Evolution — BIOLOGY STD 12 Science — Question

1. Name two groups of plants each, which have a:

1. Haploid body and
2. Diploid body.

2. What is meant by gamete transfer?

Should an ideal parasite be able to thrive within the host without harming it?

1. State how the constant internal environment is beneficial to organisms
2. Explain any two alternatives by which organisms can overcome stressful external conditions.

Draw a labelled diagrammatic sectional view of a human seminiferous tubule.
OR

1. Draw a sectional view of seminiferous tubule of a human. Label the following cells in the seminifferous tubule:

1. Cells that divide by mitosis to increase their number
2. Cells that undergo meiosis I
3. Cells that undergo meiosis II
4. Cells that help in the process of spermiogenesis.

2. Mention the role of leydig cell.

A heavily bleeding and bruised road accident victim was brought to a nursing home. The doctor immediately gave him an injection to protect him against a deadly disease.

1. Write what did the doctor inject into the patient's body.
2. How do you think this injection would protect the patient against the disease?
3. Name the disease against which this injection was given and the kind of immunity it provides.

1. Write the two limitations of traditional breeding technique that led to promotion of micro propagation.
2. Mention two advantages of micro propagation.
3. Give two examples where it is commercially adopted.

It is a common practice to plant trees and shrubs near the boundary walls of buildings. What purpose do they serve?

Explain with the help of an example each, male and female heterogamety mechanisms of sex determination.

Mention the effect of pituitary hormones on the parts labelled.

1. What is inbreeding depression?
2. Explain the importance of "selection" during inbreeding in cattle.