KNEC KCSE BIOLOGY TOPICAL QUESTIONS

State two limitations of using a quadrat to estimate the population of organisms.

1/7/2020

Comments

K.C.S.E Biology Q & A - MODEL 2018PP1QN13

State two limitations of using a quadrat to estimate the population of organisms.

ANSWERS

Cannot be used for most animals/plants;
Assumes organisms are evenly distributed;
Inaccuracy (over/under-estimation);

Comments

K.C.S.E Biology Q & A - MODEL 2017PP2QN07

1/7/2020

Comments

K.C.S.E Biology Q & A - MODEL 2017PP2QN07

Explain the importance of protecting the forest ecosystem with reference to the following:
(a) climate change
(b) biodiversity
(c) biotechnology
(d) water conservation
(e) pollution.

answers

a) Climate change

Promote(regular) rainfall/precipitation/prevent desertification;
Act as wind breakers;
Keep earth temperatures cool/reduce global warming;
Keeps biogeochemical cycles going e.g. hydrological, carbon,nitrogen, phosphorous, sulphur cycles;

b) Biodiversity

Conserve diverse flora/ fauna;
Conserve genetic variety;
Prevent extinction of rare species;
Source of research/employment;
Aesthetic/attracting tourism in foreign exchange;
Have impact on culture/religion/politics; ‘
Food and shelter for other organisms and man;
Source of oxygen;

c) Biotechnology

Manufacture of medicines/directly used as medicinal;
Source of food/food products;
Provide fuel (when regulated);
Provide paper and related by-products (when regulated);
Provide timber (when regulated);
Products used in other industries e.g. tannin, wax, rubber, oil, honey;

d) Water conservation

Increased ground water/high water tables;
Adds into rivers/lakes/permanency ¡n existing water bodies/reservoirs;
Water towers/water catchment;

e) Pollution .

Minimize soil pollution/ensuring cover against surface run-off/wind erosion/denudation;
Trees/vegetation clean the soil surface by absorbing nutrients from decomposed matter e.g. sewage;
Large scale clean-up of polluted air/dust;
Muffle noise pollution;

Comments

Name the hormone responsible for the development of secondary sexual characteristics in human males.

1/7/2020

Comments

K.C.S.E Biology Q & A - MODEL 2017PP2QN04

Name the hormone responsible for the development of secondary sexual characteristics in human males.

answer

Testosterone;

Comments

State the significance of diploidy.

1/7/2020

Comments

K.C.S.E Biology Q & A - MODEL 2017PP2QN04

State the significance of diploidy.

answers

Ensures that the chromosomes/genetic constitution of the offspring is the same as that of parents;
Ensures perpetuation of a given species’ desired/favourable traits/qualities/continuity of the species;

Comments

K.C.S.E Biology Q & A - MODEL 2017PP2QN04

1/7/2020

Comments

K.C.S.E Biology Q & A - MODEL 2017PP2QN04

(i) Define the term diploidy.
(ii) Name the type of cell division that gives rise to diploid cells.
(iii) Name the type of cells in which the process named in (b) (ii) above Occurs.

answers

i. State of being/having two sets of chromosomes and therefore two copies of genes (especially in somatic/body cells);
ii. Mitosis;
iii. Body cells/somatic cells;

Comments

Explain how the sex of a male child is determined in human beings.

1/7/2020

Comments

K.C.S.E Biology Q & A - MODEL 2017PP2QN04

Explain how the sex of a male child is determined in human beings.

answers

Male produces sperm cells with X or Y chromosomes; if (by chance), Y chromosome containing sperm from male fuses with X chromosome containing egg from female ovum, an XY zygote results, giving rise to a male child;

Comments

K.C.S.E Biology Q & A - MODEL 2017PP1QN14

30/6/2020

Comments

K.C.S.E Biology Q & A - MODEL 2017PP1QN14

The photograph below illustrates a germinating seedling.

(a) Name the type of germination illustrated in the photograph.
(b) Explain the function of each of the parts labelled G and H.
G
H

answers

a. Epigeal;
b. G- Elongates to expose the foliage leaves to light photosynthesis
H- Stores food (for growth);
For photosynthesis (it is green);
Protects plumule during germination;

Comments

K.C.S.E Biology Q & A - MODEL 2017PP1QN07

30/6/2020

Comments

K.C.S.E Biology Q & A - MODEL 2017PP1QN07

The diagram below represents a stage in the division of a cell.

With a reason, identify the organism from which the cell was obtained.

answers

.Animal - accept correct examples (of organisms)/amoeba/plasmodiurn;
Constriction of the cell membrane/ presence of centrioles;

Comments

K.C.S.E Biology Q & A - MODEL 2017PP1QN05

30/6/2020

Comments

K.C.S.E Biology Q & A - MODEL 2017PP1QN05

The photograph illustrates a housefly at various stages of its development.

(a) (i) On the photograph, name the stages of the life cycle.
(ii) Using arrows, link the stages of the life cycle in the correct order.
(b) (i) State two differences between the life cycles of a housefly and that of a cockroach.
(ii) State one advantage of the life cycle of a cockroach to itself.

answers

(ii)Absence of larva and pupa shortens the life cycle of the organism; (avoiding adverse/extreme environmental conditions that would affect its growth/general life processes);

Comments

K.C.S.E Biology Q & A - MODEL 2016PP2QN01

30/6/2020

Comments

K.C.S.E Biology Q & A - MODEL 2016PP2QN01

The diagram below represents a human foetus in a uterus.

(a) Name the part labeled S.
(b) (i) Name the types of blood vessels found in the structure labaled Q.
(ii) State the difference in composition of blood found in the vessels named in (b) (i) above.
c)Name two features that enable the structure labeled P to carry out its function.
(d) State the role of the part labeled R.

ANSWERS