Mastering KCSE Biology with Comprehensive Topical Questions and Answers

Distinguish between homologous structures and analogous structures

31/10/2021

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a) Distinguish between homologous structures and analogous structures (2mks)

Homologous structures have a similar embryonic origin but modified to perform different function;
Analogous structures have different embryonic origin but modified to perform similar function;

b) State a major shortcoming in Jean Baptiste de Lamarck’s theory of evolution (1mk)

That a phenotypically acquired characteristics can be transmitted to the offspring by their parents;

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Discuss the various evidences which show that organic evolution has taken place

18/9/2021

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Discuss the various evidences which show that organic evolution has taken place

Taxonomy/comparative anatomy: Members of a phylum show similarities; the organism have similar structure/organs performing similar functions e.g presence of digestive system, urinary , nervous system
Vestigial organs /coccyx, appendix, nictating membrane
Pentadoczl/limbs in animals e.g monkey, rats, have bones arrange in similar pattern / inner are examples of homogenous structures similar in origin but perform different function
Convergent/analogous structures like wings of birds and insects all point to common origin
Comparative embryology: vertebrate are (morphologically) similar, suggesting common origin/when two embryos of mammals, reptiles and amphibians are compared they show similarities
Geographical distribution: present continents are thought to have been a large land mass joined together; continental drift lead to isolation that lead to patterns of evolution e.g camels in south America resemble those in Africa/tiger in Asia resemble Jaguars in S.America
Cell biology; occurrence of organelles e.g. mitochondria, cytoplasm, nucleus point to a common origin

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EVOLUTION

11/7/2020

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Biology Topical Questions

EVOLUTION
1.      1989 Q7 P1
State the difference between Lamarckian and Darwinian theories of evolution.
2.   1991 Q17 P1
    (a) What is meant by natural selection
    (b) Describe the natural selection brings about adaptation of a species to its Environment
3. 1992 Q5 P1
Two populations of the same species of birds were separated over a long period of   time by an ocean. Both populations initially fed on insects only. Later it was observed that one population fed entirely on fruits and seeds, although insects were available.

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Explain the evolutionary basis for the ever changing drugs for malaria treatment.

2/7/2020

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K.C.S.E Biology Q & A - MODEL 2019PP1QN24

Explain the evolutionary basis for the ever changing drugs for malaria treatment.

answers

malaria causing parasite over time become resistant to some malaria drugs; due to (gradually changing their genetic constitutions) mutation; which with time result in the evolution and eventual, perpetuation of the new strains of parasite hence necessitating the discovery of a more effective drug to counter the new/ emerging strains;

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K.C.S.E Biology Q & A - MODEL 2019PP1QN17

2/7/2020

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K.C.S.E Biology Q & A - MODEL 2019PP1QN17

Below are photographs of two dogs.

Explain the possible reason for the difference in the length of their fur.

answers

Geographical distribution; made the animals adapt to survive in their environments(cold/hot), with those having thick fur being adapted to cold regions (for insulation); acc. Converse animal with short fur to adopt to hot area.
Genetic/being passed from parents to offspring's/genetic inheritance / genes being passed from parents to offspring;

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Name the evidence of organic evolution exhibited by occurrence of similar amino acid molecules in a range of organisms.

2/7/2020

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K.C.S.E Biology Q & A - MODEL 2019PP1QN14

Name the evidence of organic evolution exhibited by occurrence of similar amino acid molecules in a range of organisms.

answers

(b) comparative physiology/ biochemistry/cell biology;
Acc. Serology /comparative serology.

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Explain why fossil records as evidence of organic evolution are usually incomplete.

2/7/2020

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K.C.S.E Biology Q & A - MODEL 2019PP1QN14

Explain why fossil records as evidence of organic evolution are usually incomplete.

answers

(a) partial/ entire decomposition of dead organisms/ organic matter;
Some parts of or entire dead organisms are eaten by scavengers;
Soft bodied organisms do not fertilize;
Destruction of parts due to natural disasters, like earthquakes/earth movements like, faulting /folding/ volcanicity/ mass movement;
Distortion of parts of an organism due to sedimentary/ faulting/folding/volcanic

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What does the term evolution mean?

1/7/2020

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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;

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Give two illustrations of analogous structures in mammals.

1/7/2020

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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;

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Define the term analogous structures.

1/7/2020

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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);

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

1/7/2020

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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;

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State three methods of fossil formation.

30/6/2020

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K.C.S.E Biology Q & A - MODEL 2017PP1QN20

State three methods of fossil formation.

answers

i. Petrification/change into rock;
ii. Entire organism or parts preserved;
iii. Impressions (e.g. casts/moulds);

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K.C.S.E Biology Q & A - MODEL 2017PP1QN18

30/6/2020

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K.C.S.E Biology Q & A - MODEL 2017PP1QN18

Below are diagrams representing developmental stages of three different vertebrates.

(a) State the evidence of evolution illustrated by the vertebrates in the diagram.
(b) Suggest why the structure labelled J has been retained throughout the evolution of fish.
(c) State two major advantages evolution has given humans Over most of the other animals.

answers

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Explain continental drift as an evidence of evolution.

30/6/2020

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K.C.S.E Biology Q & A - MODEL 2016PP1QN06

Explain continental drift as an evidence of evolution.

answer

Current continents existed as one large land mass/ Pa.gea/ Laurentia Gondwanaland; the present continents drifted leading to isolation of organisms.Organisms in each continent evolved along different lines hence emergence of new species,

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K.C.S.E Biology Q & A - MODEL 2015PP1QN10

29/6/2020

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K.C.S.E Biology Q & A - MODEL 2015PP1QN10

The diagram below illustrates the skulls of adult human and chimpanzee.

(a) State one difference between the two skulls in the following structures:

(b) State the significance of the evolution observed on the parietal bone in the chimpanzee and human skulls.

answers

(b) Accommodate large sized brain in humans;

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K.C.S.E Biology Q & A - MODEL 2015PP1QN02

29/6/2020

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K.C.S.E Biology Q & A - MODEL 2015PP1QN02

During a lesson, students observed the structure of bat, cat and human forelimbs to determine their evolutionary relationship.
(a) State the name given to the structure of the limbs observed by the students.
(b) Name the type of evolution illustrated by the structure of the limbs observed.
(c) What evidence of evolution is illustrated by the limbs?
(d) State the significance of the type of evolution illustrated by the limbs.

answers

(a) The pentadacty/ limb/homologous structures;
(b) Divergent evolution/adaptive radiation;
(c) Comparative anatomy;
(d) It allows the organisms to exploit different habitats to reduce competition;

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Why are some bacteria able to resist the effect of antibiotics?

28/6/2020

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K.C.S.E Biology Q & A - MODEL 2014PP1QN22

Why are some bacteria able to resist the effect of antibiotics?

ANSWER

They have a gene for resistance/acquire it through mutation;
The gene for resistance is passed to offsprings establishing a population of resistant forms;

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Name two vestigial structures in human beings.

28/6/2020

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K.C.S.E Biology Q & A - MODEL 2014PP1QN22

Name two vestigial structures in human beings.

ANSWERS

Appendix/nictating membrane;
coecum and ear drum;
Tail/coccyx;

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What is meant by the term organic evolution?

26/6/2020

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K.C.S.E Biology Q & A - MODEL 2013PP1QN21

What is meant by the term organic evolution?

answers

Emergence of new life/species/organisms from pre-existing simple forms, gradually over a long period of time, to present complex forms;

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Explain the role of continental drift in evolution.

26/6/2020

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K.C.S.E Biology Q & A - MODEL 2013PP1QN21

Explain the role of continental drift in evolution.

answers

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;