Mastering KCSE Biology with Comprehensive Topical Questions and Answers
K.C.S.E Biology Q & A - MODEL 2004PP1QN17
During germination and growth of a cereal, the dry weight of endosperm, the embryo and total dry weight were determined at two – day intervals. The results are shown in the table below.
a) Using the same axes, draw graphs of dry weigh of endosperm, embryo and the total dry weight against time
b) What is the total dry weight on day 5? c) Account for: i) Decrease in dry weight of endosperm from day 0 to 10 ii) Increase in dry weight of embryo from day 0 day 10 iii) Decrease in total dry weight from day 0 to day 8 iv) Increase in total dry weight after day 8 d)Dormancy. i) Within a seed ii) Outside the seed e) Give two characteristics of meristematic cells
answers
​(b) 38.5 (mg); Acc. + 0.5 ( i.e. 38 – 39)
(c) (i) Hydrolysis of starch into simple sugars; which are translocated to the embryo; Respiration/ to give energy/ heat/ gases Acc. Simple sugar oxidized (ii) New materials are synthesized from protein); bringing about growth of embryo; acc new cells/ protoplasm synthesized (iii) The rate of respiration is faster than that of synthesis of materials for growth (iv) First leaf (carried out photosynthesis) leading to growth (d) (i) Presence of absiscic acid/ germination inhibitors; Embryo not fully developed Absence of hormones/ enzymes that stimulate germination Impermeable seed coat; rej hard seed coat Acc. Inactive enzymes/ hormones/ absence of gibberellins/ cytokinins. (ii) – Unsuitable / unfavourable temperature - absence of light - lack of water - lack of oxygen (c) Dense cytoplasm - Thin cell wall - Absence of vacuoles ( cell sap)
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K.C.S.E Biology Q & A - MODEL 2004PP1QN16
Outliner three roles of active transport in the human body
answers
K.C.S.E Biology Q & A - MODEL 2004PP1QN16
how do the following factors affect the rate of diffusion?
i) Diffusion gradient ii) Surface area volume ratio iii) Temperature
answers
(i) The higher diffusion gradient between ( two points) the rate of diffusion; acc converse.
(ii) The higher the surface area:: Volume ratio, the faster is the rate of diffusion ; acc converse (iii) Increasing temperature increases the rate of diffusion; acc converse.
K.C.S.E Biology Q & A - MODEL 2004PP1QN16
What is diffusion
answers
K.C.S.E Biology Q & A - MODEL 2004PP1QN15
a) Give the differences between the following structures in wind and insect pollinated flowers.
i) Anther ii) Pollen grains iii) Stigma b) What is the importance of cross pollination? c) Explain how a seed is formed after an ovule is fertilized
answers
​(i) anther Insect Wind
Small short anther firmly Large/ long anthers/ loosely attached to Attached to elements filaments (ii) Large heavy/ spiky small/ light/ smooth (iii) Small/ sticky Long feathery (b) Source of variation/ hybrid acc. Production of hybrid K.C.S.E Biology Q & A - MODEL 2004PP1QN14
What is meant by the following terms? Give an example in each case.
i) Homologous structures ii) Example iii) Vestigial structures Example
answers
​(i) Have a common ( embryonic) origin modified to perform different functions; vertebrae for limb/ pentadactyl limb
Example Vertebrate fore limb/ pretadactyl limb; acc beaks of birds ( fee of birds/ mouthparts in insects. (ii) Have different (embryonic) origins ( but have evolved) to perform similar functions. (iii) Are greatly reduced in size and therefore caused to function Acc. Third digit of wing of bird Halteres in flies Presence of hind limb ( buds) in python Human ear muscles Example Human appendix / kiwi ( flightless bird) with reduced wings/ vestigial wings in flies human hair/ presence of hind limbs in python; reduced pelvic girdle of whale.
K.C.S.E Biology Q & A - MODEL 2004PP1QN14
What is the difference between Darwinian and Lamarckian theories of evolution?
answers
Lamarckian
Inheritance of acquired characteristics/ Environment induces production of inheritable character which is then inherited.while Darwinian Inheritance of genetically acquired characteristics/ character happens to appear spontaneously which then gives advantage to organisms therefore better- adaptable characters are then inherited by natural selection. K.C.S.E Biology Q & A - MODEL 2004PP1QN13
The diagram below shows a vertical section through a mammalian heart.
​a) Name the parts labeled A,B,E and F
b) Use arrows to show the direction in which blood flows in the heart. c) Give a reason why the wall of chamber C is thicker than chamber D
answers
(a) A Pulmonary vein
B Left atrium I auricle E Tricuspid valve F Pulmonary artery
​(b) The left ventricle ‘C’ pumps blood a longer distance to all parts of the body; while the right ventricle ‘D’ pumps blood to a shorter distance/ to the lungs; therefore the left ventricle has thicker walls to generate exert more pressure.
K.C.S.E Biology Q & A - MODEL 2004PP1QN12
Across between a red flowered plant and white flowered produced plants with pink flowers.
Using letter R to represent the gene for red colour , and W for white colour a) What were the parental genotypes b) Workout a cross between F1 plants c) Give the i) Phenotypic ratio of F2 plants ii) Genotypic ratio of F2 plants d) Name a characteristic in humans, which is controlled through a mammalian heart?
answers
(a) RR WW
(b) Parental genotypes R W Gametes R W X WW R W Fertilization Offsprings RR RW RW WW (c) (i) Phenotypic ration Red Pink White 1 2 1 (ii) 1RR : 2RW; 1WW (d) (ABO) blood grouping; blood groups;
​K.C.S.E Biology Q & A - MODEL 2004PP1QN11
Fruit formation without fertilization is called
answer
K.C.S.E Biology Q & A - MODEL 2004PP1QN10
How are the xylem vessels adapted for support?
answer
K.C.S.E Biology Q & A - MODEL 2004PP1QN09
Name two mineral elements that are necessary in the synthesis of chlorophyll.
answers
K.C.S.E Biology Q & A - MODEL 2004PP1QN08
Name the class in the phylum arthropoda which has the largest number of individuals?
answer
K.C.S.E Biology Q & A - MODEL 2004PP1QN07
State the function of the organelles:
a) Lysosomes b) Golgi apparatus
answers
​a) Stores hydrolytic enzymes for destruction of worn out organelles / cells/ tissues / digestion of bacteria. / pathogens;
Acc. Digestion of food / accept autolysis. b) processing / packaging synthesized and transporting of packaged cell materials;. Production of lysosomes/ secretions of packaged material; K.C.S.E Biology Q & A - MODEL 2004PP1QN06
The diagram below shows the position of an image formed in a defective eye.
​a) Name the defect:
b) Explain how the defect named in (a) above can be corrected
answers
a) Myopia/ shortsightedness / short sight
b) Concave lens / divergent lends; to diverge the rays so that the image is focused on the retina Acc. Concave.
K.C.S.E Biology Q & A - MODEL 2004PP1QN05
During which phase of meiosis does crossing over occur.
answer
K.C.S.E Biology Q & A - MODEL 2004PP1QN04
Other than carbon dioxide, name other products of anaerobic respiration
answers
K.C.S.E Biology Q & A - MODEL 2004PP1QN03
How is aerechyma tissue adapted to its function
answers
K.C.S.E Biology Q & A - MODEL 2004PP1QN02
Distinguish between natural and acquired immunity
answers
K.C.S.E Biology Q & A - MODEL 2004PP1QN01
State the function of the cartilage named in (a) above
answers
K.C.S.E Biology Q & A - MODEL 2004PP1QN01
Name the cartilage found between the bones of the vertebral column
answer
​K.C.S.E Biology Q & A - MODEL 2003PP1QN19
Describe how fruits and seeds are suited to their modes of dispersal.
answers
Water dispersed fruit / seeds
K.C.S.E Biology Q & A - MODEL 2003PP1QN18
Describe the functions of the various parts of the human eye.
answers
Sclerotic layer – (made up of collagen fibres thus) protects the eye maintains shape of eyeball.
Cornea
Eyelids
Lens – Refracts light rays / focuses light on retina Vitrerous aqueous humour once. Aqueous Humour – Nourishes cornea / lens Refracts light Irus – ( pigmented thus) – gives the eye its colour / absorbs light controls amount of light entering the eye / adjusts size of pupil impulses. Pupil – light enters the eyes through pupil. Retina – has photoreceptor cells / rods / cones / image formation ;l generates impulses. Fever / yellow spot – visual acuity / most sensitive part of retina with only cones. Blind spot – point where nerve fibre emerges from the optic nerve / where the optic nerve leaves the eye / point where blood vessels & nerve fibres enter the eye. Optic nerve – transmit impulses to brain. K.C.S.E Biology Q & A - MODEL 2003PP1QN17
Some students used a model to demonstrate the effect of sweating on human body temperature. Two boiling tubes A and B were filled with hot water. The temperature of water in the tubes was taken at the start of the experiment and then at 5 minutes interval. The surface of tube A was continuously wiped with a piece of cotton wool soaked in methylated spirit. The results obtained are shown in the table below.
a) On the same axes, plot graphs of temperature of water in the tubes against time.
b) At what rate was the water – cooling in tube A? c) Why was tube B included in the set up? d) Account for the rate of cooling in tube A. e) State two processes of heat loss in tube b. f) What would be the expected results if tube A was insulated? g) What would the insulation be comparable to in: i) Bird ii) Mammals? h) Name the structures in the human body that detect: i) External temperature changes ii) Internal temperature changes
answers
​ b) 80 – 18 = 62; 2.48C /Min
2.5 25 c) Control d) Rate was faster in tube A; because the film of methylated sprit evaporated; removing heat from the tube; e) Convection ; radiation f) Lower rate of heat loss; g) i) birds Feather ii) Mammals? Fur h) i) external temperature changes Temperature ii) Internal temperature changes Hypothalamus
K.C.S.E Biology Q & A - MODEL 2003PP1QN16
K.C.S.E Biology Q & A - MODEL 2003PP1QN16
a) What is meant by:
i) Autecology ii) Synecology? b) The number and distribution of stomata on three different leaves are shown in the table below:
Suggest the possible habitat of the plants from which the leaves were obtained
Leaf Habitat A B C (c) State the modifications found in the stomata of leaf C.
answers
a) i) study of a single species within a community / ecosystem /habitat / environment.
ii) Synecology? Study of natural communities within an ecosystem b) Leaf Habitat A aquatic / fresh water B Forest; Terrestrial C Arid / semi arid; desert. c) Sunken Hairy Reserved rhythm Small stomatal pore |
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