2018 - WAEC Biology Past Questions & Answers - page 5

41

The exchange of genes between homologous chromosomes is called

A
crossing over
B
back cross
C
test cross
D
mutation
CORRECT OPTION: a

Crossing over is the process where homologous chromosomes pair up with each other and exchange different segments of genetic material to form recombinant chromosomes.

42

The diagrams above are illustrations of the inheritance of coat colour in mice. J, K, L, M and N are parents. The cross between two parent mice gave rise to offspring P, Q, R and S. Which of the offspring are all homozygous?

A
P
B
Q
C
S
D
R
CORRECT OPTION: c
43

Genes that remain linked are those

A
close to each other on the chromosomes
B
on the same locus on the chromosomes
C
on the homologous chromosomes
D
which are allelic pair
CORRECT OPTION: a

Linked genes are genes that are found near each other on the same chromosome.

44

A plant cell has 14 chromosomes prior to mitosis. What is the number of chromosomes in the daughter cells?

A
14
B
56
C
28
D
7
CORRECT OPTION: a

Mitosis is a process of cell reproduction in which one cell gives rise to two genetically identical daughter cells of the same number. Hence, the daughter cell has the same number as the parent cell prior to the process.

45

The chemical bond that holds the bases of the two strands of DNA together is

A
oxygen bond
B
hydrogen bond
C
electrovalent bond
D
covalent bond
CORRECT OPTION: b

Hydrogen bonds form between the nitrogenous bases in one strand and the nitrogenous bases in the other strand of DNA;

46

The diagram above is an illustration of one of the theories of evolution. Who proposed the theory in the illustration?

A
Louis Pasteur
B
Gregor Mendel
C
Robert Hooke
D
Jean Lamarck
CORRECT OPTION: d

This is the law of use and disuse propounded by Jean-Baptiste Lamarck.

47

The theory supports

A
natural selection
B
struggle for survival
C
independent assortment
D
the use and disuse of body parts
CORRECT OPTION: d

The theory implies that the more you use a part of your body, with time that part of your body starts adjusting in order to make the work easy.

48

In evolution, fossils are naturally preserved in

A
rocks
B
water
C
chemicals
D
trees
CORRECT OPTION: a

Some sedimentary rocks actually have fossils stored in them. Therefore, fossils are stored in rocks.

49

Which of the following is not a social insect?

A
termite
B
housefly
C
honeybee
D
ant
CORRECT OPTION: b

Social insects are characterized by Group integration (blending the new members into the already existing social structure), Division of labour and Overlap of generations (having several breeding seasons, hence having multiple generations present at a time).

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