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

Study the figures given below and answer the question.

Identify in which of the crosses is the strength of linkage between the genes higher. Give reasons in support of your answer.

How and why is the bacterium Thermus aquaticus employed in DNA technology? Explain.

Or

Name the source of the DNA polymerase used in PCR technique. Mention why it is used?

Or

Give the name of the organism from where the thermostable DNA polymerase is isolated. State its role in genetic engineering.

Name the type of immunity the colostrum provides to a newborn baby. Write giving an example where this type of immunity should be provided to a person.

Name the blank spaces A, B, C and D in the table given below:

Name of the drug	plant source	Organ system affected
A	Poppy plant	B
Marijuana	C	D

Condoms are the most popular contraceptive devices, used by human males. Give reasons.

Suggest four advanced ex-situ methods to conserve threatened biodiversity.

Write about the ancestry and evolution of bat, horse and human on the basis of a comparative study of their forelimbs. What are these limbs categorized as?

OR

What is divergent evolution? Explain taking an example of plants.

OR

Divergent evolution leads to homologous structures. Explain with the help of an example.

List the factors that affects our health?

Distinguish between exonucleases and endonucleases.

While creation and presence of variation is directionless, natural selection is directional as it is in the context of adaptation. Comment.