HEREDITY AND VARIATIONS - Jamb Biology Past Questions and Answers

Question 66:

• JAMB 2003

A man and his wife are both heterozyous for the sickle-cell trait. The likely percentage of their offspring that will be either carriers or sicklers is

A. 75%
B. 50%
C. 25%
D. 100%

Question 67:

• JAMB 2003

If the pair of alleles for baldness is given as Bb, a female carrier will be denoted by

A. X^bY^B
B. X^BX^B
C. X^BY
D. X^BbX^b

Question 68:

• JAMB 2003

A feature associated with the Y-chromosome in human is

A. Long eyelashes
B. Prominent fingernails
C. Facial hairs
D. Enlarged breast

Question 69:

• JAMB 2004

In a Mendelian cross of red and white varieties of the four O"clock plants, the F₁ generation expresses incomplete dominance by having flower which are

A. White
B. Red
C. Pink
D. Multicoloured

Question 70:

• JAMB 2004

Sex - linked genes are located on

A. Y - chromosomes
B. X - and Y - chromosomes
C. Homologous chromosome
D. X - chromosome