HEREDITY AND VARIATIONS - Jamb Biology Past Questions and Answers

Question 46:

• JAMB 1995

The F₁ of a cross between a tall and a dwarf plant was tall. The F₁ was advanced to F₂. How many of 120F₂ plants will be dwarf?

A. 30
B. 60
C. 90
D. 120

Question 47:

• JAMB 1995

All the sons of a colour-blind woman will be coloured blind regardless of the state of the father because

A. The egg determines the phenotype of the son
B. Sons inherit the sex chromosome of their mothers
C. The father's sex chromosomes is weaker in sons
D. Sex-linked traits express dominance in females

Question 48:

• JAMB 1997

One reason for the success of Mendel's work is that the

A. Was the first to carry out research work on modern genetics
B. Introduced quantitative and qualitative elements into his work
C. Selected two characteristics only at a time for study
D. Drew up his laws of inheritance based on his knowledge of chromosomes

Question 49:

• JAMB 1997

The homozygous condition Hb^sHb^sresults in sickle cell anaemia whereas Hb^AHb^s has the sickling trait. What is the probability that a couple with the sickling trait will give birth to one normal child?

A. 1/2
B. 1/4
C. 1/8
D. None

Question 50:

• JAMB 1998

The phenotype of an individual can be summed up as the

A. Totality of the expressed traits
B. Individual's physical appearance
C. Individual's entire genetical make-up
D. Physiological traits of individual