Jamb Biology Past Questions For Year 2021
Question 21
If a DNA strand has a base sequence TCA, its complementary strand must be?
- A. ATG
- B. TAG
- C. GAT
- D. AGT
Question 22
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 23
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 24
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 25
The correct sequence for the perception of smell in mammals is?
- A. chemicals --> olfactory nerve endings --> brain
- B. dissolved chemicals --> nasal sensory cells --> brain
- C. chemicals --> mucus membrane sensory cells --> brain
- D. dissolved chemicals --> sensory cells --> olfactory nerve --> brain
