Mention any two drawbacks in classifying organisms under the old two kingdom classification.

All humans on earth today may differ widely in their facial features, colour, height, etc. Yet, they belong to a single species Homo sapiens. Give one reason why they are not considered belonging to different species.

Mention any one major similarity and one major difference in the following pairs of animals:

(a) Insects and Birds

(b) Whales and Fishes

(c) Snakes and Earthworms

(d) Bat and Pigeon

(e) Cuttlefish and Dogfish

(f) Wall lizard and Frog

Distinguish between Invertebrates and vertebrates.