Science (English Medium) Class 12 - CBSE Important Questions for Biology

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.

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.

State the functions of mast cells in allergy response.

State the function of interpherons.

Mention one application of the following:
Passive immunization

Mention one application of the following:
Antihistamine

Mention one application of the following:
Colostrum

How do normal cells get transformed into cancerous neoplastic cells? Elaborate giving three examples of inducing agent.

During a field trip, one of your friend in the group suddenly became unwell, she started sneezing and had trouble in breathing. Name and explain the term associated with such sudden responses. What would the doctor recommend for relief?

Many people experience allergic symptoms of sneezing or wheezing on exposure to certain substances in the environment. Give two examples of such substances. Which type of antibodies are produced by the body in response to these substances? Mention the role of mast cells in this kind of allergic response.