Biodiversity and Conservation — BIOLOGY STD 12 Science — Question

List the components of the embryo sac and mention their fate on fertilisation.
OR
Mention the fate of all the components of the embryo sac after fertilisation.

Explain co–dominance taking an example of human blood groups in the population.

Looking at the deteriorating air quality because of air pollution in many cities of the country, the citizens are very much worried and concerned about their health. The doctors have declared health emergency in the cities where the air quality is very severely poor.

1. Mention any two major causes of air pollution.
2. Write any two harmful effects of air pollution to plants and humans.
3. As a captain of your school Eco-club, suggest any two programmes you would plan to organise in the school so as to bring awareness among the students on how to check air pollution in and around the school.

A bright student of class XI, under peer pressure started taking drugs. He started neglecting studies, misbehaving with parents and friends in school. The principal of school counselled him, but it had no effect. His parents took him to a rehabilitation center. After a few months, he came back recovered.

1. What is drug abuse?
2. Name some commonly abused drugs and their source.
3. What should be the attitude of his parents after his return?
4. What values did the principal reflect through his initiative?

1. Cancer is one of the most dreaded disease. Explain 'contact inhibition' and 'metastasis with respect to the disease.
2. Name the group of genes that have been identified in normal cells that could lead to cancer. How do these genes cause cancer?
3. Name any two techniques that are useful in detecting cancers of internal organs.
4. Why are cancer patients often given a-interferon as part of the treatment?

Study the illustration given and answer the questions that follow:
Explain the role of hormones in the formation and release of ‘a’.

Study the illustration given and answer the questions that follow:
Name and state the function of ‘c’.

It is commonly observed that parents feel embarrassed to discuss freely with their adolescent children about sexuality and reproduction. The result of this parental inhibition is that the children go astray sometimes.

1. Explain the reasons that you feel are behind such embarrassment amongst some parents to freely discuss such issues with their growing children.
2. By taking one example of a local plant and animal, how would you help these parents to overcome such inhibitions about reproduction and sexuality?

1. Draw a labelled diagram of L.S. of an embryo of grass (any six labels).
2. Give reason for each of the following:

1. Anthers of angiosperm flowers are described as dithecous.
2. Hybrid seeds have to be produced year after year.

No evidence was found on a crime scene, other than only a few hair strands. The inspector wants to proceed for DNA fingerprinting, but the amount of DNA is very less.

1. In your opinion what could be the solution to this problem?
2. Write the basic steps of this technique.
3. Name the scientist who developed this technique.
4. What values shown by the inspector?