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

Why does the platelet count decrease in dengue patient?

Why do lepidopterans die when they feed on Bt cotton plant? Explain how does it happen.

Prior to a sports event blood & urine samples of sportspersons are collected for drug tests.

1. Why is there a need to conduct such tests?
2. Name the drugs the authorities usually look for.
3. Write the generic names of two plants from which these drugs are obtained.

What is apiculture? What is its importance?

How is the amplification of a gene sample of interest carried out using Polymerase Chain Reaction (PCR)?

Rajesh was doing gel electrophoresis to purify DNA fragments. Given below is the sketch of the observations of the experiment performed by him.

1. At which end he would have loaded the samples and where?
2. Analyse the reason for different positions taken up by the DNA bands.
3. Elaborate the step he would have followed to visualize DNA bands.

What are biocontrol agents? Mention any two groups of biocontrol agents and their hosts.

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

1. Ascaris worms living in the intestine of human.
2. Wasp pollinating fig inflorescence.
3. Clown fish living among the tentacles of sea-anemone.
4. Mycorrhizae living on the roots of higher plants.
5. Orchid growing on a branch of a mango tree.
6. Disappearance of smaller barnacles when Balanus dominated in the Coast of Scotland.

Recombinant DNA technology is of great importance in the field of medicine. With the help of a flow chart, show how this techonolgy has been used in preparing genetically engineered human insulins.

For the expression of traits genes provide only the potentiality and the environment provides the opportunity. Comment on the veracity of the statement.