KNEC KCSE BIOLOGY TOPICAL QUESTIONS AND ANSWERS

Describe the role of the liver in homeostasis in the human body

23/6/2020

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K.C.S.E Biology Q & A - MODEL 2009PP2QN08

Describe the role of the liver in homeostasis in the human body

answers

Regulation of blood glucose
The normal amount of glucose in the blood is 90 mg/ 1000m3 increase in blood sugar level is detected by cell of the (batacelss) pancreases, which secrete insulin; insulin stimulates the liver to convert excess glucose to glucogen. Further excess glucose is converted to fats. Excess glucose is also oxidized to energy ( carbon iv) oxide & water/ respiration.
Decrease in blood sugar level below the normal level is detected by the ( alphacells) by the pancreases. Which secretes glucogen that stimulates the liver, to convert glucogen to glucose, fats/ amino acids are converted to glucose, and there is reduced oxidation of glucose until the normal level of blood sugar is attained.
Deamination / excess amino acids are deaminated (removal) of amino acid group, the amino group is converted to ammonia which combines with carbon (iv) oxide to form urea that is excreted through the kidney, urea is excreted through the skin as sweat.
Detoxification/ poisonous substances are converted to less harmful compounds.
Thermoregulation/ maintenance of body temperature heat is generated ( in the liver) by chemicals activities, the heat is distributed
NH2 + H →NH3
2HH3 + Co2 →Co (NH2)2 + H2O
Ammonia urea

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How are flowers adapted to wind and insect pollination?

23/6/2020

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K.C.S.E Biology Q & A - MODEL 2009PP2QN07

How are flowers adapted to wind and insect pollination?

answers

Insect pollination / Entomorphilous flowers are scented to attract insects have stick stigma for pollen grains to stick on. Are brightly coloured to attract insects.
Have nectarines to secrete nectar; nectar attracts insects
Have nectar guides to guide the insects to the nectarines
Stigma/ anthers are located inside the flower / tubular a funnel shaped corolla to increase chances of contact by insects
Sticky/ spiny/ spiky pollen grains which stick on the body of insects and on stigma
Large/ conspicuous flowers to be easily seen by the insects/ attract
Anthers firmly attached to filament for insect to brush against
Have landing platform to ensure contact with anther and stigma
Mimiory to attract (male) insects/ flowers mimic female insects which attract
Anthers firmly attached to filament for insect to brush against
Have landing platform to ensure contact with anther and stigma
Mimiory to attract (male) insects/ flowers mimic female insects which attract male insects for mating e.g. orchids.
Anthers/ stigma hang outside the flowers to increase chances of pollination; style/ filament is long to expose stigma/ anthers stigma is hairy/ feathery/ branched to increase surface are over which pollen grains land/ to trap pollen grains;
Pollen grains are smooth/ dry/ light/ small to be easily carried by wind; large amount of pollen grains to increase chances of pollination
Anthers are loosely attached to filaments to enable them sway easily to release pollen grains; pollen grains may have structures which contain air to increase buoy any 3 flowers have long stalks holding them out in the wind

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K.C.S.E Biology Q & A - MODEL 2009PP2QN06

23/6/2020

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K.C.S.E Biology Q & A - MODEL 2009PP2QN06

An experiment was carried out to investigate the effect of temperature on the rate of reaction catalyzed by an enzyme. The results are shown in the table below

(a)On t he grid provided draw a graph of rate of reaction against temperature
(b) When was the rate of reaction 2.6 mg of product per unit time?
(c) Account for the shape of the graph between
(i) 5 C and 40 C
(ii) 45 C and 60C
(d) Other than temperature name two ways in which the rate of reaction between 5C and 40C could be increased
(e) (i) Name one digestive enzymes in the human body which works best in acidic condition
(ii) How is the acidic condition for the enzyme named in (e) (i) above attained?
(f) The acidic conditions in (e) (ii) above is later neutralized
(i) Where does the neutralization take place?
(ii) Name the substance responsible for neutralization

answers

(b) 33C and 51.5 ( ± 0.5C)
32.5 - 33.5 and 51.0 – 52.0
(c)(i) As temperature is increased rate of reaction is increased/ more products are formed (per unit time) because enzymes become more active
(ii) As temperatures increases rate of reaction decreases less products are formed (unit per time) because enzymes become denatured by high temperatures.
(b) Increase in enzyme concentration and substance concentration
Increasing number of enzyme
(e) (i) Pepsin, remain/ chymosin
(ii) Wall of stomach/ gastric gland/ oxyntic/ pariental/ cell produced
Hydrochloric
(f) (i) Duodenum
(ii) Bile juice/ SANS any correct salt e.g. NaHCO3

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Give three functions of pectoral and pelvic fins in a fish

23/6/2020

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K.C.S.E Biology Q & A - MODEL 2009PP2QN05

Give three functions of pectoral and pelvic fins in a fish

answers

- Steering
- Balance
- Braking, changing direction
- Prevent fish from pitching/ up & down movement

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K.C.S.E Biology Q & A - MODEL 2009PP2QN05

23/6/2020

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K.C.S.E Biology Q & A - MODEL 2009PP2QN05

Name a support tissue in plants thickened with
(i) Cellulose
(ii) Lignin

answers

(i) Collencyma
(ii) Xylem/ tracheid/ vessels/ schlerencyma

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what happens when a wilting young plants is well watered

23/6/2020

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K.C.S.E Biology Q & A - MODEL 2009PP2QN05

what happens when a wilting young plants is well watered

answers

Root hairs/ roots absorb water by osmosis; cells of plants become turgid; leaves become firm/ spread out plant becomes firm/ upright

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K.C.S.E Biology Q & A - MODEL 2009PP2QN04

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K.C.S.E Biology Q & A - MODEL 2009PP2QN03

what is meant by the term biological control

answers

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Name the substance that is responsible for hardening of teeth

23/6/2020

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K.C.S.E Biology Q & A - MODEL 2009PP2QN02

Name the substance that is responsible for hardening of teeth

answer

Calcium phosphate;

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K.C.S.E Biology Q & A - MODEL 2009PP2QN02

23/6/2020

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K.C.S.E Biology Q & A - MODEL 2009PP2QN02

The diagram below represents the lower jaw of a mammal

(a) Name the mode of nutrition of the mammal whose jaw is shown
(b) State one structural and one functional difference between the teeth labeled J and L
Structural
Functional
(c) (i) name the toothless gap labeled K.

answers

(a) Herbivorous Rej Herbivore Acc Herbivory
(b) Tooth J is narrow/ sharp/ chisel like while tooth L is broad/ ridged
J has one root while L has 2/3/4 roots
Functional
Tooth J is used for cutting while tooth L is used for grinding cutting for biting)
(c)
(i) Diastema
(ii) For manipulation of blood by tongue

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K.C.S.E Biology Q & A - MODEL 2009PP2QN01

23/6/2020

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K.C.S.E Biology Q & A - MODEL 2009PP2QN01

When the offspring of purple and white flowered pea plants were crossed, they produced purple and white flowered plants in the ratio of 3: 1 Using letter H to represent the gene for purple colour
(a) State the genotype of:
(i) Parents
(ii) F1 Generation
(b) Work out the cross between plants in the F1 generation
(c) Account for the colour the flowers in plants of the F1 generation

answers

(a) (i) HH; and hh;

(ii) Hh
(c) The RJ if namation on the left is wrong if give the gene for purple colour is dominant/ gene for white colour is recessive;

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Biology Questions and Answers

Describe the role of the liver in homeostasis in the human body

Describe the role of the liver in homeostasis in the human body

How are flowers adapted to wind and insect pollination?

How are flowers adapted to wind and insect pollination?

K.C.S.E Biology Q & A - MODEL 2009PP2QN06

K.C.S.E Biology Q & A - MODEL 2009PP2QN06

Give three functions of pectoral and pelvic fins in a fish

Give three functions of pectoral and pelvic fins in a fish

K.C.S.E Biology Q & A - MODEL 2009PP2QN05

K.C.S.E Biology Q & A - MODEL 2009PP2QN05

what happens when a wilting young plants is well watered

what happens when a wilting young plants is well watered

K.C.S.E Biology Q & A - MODEL 2009PP2QN04

K.C.S.E Biology Q & A - MODEL 2009PP2QN04

Name a substance that is responsible for acid rain

Name a substance that is responsible for acid rain

What are the effects of eutrophication

What are the effects of eutrophication

What is eutrophication?

What is eutrophication?

Give an example of biological control

Give an example of biological control

what is meant by the term biological control

what is meant by the term biological control

Name the substance that is responsible for hardening of teeth

Name the substance that is responsible for hardening of teeth

K.C.S.E Biology Q & A - MODEL 2009PP2QN02

K.C.S.E Biology Q & A - MODEL 2009PP2QN02

K.C.S.E Biology Q & A - MODEL 2009PP2QN01

K.C.S.E Biology Q & A - MODEL 2009PP2QN01

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