Mastering KCSE Biology with Comprehensive Topical Questions and Answers
K.C.S.E Biology Q & A - MODEL 2007PP1QN25
The action of ptyalin stops at the stomach. Explain
ANSWER
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K.C.S.E Biology Q & A - MODEL 2007PP1QN24
Name two tissues in plants that provide mechanical support
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K.C.S.E Biology Q & A - MODEL 2007PP1QN24
State a characteristics that is common to all cervical vertebrae
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K.C.S.E Biology Q & A - MODEL 2007PP1QN23
What is thigmotropism?
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K.C.S.E Biology Q & A - MODEL 2007PP1QN23
Name the hormone that is responsible for apical dominance
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K.C.S.E Biology Q & A - MODEL 2007PP1QN22
The diagram below represents a neurone
​(i) Name the neurone
(ii) Name the parts labeled P and Q P……………………………………………………………………….. Q………………………………………………………………………. (c) State a function of myelin sheath
ANSWERS
​(b) Motor neutron
(ii) P- Dendrites Q- Axoplasm (Axon) (d) Insulates the axon
K.C.S.E Biology Q & A - MODEL 2007PP1QN22
Where in the human body are relay neurons found
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K.C.S.E Biology Q & A - MODEL 2007PP1QN21
Give a reason why organisms become resistant to drugs
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K.C.S.E Biology Q & A - MODEL 2007PP1QN21
What is adaptive radiation
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K.C.S.E Biology Q & A - MODEL 2006PP2QN08
Describe how water moves from the soil to the leaves in a tree.
answers
​Water exists as a thin film in the soil between soil particles. The concentration cell sap is greater than that of the surrounding solution in the soil; Thus drawing water molecules across the cell wall and membrane into the root hair cells; by osmosis; water drawn into the root hair cell dilutes the cell sap/ makes it less concentration than that in the adjacent cell into the cortex cells. (By osmosis); across the endosperm by active transport; into the xylem vessels (of the root); Then conduct the water up into the xylem (vessels) of the stem; into xylem of leaves. Water is pushed/ rises up the stem by root pressure ( in the xylem vessels) water would rise by capillary; cohesion, and adhesive forces; water moves as a continuous an uninterrupted water column in the xylem (vessel) up the tree to the leaves. As water vaporizes from the spongy mesophyll cells; their cells sap becomes more concentrated than adjacent water flows into the cells from other surroundings cells; which in turn takes in water from xylem vessels within the leaf veins. This creates a pull / suction force/ transpiration pull that pulls a stream of water from xylem vessel in the stem and roots; the transpiration pull maintains continuous column of water from the roots into the leaves (transpiration stream).
K.C.S.E Biology Q & A - MODEL 2006PP2QN07
Describe how human kidney functions
answers
The afferent arteriole which is the branch of renal artery supplies blood to glomerulus; The afferent arteriole has a wider diameter than the afferent arteriole; this causes high pressure; leading to ultra filtration. The walls of the blood capillaries are one cell thick hence glucose, amino acids, (vitamins, hormones) salts, (creatinine) urea and water filter into Bowman’s Capsule to form glomerular filtrate; White blood cells/ red blood cells and plasma proteins such as (Globulin, fibrinogen, platelets) are too large to pass through the capillaries: the filtrate flow into the proximal convoluted tubule; where amino acids (vitamin) and all glucose are selectively reabsorbs back into the blood stream. Many mitochondria provides energy for re- absorption of these substances against concentration gradient/ by active transport. The Glomerular filtrate flow into loop of henle. Water in descending loop moves by osmosis into the blood capillaries; sodium chloride is actively pumped from the ascending arm of loop henle into the blood capillaries. The glomerular filtrate flow into the distal convoluted tubule, water is absorbed from distal convoluted tubule into blood capillaries; the glomerular filtrate flows into collection tube/ duct from where more water is reabsorbed into the blood stream.
Antidiuretic hormone influences the amount of water reabsorbed ( depending on osmotic pressure of blood); The glomerular filtrate from collecting duct now referred to as urine; is emptied into pelvis. The urine passes though pelvis and ureter into bladder out of the body through urethra. K.C.S.E Biology Q & A - MODEL 2006PP2QN06
An experiment was carried out to investigate the effect of hormones on growth of lateral buds of three pea plants
The shoots were treated as follows: Shoot A – Apical bud was removed. Shoot B – Apical bud was removed and gibberellic acid placed on the cut shoot. Shoot C – Apical bud was left intact. The length of the branches developing from lateral buds were determined at regular intervals. The results obtained are as shown in the table below.
a) Using the same axes, draw graphs to show the lengths of branches against time.
b)i) What was the length of the branch in shoot B on the 7th day? ii) What would be the expected length of the branch developing from shoot A on the 11th day? c) Account for the results Obtained in the experiment d) Why was shoot C included in the Experiment? e) What is the importance of gibberellic acid in agriculture? f) State two physiological processes that are brought about by the application of gibberellic acid on plants.
answers
(b) (i) 105 + 1 (mm)
(ii) 134 – 140 (mm) (c) Graph A: The tip of the shoot which was removed contained indole acetic acid (IAA); which causes apical dominance/ inhibits growth/ development of more lateral buds; hence lateral buds sprouted/grew. Graph B; the gibberellic acid which was added on the cut. Promotes formation of lateral branches of stems, hence the fast growth of branches on shoot b. Graph C; The shoot tip which remained intact contains IAA which inhibits growth/ development of lateral buds; hence little change of length of lateral branches. (d) Control (e) Increase productivity (f) Promote cell division, and cell elongation
K.C.S.E Biology Q & A - MODEL 2006PP1QN22
State two functional differences between the rods and cones in the human eye.
answers
Rodes Cones
K.C.S.E Biology Q & A - MODEL 2006PP1QN22
State the function of ciliary muscles in the human eye.
answer
K.C.S.E Biology Q & A - MODEL 2006PP1QN21
The diagram below represents a reflex are in human.
​a) Name the parts labeled X and Y
b) Name the substance that is responsible for the transmission of an impulse across the synapse.
answers
​(a) X- motor neurone- accept of motor neurone rej. Axon alone
Y- Sense organ/ receptor (b) Acetyl; chlorine/ noradrenaline ( Nerepinephrine)
K.C.S.E Biology Q & A - MODEL 2006PP1QN20
State three biological importance of tropisms plants.
answers
K.C.S.E Biology Q & A - MODEL 2006PP1QN20
What name is given to response to contact with surface exhibited by tendrils and climbing stems in plants?
answer
K.C.S.E Biology Q & A - MODEL 2006PP1QN19
Give three advantages of cross pollination.
answers
K.C.S.E Biology Q & A - MODEL 2006PP1QN19
a) Explain how the following prevent self pollination.
(i) Protoadry (ii) Self – sterility.
answers
(i) Protoandry – Male reproduction organ/ anthers androecia/ stamens mature earlier than female reproduction organ/ carpels/ stigma/ pistil/ gynoecium.
(ii) Self sterility- pollen grains are sterile to stigma of some plants/ flowers
K.C.S.E Biology Q & A - MODEL 2006PP1QN18
How does substrate concentration affect the rate of enzyme action?
answer
K.C.S.E Biology Q & A - MODEL 2006PP1QN18
State two functions of bile juice in the digestion of food.
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K.C.S.E Biology Q & A - MODEL 2006PP1QN17
A certain animal has no incisors, no canines, 6 premolars and 6 Molars in its upper jaw. In the lower jaw there are 6 incisors, 2 canines, 6 Premolars and six molars. Write its dental formula.
K.C.S.E Biology Q & A - MODEL 2006PP1QN17
What is the function of carnassials teeth?
answer
K.C.S.E Biology Q & A - MODEL 2006PP1QN17
Distinguish between the terms homodont and heterodont.
answers
​Homodont – having same kind/ type/ similar teeth.while Heterodont – having different type kind of teeth
K.C.S.E Biology Q & A - MODEL 2006PP1QN16
What is the importance of the following in an ecosystem?
a) Decomposers b) Predation
answers
(a) Decomposer – recycling of nutrients
(b) Predation – regulation of numbers/ population |
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