All 20 questions from the Post-UTME Screening (Post-UTME) Biology 2016 Objective paper, with the correct answer and a full explanation for each. Free, no signup needed.
Investigation of respiration in green plants is carried out in the dark because
A. respiration occurs in plants only in the dark
B. light is destructive to potted plants
C. respiration is faster than photosynthesis in the presence of light
D. carbon dioxide released in the presence of light is used up in photosynthesisCorrect
Explanation
In the light, plants photosynthesise, consuming the CO2 released by respiration, which would mask/interfere with measuring respiration alone. Working in the dark removes photosynthesis from the picture.
Use the diagram (a seed with parts labelled I, II, III, IV) to answer this question and the next. Which number represents the structure that will develop into stem and leaves?
A. I
B. IICorrect
C. III
D. IV
Explanation
The plumule is the embryonic structure that develops into the stem and leaves of the seedling; it is typically the second labelled part in such seed diagrams.
A seed with two large cotyledons and no separate endosperm tissue (food stored directly in the cotyledons) is characteristic of a dicot non-endospermous seed, e.g. a bean seed.
Use the diagram below (a population growth curve, number of organisms against time, with phases labelled I to V) to answer this question and the next. The area with the highest growth rate is labelled
A. V
B. IV
C. IIICorrect
D. I
Explanation
The steepest part of a typical sigmoid population growth curve (the exponential growth phase) represents the highest growth rate.
Environmental resistance (factors limiting population growth) becomes greatest as the population approaches and reaches its carrying capacity, near the plateau of the curve.