Microbes in Human Welfare — BIOLOGY STD 12 Science — Question

Give the name of the STD, which can be transmitted through contaminated blood.

What technical term is given to the fish-like reptiles?

Explain (in one or two lines) the function of the following:
tRNA.

Why type II restriction enzymes are used in recombinant DNA technology?

The trigger for activation of toxin of Bacillus thuringiensis is:

1. Acidic pH of stomach.
2. High temperature.
3. Alkaline pH of gut.
4. Mechanical action in the insect gut.

Name a microbe used for the production of Swiss cheese.

Two statements are given-one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.

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.

Assertion: PCR is routinely used for early diagnosis of HIV in suspected AIDS patients.
Reason: PCR can detect low amounts of DNA.

Why do we add an inoculum of curd to milk for curdling it?

OR

Why is 'starter' added to set the milk into curd? Explain.

OR

During the production of curd, a small amount of curd is added as a starter to the fresh milk at a suitable temperature. Explain the changes the milk undergoes when it sets into the curd.

OR

Why is a little curd added to milk to set it into curd? Explain.

Name the two intermediate hosts which the human liver fluke depends on to complete its life cycle so as to facilitate parasitization of its primary host.

Why is the period between day 10 and 17 of the menstrual cycle, called 'fertile period"?