Microbes in Human Welfare — BIOLOGY STD 12 Science — Question

How have transgenic animals proved to be beneficial in:

1. Production of biological products.
2. Chemical safety testing.

Explain two situations when independent assortment of genes occurs resulting in 50% recombinations.

Is it true that there is more solar energy available in the tropics? Explain briefly.

Since the origin of life on earth, there were five episodes of mass extinction of species.

1. How is the 'Sixth Extinction', presently in progress, different from the previous episodes?
2. Who is mainly responsible for the 'Sixth Extinction?
3. List any four points that can help to overcome this disaster.

A population of 100 spotted deer was living without any carnivores in an enclosure of a few hectares of rich tropical forest land. Deer census was taken after a few years. Now study the graph given below and answer the questions that follow:

1. Identify the curve that represents the deer population.
2. Is it a realistic one? Justify.

How many recombinant therapeutics have been approved for human use in the world? And how many are presently being marketed in India?

After a brief medical examination a healthy couple came to know that both of them are unable to produce functional gametes and should look for an 'ART' (Assisted Reproductive Technique). Name the 'ART' and the procedure involved that you can suggest to them to help them bear a child.

What is endometrium?

In a certain mammal, erect ears are dominant over drooping ears. In a cross between the two types, out of the four offsprings produced in F₂ generation, three had erect ears and one had drooping ears. What were the genotypes of the parent? (You may represent the dominant gene as E.)

Draw a labelled diagram of:

1. An apocarpous pistil and.
2. A syncarpous pistil. Name an example for each.