P530/1
BIOLOGY
Paper 1
Aug 2009
2 hours 30 minutes
BUGEMA S .D.A MOCK SENIOR SIX
BIOLOGY
(THEORY)
Paper 1
2 hours 30 minutes
INSTRUCTIONS
Answer all questions in both sections A and B
SECTION A
Answers to this section must be written in the spaces provided.
SECTION B
Answers to this section should be written in the spaces provided and not anywhere else.
For Examiner’s Use OnlySECTION A : 1 – 40
SECTION B : 41
42
43
44
45
46
TOTAL
SECTION A
1. What is the most likely effect of a population explosion among carnivores in a national park?
A.The population of herbivores will go up.
B.The vegetation cover will increase.
C.There will be an increased demand on the primary producers.
D.There will be increased numberof decomposers
2. One of the amphibians that is able to flourish in hot deserts is the desert frog. It has fewer glomeruli than its counterparts living in the moist tropical regions. How has this animal overcome the problem of water shortage?
A. By reduction of filtrate volume.
B. By reabsorption of water from the loop of Henle.
C. By using metabolic water.
D. By production of non toxic nitrogenous waste product.
3. Which one of the following is not lined with a ciliated epithelium in mammals?
A. Crypts of Lieberkuhn.
B. Fallopian tubes.
C. Vestibular apparatus of the ear.
D. Trachea.
.
4. The dissociation curve of human oxyhaemoglobin,when measured in the absence of CO2 is found to be to the left of the curve which is obtained in the presence of 40mm CO2 pressure. Which one of the following statements gives the fullest explanation of this phenomenon?
A. In the absence of CO2, there is a higher concentration of oxygen and therefore dissociation is slower.
B. CO2 competes with oxygen to combine with haemoglobin forming carbaminohaemoglobin.
C. Hydrogen ions from carbonic acid depress the dissociation of oxyhaemoglobin and favour its formation.
D. In presence of CO2, the dissociation of oxyhaemoglobin is favoured and its formation is depressed.
5. Which one of the following causes the transmission of the electric impulse across the synaptic cleft between two nerves?
A. Sodium pump mechanism.
B. Release of acetylcholine.
C. Release of cholinesterase.
D. Depolarisation ions.
6. What is the role of the centrosome during meiosis in animal cells?
A. Breaking down the nuclear membrane during prophase
B. Homologous chromosomes to pair and form bivalents.
C. Holding the two chromatids of a chromosome together
D. Organising microtubules to form spindle fibres.
.
7. The youngest layer of the phloem in wood stem is located just
A. Inside the cambium.
B. Outside the pith.
C. Inside the epidermis.
D. Outside the cambium.
8. In the mammalian ear the speed of transmission of sound is slowest through the :
A. Endolymph.
B. Perilymph.
C. Ossicles.
D. External auditory meatus.
9. Which one of the following statements best describes Hydra.
A.Unicellular organismhaving trichocysts.
B.Triploblastic multicellular organism.
C. Diploblastic multicellular organism
D. An animal with three distinct cell layers.
10. Which one of the following is a function of fibrous proteins in the body?
A. Act as buffer in the blood plasma.
B. Form structural proteins.
C. Are vital constituents of the plasma membrane.
D. Form enzymes.
11. Which one of the following glands has a compound tubular structure?
A. Mucus glands in the skin of the frog and other amphibians.
B. Salivary glands in he mouth of a mammal.
C. Brunner’s glands in the wall of a mammalian small intestine.
D. Sweat glands in the mammalian skin.
12. Which one of the following best describes the Sodium-potassium pump?
A. Active pumping of potassium ions out of the axon and sodium ions into it.
B. Equal concentration of the ions on either side of the axon when it is at rest.
C. Inability of the axon to absorb the two ions passively.
D. Active pumping of the sodium ions out of the axon and potassium ions into it.
13. Which of the following statements best describes how pesticides have become dangerous today?They______
A. persist in he soil and make it infertile.
B.harden the soil.
C.Pass through food chains in more concentrated forms.
D. Cause eutrophication in the water and kill the fish.
14.Which two of the following strands of nucleotides would pair with strand X in the figure below.
X / i / ii / iii / iv-A / A- / T- / A- / U-
-C / C- / G- / C- / G-
-A / A- / T- / A- / U-
-G / G- / C- / C- / C-
-T / T- / A- / U- / A-
- i and iii.
- ii and iv.
- i and ii.
- iii and iv.
15.The interstitial cells in the mammalian testes______
A. provide nourishment for the maturation of the spermatozoa.
B.store mature spermatozoa.
C.secrete the male hormone testosterone.
D.give rise to spermatogonia.
16. The competitive exclusion principle attempts to explain why______
A. a particular niche only contains one species.
B. pioneer plants are not found in an established community.
C. there are rarely more than five trophic levels in an ecosystem.
D. the diversity of a habitat increases as succession proceeds.
17. Two populations of a given species could only evolve into two distinct species if they were subjected to
A. Disruptive selection.
B.Geographical isolation.
C. Stabilising selection.
D. Genetic isolation.
18. Which part of the brain controls the pace maker?
A.Cerebellum.
B. Medulla Oblongata.
C. Cerebrum.
D. Hypothalamus.
19. Vitamin K is required in the clotting process for the formation of______
A. thrombin.
B.prothrombin.
C. fibrinogen.
D. fibrin.
20. Marine teleosts have body fluids hypotonic to the surrounding water.The problem of osmotic extraction of water from their bodies is overcome by:
A. Active uptake of salts by chloride secretory cells.
B. swallowing sea water and having a kidney with low filtration rate.
C. having a very high glomerular filtration rate.
D.losing a lot of salt in water.
21. Which of the following pathways offers the least resistance to water flow?
A. Apoplast.
B.Symplast.
C.Vacuolar.
D.Cytoplasmic.
22. What does ‘portal’ mean e.g in hepatic portal vein?
A. a vessel that carries digested food.
B. a vessel that carries food from the stomach to the liver.
C. a vessel that carries blood towards the heart.
D. a vessel that joins capillary beds of one organ to another.
23. During anaerobic respiration,the hydrogen atoms taken up by NAD are handed to
A. FAD
B. Cytochrome oxidase.
C. Pyruvic acid.
D. Acetyl coenzyme.
24. Which of the following techniques is most suitable for investigating the distribution of a plant species in an open grassland?
A. Line transect .
B. Lincoln index method.
C. Random quadrats.
D. Belt transect.
25. One evolutionary advantage of sexual reproduction over asexual reproduction is
A. the formation of diploid gametes.
B. linkage of genes.
C. development of specialized somatic tissue.
D. an increased potential for variation.
26. Which biological process takes place in the matrix of the mitochondrion?
A. Glycolysis.
B. Formation of the lactic acid.
C. Tricarboxylic acid cycle.
D. Alcoholic fermentation.
27. Which one of the following is not a function of the mammalian placenta?
A. Secretion of some hormones.
B. Supply of nutrients to the foetus.
C. Supply of mother’s blood to the foetus.
D. Removal of excretory products from the foetus.
28. Which of the following pairs of phenomena is caused by unequal distribution of auxins in plants?
A. Phototropism and Photoperiodism.
B. Geotropism and Phototropism.
C. Nastic movements and Geotropism.
D. Photoperiodism and Geotropism.
29. The functional unit of a skeletal muscle is the
A. sarcomere.
B. filament.
C.fibril.
D.myofibril.
30. Which of the following have homologous organs?
A. Bats,ostrich,insects.
B. Bats,man,whales.
C. man,hydra,salamander.
D.mite,obelia,insects.
31. For diffusion to occur
A. the diffusing particles should all be of uniform size.
B. the diffusion medium should be of uniform density.
C. there must be uniform distribution of the diffusing particles.
D. a free energy gradient must exist.
32. Which of the following is the correct sequence of electron flow in the light reaction in green plants?
A. Water, photosystem II , NADPH , photosystem I.
B. Photosystem I , photosystem II , NADPH , water.
C. Photosystem I , water , NADPH , photosystem I .
D. Water, photosystem II , photosystem I , NADPH .
33. Which one of the following t RNA anticodons will bind to the m RNA codon CAG?
A. GUC .
B. GTC .
C. GAC .
D. UGA .
34. What is meant by ‘the green house effect ‘ ?
A. Reduction in the earh’s ozone layer.
B. Increase in the green house temperature.
C. Gradual warming of the atmosphere.
D. Increase in toxic gases in the atmosphere.
- Which of the following is an example of secondary succession in progress?
A. Former pond now supporting growth of shrubs and trees.
B. Appearance of lichens and mosses on a bare rock surface.
C. Establishment of plants on a newly formed island.
D. Abandoned farmland now covered with weeds and shrubs.
36. Which one of he following forces is the most effective in raising water to the top of tall trees?
A. Capillarity.
B. Root pressure.
C. Cohesive and adhesive force.
D. Adhesive force.
37 . The immediate effect in a child born with a hole in the wall between the two ventricles is to
A. prevent flow of blood into the aorta.
B. . prevent blood flow to the pulmonary artery.
C. cause blood to flow back into the veins.
D. mix oxygenated with deoxygenated blood.
38. During double fetilisation in flowering plants the cells involved include only two male nuclei,
A. antipodal and egg cells.
B. egg cell and polar nuclei.
C. synergids and polar nuclei.
D. antipodal cells and synergids.
39. Which one of the following series of reactions uses the acetyl Co A?
A. Photosynthesis.
B. Glycolysis.
C. Fermentation.
D. The citric acid cycle.
40. Which of the following statements about immunity is incorrect?
A. Antibodies are produced against specific antigens.
B. Heat killed bacteria become antibodies when injected into an animal.
C. Antibodies are special proteins.
D. Antigens can be molecules on a foreign microbe.
SECTION B
41. a) What is meant by an ‘ open circulatory system’?
b) Give three structural ways in which the circulatory system of an earthworm is similar to that of man.
i)
ii)
iii)
c) State two structural features of the human cardiac muscle.
i)
ii)
d) What property of the cardiac muscle has been exploited in heart transplant surgery?
e) How is the blood pressure generated in the human blood circulatory system?
42.
The graph above shows the results of an experiment carried out to determine the Respiratory Quotient(R.Q.) values of germinating seeds over a period of 6 days.
Study the graph and answer the following questions.
a)How does the R.Q. of the germinating seeds change with time?
b)How do you account for the high R.Q. value at the beginning of the experiment?
c)Explain the change in R.Q. value between day 1 and day 2.
d)Suggest with a reason,the major substrate at the end of the experiment.
43.
The figure above shows a food web in a terrestrial habitat.
a)Complete it by inserting the arrows linking the different organisms.
b)State with reasons,which organisms in the food web would be most directly affected if saprophytic fungi and bacteria were removed.
44. The following experiments were performed using the fruit fly Drosophila melanogaster.
Experiment 1 :-
Male flies showing two recessive sex linked characteristics: white eyes and vestigial wings were mated with females which were true breeding for wild type eyes and wild type wings.
The female offsprings of this first cross were then mated with their parents.The results of this second cross had 72 flies with white eyes, vestigial wings,80 flies with white eyes, wild type wings, 76 flies with wild type eyes, vestigial wings and 84 flies with wild type eyes, wild type wings.
Experiment 2 :-
Male flies showing two recessive sex linked characteristics: white eyes and vestigial wings were mated with females which were true breeding for wild type eyes and wild type wings.
The female offsprings of this first cross were then mated with their parents.The results of this second cross had 128 flies with white eyes, vestigial wings,21 flies with white eyes, wild type wings, 17 flies with wild type eyes, vestigial wings and 136 flies with wild type eyes, wild type wings.
a)i) Using suitable symbols, explain the crosses responsible results obtained in Experiment 1 .
ii) What is the cross over value?
iii) What are the positions of the alleles of white eyes and vestigial wings on the Drosophila chromosome in Experiment 1 ?
b)i) Why are the results observed in the second cross of Experiment 2 different from those observed in a similar cross in Experiment 1 ?
ii)What are the positions of the alleles of white eyes and vestigial wings on the Drosophila chromosome in Experiment 2 ?
c) Briefly comment on the significance of these results in relation to Mendel’s law of Independent Assortment.
45. a) Give any
i) Two similarities between DNA and RNA molecules.
Similarities:-
1.
2.
ii) Three structural differences between DNA and RNA MOLECULES
DNA / RNA1.
2.
3.
b) The diagram shows the sequence of bases on one strand of a short length of DNA
ACC CGACCCCAG
This sequence should read from left to right
i) Give the base sequence that will be produced as a result of transcription of the complete length of DNA shown in the diagram.
ii) Give the bases of the transfer RNA which will correspond to the sequence of bases shown in the box on the diagram.
c) Of what importance are the following during protein synthesis?
i) Nonsense triplets.
ii)Ribosomes.
iii)ATPase enzyme.
46.
The diagram represents a phospholipid molecule.
a)i) Name the parts of the molecule A,B and C.
A-
B-
C-
ii) Explain how the phospholipids molecules form a double layer in a cell membrane.
b)Give two functions of the protein molecules in the cellmembranes.
d) The diagram below shows a plant cell immersed in a sucrose solution. The pressure potential(p) of the cell and solute potential(s) of the cell and of the sucrose solution are shown in the diagram.
i)Calculate the water potential((cell).Show your working.
ii)State whether water will move into or out of the cell.Explain your answer.
iii) State the water potential at the point of incipient plasmolysis.Assume that changes in s(cell) are negligible.
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