WAEC Past Questions and Answers - Page 3675

18,371.

Heterozygous tall plants were crossed with pure-breeding dwarf plants of the same species. What were the approximate percentages of the offspring?

A.

100% tall 0% dwarf

B.

75% tall 25% dwarf

C.

50% tall 50% dwarf

D.

 25% tall 75% dwarf

Correct answer is C

A heterozygous tall plant (say Tt) crossed with pure-breeding dwarf plants (tt) will give a set of Tt, Tt, tt and tt. This is 50% tall and 50% dwarf approximately.

18,372.

Which of the following traits in humans can be affected by environmental factors?

A.

skin colour

B.

eye colour

C.

baldness

D.

tongue-rolling

Correct answer is A

No explanation has been provided for this answer.

18,373.

What will be the genotypic ratio when two heterozygous red pea plants are crossed?

A.

1 : 0

B.

1 : 2 : 1

C.

2 : 1

D.

3 : 1

Correct answer is B

No explanation has been provided for this answer.

18,374.

In man, sex is determined by the inheritance of

A.

 a pair of homologous chromosomes

B.

an extra chromosome in the cells of a female

C.

a dominant gene for maleness present in man

D.

two similar X chromosomes in the female and X and Y chromosomes in the male

Correct answer is D

No explanation has been provided for this answer.

18,375.

The ability of some individuals to taste phenylthiocarbamide (PTC) is a

A.

morphological adaptation

B.

morphological variation

C.

physiological adaptation

D.

physiological variation

Correct answer is D

No explanation has been provided for this answer.