Biotechnology — BIOLOGY STD 12 Science — Question

1. Differentiate between: Autogamy, Geitonogamy and Xenogamy.
2. Explain the events that occur during pollen-pistil interaction.

Give equations of physical nitrogen fixation.

Give the term/ reason:
Sperm cannot reach ovum without seminal plasma.

1. Explain the development of female gametophyte from a megaspore mother cell in an angiosperm.
2. Draw a leballed diagram of a fully-developed embryo sac.

OR

1. Describe the process of megasporogenesis in angiosperms, until 8-nucleate stage.
2. Draw the labelled structure of mature embryo sac.

Read the following and answer any four questions from (i) to (v) given below:
Crown gall is a neoplastic disease of most dicotyledonous plants and is caused by the soil bacterium Agrobacterium tumefaciens. A large extra chromosomal plasmid in these bacteria was found to be responsible for this disease. The plasmid is known as Ti plasmid. Bacteria free crown gall cells can be cultured in the absence of phytohormones. Ti plasmid is widely used in genetic engineering to deliver the desirable genes. The part of Ti plasmid transferred into plant cell DNA is called T-DNA. T-DNA with desired DNA segment is inserted into the chromosome of the host plant where it produces copies of itself.

1. Which of the following is the full full of T-DNA?

1. Transfer DNA.
2. Tumour inducing DNA.
3. Transgenic DNA.
4. None of these.

2. Ti plasmid cannot infect and develop crown gall in,

1. Tomato.
2. Maize.
3. Soybean.
4. sunflower.

3. While making transgenic plant, T-DNA is inserted into the host cell, it is then:

1. Integrated into the target host genome.
2. Lie independent of the host genome.
3. Rupture the host cell wall.
4. Produce oncogenic factors in the host.

4. Agrobacterium mediated gene transfer in plants:

1. Allows relatively large segment of DNA.
2. Transfer of DNA with defined ends and minimal rearrangement.
3. High quality and fertility in transgenic plants.
4. All of these.

5. Assertion: In Agrobacterium mediated gene transfer in plants, transgenic plants do not develop tumors.

Reason: In T-DNA tumor producing genes are deleted during the process of gene transfer.

1. Both assertion and reason are true and reason is the correct explanation of assertion.
2. Both assertion and reason are true but reason is not the correct explanation of assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false.

Enumerate the events in the ovary of a human female during:
Luteal phase of menstrual cycle.

Describe in detail the steps involved in the replication of DNA.

Distinguish between: Food chain and Food web.

Haldane described ‘Hot dilute soup’ in his theory. Describe how this soup led to formation of some important molecules.

ATP is called energy currency of the cell.