K.C.S.E Biology Q & A - MODEL 2019PP2QN08
Explain the effect of increased physical activity on the following organ systems:
(a) heart (b) lungs (c) kidneys (d) skin. 
answers
​(a) Heart
-Increased heart beat/ rate/cardiac frequency; increase blood pressure; pumping more blood to the muscles/Peripheral blood vessels; at a faster rates; supplying oxygen; Nutrients; for continued oxidation/respiration; to yield energy needed to sustain the (vigorous) contraction/relaxation of muscles during the physical activity; carbon (iv) oxide /Lactic acid/other Nitrogenous wastes/Metabolic wastes produced during the process are also eliminated/ transported to the relevant excretory organs for elimination; the wastes ,if left to accumulate Can also intoxicate/poison cells/cause muscle cramps/pain/fatigue; (b) Lungs -Panting /increased breathing rates; cause the lungs to expand/increase in volume to take in more air/oxygen; and deflate to expel more carbon (iv) oxide; more oxygen is taken in (during exercise) to sustain the process of muscle respiration/to produce the required energy (for constant muscle contraction and relaxation);
Kidneys also maintain the blood plasma pH; and osmotic balance; by elimination excess hydrogen ions(H+) that accumulate to production of Lactic acid/CO2 during the exercise; To maintain the osmotic balance kidneys conserve sodium ions (Na+); and reabsorb water (in the kidney tubules); Leading to reduction in the volume of urine produced; During exercise the kidney tend to filter out urine releasing more in the urine; (d) Skin - Due to increased muscle activity during physical exercise are sweats(more); Eliminating Nitrogenous wastes/ excess water; through the skin/sweat pores) cooling the body; After (water in) sweat evaporates the increased internal body temperature also leads to dilation of superficial blood vessels (vasodilation)/ blood flowing near the skin; leading to loss of excess heat (to the atmosphere) by radiation/ convection; the hair on the skin surface also lie Flat to allow for loss of heat( to the environment) by radiation/convection; K.C.S.E Biology Q & A - MODEL 2019PP2QN02
The table below shows results of blood cell counts per mm3 of blood from a sample of people living at different altitudes.
​(a) Explain the relationship between:
(i) red blood cells count and the altitude; (ii) white blood cells count and the altitude. (b) Explain why chances of nose-bleeding increase with altitude in humans.
answers
(a) i) Number of red blood cells increase with altitude; to increase oxygen carrying capacity (by haemoglobin molecules in blood); since oxygen concentration is lower at higher altitude;
ii) white blood cells serve to protect the body against harmful microorganisms/pathogens; thernadites of pathogen of the body to microbial attack is not dependent on the altitude (to be countered by the white blood cell); hence 6 the number of white blood cell count is constant at whatever altitude; (b) Atmospheric Pressure decreases with the increase in altitude; the imbalance between the (outer) atmospheric pressure at high altitude and the internal blood pressure (generated by the heart) results in (one) nose bleeding at high altitudes/ internal blood pressure is higher than the (outer) atmospheric pressure.
K.C.S.E Biology Q & A - MODEL 2019PP1QN23
State three homeostatic roles of the liver.
answers
K.C.S.E Biology Q & A - MODEL 2019PP1QN22
The chart below illustrates how respiratory gases are transported in the human blood.
​(a) Identify gas Q.
(b) Explain the advantage oxyhaemoglobin has over carboxyhaemoglobin.
answers
(a) carbon(ii) oxide acc. CO
(b) Oxyhaemoglobin is unstable/fully dissociate, releasing oxygen to the tissues/dissociate giving haemoglobin free to take up more gaseous molecules(hence constantly supplying the much needed oxygen to the respiratory tissues); carboxyhaemoglobin is stable/binds itself on the haemoglobin molecules /does not dissociate ,hence starving the tissues/cells of the oxygen ,leading to suffocation/death K.C.S.E Biology Q & A - MODEL 2019PP1QN20
State how each of the following features enhance efficient movement of fish in water:
(a) Scale (b) body shape
answers
​(a) faces towards the back/overlap/points backwards to provide a smooth surface for easier movement in water/are stony/ covered with mucus for easier /smooth movement in water/ reduce friction making
(b) streamlined body shape to reduce friction / pointed(stuff) head for easier penetration / passage in water.;
K.C.S.E Biology Q & A - MODEL 2019PP1QN15
State the significance of transpiration to a plant.
answers
(b) enable the plant to get rid of excess water
Creates a suction force /help in the uptake of water /mineral/salts from the soil Maintains turgor in plants/turgidity in cells Cools the plant
K.C.S.E Biology Q & A - MODEL 2019PP1QN15
Distinguish between guttation and transpiration.
answers
K.C.S.E Biology Q & A - MODEL 2019PP1QN12
While investigating a certain metabolic process in plants, students set up the apparatus as shown be low in a classroom and monitored it for 48 hours.
​(a) Identify the metabolic process under investigation.
(b) Account for the observations made in the test tube at the end of the investigation.
answers
K.C.S.E Biology Q & A - MODEL 2019PP1QN08
State the role of each of the following in the mammalian respiratory system:
(a) mucus (b) cartilage rings (c) epiglottis
answers
.(a) trap foreign particles (from the inhaled /entering air); moisten the (inhaled/incoming) air (for efficient gaseous exchange);
(b) keep the wind pipe /trachea open / not to collapse (to allow for continuous flow of air); (c) acts as a valve / flap between the larynx and the oesophagus to permit air to enter the air way to the lungs and food particles to pass into the gut / oesophagus: acc prevent food particles from entering the trachea /air passage during swallowing; K.C.S.E Biology Q & A - MODEL 2019PP1QN06
​(a) Name the respiratory structure in the amoeba.
(b) Give a reason for your answer in (a) above.
answers
(a) cell membrane/plasma membrane /plasmalemma;
(b) has a large surface area to volume ratio
K.C.S.E Biology Q & A - MODEL 2019PP1QN05
Explain why significantly increasing the blood pH slows down the rate of selective reabsorption of materials in the kidney tubules.
answers
K.C.S.E Biology Q & A - MODEL 2018PP2QN01
The diagram below illustrates a section of the mammalian kidney.
​(a) Name the structures labelled E and F.
E F (b) Explain the processes that take place in the regions labelled G and H. Region G Region H
answers
​ (a) E—Glomerulus;
F — Interlobular artery/branch of renal artery; (b) Region G At the (glomerulus), the afferent arteriole which brings blood to the glomerulus is wider than the efferent arteriole; this creates high pressure; leading to ultrafiltration; At the proximal convoluted tubule /distal convoluted tubule, substances required by the body/amino acid substances required by the body (amino acids/glucose/vitamins! some water; are selectively re-absorbed (into the blood stream); hence selective reabsorption; Region H At the descending arm of/limb of the Loop of Henle, water is selectively reabsorbed; At the ascending arm/limb of the Loop of Henle, sodium ions/salts are actively/selectively reabsorbed; At the collecting duct, water is (selectively) reabsorbed: K.C.S.E Biology Q & A - MODEL 2018PP1QN27
Below is a graphical representation of how basal metabolic rates compare in Various animals.
​From the graph, explain why the mouse has a higher breathing rate than the elephant.
answers
K.C.S.E Biology Q & A - MODEL 2018PP1QN26
State two advantages terrestrial animals have in excreting urea as their main nitrogenous waste product.
answers
K.C.S.E Biology Q & A - MODEL 2018PP1QN24
Explain why a camel has a longer nephron than a whale.
answers
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