KNEC KCSE BIOLOGY TOPICAL QUESTIONS AND ANSWERS

State two physiological mechanisms of controlling the human body temperatures during a hot day

1/11/2021

Comments

(a) State two physiological mechanisms of controlling the human body temperatures during a hot day (2mks)

Vasodilation/blood flows on the surface;
Hair lies on the skin/hair lies flat on the skin;
Metabolic rate decreases;
Sweating;

b) Name two ways in which loop of Henle is adapted to its function (2mks)

It is long to increase surface area for reabsorption of water.
It is lined with a network of capillaries to enhance reabsorption of water;
It is u-shaped to bring about counter current multiplier effect/to concentrate salts in the medulla to bring about reabsorption of water

Comments

List down the processes responsible for ;

30/10/2021

Comments

List down the processes responsible for; (2mks)

(i) The formation of glomerular filtrate

ultra filtration

(ii) Absence of glucose and amino acids in urine.

Reabsorption;

Comments

State the functions of nerve cells and plasma then give functions of the excretory system and endocrine system

14/9/2021

Comments

(a) State the functions of the following

(i) Nerve cells (2mks)

Detect changes in the environment; internal and external
Transmit/conduct impulses to brain an spinal cord/from brain to effector organs/tissues
In brain –coordinates movements/activities of different body parts

(ii) Plasma (2mks)

Transport medium; transports glucose, amino acids
Forms the tissue fluid

(b) Give the functions of the following organ systems

(i) Excretory system (2mks)

Removal of waste products/excess materials from the body

(ii) Endocrine system (2mks)

Homeostasis/maintains internal environment of the body constant.
Growth and development of the body

Comments

Name the excretory products eliminated by the following animals (Tilapia and Chicken)

9/9/2021

Comments

Name the excretory products eliminated by the following animals

(i) Tilapia (1mk)

Ammonia

(ii) Chicken (1mk)

Uric acid

Comments

State two functions of the spleen

8/9/2021

Comments

State two functions of the spleen (2mks)

Store red blood cells; as reservoir
produce lymphocytes
site for breakdown of worn out red blood cells
Stores iron

Comments

Distinguish precisely between diabetes mellitus and diabetes insipidus

7/9/2021

Comments

Distinguish precisely between diabetes mellitus and diabetes insipidus (2mks)

Diabetes mellitus	Diabetes insipidus
condition resulting from insufficient production of insulin causing presence of glucose in urine	a condition where less of antidiuretic hormone is secreted hence large volume of water is passed out in urine

Comments

State three homeostatic roles of the liver.

2/7/2020

Comments

K.C.S.E Biology Q & A - MODEL 2019PP1QN23

State three homeostatic roles of the liver.

answers

Thermoregulation;
Blood sugar regulation
Protein/amino acid/fat regulation

Comments

K.C.S.E Biology Q & A - MODEL 2019PP1QN12

2/7/2020

Comments

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

Comments

Explain why significantly increasing the blood pH slows down the rate of selective reabsorption of materials in the kidney tubules.

1/7/2020

Comments

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

selective reabsorption of materials in the kidney tubules is energy dependent/require energy ; synthesized through the process of (cellular) respiration/action of respiratory enzymes; whose working (effectiveness)is affected by change in pH/are denatured at high pH; pH affects the working / permeability of the (kidney tubule cells)membrane;

Comments

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

1/7/2020

Comments

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:

Comments

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

1/7/2020

Comments

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;

Comments

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

1/7/2020

Comments

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;

Comments

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

1/7/2020

Comments

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)

Comments

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

1/7/2020

Comments

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

Comments

State one homeostatic role of the human skin.

1/7/2020

Comments

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

State one homeostatic role of the human skin.

ANSWERS

Thermoregulation;
Osmoregulation;
Regulating salt balance;

Comments

<<Previous

(a) State two physiological mechanisms of controlling the human body temperatures during a hot day (2mks)

b) Name two ways in which loop of Henle is adapted to its function (2mks)

List down the processes responsible for; (2mks)

​(i) The formation of glomerular filtrate

​(ii) Absence of glucose and amino acids in urine.

(a) State the functions of the following

(i) Nerve cells (2mks)

(ii) Plasma (2mks)

(b) Give the functions of the following organ systems

(i) Excretory system (2mks)

(ii) Endocrine system (2mks)

Name the excretory products eliminated by the following animals

(i) Tilapia (1mk)

(ii) Chicken (1mk)

State two functions of the spleen (2mks)

​Distinguish precisely between diabetes mellitus and diabetes insipidus (2mks)

Diabetes mellitus

Diabetes insipidus

State three homeostatic roles of the liver.

K.C.S.E Biology Q & A - MODEL 2019PP1QN12

Explain why significantly increasing the blood pH slows down the rate of selective reabsorption of materials in the kidney tubules.

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

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

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

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

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

State one homeostatic role of the human skin.

TOPICS

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Form 4

Archives

Categories

(i) The formation of glomerular filtrate

(ii) Absence of glucose and amino acids in urine.

Distinguish precisely between diabetes mellitus and diabetes insipidus (2mks)