Jamb Biology 2021 Past Questions and Answers

Question 16:

• JAMB 2021

I. High birth rate and high immigration rate
II. Low birth rate and high immigration rate
III. Low mortality rate and low emigration rate
IV. High mortality rate and high emigration rate.

Which combination of the above can cause rapid over-crowding in climax biotic communities and human settlements?

A. II and III
B. I and III
C. I and IV
D. I and II

Question 17:

• JAMB 2021

The number of plant species obtained from a population study of a garden is as follows: Guinea grass (15), Ipomoea spp (5), Sida spp (7) and Imperata spp (23)

What is the percentage of occurrence of Imperata spp?

A. 35%
B. 16%
C. 46%
D. 23%

Question 18:

• JAMB 2021

When a marine fish was taken from the ocean and put in a tank of fresh water, it died after a short period because?

A. The tank was too small compared to the large-ocean
B. The body cells of the fish swelled and burst as a result of the hypotonic fresh water
C. The body cells of the fish shrank as their sap was hypertonic to the freshwater
D. There was no food in the tank, so the fish starved

Question 19:

• JAMB 2021

If a DNA strand has a base sequence TCA, its complementary strand must be?

A. ATG
B. TAG
C. GAT
D. AGT

Question 20:

• JAMB 2021

The appendicular skeleton is composed of the pectoral girdle?

A. Pelvic girdle, fore and hind limbs
B. Pelvic girdle and fore limbs
C. Lumbar vertebrae and pelvic girdle
D. Lumbar vertebrae, fore and hind limbs