Mastering KCSE Biology with Comprehensive Topical Questions and Answers
K.C.S.E Biology Q & A - MODEL 1999PP1QN13b
Describe how population of grasshoppers in a given area can be estimated.
answers
​Use the capture and recapture methods; Catch the grasshoppers count and mark using permanent ink; record and release; and allow time 1 to 2 hours; recapture and count the marked and the unmarked; total population is equal to the number of marked and unmarked grasshoppers in the second sample multiplied by number marked grasshoppers in the first sample; divided by the number of grasshoppers marked in the second sample that were recaptured.
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K.C.S.E Biology Q & A - MODEL 1999PP1QN13a
Distinguish between a community and population.
answers
K.C.S.E Biology Q & A - MODEL 1999PP1QN12
A student set up an experiment as shown in the diagram below..
a) i) What is being investigated in the experiment?
ii) On the diagram below indicate the expected results after three days.
​iii) Why was it necessary to have wet cotton wool in the containe?
b) What is the role of the following to a germinating seed/ i) Oxygen ii) Cotyledons.
answers
​.a) i) Region of elongation (rapid) growth in a root.
b) i) Oxygen
Oxidation of stored food; to provide energy (for germination) ii) Cotyledons Store food necessary for germination; protecting the plumule. K.C.S.E Biology Q & A - MODEL 1999PP1QN11
Give reasons for each of the following:
a) Constant body temperature is maintained in mammals. b) Low blood sugar level is harmful to the body.
answers
​a) Most enzymes in the body function within a narrow range of temperature;
High temperature denature enzymes Low temperature inactive /inhabit enzymes b) Sugar in a raw material for respiration, hence less energy, available to body/low/rate of metabolism. K.C.S.E Biology Q & A - MODEL 1999PP1QN10
Below is a list of organisms, which belong to classes Insecta, Myriapoda and Archnida: Tick, centipede, praying mantis, tsetse fly, millipede and spider. Place the organisms in their respective classes in the table below.
Give reason in each case. K.C.S.E Biology Q & A - MODEL 1999PP1QN09
The diagram below shows surface view of a human brain.
a)Name the parts labeled B and C.
b) State three functions of the part labelled A c) State what would happen if the part labeled B was damaged.
answers
a) B- Cerebellum
C- Medulla Oblongata ; Acc Oblongata alone b) Control locomotion motor area/sends impulse to affectors/controls
K.C.S.E Biology Q & A - MODEL 1998PP1QN18
​ A hungry person had a meal, after which the concentration of glucose and amino acids in the blood were determined. This was measured hourly as the blood passed through the hepatic portal vein and the iliac vein in the leg. The results were as shown in the table below.
(a) Using the same axes draw graphs of concentration of glucose in the heptic portal vein and the iliac vein in the leg against time
(b) Account for the concentration of glucose in the hepatic vein from: (i) 0/1 hour (ii) 1-2 hour (iii) 2- 4 hours (iv) 5 – 7 hours (c) Account for the difference in the concentration of glucose in hepatic portal vein and the iliac vein between 2 and 4 hours. (d) Using the data provided in the table explain why the concentration of amino acids in the hepatic portal vein took longer to increase.
answers
​(a) If axes reversed allow marks for identification of curves only max 2
Correct scales Correctly leveled axes Curves reject broken lines for curves (b) 0-1 hour. i) Acc constant/low/below normal levels in blood; No/little digested foods/glucose from the intestines/gut/alimentary canal/absorption. ii) 1-2 hours Sharp increase in concentration of glucose in blood; (more) absorption of glucose; after digestion of the meal. iii) 2-4 hours. Glucose concentration declining/decreasing; less glucose being absorbed; (more) glucose being converted to glycogen in the liver/tissue/used for (tissue) respiration. iv) 5-7 hours. Concentration of glucose stabilizes/constant/ this is the normal glucose level concentration in the blood. (c) The concentration of glucose in the iliac vein is lower than in the hepatic portal vein because it hasn’t been stored in the liver to be used respiration. Portal vein because most of it was stored/used up by the liver/other tissues/respiration. (d) Proteins take longer to digest. K.C.S.E Biology Q & A - MODEL 1998PP1QN17
The diagram below represents a nerve cell.
(a) (i) Identify the nerve cell.
(ii) Give a reason your answer in (a) (i) above (b) Name the structure labeled T (c) Using an arrow indicate on the diagram the direction of movement of an impulse in the cell.
answers
(a) (i) Sensory neurone/sensory nerve cell; reject sensory nerve
(ii) Cell body on a branch/ at the side of axon/off the axon/cell body unipolar both axon and dendron are long. (b) T- myelin sheath; Acc Neurilema (c) Direction of impulse from receptor towards cell body. K.C.S.E Biology Q & A - MODEL 1998PP1QN16
​ A student placed a drop of pond water in a cavity slide and observed it under the microscope. The student observed many fast moving organisms, one of which is represented in the diagram below.
(a) (i) Name the phylum to which the organism belongs
(ii) Give a reason for your answer in (a) (i) above (b) Name the structures labeled N, P and Q. (c) State two observable features that enable the organism to move fast.
answers
(a) (i) Protozoa
(ii) Unicellular/ single celled (b) N- Contractile vacuole P – Cilia, Acc cilium Q – Gullet/cytopharynx (c) Cilia Streamlined body. K.C.S.E Biology Q & A - MODEL 1998PP1QN15
The herbivorous mammalian species were introduced into an ecosystem at the same time and in equal numbers. The graph below represents their populations during the first seven years. Study the graph and answer the questions that follow..
(a) (i) Which species has a better competitive ability?
(ii) Give reason for your answer (b) Account for the shape of the curve species A between (i) One year and three years (ii) Three years and seven years (c) A natural predator for species A was introduced into the ecosystem. With a reason state how the population of each species would be affected.
answers
(a) (i) Species A;
(ii) The rate of multiplication/ growth in A is faster than of species B (b) (i) One year and three years 1-3 years shortage of resources more suitable environmental Conditions/ such as food space e.t.c resource were not limiting hence the population increased exponentially rapidly; acc correctly named resource e.g food space. (iii) Three years and seven years 3-7 years shortage of resources/ limiting/ birth rate equals death rate; hence the population had become stagnant/ constant; acc; Environmental resistance has set in rej. Incorrect resources e.g PT and T. (c) Species A would decrease (because of there is less competition with species A/ More resources available. K.C.S.E Biology Q & A - MODEL 1998PP1QN14
In an experiment to investigate a factor affecting photosynthesis, a leaf of a potted plant which had been kept in the dark overnight was covered with aluminum foil as shown in the diagram below
The set up was kept in sunlight for three hours after which a food test was carried out on the leaf.
(a) Which factor was being investigated in the experiment? (b) What food test was carried out? (c) (i) State the results of the food test (ii) Account for the results in c (i) above (d) Why was it necessary to keep the plant in darkness; before the experiment?
ANSWERS
(a) Light; Rej: light intensity
(b) Test for starch (c) (i) The covered part of the leaf remain brown/yellow/ retain color of iodine, and the uncovered parts turned blue/ black; rej blue alone black alone. (ii) Starch was formed in the covered part of the leaf (because of the presence); while starch was not formed in the covered part of the leaf ( because of lack light) (d) To destarch the leaf; K.C.S.E Biology Q & A - MODEL 1998PP1QN13
(a) List four differences between meiosis and mitosis
(b) Which sex chromosomes are found in human? Sperm cell? Ova? K.C.S.E Biology Q & A - MODEL 1997PP1QN17
​Figures 1 and 2 below represent reproductive organ of plants and an animal respectively.
​(a) Which letters in figures 1 and 2 represents the organs that produce female gametes?
Figure 1 Figure 2 (b) What is the function of the structure labeled S? (c) Name the structure labeled W (d) Which letters in figures 1 and 2 represents the structures where fertilization takes place (e) Which letter in figure 1 represents the structure where male gametes are produced?
answers
​(a) Figure 1 R:
Figure 2 T: (b) Development of the foetous/zygote/fertilized/ova/egg/embryo (c) Style (d) R;P; (e) X K.C.S.E Biology Q & A - MODEL 1997PP1QN16
In a breeding experiment, plants with red flowers were crossed. The produced 123 plants with red flowers and 41 with white flowers
(a) Identify the recessive character Give a reason (b) What was the genotype of the parent plants that gave rise to the plants with a red and white flowers?
answers
​(a) White
Give a reason – Fewer numbers/ lower ratio; lower in numbers/ absence of white in parents & absence in offspring. (b) Heterozygous (c) Double recessive / homozygous (recessive)
K.C.S.E Biology Q & A - MODEL 1997PP1QN15
The equation below represent a metabolic that occurs in the mammalian live Amino acids →Organic compounds + urea
​(a) Name the process.
(b) What is the importance of the process to the mammal? (c) What is the source of amino acids in this process (d) What is the difference between essential and nonessential amino acids?
ANSWERS
​(a) Deamination
(b) Removal of excess amino acids availing energy in the body formation glycogen/ fat for storage. (c) Proteins (d) Essentials amino acids are acquired from food Non- essential are synthesized in the body K.C.S.E Biology Q & A - MODEL 1997PP1QN14
The diagram below represents a simplified nitrogen cycle.
​(a) Name the organisms that cause process E and J
(b) Name the process represented by F and H. (c) Name the group of organism represented by G
ANSWERS
(a) E- Denitrifying bacteria; e.g pseudomonas denitrifications
J- Nitrifying bacteria; Nitrobacteria reject nitrosamines (b) H- Death decay/ decomposition; excretion/ Aminonification putrefaction egestion. F- Nitrogen fixation (c) Plants K.C.S.E Biology Q & A - MODEL 1997PP1QN13
An experiment was carried out to determine the rate of transpiration in three plants A, B and C. Plants, A and B belonged to different species while plants B and C belonged to the same species. Plant C had all its leaves removed. The three plants were of similar size and were exposed to the same environment conditions. The results are as shown below in the graphs below
​(a) Suggest possible environment conditions under which the experiment was carried out between 30 and 60 minutes
(b) Account for the results obtained for plant C (c) Suggest the habitat for plant A and B. Give reasons for your answer. Habitat for plant A Habitat for plant B
ANSWERS
​(a)strong air/ winds
High temperature Low humidity; accept dry conditions/ sunlight (b)Absence of leaves/ stomata absent Transpiration; / little transpiration (c)Arid/dry/ desert/ accept semi- desert Reason Low rate of water loss; accept more/ a lot of water loss Wet/Moist/aquatic Reason High rate of water/ high rate of transpiration /acc. A lot of water loss K.C.S.E Biology Q & A - MODEL 1997PP1QN12
A person was able to read a book clearly at arm’s length but at normal reading distance.
(a) State the detect the person suffered from? (b) Why was he unable to read book clearly at normal distance (c) How can the defect be corrected?
ANSWERS
(a) Long sightedness/ hypermetropia
(b) Eye ball too short/ eye lens are unable to focus because they are flat/weak, unable to focus the image on the retina; eyes are unable to accommodate/ change their focal length (c)By wearing convex / biconvex lenses; accept converging lenses K.C.S.E Biology Q & A - MODEL 1997PP1QN11
​The following below represents a feeding relationship in an ecosystem
​(a) Write down the food chains in which the guinea fowls are secondary consumers
(b) What would be the short term effects on the ecosystem if lions invaded the area? (c) Name the organism through which energy from the sun enters the food web.
ANSWERS
​(a) Grass→ Grasshoppers → Guinea fowls
Grass→ Termites → Guinea fowls (b) Lions would compete with leopards Gazelle numbers would reduce Grass would increase (c) Grass; K.C.S.E Biology Q & A - MODEL 1996PP1QN 19
​The diagram below represents then pathways of water from the soil into the plant.
(a) Name the structures labeled K and L.
(b) Explain how water from the soil reaches the structure labeled L. (c) Name the process by which mineral salts enter into the plant
ANSWERS
(a) K- Root hair
L- Xylem vessel (b) Water moves from the soil into the root hair by osmosis; because concentration of cell sap is higher than water in the soil; the cell sap in the root hair is diluted, thus making it less concentrated than neighboring cell; therefore water moves into the neighboring cell; it is actively secreted into structure L. (c) Active transport/ diffusion K.C.S.E Biology Q & A - MODEL 1996PP1QN 18
​In an experiment black mice were crossed and the offspring were back and brown. The gene for black colour is dominant over that of brown colour.
Using letter B to represent the gene for black colour and b to represent the gene for brown colour (a) Work out the genotypes of the F1 generation (b) What is the phenotype ration of the spring
K.C.S.E Biology Q & A - MODEL 1996PP1QN 17c
How can low blood volume be brought back to normal
answers
K.C.S.E Biology Q & A - MODEL 1996PP1QN 17b
Name the process by which the human body naturally stops Bleeding?
answers
K.C.S.E Biology Q & A - MODEL 1996PP1QN 17a
How may excessive bleeding results in death?
answers
K.C.S.E Biology Q & A - MODEL 1996PP1QN 16
​A shoot of seedling exposed to light on one side bends towards the source of light as it grows
(a) Name the response exhibited by the shoot of the seedling (b) Explain how the bending towards the source of light occurs
answers
​(a) Phototropism
(b) Auxins / hormones; move diffuse to the demised/ away from the light side; causing elongation/ growth on the dark sides hence bending |
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