Mastering KCSE Biology with Comprehensive Topical Questions and Answers
K.C.S.E Biology Q & A - MODEL 2012PP1QN14
Name the type of respiration that is most efficient.
b) Give a reason for your answer in (a) above
answer
a)Aerobic respiration;
b)It releases more energy per unit mass;
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K.C.S.E Biology Q & A - MODEL 2012PP1QN13
State three factors that affect the rate of diffusion.
answers
Temperature; surface area; distance that particles have to travel; diffusion/concentration gradient; size/density of particles; surface area to volume ratio; thickness of membrane; medium of diffusion
K.C.S.E Biology Q & A - MODEL 2012PP1QN12
Why is it recommended to keep the stage of the microscope dry?
answers
Name the part of a light microscope used to bring an image of a specimen into sharp focus.26/6/2020
K.C.S.E Biology Q & A - MODEL 2012PP1QN12
Name the part of a light microscope used to bring an image of a specimen into sharp focus.
answer
K.C.S.E Biology Q & A - MODEL 2012PP1QN11
Name the muscles found in the following organs:
stomach; bone
answers
K.C.S.E Biology Q & A - MODEL 2012PP1QN11
State two ways in which heart muscles are special.
answers
K.C.S.E Biology Q & A - MODEL 2012PP1QN10
What is meant by the term irritability?
answers
K.C.S.E Biology Q & A - MODEL 2012PP1QN09
State the importance of negative phototaxis to termites.
answer
What is the probability of a couple with blood group AB getting a child with blood group AB?26/6/2020
K.C.S.E Biology Q & A - MODEL 2012PP1QN08
What is the probability of a couple with blood group AB getting a child with blood group AB?K.C.S.E Biology Q & A - MODEL 2012PP1QN07
The diagram below represents a set-up that students used in an investigation.
​(a) Name the physiological process that was being investigated.
(b) State the role of potassium hydroxide in flask K. (c) Account for the observation in boiling tube L and flask N. L . N
answers
​(a) Respiration/aerobic respiration;
(b) Flask K Potassium hydroxide removes Carbon IV Oxide from atmospheric air; (c) L - Lime water remains clear because Carbon (IV) Oxide has been removed; Flask N lime water forms a white precipitate because the respiring cockroaches produce Carbon (IV) Ovide; K.C.S.E Biology Q & A - MODEL 2012PP1QN06
The diagram below represents part of the gaseous exchange system in human.
​(a) Name the parts labelled F and G.
F G (b) State one function of each of the parts labelled H and J. H J
answers
​(a) F - Bronchiole;
G - Intercostal muscles/external intercostal muscles; (b) H - (Pleural membranes) secretes encloses pleural fluid to lubricate lungs/protect lungs; J - (Diaphragm) separates chest cavity from abdominal cavity/works to effect volume and pressure changes in chest cavity necessary for inhalation and exhalation! Ventilation/breathmg; K.C.S.E Biology Q & A - MODEL 2012PP1QN05
The table below shows results of a study of three plants C, D and E growing in different habitats.
(a) Which one of the plants C, D and E grows in an area of relatively low water availability?
(b) Explain your answer in (i) above.
answers
​(a) Plant C;
(b) Thick cuticle reduces water loss; Low number of stomata reduces water loss; Large root-surface area enhances water absorption; K.C.S.E Biology Q & A - MODEL 2012PP1QN04
In an investigation, a student extracted three pieces of paw paw cylinders using a cork borer.
The cylinders were cut back to 50 mm length and placed in a beaker containing a solution. The results after 40 minutes were as shown in the table below.
​(a) Account for the results in the table above.
(b) What would be a suitable control set-up for the investigation?
answers
​(a) The solution was hypotonic/less concentrated compared to the cell sap of pawpaw cylinder cells;
The tissue/cells gained water by osmosis; becoming turgid/longer/stiff; (b) Pawpaw cylinders of the same size/length; placed in an isotonic solution; Boiled potato cylinders of the same size; placed in a similar solution; K.C.S.E Biology Q & A - MODEL 2012PP1QN03
The figure below is a fine structure of a generalised animal cell as seen under an electron microscope.
​(a) Name the parts labelled A and B.
A B (b) How is the structure labelled B adapted to its function?
answers
​(a) (i) A - nucleopore;
B - Rough Endoplastic Reticulum; (b) Surface covered with ribosomes; for protein synthesis; Has interconnected channels: for transportation of proteins; K.C.S.E Biology Q & A - MODEL 2012PP1QN02
The diagram below represents a certain organism collected by a student at the sea shore.
​(a) Name the class to which the organism belongs.
(b) Give three reasons for your answer in (a) above.
answers
K.C.S.E Biology Q & A - MODEL 2012PP1QN01
How does nutrition as a characteristic of living organisms differ in plants and animals?
answers
Describe how accommodation in the human eye is brought about when focusing on a near object.25/6/2020
K.C.S.E Biology Q & A - MODEL 2011PP2QN08
Describe how accommodation in the human eye is brought about when focusing on a near object.
answers
Light rays from a near object are more diverged and need to bend more; in order to be focused properly on the retina; ciliary muscles contract; suspensory ligaments attached to the ciliary muscles relax; the lens becomes thicker; increasing its curvature/becomes more convex; light from the object is refracted more; in order to be focused/more sharply on the retina to form an image.
K.C.S.E Biology Q & A - MODEL 2011PP2QN08
Describe the exoskeleton and its functions in insects.
answers
The exoskeleton is made of chitin; chitin is not evenly distributed; hence it allows for movement; exoskeleton is secreted by the epidermal cells; when still soft it allows for growth of the insect; when in contact with the air it hardens limiting growth; It is shed regularly; thus regulating the growth of insects. It also supports the internal structures; Because it is hard; it protects; internal organs from mechanical damage. It is water proof; preventing water loss/dessication; of the insect. It also provides a surface for attachment of muscles;
K.C.S.E Biology Q & A - MODEL 2011PP2QN07
Explain how the human skin brings about cooling of the body on a hot day.
answers
Erector pilli muscle relax; and hair lie flat; trapping less air; thus reducing insulation;
Blood capillaries under the skin vasodilate; and more blood is brought under the skin; increasing heat loss; sweat glands release more sweat to the skin surface; the sweat take away heat from the body when it evaporates;
K.C.S.E Biology Q & A - MODEL 2011PP2QN07
Explain how structural features in terrestrial plants affect their rate of transpiration.
answers
Plants in arid, semi-arid and desert habitats have leaves covered with thick/waxy cuticles; that are waterproof/impermeable to water; allowing for reduced rate of transpiration; Sunken stomata; in some desert/semi arid areas plants have water vapour accumulating in the pits; reducing rate of transpiration (as the moisture in the pit is carried away by wind.) Most plants have few or no stomata on the upper surface of leaf; the fewer the stomata the less the water lost from the plant. Some plants have small stomata/stomatal size decrease when guard cells are flaccid; thus reducing transpiration rate. Plants with small/folding leaves; expose less surface area; hence reduce the rate of transpiration. Leaves with shinny surfaces; reflect light resulting
reduced leaf temperatures; thus reducing the rate of transpiration. Some plants have leaves covered with hairs/scales; which trap a layer of moisture; the leaf surface reducing rate of transpiration. Mesophyte have a thin layer of cuticle; to facilitate high transpiration rate; brad lenses exposing large area to transpiration; Many stomata on both leaf surfaces provide many apartunes to enhance transpiration.
K.C.S.E Biology Q & A - MODEL 2011PP2QN06
Explain how the osmotic pressure in the human blood is maintained at normal level.
answers
K.C.S.E Biology Q & A - MODEL 2011PP2QN06
An experiment was carried out to investigate the population of a certain micro-organism. Two petri-dishes were used. Into the petri-dish label led M, 60cm3 of a culture medium was placed while 30cm3 of the same culture medium was placed in petri-dish labelled N. Equal numbers of the micro-organisms were introduced in both petri-dishes. The set-ups were then incubated at 35°C. The number of micro-organisms in each petri-dish was determined at irregular intervals for a period of 60 hours. The results were as shown in the table below.
(i)On the same axes, draw the graphs of relative number of micro-organisms against time on the grid provided.
(ii) After how many hours was the difference between the two populations greatest? (iii) Work out the difference between the two populations at 50 hours. (iv) With a reason state the effect on the population of micro-organisms in petri-dish M if the temperature was raised to 60°C after 20 hours. (v) Account for the shape of the curve for population in petri-dish N between 46 hours and 59 hours.
answers
​(ii) 42 hours;
(iii) Graph M at 50 hrs is 1220 ± 20. Graph N at 50 hrs is 540 ± 20 (2 m 1220-540=680±4; (iv) Population growth stops; . High temperatures kill the microorganisms/denature enzymes; (v) 46 hours to 59 hours death rate of the microorganisms is higher, than their population growth rate; due to exhaustion of nutrients; and accumulation of toxic wastes; K.C.S.E Biology Q & A - MODEL 2011PP2QN05
The diagram below represents a flower.
(i) On the diagram, name two structures where meiosis occurs.
(ii) How is the flower adapted to prevent self-pollination? (ii) How is the flower adapted to prevent self-pollination? (b) The diagram below represents a human reproductive organ.
​(i) Explain two adaptations of the structure labelled L to its functions.
(ii) Explain the role of the gland labelled K.
answers
​(a) (i) Anthers; Ovary;
(ii) Anthers are below the stigma to minimise self pollination;
production; it has many, long and coiled seminiferous tubules to increase the surface area for production/storage of sperms; (ii) K produces an alkaline fluid that neutralizes acid in the vagina; this fluid contain nutrients for the sperms; and also activates sperms; K.C.S.E Biology Q & A - MODEL 2011PP2QN04
The diagram below represents a section of the human brain.
(i)Name the structures labelled P and R.
P R (ii) State two functions of the part labelled Q. (b) (i) Name two reproductive hormones secreted by the pituitary gland in women. (ii) State one function of each of the hormones named in (b)(i) above.
answers
(a) (i) - is cerebral hemisphere/cerebrum;
R - medulla oblongata; (ii) Muscular co-ordination; maintaining body posture; manual/motar dexterity; (b) (i) Follicle stimulation hormone; luteinizing hormone; oxytocin; prolactin; (ii) FSH - stimulates secretion of oestrogen; stimulates development of the Graafìan follicle; LH - Brings about ovulation; causes development of corpus luteum; Oxytocin - causes contraction of uterus; causes expulsion of milk from mammary glands; Prolactin - stimulates milk production/secretion;
K.C.S.E Biology Q & A - MODEL 2011PP2QN03
How are the pneumatophores adapted to their function?
answers
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