Mastering KCSE Biology with Comprehensive Topical Questions and Answers
K.C.S.E Biology Q & A - MODEL 2000PP1QN03
State two ways in which some fungi are beneficial to humans
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K.C.S.E Biology Q & A - MODEL 1999PP1QN15
An experiment was carried out to investigate haemolysis of human red blood cells. The red blood cells were placed in different concentrations of sodium chloride solution. The percentage of haemolysed cells was determined. The results were as shown in the table below.
a) i) On the grid provided, plot a graph of harmolysed red blood cells against salt concentration.
ii) at what concentration of salt solution was the proportion of haemolysed cells equal to non-haemolysed cells? iii) State the percentage of cells haemolysed at salt concentration of 0.45% b) Account for the results obtained at: i) 0.33 percent salt concentration. ii) 0.48 percent salt concentration. c) What would happen to the red blood cells if they were placed in 0.50 percent salt solution? d) Explain what would happen to onion epidermal cells if they were placed in distilled water.
answers
a) (i)0.403; 0.404; + 0.002
ii) 0.402; iii) 9-10-11% b) Account for the results obtained at: (i) 0.33 percent salt concentration. Less concentration /hypotonic / dilute than blood cells cytoplasm/ red blood cells; water is drawn in by osmosis the cells swells and eventually burst. (ii)0.48 (ii)0.48 percent salt concentration. Concentration of cytoplasm same as concentration of salt solution/isotonic; therefore no net movement of water; hence no heomolysis. c)Percentage of cells haemolysed would still be zero? Becomes turgid; but does not burst; due to the cell wall. d)The cells would absorb water due to osmosis, swell and become turgid. The cell sap move conc. than surrounding water gate into the cell by osmosis; the cell swells/becomes turgid; but does not burst due to the cell wall K.C.S.E Biology Q & A - MODEL 1999PP1QN14
The photograph below represents a blood smear obtained from a person suffering from a certain disease.
a) Name the structure labeled X.
b) i) Name the structure labeled L ii) State the function of the source labeled M c) What disease was the person suffering from? d) List three ways by which micro-organisms enter the human body.
answers
a) Trypanosome
b) i) Locomotion ii) c) Sleeping sickness/trypanosomiasis d) -Orally ingested including boring through bites Sexually; cuts and wounds (contaminated) needles syringes/surgical instruments; contaminated blood transfusion. 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 1999PP1QN07
An investigation plants with red flowers were crossed with plants with white flowers.
All the plants in the F1 generation had pink flowers. a) Give a reason for the appearance of pink flowers in the F1 generation. b) If the plants the F1 generation were selfed, state the phenotypic ratio of the F2 generation.
answers
​a) Co dominance
Acc; partial/incomplete/equal b) 1 red flower 2 pink flowers 1 white flower Acc 1:2:1
K.C.S.E Biology Q & A - MODEL 1999PP1QN01
Name two processes that bring about the translocation of manufactured food
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K.C.S.E Biology Q & A - MODEL 1998PP1QN20
Explain how the mammalian intestines are adapted to perform their function.
answers
​The mammalian intestines are relatively long/coiled/folded. This allows food enough (enough) lime/increases surface area for digestion and absorption of products of digestion. The intestinal surface area for absorption. The glands have enzymes which secrete enzymes for digesting e.g. of correct enzyme, maltase, sucrase, lactase, enterokinase and peptidases. Some glands/goblets cells also produce mucus which protects the intestinal wall from being digested, reduce friction. Intestines have opening of ducts which allows bile/pancreatic juice into the lumen. The intestines have circular and longitudinal muscles whose contraction/relaxation/peristalis leads to the mixing of food with acc. At least enzymes/juices facilitating rapid digestion and helps pus food along the gut. Intestines are well supplied with blood vessels to supply oxygen/remove digested food. Presence of lacteal vessels for transport of fats/lipids.
Have thin epithelia to facilitate fast/rapid absorption/diffusion. Allow increase in surface area for absorption only. Cell biology/cytology. Occurrence of cell e.g. mitochondria, ribosome’s, nucleas, cytochromes organelle point to a common ancestry. 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 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 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 1998PP1QN11
State two ways by which the human immuno deficiency (H.I.V) is transmitted other than through sexual intercourse?
ANSWERS
What is the relationship between leguminous plants and bacteria found in their root modules?15/6/2020
​K.C.S.E Biology Q & A - MODEL 1998PP1QN05
What is the relationship between leguminous plants and bacteria found in their root modules?
ANSWERS
K.C.S.E Biology Q & A - MODEL 1998PP1QN03
Which organelle would be abundant in:
ANSWERS
Skeletal muscle cell
K.C.S.E Biology Q & A - MODEL 1998PP1QN02
State one effect of magnesium deficiency in green plants
ANSWERS
K.C.S.E Biology Q & A - MODEL 1997PP1QN20b
Describe how the mammalian small intestine is adapted to its function
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K.C.S.E Biology Q & A - MODEL 1997PP1QN20.
What is meant by the term digestion?
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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 1997PP1QN10
Name a disease caused by lack of each of the following in human diet.
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K.C.S.E Biology Q & A - MODEL 1997PP1QN04
State two ways in which xylem vessels are adapted to their function
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K.C.S.E Biology Q & A - MODEL 1997PP1QN02
A student caught an animal which had the following characteristics:
ANSWERS
K.C.S.E Biology Q & A - MODEL 1997PP1QN01.
State the functions of the following cell organelles
(a) Golgi apparatus
(b) Ribosomes
ANSWERS
​(a) Golgi apparatus
K.C.S.E Biology Q & A - MODEL 1996PP1QN 17c
How can low blood volume be brought back to normal
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K.C.S.E Biology Q & A - MODEL 1996PP1QN 17b
Name the process by which the human body naturally stops Bleeding?
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K.C.S.E Biology Q & A - MODEL 1996PP1QN 17a
How may excessive bleeding results in death?
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When is glycogen which is stored in the liver converted into glucose and released into the blood.KNEC ANSWER
After vigorous activity when blood fall below normal |
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