Sexual Reproduction In Flowering Plants — BIOLOGY STD 12 Science — Question

How did the idea of a vector for delivering foreign DNA fragments to host organisms come to the minds of biotechnology scientists?

How does a Monarch butterfly defend itself from predation? Explain.

Differentiate between:

1. Hypocotyl and coleoptile.
2. Protandry and protogyny.

In a dihybrid cross white eyed, yellow bodied female Drosophila crossed with red eyed, brown bodied male Drosophila produced in F₂ generation, 1.3 per cent recombinants and 98.7 per cent progeny with parental type combinations. This observation of Morgan deviated from Mendelian F₂ phenotypic dihybrid ratio. Explain, giving reasons, Morgan’s observations.

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?

How PCR is used to detect bacterial and viral diseases and the gene mutation in cancer patient when the symptoms are not visible?

Write a short note on sperm. (With a labeled diagram.)###Draw a labelled diagram of sperm.

(a) Name the green house gases which causes global warming ?
(b) By which causes the hole in ozone layer and how?

Heat loss or heat gain depends upon the surface area of the organism's body. Explain with the help of a suitable example.

OR

Explain, why are small animals rarely found in the polar regions?

Mention the steps of Isolate DNA from bacteria.