A high concentration of harmful chemical is highly injurious, even fatal to higher trophic level organisms. Mention the basis of classifying substances as biodegradable and non-biodegradable. Give two examples of each.

(a) Write foil form of DNA. (b) Why are variations essential for the species ? (CCE 2011)

Updated 1/12/2026

What is the function of genes in an organism?

Updated 1/12/2026

Name the three major regions of human brain. Which part of brain maintains posture and equilibrium of the body?

Updated 1/12/2026

What is geographical isolation? (b) Illustrate formation of a species with the help of an example where individuals are very different from each other and are capable of reproduction among themselves.

Updated 1/12/2026

(b) What is • Phototropism and • Geotropism? With labelled diagrams describe an activity to show that light and gravity change the direction that plant parts grow in. (b) Mention the role of each of the following plant hormones: • Auxin • Abscisic acid.

Updated 1/12/2026