The organs P and Q of two animals have different structures but similar functions. On the other hand, the two organs R and S of two other animals have the same basic structure but different functions.

(a) What are the organs like P and Q known as?

(b) Name the organs like P and Q. Also name the animals which have such organs.

(c) What are the organs like R and S called?

(d) Name the organs like R and S. Also name the animals which have such organs.

The farmers have been cultivating a food plant X for over two thousand years and have produced as many as five entirely different looking vegetables A, B, C, D and E from it.

(a) What could the plant X be?

(b) What are A, B, C, D and E?

(c) What is the process of evolution involved in this example known as?

There are five animals A, B, C, D and E. The animal A uses its modified forelimbs for flying. The animal B uses its forelimbs for running whereas the animal C uses its forelimbs for grasping. The animal D can live on land as well as in water and uses its forelimbs to prop up the front end of its body when at rest. The animal E which respires by using spiracles and tracheae uses wings for flying but its wings are analogous to the modified forelimbs of animal A.

(a) What could the animals A, B, C, D and E be?

(b) Why are the forelimbs of animals A, B, C and D called homologous organs ?

(c) What does the existence of homologous organs in animals A, B, C and D tell us about their ancestors?

(d) Why are the modified forelimbs of animal A and the wings of animal E called analogous organs?

(e) State whether animals A and E have a common ancestor or not.

X, Y, and Z are three animals. The animal X can fly but animal Y can only run on ground or walls. The forelimbs of animals X and Y have the same basic design but they are used for different purposes such as flying and running respectively. The animal Z became extinct a long time ago. The study of fossils of Z tells us that it had some features like those of X and some like those of Y. In fact, Z is said to form a connecting link in the evolutionary chain of X and Y.

(a) What could the animals X, Y and Z be?

(b) What name is given to the forelimbs like those of X and Y which have the same basic design but different functions?

(c) Name one feature in which Z resembled X.

(d) Name one feature in which Z resembled Y.

(e) Which is the correct evolutionary chain involving X, Y and Z: X Z Y or YZ X?

A population of red beetles lives in green bushes in a garden. Once during the process of breeding, a green beetle is produced.

(a) State whether the change in color of beetle is a process of evolution or not.

(b) Can the new color of green beetle be passed on to its next generations?

(c) What will be the advantage (if any) of the green color to the beetle?

(d) State whether the production of green color involved a change in genetic material or not.