KNEC KCSE BIOLOGY TOPICAL QUESTIONS

Continents existed as one large Landmass/Pangea/Laurasian and Gondwana Land;
Present continents drifted from it leading to isolation of organisms; organisms in each Continent evolved along different lines hence emergence of new species;

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Explain the theory of evolution by natural selection.

26/6/2020

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K.C.S.E Biology Q & A - MODEL 2013PP1QN20

Explain the theory of evolution by natural selection.

answers

Genetically acquired bene1cial characteristics which occur spontaneously; are perpetuated through reproduction;

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K.C.S.E Biology Q & A - MODEL 2012PP1QN26

26/6/2020

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K.C.S.E Biology Q & A - MODEL 2012PP1QN26

(a) State the theories of evolution proposed by the following scientists.

Charles Darvin
Jean-Baptiste de Lamark

(b) State the evidence of evolution based on
(i) cell organelles
(ii) fossils

answers

(a) Theory of natural selection;
Theory of environmental influence on inherited characteristics;
(b) (i) Similar organelles performing similar functions in different organisms suggest a common ancestry/cell biology;
(ii) Fossil records/palaeontology/by comparing fossils to show phyllogenetic relationship between organisms/common ancestry;

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State the importance of divergent evolution to organisms.

26/6/2020

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K.C.S.E Biology Q & A - MODEL 2012PP1QN22

State the importance of divergent evolution to organisms.

answer

Results in adaptations that enable organisms to exploit different ecological niches; leads to the formation of new species;

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Explain how comparative embryology is an evidence for organic evolution.

25/6/2020

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K.C.S.E Biology Q & A - MODEL 2011PP2QN02

Explain how comparative embryology is an evidence for organic evolution.

answer

Vertebrate embryos have similar morphological features; which suggest a common ancestry;

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State two limitations of fossils as an evidence of evolution.

25/6/2020

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K.C.S.E Biology Q & A - MODEL 2011PP1QN21

State two limitations of fossils as an evidence of evolution.

answers

Missing links;
Distortion of parts during sedimentation/earthquakes/putrefìcation;
Destruction of fossils by geological activities/faulting/folding;

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What is meant by convergent evolution?

25/6/2020

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K.C.S.E Biology Q & A - MODEL 2011PP1QN21

What is meant by convergent evolution?

answer

Where different structures evolve to perform the same function (e.g. wings of insects and birds are different in structure but are used for flying);

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Why is Lamark’s theory not acceptable?

24/6/2020

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K.C.S.E Biology Q & A - MODEL 2010PP1QN24

Why is Lamark’s theory not acceptable?

answer

Acquired characteristics cannot be inherited;

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State two ideas proposed by Lamark in his theory of evolution.

24/6/2020

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K.C.S.E Biology Q & A - MODEL 2010PP1QN24

State two ideas proposed by Lamark in his theory of evolution.

answers

Use and disuse;
Acquired traits can be passed on to offspring;

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Explain why certain drugs become ineffective in curing a disease after many years of use.

23/6/2020

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K.C.S.E Biology Q & A - MODEL 2009PP1QN10

Explain why certain drugs become ineffective in curing a disease after many years of use.

ANSWER

Disease causing organisms mutate; and become resistant

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Give an example of a vestigial structure in human

23/6/2020

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K.C.S.E Biology Q & A - MODEL 2009PP1QN10

Give an example of a vestigial structure in human

ANSWERS

Appendix/ coccyx/tail ( tail bone)/ semi - lunar folds of cornea of eye/ nictitating membrane caecum/ ear muscles/ body hair/

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What is meant by vestigial structures ?

23/6/2020

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K.C.S.E Biology Q & A - MODEL 2009PP1QN10

What is meant by vestigial structures ?

ANSWER

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How does convergent evolution occur

22/6/2020

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K.C.S.E Biology Q & A - MODEL 2008PP1QN07

How does convergent evolution occur

ANSWERS

When two dissimilar species/ structures/ organisms of different embryonic origin; change in same and develop similar characteristics/ or modify to perform similar function

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Name two vestigial structures in human beings.

Name two vestigial structures in human beings.

What is meant by the term organic evolution?

What is meant by the term organic evolution?

Explain the role of continental drift in evolution.

Explain the role of continental drift in evolution.

Explain the theory of evolution by natural selection.

Explain the theory of evolution by natural selection.

K.C.S.E Biology Q & A - MODEL 2012PP1QN26

K.C.S.E Biology Q & A - MODEL 2012PP1QN26

State the importance of divergent evolution to organisms.

State the importance of divergent evolution to organisms.

Explain how comparative embryology is an evidence for organic evolution.

Explain how comparative embryology is an evidence for organic evolution.

State two limitations of fossils as an evidence of evolution.

State two limitations of fossils as an evidence of evolution.

What is meant by convergent evolution?

What is meant by convergent evolution?

Why is Lamark’s theory not acceptable?

Why is Lamark’s theory not acceptable?

State two ideas proposed by Lamark in his theory of evolution.

State two ideas proposed by Lamark in his theory of evolution.

Explain why certain drugs become ineffective in curing a disease after many years of use.

Explain why certain drugs become ineffective in curing a disease after many years of use.

Give an example of a vestigial structure in human

Give an example of a vestigial structure in human

What is meant by vestigial structures ?

What is meant by vestigial structures ?

How does convergent evolution occur

How does convergent evolution occur

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