What are two main components of our environment?

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

Updated 1/12/2026

For two statements are given- one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below: a. Both A and R are true, and R is correct explanation of the assertion. b. Both A and R are true, but R is not the correct explanation of the assertion. c. A is true but R is false. d. A is false but R is true. Assertion: A child which has inherited X chromosome from father will develop into a girl child. Reason: Girl child inherits X chromosome from father and Y chromosome from mother.

Updated 1/12/2026

List any two factors that could lead to speciation.

Updated 1/12/2026

For two statements are given- one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below: a. Both A and R are true, and R is correct explanation of the assertion. b. Both A and R are true, but R is not the correct explanation of the assertion. c. A is true but R is false. d. A is false but R is true. Assertion: ln grasshoppers, females are hetero gametic and males are homo gametic. Reason: ln grasshoppers, male has only one sex chromosome (XO) whereas the female has sex chromosomes (XX).

Updated 1/12/2026

For two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below: a. Both A and R are true, and R is correct explanation of the assertion. b. Both A and R are true, but R is not the correct explanation of the assertion. c. A is true but R is false. d. A is false but R is true. Assertion: Seeds are matured ovules. Reason: The part of seed which contains stored food for baby plant is called cotyledon.

Updated 1/12/2026