Biology
Assertion (A): Antigens are produced by a type of specialised lymphocytes on exposure to antibodies.
Reason (R): Antibodies recognise a particular antigen and binds to it rendering it harmless. Thus antibodies protect us from disease-causing germs.
- A is True and R is False.
- A is False and R is True.
- Both A and R are True.
- Both A and R are False.
Answer
A is False and R is True.
Reason — Antigens are chemical substances found on germs' cells that enter the body and trigger an immune response. They are not produced by the body or lymphocytes instead, they stimulate lymphocytes to produce antibodies.
Antibodies, produced by lymphocytes, bind specifically to the antigen and help neutralize or destroy the pathogen.
Related Questions
A biology teacher asked her students to give two examples of antiseptics, which can be used to kill germs.
Prerna said: Boric acid and 40% Formalin.
Shreya said: Benzoic acid and Bordeaux mixture.
Rahul said: Carbolic acid and Boric acid.
Rishi said: Mercurochrome and Benzoic acid.
Who were correct ?
- Prerna and Shreya
- Shreya and Rahul
- Rahul and Rishi
- Rishi and Prerna
Assertion (A): Immunity is the resistance to the onset of a disease after infection by harmful germs.
Reason (R): A body's immunity is maintained by two proteinaceous substances — antigens and antiseptics.
- A is True and R is False.
- A is False and R is True.
- Both A and R are True.
- Both A and R are False.
Assertion (A): The vaccine for tuberculosis is made up of living, fully poisonous germs.
Reason (R): Living, weakened germs in the vaccine were not satisfactory to prevent the disease.
- A is True and R is False.
- A is False and R is True.
- Both A and R are True.
- Both A and R are False.
Assertion (A): Active immunity is produced by one's own body.
Reason (R): Active immunity is induced by infection or by contact with immunogens.
- A is True and R is False.
- A is False and R is True.
- Both A and R are True.
- Both A and R are False.