The base sequence in one of the strands of DNA is TAGCATGAT.

(i) Give the base sequence of its complementary strand.

(ii) How are these base pairs held together in a DNA molecule?

(iii) Explain the base complementarity rules. Name the scientist who framed this rule.

(a) Sickle celled anaemia in humans is a result of point mutation. Explain.

(b) Write the genotypes of both the parents who have produced a sickle celled anaemic offspring.

24. What is inbreeding depression and how is it caused in organisms? Write any two advantages of inbreeding.

(a) Identify (A) and (B) illustrations in the following:

i. 



ii. 

(b) Write the term given to (A) and (C) and why?

(c) Expand PCR. Mention its importance in biotechnology.

The diagram above is that of a typical biogas plant. Explain the seQ uence of events occurring in a biogas plant. Identify a, b and c.

How can crop varieties be made disease resistant to overcome food crisis in India? Explain.

Name one disease resistant variety in India of:

(a) Wheat to leaf and stripe rust

(b) Brassica to white rust

Write the source and the effect on the human body of the following drugs:

(i) Morphine

(ii) Cocaine

(iii) Marijuana

Name the type of interaction seen in each of the following examples:

(i) Ascaris worms living in the intestine of human

(ii) Wasp pollinating fig inflorescence

(iii) Clown fish living among the tentacles of sea-anemone

(iv) Mycorrhizae living on the roots of higher plants

(v) Orchid growing on a branch of a mango tree

(vi) Disappearance of smaller barnacles when Balanus dominated in the Coast of Scotland.

(a) Draw a labelled diagram of the human female reproductive system. 

(b) Enumerate the events in the ovary of a human female during: 

(i) Follicular phase

(ii) Luteal phase of menstrual cycle