Principles of Inheritance and Variation — BIOLOGY STD 12 Science — Question

Describe how do oxygen and chemical composition of detritus control decomposition.

Both haemophilia and thalassemia are blood related disorders in humans. Write their causes and the difference between the two. Name the category of genetic disorder they both come under.

(a) Why must a cell be made 'competent' in biotechnology experiments? How does calcium ion help in doing so ?
(b) State the role of 'biolistic gun' in biotechnology experiments.

What do you mean by foetal ejection reflex?

Explain giving two reasons why pollen grains can be best preserved as fossils.

Describe the technique that can help a healthy married woman, who is unable to produce viable ova, but wants to bear a child.

Why do people suffer from altitude sickness after reaching the high altitude regions? How does their body acclimatised after a couple of days?

Majority of angiosperms have hermaphrodite flowers, but self-pollination is discouraged by them. Explain any three outbreeding devices that they have developed to achieve this.

(a) Draw the well labelled diagram of nucleosome.
(b) Mention what enables histones to acquire a positive charge?

A3' ............ 5'B
C5’ ........... 3'D.
AB and CD represent two strands of a DNA molecule. When this molecule undergoes replication, forming a replication fork between A and C in the above.

1. Name the templete strand for replication.
2. Using which strand as the templete, will there be continuous synthesis of a complementary DNA strand
3. Complementary to which strand will okazaki segments get synthesised, discontinuous synthesis occurs.
4. What are templete strands and Okazaki pieces?
5. In which direction is a new strand synthesised?