements is correct about the exponential phase in the population growth?
a. Death rate and birth rate are equal
b. Numbers of individuals and rate of growth increase
c. The numbers outstrip the supply of factors for support
d. Slow growth of the population.

31. An organism living in an oxygen deficient environment has
a. Haemoglobin that easily picks up oxygen
b. Its oxygen dissociation curve to the right
c. Haemoglobin that readily releases its oxygen
d. Haemoglobin that less readily picks up oxygen

32. Which one of the following is not a purpose for courtship behavior among animals?
a. Ensuring the both partners are sexually mature
b. Establishing a pair-bond
c. Ensuring that both partners are ready for mating
d. Establishing territories.

33. Which one of the following statements is not correct about seed dormancy?
a. It allows further development of the seed
b. It is induced by internal factors
c. It increases the chances of survival of the seed
d. It is ended by external factors

34. Figure 2 shows that

a. NAD is oxidized to NADH
b. NADH reduces FAD to FADH
c. FADH is reduced to FAD
d. NADH + H----------NAD

35. The number of organisms in each tropical level reduces as one moves up food chain because
a. Energy is lost in moving from one trophic level to another
b. Energy is lost from the top trophic levels
c. Organisms in higher trophic levels are less productive
d. Of high level of predation at the top trophic levels.

36. Anerobes thrive better than aerobic organisms in waters experiencing thermal pollution because
a. High temperature kill aerobic organisms
b. Anaerobes posses enzymes that work best at high temperatures
c. High temperatures reduce solubility of oxygen
d. High temperatures encourage multiplication of aerobes’ predators.

37. Which one of the following is correct about parallel flow of water across the gills?
a. Water has a higher oxygen concentration at each point of contact
b. Low blood oxygen concentration is attained
c. Diffusion occurs over the whole region of the grill filament
d. High blood oxygen concentration is achieved.

38. Which one of the following adaptations of xerophytes does not reduce transpiration?
a. Hairy leaves
b. Leaves with thick waxy circle
c. Small sized leaves
d. Succulent stems

39. The influx of water in fresh water bony fish is offset by possession of
a. Numerous, large glomeruli and re-absorption of salts from the renal fluid.
b. Numerous, small glomeruli and extrusion of salts from the body.
c. Few large glomeruli and uptake of salts
d. Many small glomeruli and uptake of salts.

40. The main difference between endotherms and ectotherms is that ectotherms
a. Gain their body heat from internal sources
b. Gain less heat than endotherms
c. Gain the body heat from external sources
d. Are lower animals while endotherms are higher animals.

SECTION B
Answer all questions in this section in the spaces provided.

41. Figure 3 shows the variation of rate of photosynthesis with temperature in C3 and C4 plants, at different light intensities.

a. Using the figure, state how differently temperature affects the rate of photosynthesis in C3 plants from C4 plants at high intensity.
b. Explain the differences in the effect of temperature on the rate of photosynthesis in C3 and C4 plants at high light intensities stated in (a).
c. Explain the pattern of curve (c ) in the figure

42. What is meant by apical dominance?
b. state the causes of each of the following
(i). Apical dominance
(ii). Seed dormancy
d. What is the ecological importance of
(i) Apical dominance?
(ii) Seed dormancy?

43. Explain the absence of a yolk sac in the development of a human foetus while it is an important structure in the development of birds.
b). state the reproductive adaptations of birds to terrestrial life.

c). Give three forms of parental care provided by mammals.

44. What is instinctive behaviour?
b). state two factors that influence instinctive behavior.
C ). Territorial behavior is common among many animal species. Give
(i) Four advantages of this behavior
(ii) Three disadvantages of this behavior

45. Illustrating with a cell of one pair of homologous chromosomes, draw diagrams in the space below to show
(i) Mitotic metaphase
(ii) Meiotic metaphase I
(iii) Meiotic metaphase II
b) explain how meiosis contributes to genetic variation.

 

46. Figure 4 shows the immune response of a person’s blood after vaccinations are given on day one and 60 days later.

a). what is the effect of giving immunization to the individual?
b) from the graph, state the type of immunity acquired by the individual, giving a reason.
C ) explain the shape of the graph
d). describe three ways in which antibodies combat antigens.

PAPER TWO

Theory
Answer question one in section A plus three others from section B.

1. Table 1 shows percentages by volume of some gases in inspired air, expired air and alveolar, in a resting human being.

Table 1

  Percentage volume(%)    
Gas Inspired Air Expired air Alveolar air
Oxygen      
Nitrogen     No data
Carbondioxide      
Water Vapour     No data

Figure 1 a and b show effects of increased carbondioxide concentrations in inspired air, on the volume of air breathed in and out per minute and on the breathing rate respectively.

a. Explain why
(i) The percentage volume of oxygen in expired air is intermediate between the inspired and alveolar values.
(ii) There is a difference in the percentage volume of nitrogen between inspired and expired air.

b. (i) Using the information in figure 1, calculate the mean volumes of a single breathe in and out, at a different carbondioxide concentrations in inspired air indicated in

Table 2

Percentage concentration of CO2 in inspired air.

0 1 2 3 4 5 6


(iii) Plot a graph showing the mean volume of a single breath against percentage concentration of carbondioxide in inspired air.

c. Describe the effect of the increase in carbondioxide concentration in inspired air on the
(i) Volume of air breathed in and out per minute
(ii) Breathing rate
(iii) Mean volume of a single breathin and out

d. Outline the physiological effects in the body, of breathing in excess
(i) Carbondioxide
(ii) Oxygen

SECTION B
Answer any three questions from this section.

2. (a) ouline the events that lead to the formation of pollen grains in flowering plants.

(b) How does the development of the embryo sac in flowering plants differ from oogenesis in humans.

(c ) give an outline of the life cycle of a named pteridophyte.

3 Describe the structure of DNA?

b. using an example, explain an effect of gene mutation in humans.

c. What is the significance of mutation in crop husbandry?

4. (a) Give an outline of the classification of muscular tissues.

(b) Describe the structure of the phloem and cardiac tissues.

(c ) Explain how the structures of the phloem and cardiac muscle are related to their functions.

5. (a) Explain how light may affect the activities of organisms.

(b) Why does transpiration occur mainly through leaves other than other parts of plant.

6. (a) (i) What are chemoheterophic bacteria?

(ii) Give the groups of the type of bacteria in (a) (i).

(b) Using examples, explain the ecological importance of each of the groups in (a) (ii) in an ecosystem.

PAPER ONE
Answer all questions in both sections A and B.

SECTION A.

1. Which one of the following is a simple branched tubular gland?
a. Brunner’s gland
b. Salivary gland
c. Sweat gland
d. Mammary gland

2. Which one of the following activities does not contribute to global warming?
a. Use of pesticides
b. Deforestation
c. Burning fossil fuels
d. Use of CFCs.

3. The significance of etiolation to a germinating seed in the soil is that it
a. Leads to rapid elongation of the hypocotyls in monocotyledonous plants.
b. Allows maximum growth in length with minimum use of food reserves.
c. Allows the seedling to grow in the dark
d. Ensures that leaves remain small to break through the soil.

4. Dioecious plants are rare inspite of having the advantages of cross pollination because
a. Anthers and stigmas mature at different times
b. The male and female plants are usually apart
c. Half of the individuals do not produce seeds
d. Only few agents of dispersal are involved

5. Which one of the following substances would be produced by plants under conditions of water stress?
a. Indoleacetic acid
b. Ethane
c. Bibberellins
d. Abscisic acid

6. Which one of the following does not lead to change in allele frequency of a population?
a. Mutation
b. Selection
c. Sexual recombination
d. Genetic drift

7. Birds learn to ignore a scare crow that is left in the same spot for a long time. This type of behavior is called?
a. Habituation
b. Associative learning
c. Imprinting
d. Conditioning

8. Mendelian expected probabilities of genotypes in a cross occur when
a. Small numbers of offspring are produced
b. Migrations occur in a population
c. Mutations arise
d. Fertilization is random

9. Which one of the following is not correct about the cells of a tissue?
a. Have similar function
b. Are of same origin
c. Are of one type
d. Have physical linkage

10. When a foetus receives antibodies from the mother through the placenta, it acquires
a. Active immunity
b. Long term immunity
c. Passive immunity
d. Artificial immunity

11. Worker bees are
a. Sterile females developed from fertilized eggs
b. Fertile males developed from unfertilized eggs
c. Sterile males developed from unfertilized eggs
d. Fertile females developed from unfertilized eggs.

12. The process of changing the information on mRNA into formation of polypeptides is known as
a. Transcription
b. Translation
c. Transduction
d. Transformation.

13. Which one of the following is an essential feature for successful terrestrial life of flowering plants?
a. Reduction of gametophyte to spores.
b. Development of pollen tube to transfer male gametes
c. Possession of well developed vascular system
d. Reduction of sporophyte to seeds

14. Which one of the following movements In fish is counteracted by the vertical horizontal fins?
a. Rolling
b. Backward drag
c. Pitching
d. Yawing

15. During which transfer of energy is most energy lost in an ecosystem?
a. Producers ----> primary -------> consumers
b. Primary ----> consumers ----> secondary ----> consumers
c. Secondary ----> consumers ----> tertiary ----> consumers
d. Tertiary ----> consumers ----> decomposers

16. The role of oestrogen during birth is
a. Causing contraction of the uterine wall
b. Increasing the sensitivity of the uterine muscles to oxytocine
c. Inhibiting the production of progesterone
d. Promoting milk production in the mammary glands.

17. Which one of the following does not contribute to the movement of water from the root system to the leaves in a flowering plant.
a. Root pressure
b. Cohesion forces
c. Transpiration pull
d. Atmospheric pressure.

18. Arthropods have a lower visual acuity compared to vertebrates because
a. The ommatidia are less sensitive than rods and cones
b. Compound eyes contain fewer rods and cones
c. The ommatadia are big and only few are packed in an equal area
d. The ommatidia contain photochemical pigments which are less readily bleached.

19. High carbondioxide concentration in respiring tissues is important because it causes
a. Local vasodilation, allowing more blood into the tissues
b. Low PH in the tissues leading to unloading of oxygen
c. Local vasoconstriction creating high blood pressure
d. Increased heart beat

20. A major difference between respiration and burning is that
a. No heat is produced during respiration
b. Burning Is a faster process
c. Burning is a chemical process
d. Chemical energy is stored in respiration

21. Which one of the following is the main form of the photosynthetic product transported through the phloem?
a. Starch
b. Amino acid
c. Sucrose
d. Glucose

22. Which one of the following structures supplies oxygenated blood to the foetus?
a. Umbilical cord
b. Umbilical vein
c. Placenta villi
d. Umbilical artery

23. Which one of the following best describes basal metabolic rate?
a. Average amount of energy produced by the body
b. Average amount of energy produced when at rest
c. Amount of energy produced by an average body
d. Amount of energy produced when all voluntary movements have ceased.

24. A property of cells in a multicellular organism is that they are
a. Small sized
b. Less functional
c. Less specialized
d. Dependant

25. Which one of the following tissues has the least power of regeneration?
a. Blood tissues
b. Epithelium tissue
c. Bone tissue
d. Nerve tissue

26. Which one of the following is likely to occur if a photosynthesizing plant was suddenly removed from light?
a. Reduction in PGA
b. Accumulation of PGAL
c. Accumulation of PGA
d. No change in amount of PGAL

27. Which one of the following molecules is represented in figure 1?

a. Fatty acid
b. Deoxyribose
c. Glucose
d. Ribose

28. Establishing the genotype of an organism by crossing it with a homozygous recessive individual is carrying out a
a. Test cross
b. Dihybrid cross
c. Back cross
d. Monohybrid cross

29. In guinea pigs, the allele for rough coat (R) is dominant over one for smooth coat (r ) and that for black ( B) is dominant over one for white coat (b). the alleles for coat type and color are not linked. Across between rough black guinea pig and rough white one produced 28 rough black, 31 rough white, 11 smooth black and 10 smooth white. Which one of the following could be the genotype of the parents?
a. RrBb x Rrbb
b. RRBB x RRbb
c. RRBb x Rrbb
d. RrBB x Rrbb

30. Which one of the following is the reason why insects’ eggs usually hatch rapidly into larvae?
a. Eggs have little York
b. Hatching is controlled by external factors
c. It is a way of avoiding predators
d. Due to excessive production of juvenile hormone

31. Higher concentrations of some ions in the cell sap of some fresh water algae compared to the external water is due to?
a. Diffusion
b. Active transport
c. Pinocytosis
d. Osmosis

32. Mixing of oxygenated and deoxygenated blood in amphibians is minimized by?
a. Rapid contraction of the ventricle
b. Spongy nature of heart muscles
c. Spiral valve in the trances arteriosus
d. Columnae carnae in the ventricular walls

33. Which one of the following describes the state of the membrane during resting potential?
a. Polarized
b. Neutral
c. Depolarized
d. Discharged

34. Which one of the following tissues would be stained deepest red by a dye that stains nuclei red?
a. Sieve tube
b. Tracheid
c. Collenchyma
d. Cambium

35. In which one of the following parts of chloroplast are water splitting enzymes mostly located?
a. Stroma
b. Intergrana
c. Cytoplasm
d. Grana

36. In which of the following may sporophytes contain haploid, diploid and triploid cells at some stage?
a. Conifers
b. Mosses
c. Flowering plants
d. Ferns

37. Compared to carbohydrates, fats have higher energy value because fats
a. Have long chains of fatty acids
b. Have a higher proportion of hydrogen
c. Are more compact in structure
d. Have a high proportion of oxygen

38. Which one of the following would delay flowering in a short day plant?
a. Twelve hours of darkness
b. More than ten hours of light
c. Interruption of dark period with a flash of light
d. Less than twelve hours of darkness

39. Which one of the following nitrogenous wastes is suitable foe elimination by a fresh water fish?
a. Urea
b. Uric acid
c. Ammonia
d. Trimethylamine oxiode

40. Which one of the following is correct about the sympathetic nervous system?
a. Nerve endings produce nor-adrenaline.
b. Preganglionic fibres are long and post ganglionic fibres are short
c. Nerve endings produce acetylcholine
d. Ganglia are embedded in the walls of the effector organs

SECTION B
41. Figure 2 shows oxygen dissociation curves for haemoglobin of two animals x and y, living in different habitats.

a. From the figure, state three differences in the behavior of haemoglobin of the two animals.

b. (i) outline the characteristics of the haemoglobin of animal y.
(ii). From the characteristics in b) (i) suggest the nature of the habitat in which animal y lives.

c. Human haemoglobin has a higher affinity for carbonmonoxide than oxygen. What is the effect of this fact?

42.Differentiate between respiratory quotient (RQ) and basal metabolic rate (BMR)
b. Table 1 shows the respiratory quotient in germinating seeds under different treatments.
Table 1

             Treatment RQ
  1. 4 hr soaking in water
6.0
  1. 4 hr soaking then 4 hr exposure to air
1.8
  1. 4 hr soaking then 24 hr exposure to air
1.0

Explain the different respiratory quotients of the germinating seeds under the different treatment.
C. Explain why the BMR varies with the age of the individual.

43. Table 2 shows the increase in size of a leaf of a plant with time.
Table 2

Days Area of leaf (cm2) Rate of growth (cm2 day-1)
0 0  
5 40  
10 200  
15 250  
20 250  

a. Complete the table by working out the growth rate at 5 days intervals.
b. In the space provided, plot actual growth and growth rate curves.


c. State the main differences between growth in plants and that in animals
d. What are the limitations of measuring leaf area as a way of measuring growth in a plant?

44. (a) (i) describe how the quadrat method can be used to determine species density.
(ii) State the advantage and disadvantage of the method.

(b) (i) Why is it important to estimate population size?
(ii) in estimating the number of fish in a small lake, 625 fish were caught, marked and released. After one week, 920 fish were caught and of these, 150 had been marked. What was the estimated size of fish population?
(iii). In using the method of b (ii) to estimate the population size of fish, state two assumptions that were made.

45. (a) With reasons, give examples of animals which produce each of the following excretory products:
(i) Ammonia
(ii) Uric acid

b. State
(i) Why the pH of the body fluids in a human body is kept constant.
(II) Three ways of keeping pH in b (i) constant.

46 (a) What is placenta activity?

(b) state the ecological importance of each of the following forms of behavior.
(i) Territorial behavior
(ii) Courtship behavior

C . Give two ways in which animals avoid predation.

PAPER TWO
Answer questions one in section A plus three others from section B.


1. Two groups of maize seeds were germinated and grown in different culture solutions. Group A were provided with a complete nutrient solution while group B were provided with a solution lacking magnesium. An extract of photosynthetic pigments was made from leaves of each group of seedlings the end of three week. Figure 1 is the absorption spectra obtained from the extracts.

In another experiment, six identical shoots of pond weed were placed in separate test tubes of pond water in which a dilute solution of sodium hydrogen carbonate had been added. Each test tube was then exposed to light which had passed through a different colored filter. The light in all cases was from a 40 watt bulb, placed 40 cm from the test tube. The time taken for 20 bubbles to leave cut end of each shoot was recorded three times and the average results are recorded in Tble1.

Table 1

Colour of filter Average time taken to release 20 bubbles in seconds Number of bubbles released per minute
Violet 58  
Bleu 40  
Blue-green 62  
Green 132  
Yellow 96  
Orange-red 70  

Use the information to answer the questions that follow.

a. Compare the light absorption by extract from A and that from group B across the light spectrum.

b. Explain the light absorption across the light spectrum for each extract

c. How does a colored filter affect light passing through it

d. (i) Copy and complete Table 1 by calculating the number of bubbles released by each shoot per minute.
(ii). Plot a graph to show the relationship between the color of the filter and the rate at which bubbles are released.

e. (i) compare your graph with that in figure 1 and state the relationship between the two.
(ii). What conclusion can you draw from the relationship?

f. State what would be absorbed if the distance between the bulb and the test tubes was gradually reduced. Explain your answer.

g. Explain why
(i) They type of bulb and the distance of the bulb from the test tubes were kept constant
(ii) A dilute solution of sodium hydrogen carbonate was added to pond water in the test tubes.
(iii) There were three measurements made on each shoot rather than a single one.
(iv) Measuring the rate of photosynthesis by counting bubbles is not an accurate method.

Section B

2. (a) What is meant by negative feedback in body processes?
(b) Describe how each of the following affects the metabolism of carbohydrates
(i). Insulin
(ii) Adreline
(c ) Describe how hormones from the ovary and the pituitary gland interact to control the human menstrual cycle.

3. Explain how the epithelia tissue is adapted for it’s functions

4. (a) Describe the structure of guard cells in a plant leaf
(b) Explain how stomatal opening occurs according to:
(i) Starch ------ sugar interconversion.
(ii) Photosynthetic theory

5. Outline the functions of cell nucleus
a. Describe the changes that occur in a nucleus during meiosis
b. Explain the significance of mitosis and meiosis in organisms

6. Explain the meaning of the following
(i) Genetic isolation
(ii) Reproductive isolation
(b). Explain how the gene frequency of a population may be altered.

PAPER ONE

Write the letter corresponding to the best answer in the box provided.
1. Which one of the following is not a reason for classifying a mouse and a frog in one phylum? Presence of
a. Pharungeal grill slits
b. Post-anal trail
c. Notochord
d. Endoskeleton

2. In photosynthesis, the major advantage of the C4 pathway is to
a. Fix carbondioxide in the calvin cycle
b. Concentrate carbondioxide in the cells of leaves
c. Fix carbondioxide from the atmosphere into the leaves
d. Store carbondioxide in form of organic acids

3. An atheletics competition organized on high lands required participants from lowlands to report three months before the competition in order to enable them
a. Get familiar with the place
b. Develop strong muscles
c. Acquire high red blood cell count
d. Have extensive deposition of fat under their skins

4. The main distinguishing character of a eukaryotic cell is
a. Membraned orbanelles
b. Lack of nuclear membrane
c. Presence of nucleus
d. Presence of DNA double strands

5. Starch, glycogen and cellulose are all composed of
a. A-glucose
b. B-glucose
c. Monosaccharides
d. Polysaccharides

6. Which of the following organelles would most likely be abundant in the tail of a tadpole at a time of its reabsorption during metamorsphosis?
a. Centrioles
b. Lysosomes
c. Golgi apparatus
d. Endoplasmic reticulum

7. If the rate of transpiration legs behind that of absorption, movement of water up the plant is mainly by
a. Root pressure
b. Capillarity
c. Mass flow
d. Transpiration pull

8. An impulse crosses a synapse by means of
a. Sodium ions
b. Potassium ions
c. Calcium ions
d. Neurotransmitter chemical

9. Which of the following increases the rate of phosphorylation of hexose sugar during the normal respiration process?
a. An increase in ADP concentration
b. An increase in ATP concentration
c. An increase in concentration of hexose sugar
d. A decrease in concentration of phosphorylated sugar

10. Which of the following factors would contribute least to the development of new species?
a. Gene mutation
b. Chromosomal mutation
c. Geographical isolation
d. Environmental stability

11. Which one of the following explains why digestion of fats does not occur in the human stomach?
a. Absence of fat-digesting enzymes
b. Low pH for the fat-digesting enzymes
c. High pH for the fat-digesting enzymes
d. Absence of bile salts that emulsify the fats

12. Which one of the following would contribute to the green house effect
a. Use of nuclear power
b. Use of fossil fuels
c. Excessive use of fertilizers
d. Accumulation of sewage in water bodies

13. The increase in supply of blood to heavily respiring tissues, is caused by high
a. Ventilation rate
b. Concentration of oxygen in the inhaled air
c. Carbon dioxide concentration in the blood
d. Carbon dioxide concentration in the tissues

14. Impulse transmission in mammals is usually faster than it is in amphibians because
a. Axons in amphibians lack myelin sheath
b. Mammals have axons with large diameter
c. Mammals usually have higher body temperature
d. The distance between the nodes of ranvier in mammals is horter

15. Which one of the following would occur at the onset of an action potential in a neurone?
a. Potassium ions enter
b. Sodium ions leave
c. Potassium ions leave
d. Sodium ions enter

16. Which of the following applies to the cones of the retina? They
a. Show visual acuity
b. Perceive dim light
c. Show much retinal convergence
d. Contain rhodopsin pigment

17. The flagellum and skeletal muscle are structurally similar in that they both have
a. Microtubules
b. Actin and myosin tubules
c. A pattern of 9+2 microtubes
d. Light and dark bands

18. During the light stage of photosynthesis, water is an important raw material in that it
a. Gives off oxygen
b. Provides hydrogen that reduces NAD
c. Reduces carbon dioxide to carbohydrates
d. Provides electrons

19. Which one of the following activities in living organisms can result in a respiratory quotient of less than 1.0?
a. When carbohydrates are respired
b. During extensive laying down of fat in livestock
c. At compensation point, during photosynthesis
d. When the rate of exhalation equals that of inhalation

20. Which of the following is a difference between flowers of dicotyledonous plants and those of monocotyledonous plants? Flowers of dicotyledonous plant usually
a. Lack sepals
b. Posses superior ovaries
c. Bear floral parts in groups of 4s and 5s
d. Posses fused petals

21. Deciduous plants in temperate zones shade off their leaves during winter
a. Because of water shortage
b. To cut down the process of guttation
c. Because of too much water availability
d. To avoid freezing temperatures

22. Which of the following is true about non-competitive inhibition in enzyme catalysed reactions?
a. The degree of inhibition decreases with increase in substrate concentration
b. The inhibitor has a similar structure and chemical composition with the substrate
c. The degree of inhibition is independent of the substrate concentration
d. The shape of the enzyme is not affected by the inhibitor

23. Which of the following is not true of conifers?
a. Lack vessels in xylem
b. Bear reproductive structures on leaves
c. Bear sporangia on cones
d. Posses unprotected ovules

24. The lack of a nucleus in the red blood cell enables it to
a. Have a high affinity for oxygen
b. Be more permeable to oxygen
c. Give up oxygen more readily
d. Contain more haemoglobin

25. Which one of the following types of behavior is least learnt?
a. Association
b. Instinct
c. Imprinting
d. Insight

26. The primary meristematic tissue in plants which gives rise to the cortex ismthe
a. Ground meristem
b. Procambium
c. Protoderm
d. Protoxylem

27. Which one of the following organisms does not possess simple eyes?
a. Spider
b. Millipede
c. Butterfly
d. Centipede

28. Contraction of longitudinal muscles in insects during flight, results into
a. Flapping of wings
b. Moving down of wings
c. Holding wings horizontally
d. Moving up of wings

29. During fertilization in plants, the
a. Vegetative nucleus fuses with the pollen nucleus
b. Generative nucleus fuses with the egg nucleus
c. Vegetative nucleus fuses with the egg nucleus
d. Generative nucleus fuses with the antipodal cell nucleus

30. A desert mammal’s lower lethal temperature is higher than that of a mammal living in cold regions because a desert mammal has
a. Small extremeties
b. Poor insultation mechanisms
c. Thick fur
d. A small surface area: volume ratio

31. In the energy transfer in an eco system, the greatest loss in energy is between
a. Primary producers and primary consumers
b. Primary consumers and secondary consumers
c. Secondary consumers and tertiary consumers
d. Tertiary consumers and decomposers

32. A rhesus positive foetus whose mother is rhesus negative may not be born alive because the
a. Mother’s body produces antigens against foetal antibodies
b. Foetus lacks anti bodies against the mothers antigens
c. Mother’s body produces antibodies against the foetal antigens
d. Mother’s red blood cells mix with the foetal blood

33. From a bush, 120 beetles were collected, marked and released back into the bush. A few days later, 120 beetles were collected from the same place, and 30 of them carried the mark. The estimated number of beetles in the bush is
a. 240
b. 360
c. 480
d. 560

34. Insects have different mouth parts modified to suit their different modes of feeding. This shows
a. Speciation
b. Convergent evolution
c. Divergent evolution
d. Development of analogous structures.

35. Which one of the following is true of linked characteristics? They
a. Are always transmitted as a single block
b. Are allelic to each other
c. Occur on non-homologous chrosomes
d. Can be transmitted independently

36. Which one of the following may act as a respiratory surface in animals?
a. Spiracle
b. Bronchus
c. Skin
d. Trachea

37. Which one of the following pairs of responses in plants is caused by unequal distribution of auxins?
a. Photoperiodism and phototropism
b. Geotropism and phototropism
c. Nastic movement and geotropism
d. Photoperiodism and abscission

38. The amount of progesterone in the blood increases steadily from ovulation to menstruation, then it begins to decline because
a. Luteinizing hormone inhibits its production
b. It is washed out with blood during menstruation
c. Implantation of a zygot occurs
d. Its work of repairing the uterine wall gets complete

39. Figure 1 shows the relationship between temperature and rate of photosynthesis in two plant species A and B

Which one of the following is a correct conclusion from the results?
a. B is a shade plant while A is a sun plant
b. A has a lower compensation point than B
c. A has a higher optimum temperature for photosynthesis than B
d. Photorespiration does not occur in A but occurs in B

40. The absorption of amino acids after eating a heavy protenous meal is aided by
a. Diffusion and active transport
b. Osmosi and diffusion
c. Diffusion and pinocytosis
d. Active transport only.

Section B
41. Figure 2 shows the effect of red light and far-red light interruption of night period, on flowering of a plant.

a. What is the effect of interruption of the night period by each type of light?

(i) Red light

(ii) Far –red light

b. Suggest the type of plant that would exhibit responses to light treatments as shown in figure 2

c. How can the knowledge of the effect of red light and far-red light on flowering be utilized in the commercial growing of flowers?

42. Figure 3 56+shows diagram of two types of blood circulatory systems A and B, in animals. The arrows show the direction of the blood flow.

a. Describe each circulatory system

(i) A

(ii) B

b. How does each system maintain a high blood pressure?

(i) A

(ii) B

c. What is the advantage of maintaining a high blood pressure over a fluctuating pressure in a circulatory system of an animal?

43. Give one ecological importance of each of the following structural arrangements in plants.
(i) Monoecious

(ii) Dioecious

a. Explain why
(i) In dioecious, male plants are usually associated with dry soils while female plants are associated with moist soil.

(ii) Nearly all dioecious plants are wind pollinated.

b. Give one reason why dioecious plants are rarer than monoecious plants

44. State the importance of the following elements in plant metabolism
(i) Calcium
(ii) Magnesium

a. How does water logging of soil affect it’s nitrate content?

b. Describe three special ways of obtaining essential elements by some plants growing in soil deficient of those elements.

(i)

(ii)

(iii)

45. State two human activities that increase the levels of carbon dioxide in the atmosphere

a. What is the effect of high levels of each of the following gases in the atmosphere?
(i) Carbon dioxide
(ii) Sulphur dioxide

b. State one indicator in the environment where there is prevalence of high levels of sulphur dioxide in the atmosphere.

46. In drosophila, the genes for broad abdomen and long wing are dominant over the genes for narrow abdomen and vestigial wing. Pure breeding strains of the double dominant variety were crossed with a double recessive variety and a test cross was carried out on the F1 generation.

a. Using suitable symbols, work out the expected phenotypic ratio of the test cross of the F1 generation, if the genes for abdomen width and length of wing are linked.

b. It was however observed that when the test cross of the FI generation was carried out, the following results were obtained.
Broad abdomen, long wing 380
Narrow abdomen, vestigial wing 396
Broad abdomen, vestigial wing 14
Narrow abdomen, long wing 10

Calculate the distance in units, between the genes for abdomen width and length of wing.

PAPER TWO

 1. Table 1 shows the number of individuals with a given length of fur in population of a terrestrial mammalian species for two different generations. The prevailing climatic temperature during the two generations changed from 15oC to 10oC.

Table 1

Length of fur (cm) Number of Individuals  
  At 150C At 10oC
  0 0
  25 0
  60 0
  120 20
  155 60
  120 130
  60 155
  25 130
  0 60
  0 60
  0 20
  0 0

Figure 1 shows the variation of resistant strains of bacteria in relation to the amount of antibiotics given during a period of several years in one hospital.
Figure 1

a. Draw a graph of the relationship between fur length and number of individuals to the two temperatures.

b. What is the optimum length of fur at each temperature?

c. What is the effect of temperature on fur temperature among the individuals?
(i) Suggest an explanation for the effect of temperature on fur length.

d. From figure 1, describe the trend of resistant strains with amount of antibiotics used.
(i) Suggest an explanation for the observed trend of resistant strains with the amount of antibiotics used.

e. A bacterium is a haploid organism that produces asexually by fission, twice every minute on average. Using this information, explain the rapid emergence of resistant strains.

f. The data in table 1 and figure 1 illustrate the process of natural seletion. state the selection pressure in each case.

g. Giving a reason in each case, predict what the effect of each of the following would be.

(i) If the use of antibiotics was stopped for a year

(ii) If the generation of the terrestrial mammal at a prevailing temperature of 10oC was supplied with an abundance of food.
Section b

2. Describe how terrestrial plants overcome the challenges of terrestrial environment.

3. Discuss the factors that affect the rate of diffusion at a respiratory surface.

(i) How are the conditions for efficient gaseous exchange fulfilled in mammalian lungs?

(ii) The diameter of capillaries is smaller than the diameter of the red blood cells passing through them. How does this relationship help in gaseous exchange in the lungs?

4. Both haemophilia and colour blindness are transmitted in the same way.

a. What are the effects of each disease?

b. Describe the transmission of the disease

c. Explain why there are more colourblind individuals than haemophiliacs among the human population inspite of the similar way of transmission.

5. Describe the working of an enzyme using the lock and key hypothesis.

a. Explain the
(i) Effect of excessive heat on enzyme action

(ii) Non-competitive inhibition in an enzyme controlled reaction.

6. What is the effect of inbreeding in a population?

a. Describe the mechanisms which limit breeding in plants

b. How does meiosis contribute to variation?

PAPER ONE
Answer all questions in both sections A and B

1. Which one of the following does not contribute to the short reaction times in insects?
a. Large size of omatidia
b. High flicker fusion frequencies
c. Rapid transmission of impulses
d. Large coverage of head by compound eyes

2. Figure 1 below represents of cell division.

Which one of the following stages is represented in the figure?
a. Metaphase of mitosis
b. Interphase
c. Anaphase of mitosis
d. Metaphase I of meiosis.

3. Which of the following structures is found in both xylem and phloem tissues of higher plants?
a. Sieved tracheids
b. Parenchyma cells
c. Companion cells
d. Hollow vessels

4. Which one of the following pairs of events occur together to increase the oxygen concentration in the alveoli of the lungs?
a. Contraction of diaphragm muscles and internal intercostal muscles.
b. Relaxation of diaphragm muscles and internal intercostals muscles
c. Contraction of diaphragm muscles and external external intercostals muscles
d. Relaxation of the diaphragm muscles and external intercostals muscles.

5. Loud and low oitched sound is caused by sound waves of
a. Large amplitude and high frequency
b. Low frequency and large amplitude
c. High frequency and small amplitude
d. Small amplitude and low frequency

6. During flight insects, upstroke is brought about by
a. A contraction of direct flight muscles
b. Relaxation of indirect flight muscles
c. Contraction of indirect flight muscles
d. Sudden upthrust of the body

7. The following are characteristics of amphibians.
(i) Have moist skins
(ii) Carry out external fertilization
(iii) Use gills at early stage of respiration
(iv) Use lungs for respiration

8. Figure 2 shows an ovule of a flowering plant.

A triploid nucleus is formed by fusion of a male nucleus with
a. D and C
b. B and C
c. A and B
d. D and E

9. Which one f the following is not a function of progesterone?
a. Increasing the sensitivity of uterine muscles
b. Inhibiting release of follicle stimulating hormone
c. Inhibiting release of prolactin
d. Promoting growth of mammary glands

10. Which one of the following pairs of adjustments at a respiratory surface would increase its efficiency?
a. Decreasing the rate of ventilation and increasing blood supply
b. Increasing the rate of blood flow and the rate of ventilation
c. Increasing the ventilation rate and the rate of ventilation
d. Decreasing the blood supply and the distance of diffusion of molecules.

11. Which of the following have a sole function of offering support to the plant?
a. Sclerenchyma and vessels elements
b. Vessel elements and tracheids
c. Sclerenchyma and colenchyma
d. Parenchyma and collenchymas

12. The bacteria which converts nitrates to nutrients during the nitrogen cycle are an example of
a. Nitrogen fixing bacteria
b. Nitrifying bacteria
c. Decomposing bacteria
d. Denitrifying bacteria

13. The significance of vascularisation of the endometrium before implantation in mammals is to
a. Ensure firm attachment of the foetus onto the uterine wall
b. Prevent menstruation
c. Assist in producing hormones which maintain pregnancy
d. Facilitate food and oxygen supply to the foetus

14. In a human with a non-functional pancrease, digestion of starch in the intestines would
a. Be possible because of the suitable pH due to bile
b. Not occur for absence of enzymes
c. Would be possible because succus entericus contains the necessary enzymes
d. Would not occur because of the acidic pH of chime.

15. Which one of the following is true about sex linked characters in humans?
a. Females never suffer from the trait
b. Fathers do not pass on their character to their sons
c. Females are either normal or carriers
d. Males are either carriers or nufferers

16. The similarities of the skeletal structures of moles, monkeys and whales lead to the conclusion that they
a. Belong to the same class
b. Originate from the same environment
c. Descend from a common ancestor
d. Envolved convergingly

17. Which one of the following sets of characteristics is an adaptation in mammals to desert conditions?
a. Uric acid production and short loop of Henle
b. Long loop of Henel and urea production
c. Ammonia production and long loops of Henle
d. Man of blood group AB and woman of blood O.

18. Which of the following cannot be parents of a child of blood group O?
a. Man of blood group A and woman of blood group O?
b. Both man and woman of blood group A?
c. Both man and woman of blood group B?
d. Man of blood group AB and woman of blood group O?

19. Which one of the following characteristics is not used in classifying amphibians and reptiles together? Possessions at some stage of,
a. Post-anal tail
b. Two pairs of pentadactyl limbs
c. Notorchord
d. Nerve cord

20. If carbon dioxide containing radio active carbon was added to a suspension of photosynthesis algae, in which one of the following compounds would the radio active carbon show first?
a. Glucose
b. Phosphoglyceric acid
c. Ribulose biphosphate
d. Triose phosphate

21. Etiolation in plants is usually a response to
a. Insufficient nutrients
b. Low temperatures
c. Insufficient light
d. Too much water

22. Figure 3 shows changes in electrical potentials in an axon membrane when an impulse is transmitted.

At what stage of the electrical potentials marked, is axon most permeable to sodium ions?

23. Which one of the following is a disadvantage of a tracheal system for gaseous exchange in insects?
a. Ventilation is limited
b. Tracheales are impermeable
c. Spiracles are too small
d. The system does not supply all bordy parts

24. A climax community is one in which
a. Succession is at its peak
b. A carrying capacity has been reached
c. Succession has been ceased
d. Death rate of organisms is at its lowes

25. Which one of the following is not a function of the skeleton in insects?
a. Support of body
b. Protection of delicate body parts
c. Prevention of desiccation
d. Secretion of wax

26. Which of the following structures is haploid?
a. Primary oocyte
b. Spermatogonium
c. Secondary oocyle
d. Germinal epithelium

27. In higher plants, the problem of obtaining oxygen for respiration is solved by leaves possessing
a. Large intercellular spaces
b. Compact palisade layer
c. Thin lower epidermis
d. Numerous stomata on a lower epidermis

28. Which one of the following is a method used by marine bony fish to overcome the problem of possessing body fluids that are hypotonic to the sorroundings?
a. Increase in the glemerular filtrate
b. Extensive reabsorption of salts
c. Retension of urea
d. Elimination of non-toxic nitrogenous wastes

29. Good drainage and ploughing of soil reduces the process of
a. Nitrification
b. Decomposition
c. Denitrification
d. Nitrogen fixation

30. If the solute potential of the external solution is higher than that of the cell, the external solution is said to be
a. Hypotonic to the cell solution
b. Hypertonic to the cell solution
c. Isotonic to the cell solution
d. Of lower osmotic pressure than the cell solution

31. Which one of the parts of a mammal possesses an epithelia tissue as shown in figure 4?

a. Oviduct
b. Ileum
c. Respiratory tract
d. Loop of Henle

32. The type of learning that involves the immediate understanding and and responding is?
a. Imprinting
b. Associative learning
c. Insight learning
d. A deficiency in oestrogen

33. Prolonged menstrual period may be caused by?
a. High levels of progesterone
b. A decrease in production of follicle stimulating hormone
c. High levels of luteinizing hormone
d. A deficiency in oestrogen

34. Auxins are often used as selective weed killers on lawns because
a. Same dosage of auxins affects different plant parts, differently.
b. They can be manufactured artificially
c. Auxins always kill dicotyledonous plants
d. Auxins remain on the vegetation long after application

35. The compounds which act as oxidizing agents during anerobic respiration in plants are?
a. NAD and pyruvic acid
b. Ethanol and NAD
c. NAD and FAD
d. NADp and pyruvic acid

36. In any ecosystem, a continued input of energy is required because
a. Matter is continually used in metabolic process
b. Biological succession occurs very slowly
c. Of the continued increase in population in the ecosystem
d. Energy is lost each time it is transferred between organisms

37. During the heat of the day, control of the stomatal movements to reduce excessive water loss is due to
a. Active accumulation of mineral ions in the guard cells
b. Synthesis of abscisic acid
c. Inter conversion of glucose and starch in the guard cells
d. Synthesis of glucose during photosynthesis

38. Sucrose is a non-reducing sugar because it
a. It is not fully digested
b. Lacks reducing groups
c. Is a disaccharide molecule
d. Is a ketose sugar

39. Which of the following animals have the most efficient system of gaseous exchange?
a. Insects
b. Bony fish
c. Mammals
d. Amphibians

40. Which one of the following activities contributes least to the green house effect?
a. Use of CFC s
b. Deforestation
c. Excessive use of fertilizers
d. Burning fossil fuels

SECTION B.
Answer all questions in this section

41. Figure 5 shows two types of arrangements, A and B, of sensory cells in the mammalian eye.

a. What is the effect of each arrangement on the response of the eye
(i) Effect of the arrangement A
(ii) Effect of arrangement B

b. Explain how the effect of each arrangement is brought about.
(i) Effect of arrangement A
(ii) Effect of arrangement B
c. Under which light conditions is each arrangement most effective and why?
(i) Arrangement A
(ii) Arrangement B

42. What is meant by water stress in relation to plants?
a. What is the effect of water stress in green plants?
b. Outline the structural adaptations of the xylem vessel for long distance transport of water and mineral salts.

43. Figure 6 shows the effect of changing the osmotic pressure of the external medium (Ope), on the osmotic pressure of the blood (Opi), of the sea animals A and B.

a. Explain the effect of decreasing the Ope on the Opi of each animal.
(i) Animal A
(ii) Animal B
b. Using the information provided, suggest an ecological advantage animal B has over animal A.
c. What is the main osmotic problem faced by sea animals whose Opi is less than Ope?

44. What is meant by alternation of generation?
a. Ferns and mosses show alternation of generations. State the dominant stage in each case.
(i) Ferns
(ii) Mosses
b. Give the importance of alternation of generations in the life cycle of an organism.
c. Outline the limitations that mosses face in growing in terrestrial habitats.

45. Outline the causes of gene reshuffling
a. In what way may variation resulting from gene reshuffling differ from that caused by mutation?
b. What is the importance of variation in a population?
c. Explain how constancy of species may be maintained through naturl selection.

46. Table 1 shows the amount of DDT measured in parts per million (ppm) found in a variety of organisms associated with a fresh water lake.

Where the DDT level was measured Ammount of
DDT/ppm

 Water

Phytoplankton

Zooplankton

Herbivorous fish

Carnivorous fish

Fish - eating birds

0.0003

0.006

0.39

1.8

14.3

   


a. Calculate how many times the DDT is more concerned in carnivorous fish compared with its concentration in water.
(i) What do the results In a show?
b. Explain why the concentration of DDT changes from water to carnivorous fish.
c. State two effects of DDT to organisms.
d. Explain how a pest sprayed with a pesticide may flourish afterwards.

PAPER TWO

1. Figures 1,2 and 3 show the immigration and extinction of species on different categories of virgin islands.

Figure 1 shows the rate of immigration of new species on an island and near by the shore and one that is far from the shore.

Figure 2 shows the rate of extinction of species on a large island and on a small island.

Figure 3 shows the rate of immigration and extinction of species on an island

Study the information and use it to answer the questions that follow.
FIGURE 1

FIGURE 2

FIGURE 3

a. Explain the rate of
(i) Immigration of new species on an island that is near to the shore and one that is far from the shore(figure 1)

(ii) Extinction of species on a small island and on a large island (figure 2)

(iii) Immigration and extinction of species on an island (figure 3)

b. From figures 1,2 and 3, what conclusion can you draw about what determines the number of species on an island?

c. Describe the factors other than those depicted in the information provided, may affect the immigration of new species on an island.

d. Suggest the factors that would cause immigration of new species to a virgin island.

SECTION B

2. Describe the physiological changes that occur in a seed during germination.

a. Giving reasons, suggest suitable conditions under which seeds for planting should be stored.

b. Even when supplied with suitable conditions for germination, some seeds remain dormant. Explain the importance of dormancy in seeds.

3. Describe the adaptations of blood in terrestrial animals living the following environmental conditions.

(i) Increased body temperature

(ii) Small body size

4. Explain the factors that influence the type of nitrogenous wastes excreted by animals.

a. Describe osmoregulation in a terrestrial insect

5. Compare DNA nad RNA molecules

b. Describe the role of the mRNA in the proteins relate to their functions.

c. How does the molecular structure of proteins relate to their functions?

6. Discuss how structure and function are related for each of the following tissues.

a. Voluntary muscle tissue

b. Parenchyma tissue in plants.

 

NOTE: Paper One is missing from the source of information.

PAPER TWO

1. Graphs A,B and C show results of three experiments that were carried out to study the relationship between a predator, didinium and prey paramecium, under three sets of conditions.

In the first experiment, the paramecium was introduced into a culture at point P and Didinuim at point D as shown in graph A of figure 1.

In the second experiment, the paramecium and didinium were introduced together at point P+D at different population densities. This is shown in graph B of figure 1.

In the third experiment, paramecium and didinium were introduced together at point P+D at different densities and after every three days as shown by the arrows in graph C of figure 1.

a. Describe the trend of population growth of paramecium and didinium in graph
(i) A

(ii) B

(iii) C

b. Explain the interaction of the two species of organisms in graph
(i) A

(ii) B

c. Compare the trend of the population growth of the two species in graph B and C.

d. Supposing paramecium and didinium were introduced at the same time under natural environment conditions, sketch curves to show time expected trend of the populations with time.

e. Explain the trends of the population curves of paramecium and didinium you have drawn in (d)

SECTION B

2. Describe how xerophytes survive conditions of unfavorable water balance.

3. Giving an example, explain what is meant by discontinuous variation?

a. How does sexual reproduction cause variation?

b. Explain how the environment may influence the process of natural selection.

4. Using examples, explain the meaning of displacement activity.

a. What is the importance of each of the following forms of behavior to the survival of organisms in a community?
(i) Territorial behavior

(ii) Courtship behavior

5. Explain

a. The need for special respiratory surfaces and transport system pigments in higher animals.

b. How gaseous exchange occurs adequately in higher plants without transport system pigments.

6. What is biological pest control?

a. Explain the precautions to be taken in application of biological pest control.

b. Describe the ecological qualities of a good pesticide.

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