KNEC KCSE BIOLOGY TOPICAL QUESTIONS - ATIKA SCHOOL

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K.C.S.E Biology Q & A - MODEL 2018PP2QN04

1/7/2020

K.C.S.E Biology Q & A - MODEL 2018PP2QN04

The diagram below illustrates the arrangement of bones in a human arm.

(a) Name:
(i) the type of joints formed at points H and M.
H
M
(ii) bone G
(b) Name bone J and state how it is adapted to its functions.
Name
Adaptation
(c) State one functional difference between a tendon and a ligament.

answers

a) i. H-Ball and socket (joint);
M - Gliding/planar/plane
ii. Clavicle;
b) Scapula;
Has a spine to increase surface area for muscle attachment;
It is broad/flat to increase the surface area for muscle attachment;
Forms flexible attachment above the ribs that allows movement of the arms;
Has a glenoid cavity/depression for articulation with the humerus/forming the ball and socket joint;
Has acromion for articulation with clavicle/for muscle attachment;
Has coracoid process to increase surface area for muscle attachment;
c) Ligaments hold the bones together (at a joint) while tendons attach muscles to bones;

K.C.S.E Biology Q & A - MODEL 2018PP2QN03

1/7/2020

K.C.S.E Biology Q & A - MODEL 2018PP2QN03

The amount of blood flowing tough certain pans in the mammalian body at different activity levels was measured and results tabulated as Shows in the table below.

(a) Account for:
(i) the high blood flow through the cardiac and skeletal muscles during strenuous exercises.
(ii) the results obtained for the alimentary canal at rest.
(b)Name two waste materials excreted by both the skin and the kidneys.

answers

K.C.S.E Biology Q & A - MODEL 2018PP1QN25

1/7/2020

K.C.S.E Biology Q & A - MODEL 2018PP1QN25

Desert kangaroo rats spend most of their time in underground burrows,
(a) Name this type of behavioral activity
(b) Explain the significance of this behaviour to the organism.

answers

(a) Aestivation;
(b) Reduced metabolic activity; hence low rate of respiration; minimizing water loss/dessication (to the environment);

What does the term evolution mean?

1/7/2020

K.C.S.E Biology Q & A - MODEL 2018PP1QN22

What does the term evolution mean?

answers

Gradual change from simple life forms to complex forms over a (long) period of time;

State two ways in which plants with weak stems obtain mechanical support.

1/7/2020

K.C.S.E Biology Q & A - MODEL 2018PP1QN21

State two ways in which plants with weak stems obtain mechanical support.

answers

Twinning around a support;
Use of tendrils/spines/thorns/hooks (to cling on nearby plants/trees);
Turgid cells (in their stems);

Give two illustrations of analogous structures in mammals.

1/7/2020

K.C.S.E Biology Q & A - MODEL 2018PP1QN20

Give two illustrations of analogous structures in mammals.

answers

wings of bats and insects;
Eyes of mammals and molluscs;
Limbs of mammals and arthropods;
Flipper in whales/dolphins and fins of fish;

Define the term analogous structures.

1/7/2020

K.C.S.E Biology Q & A - MODEL 2018PP1QN20

Define the term analogous structures.

answers

Different embryonic origin but evolved to perform similar functions (due to exploitation of same kind of environment);

K.C.S.E Biology Q & A - MODEL 2018PP1QN19

1/7/2020

K.C.S.E Biology Q & A - MODEL 2018PP1QN19

The diagrams below illustrate some forms of beaks in birds.

(a) Which diagram represents the beak from which the others are likely to have evolved?
(b) Explain your answer in (a) above.

answers

(a) Beak M
(b) Beak M is simple/basic; original beak; the birds separated to occupy different niches; and specialized for different diets; leading to more complex/developed beaks over time;

K.C.S.E Biology Q & A - MODEL 2018PP1QN18

1/7/2020

K.C.S.E Biology Q & A - MODEL 2018PP1QN18

A tall, light skinned lady with pimples on her face has long hair and limps.

(a) List two features which the lady has that are due to inheritance.
(b) Explain why most recessive genes are expressed phenotypically in male offspring of humans.

answers

(a) Height (tallness);
Long hair;
Skin colour (light);
(b) Most of the genes are sex-linked and are carried on the X - chromosomes; boys receive X chromosomes from the mother (and Y chromosomes from the father); if the X carries a recessive gene, it is more likely to be phenotypically expressed in boys;

Name the bones that articulate to form a ball and socket joint at the hip.

1/7/2020

K.C.S.E Biology Q & A - MODEL 2018PP1QN16

Name the bones that articulate to form a ball and socket joint at the hip.

answers

Femur;
Pelvic girdle;

Explain why the nephron is long and convoluted.

1/7/2020

K.C.S.E Biology Q & A - MODEL 2018PP1QN12

Explain why the nephron is long and convoluted.

ANSWERS

Describe how the mammalian eye is structurally adapted to its function.

1/7/2020

K.C.S.E Biology Q & A - MODEL 2017PP2QN08

Describe how the mammalian eye is structurally adapted to its function.

answers

Has the eyelid; which protects the cornea from mechanical/physical/chemical damage;
Eye lid; protects the eye from bright light by reflex action;
Sclera/Sclerotic layer; which contains (inelastic) collagen fibres which protects/maintains shape of the eyeball;
Cornea; transparent to allow light pass through/has convex shape to refract light towards the retina;
Conjunctiva (thin) epithelium for protection of cornea/has goblet cells for secretion of mucus for lubrication/ transparent to allow light pass through;
Choroid/choroid layer; rich in blood vessels/highly vascularized, supplying the retina with nutrients/oxygen/remove metabolic wastes/covered with (black) pigment cells to prevent reflection of light within the eye;
Ciliary muscles; have (contractile) muscles that contract/relax to alter the shape of the lens during accommodation;
Lens; transparent to allow light pass through/elastic to allow adjustment of the shape of lens/ biconvex to refract light/focus light onto retina;
Iris; — has radial and circular muscles to alter diameter/size of the pupil, hence controlling the amount of light entering the eye/contain pigments that absorb light and stop it getting through to the retina;
Vitreous homour; — clear/transparent to allow light pass through/is a fluid that refracts light rays onto the retinal maintain shape of the eye balls supports the eye;
Retina; contains cones, rods/photoreceptors to perceive light;
Optic nerve;- has sensory neurons/nerve cells that transmit impulses to the brain;
Fovea (centralis); — (most sensitive part of retina) contains numerous/high concentration of cones for visual acuity/accurate vision;
Pupil ; a hole/an aperture/opening in the iris, lets in light;
Suspensory ligaments;-are fibrous/inelastic fibres that hold lens in position;
Aqueous humour is clear/transparent to allow light to pass through/is a fluid/liquid (exerting hydrostatic pressure) to maintain the shape of the eyeball/refract light rays onto the lens/cornea/contain glucose for nourishment;
Blind spot a point where the optic nerve leaves the eye to the brain/passage of blood vessels since has no photoreceptors;

State how in-breeding leads to reduced hybrid vigour

1/7/2020

K.C.S.E Biology Q & A - MODEL 2017PP2QN05

State how in-breeding leads to reduced hybrid vigour

answer

Chances of recessive/defective genes being combined increase,hence weaker offspring;

State two advantages of using genetically modified varieties in bean farming.

1/7/2020

K.C.S.E Biology Q & A - MODEL 2017PP2QN05

State two advantages of using genetically modified varieties in bean farming.

answers

Higher yields;
Enhanced resistance to diseases/pests;
Early/faster maturity;
Enhanced resistance to harsh climatic conditions (drought/extremes in temperature);

K.C.S.E Biology Q & A - MODEL 2017PP2QN05

1/7/2020

K.C.S.E Biology Q & A - MODEL 2017PP2QN05

In beans, the gene for purple colour is dominant over the gene for white colour. A pure breeding bean plant with purple colour was crossed with a heterozygous bean plant.
Using the letter P to represent the gene for purple colour, work out the genotypic ratio of the offspring.

answer

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