KNEC KCSE BIOLOGY TOPICAL QUESTIONS - ATIKA SCHOOL

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K.C.S.E Biology Q & A - MODEL 2018PP2QN01

1/7/2020

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:

vvK.C.S.E Biology Q & A - MODEL 2018PP1QN27

1/7/2020

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

Mouse is active/has a large surface area to volume ratio; hence has a higher metabolic rate (rate of breathing) to cope with the rate at which energy (oxygen) is consumed or lost to the environment; an elephant is less active/has a small surface area to volume ratio hence has a lower rate at which energy (oxygen) is used or lost; or
Mouse is small in size/has large surface area to volume ratio; hence has a metabolic rate (rate of breathing) to cope with the rate at which oxygen is consumed/energy ¡s lost to the environment; an elephant is large in size/has small surface area to volume ratio; hence has a lower rate at which oxygen/energy is lost;

State two advantages terrestrial animals have in excreting urea as their main nitrogenous waste product.

1/7/2020

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

Less-toxic;
Very soluble;
A small molecule (easily filtered in the kidneys);
Requires less water to excrete;

Explain why a camel has a longer nephron than a whale.

1/7/2020

K.C.S.E Biology Q & A - MODEL 2018PP1QN24

Explain why a camel has a longer nephron than a whale.

answers

A camel is a desert animal, a longer nephron increases the surface area for reabsorption of water; to conserve it; a whale is aquatic animal (codes not need to conserve water)

Explain the role of carbonic anhydrase in red blood cells.

1/7/2020

K.C.S.E Biology Q & A - MODEL 2018PP1QN17

Explain the role of carbonic anhydrase in red blood cells.

answers

Converts carbon (IV) oxide to carbonic acid; which easily dissociates into hydrogen ions (H+ and hydrogen carbonates (HCO3-for easier transportation; reducing acidity in blood;

Explain why a bony fish dies shortly after being removed from water.

1/7/2020

K.C.S.E Biology Q & A - MODEL 2018PP1QN15

Explain why a bony fish dies shortly after being removed from water.

answers

Fish uses dissolved oxygen for gaseous exchange; gill filament epithelium dries up; gill filaments clamp together; surface area for
gaseous exchange reduced; oxygen lacks moist surface for dissolution causing death(due to suffocation);

Name three structures of the skin essential for its homeostatic function.

1/7/2020

K.C.S.E Biology Q & A - MODEL 2018PP1QN11

Name three structures of the skin essential for its homeostatic function.

ANSWERS

Blood vessels/arterioles;
Hair;
Sweat glands;
Erector pill muscles;
Nerve endings

State one homeostatic role of the human skin.

1/7/2020

K.C.S.E Biology Q & A - MODEL 2018PP1QN11

State one homeostatic role of the human skin.

ANSWERS

Thermoregulation;
Osmoregulation;
Regulating salt balance;

Name two products of respiration in plants.

1/7/2020

K.C.S.E Biology Q & A - MODEL 2018PP1QN10

Name two products of respiration in plants.

ANSWERS

Water;
Carbon (IV)oxide;
Energy/Adenosine Triphosphate;
Alcohol/ethanol/ethyl alcohol;

K.C.S.E Biology Q & A - MODEL 2018PP1QN09

1/7/2020

K.C.S.E Biology Q & A - MODEL 2018PP1QN09

The diagram below represents an organ in a bony fish

(a) Name the organ.
(b) Describe how air in water reach the capillaries inside structure L.

ANSWERS

a) Gill;
b) Fish mouth opens lowering pressure in buccal cavity and water rushes in; mouth closes increasing pressure that forces
water into the gill cavity/opercular cavity; O2 rich water flows over the gills in a counter current direction to capillary blood
flow; causing O2 to diffuse into the gill capillaries;

State three ways in which blood capillaries are structurally adapted to their functions.

1/7/2020

K.C.S.E Biology Q & A - MODEL 2018PP1QN08

State three ways in which blood capillaries are structurally adapted to their functions.

answers

Numerous to increase surface area through which materials diffuse;
Thin/one-cell thick/single cell epithelium/endothelium for faster diffusion;
Lined with a single cell epithelium for faster diffusion;
Are selectively permeable for passage of materials;
Narrow lumen to maintain pressure;

State three activities in the human digestive System that depend on respiration.

1/7/2020

K.C.S.E Biology Q & A - MODEL 2018PP1QN07

State three activities in the human digestive System that depend on respiration.

answers

Peristalsis;
Absorption of materials;
Chewing (movement of jaw muscles);
Churning;
Secretion of digestive enzymes

Define respiration

1/7/2020

K.C.S.E Biology Q & A - MODEL 2018PP1QN07

Define respiration

answers

Process by which living organisms/cells break down /oxidize (organic) food materials into simpler compounds to release energy;

State why it is important for plants to lose water to the atmosphere.

1/7/2020

K.C.S.E Biology Q & A - MODEL 2018PP1QN05

State why it is important for plants to lose water to the atmosphere.

answers

Cools the plant;
For uptake of water up the xylem vessels;
Mechanism through which mineral elements are transported in the plant; ‘
Removal excess water;
Maintains turgor, pressure;

K.C.S.E Biology Q & A - MODEL 2017PP2QN02

30/6/2020

K.C.S.E Biology Q & A - MODEL 2017PP2QN02

The table below shows variations in the form carbon (IV) oxide is transported in the blood at rest and during physical exercise.

(a) Explain why more carbon (IV) oxide ¡s transported in the form of bicarbonate ion.
(b)Account for the high total plasma content of carbon (IV) oxide during exercises.
(c) State how one’s involvement in the exercises affects blood pH.
(d) Name the protein responsible for the transport of carbon (IV) oxide in the blood.

ANSWERS

(a) Presence of carbonic anhydrase enzyme; which speeds up the conversion of carbon (IV) oxide to weak carbonic acid; which dissociates into hydrogen carbonate ion/(HCO3) (that diffuses out of the red blood cells into the blood plasma);
(b)The body needs high amount of energy; (for the exercise/muscle activity) hence high respiration rate (more oxygen intake); releasing more carbon (IV) oxide (in the blood plasma);
(c)The high rate of respiration (during physical exercises coupled with normal cellular metabolism) results in the production of more carbon(IV) oxide/faster accumulation of lactic acid; lowering the blood plasma pH/making it more acidic (compared to when one is at rest);
(d)Haemoglobin

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