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

Which of the following requires the use of carbon dating to prove that evolution has occurred?

The presence of sunken stomata and the folding of leaves are adaptations to

An organism that has been extensively used to test the chromosomes theory of heredity is

An example of cryptic colouration is the

Spines and shells on animals are adaptation for

A feature associated with the Y-chromosome in human is

In the egg of a bird, the embryo is located in the

The inactive state exhibited by an animal during hot dry seasons is termed