Science (English Medium) कक्षा १२ - CBSE Important Questions for Biology

Explain the various types of cancer

It is generally observed that the children who had suffered from chickenpox in their childhood may not contract the same disease in their adulthood. Explain, giving reasons, the basics of such immunity in an individual. Name this kind of immunity.

State the cause of adenosine deaminase enzyme deficiency.

How does smoking tobacco in human lead to oxygen deficiency in their body?

Highlight the role of thymus as a lymphoid organ.

A group of youth were having a ‘rave party’ in an isolated area and was raided by police. Packets of ‘smack’ and syringes with needles were found littered around.

1. Why is taking ‘smack’ considered an abuse?
2. Write the chemical name of ‘smack’ and the name of its source plant.
3. Syringes and needles used by the youth for taking the drug could prove to be very fatal. Why?

What are interferons?

Mention role of interferons

Name the cells that are released from the above-mentioned gland. Mention how they help in immunity.

You have attended a birthday party hosted by one of your classmates. You found some guests at the party sitting in a corner making a lot of noise and consuming 'something'. After a while one of the boys from the group started screaming, behaving abnormally and sweating profusely. On enquiry you found that the group members were taking drugs.

(a) Would you inform your parents/school authorities ? Yes/No. Give reasons in support of your answer.

(b) Prepare a note to be circulated amongst the schoolmates about the sources and dangers of any two drugs.

(c) Write any two ways that you will suggest to your school principal so as to promote awareness amongst the youth against the use of these drugs.

Under polio prevention programme, infants in India were given polio vaccines on a large scale at regular intervals to eradicate polio from the country.

(a) What is a vaccine? Explain how does it impart immunity to the child against the disease.
(b) With the help of an example each, differentiate between active and passive immunity.

Explain the relationship between B-lymphocytes and T-lymphocytes developing an immune response.

Write the scientific name of the source plant and the part from which opiods are extracted. What is it commonly and chemically called ?

Where in the human body are its specific receptors located ? How do opioids affect the human body ?

It is said that vaccinations are a must for a healthy society. Justify.

How does the human body respond when vaccine is introduced into it?

Mention one application for the following:

Cytokinin-barrier

Answer the following question.
Why is there a fear amongst the guardians that their adolescent wards may get trapped in drug/alcohol abuse?

Answer the following question.
Explain ‘addiction’ and dependence’ in respect of drug/alcohol abuse in youth.

Name the pattern of inheritance where F₁ phenotype

resembles only one of the two parents.