WAEC Past Questions and Answers - Page 4060

20,296.

The genetic make-up of an organism is described as its

A.

phenotype

B.

genotype

C.

character

D.

chromosome

E.

allele

Correct answer is B

No explanation has been provided for this answer.

20,297.

A pair of genes that control a trait is described as?

A.

dominant

B.

recessive

C.

allele

D.

variant

E.

hybrid

Correct answer is C

Alleles are different forms of the same gene that are located on the same part of the chromosome. 

Alleles contribute to the organism's phenotype (the outward appearance of the organism).

20,298.

The density of a body is \(5\times10^3kgm{^-3}\) and it weighs 1N in air. Calculate the apparent weight of the body when totally immersed in water. (Density of water =\(10^3kgm{-3}, g= 10ms^{-2}\) )

A.

0.02N

B.

0.08N

C.

0.20N

D.

0.80N

E.

1N

Correct answer is D

Upthrust = weight of the water displaced =pvg= 1000 x 2 x \(10^{-5}\)=0.20N \\ Apparent weight = weight in air – upthrust = 1-0.2N=0.8N

20,299.

A light wave travels from air into a medium of refractive index 1.54. If the wavelength of the light in air is \(5.9\times10^{-7}\)m, calculate its wavelength in the medium

A.

\(2.5\times10^{-7}\)m

B.

\(3.8\times10^{-7}\)m

C.

\(4.6\times10^{-7}\)m

D.

\(5.2\times10^{-7}\)m

E.

\(6.1\times10^{-7}\)m

Correct answer is B

n =\(\frac{wavelength\, in\, air}{wavelength\, in \,medium}= \frac{5.9\times10^{-7}}{1.54}= 3.8\times10^{-7}\)m

20,300.

Calculate the time taken to heat 2kg of water from 50°C to 100°C in an electric kettle taking 5A, from a 210V supply. (Specific heat capacity of water = 4200\(kg^{-1}K{-1}\)

A.

2.5 minutes

B.

5.7 minutes

C.

6.7 minutes

D.

7.5 minutes

E.

9.5 minutes

Correct answer is C

t = \(\frac{mc\theta}{p}= \frac{2\times4200\times50}{210\times5} \\ = 400s = 6.7\)