In spite of the removal of carbondioxide from the atmosphere, its amount remains more or less constant because

Scales on reptiles are a feature for

The specific number of chromosomes in each somatic cell is represented by

The diagram represents

The colour of the ventral surface of a fish is lighter than that of the dorsal. This is mainly

The part labelled X is the

From which group of animals are the mammals generally believed to have most recently evolved?

The least evidence in support of the theory of evolution is provided by the study of

A man with blood group a is married to a woman with blood group A. Which of the following group combinations is possible if the family has three children?