Which one of the following statements best describes the role of B cells and T cells in the human body?
- A.They protect the body from environmental allergens.
- B.They alleviate the body's pain and inflammation.
- C.They act as immunosuppressants in the body.
- D.They protect the body from the diseases caused by pathogens.
Correct answer
Explanation
The correct answer is D, They protect the body from the diseases caused by pathogens. B cells and T cells are lymphocytes, the white blood cells of the adaptive immune system that recognise and fight specific bacteria, viruses and other pathogens. Both arise from stem cells in the bone marrow; B cells mature there, while T cells mature in the thymus. B cells make antibodies that bind to a particular antigen and mark it for destruction, which is called humoral immunity. T cells give cell-mediated immunity: helper T cells coordinate the response, and cytotoxic T cells kill infected cells. Some of both kinds stay on as memory cells, which is why vaccines give lasting protection. Option A is wrong because allergy is an unwanted overreaction of the immune system, not the main job of these cells. Option B is wrong because relieving pain and inflammation is the work of drugs and certain body chemicals, not of lymphocytes. Option C is wrong because they activate immunity rather than suppress it. Exam tip: B cells — bone marrow, antibodies (humoral); T cells — thymus, cell-mediated immunity; HIV attacks helper T cells.
Practice Questions
View allA recent movie titled The Man Who Knew Infinity is based on the biography of
- A.S. Ramanujan
- B.S. Chandrasekhar
- C.S. N. Bose
- D.C. V. Raman
Show answer
The 2015 film 'The Man Who Knew Infinity' tells the life of the Indian mathematician Srinivasa Ramanujan and is based on Robert Kanigel's 1991 biography of the same name.
Read the full explanation →The word 'Denisovan' is sometimes mentioned in media in reference to
- A.fossils of a kind of dinosaurs
- B.an early human species
- C.a cave system found in North-East India
- D.a geological period in the history of Indian subcontinent
Show answer
Denisovans were an archaic group of humans, close relatives of the Neanderthals, first identified in 2010 from a finger bone found in Denisova Cave in the Altai Mountains of Siberia.
Read the full explanation →Which one of the following is not used as fertilizer?
- A.Ammonium nitrate
- B.Ammonium sulphide
- C.Ammonium phosphate
- D.Ammonium sulphate
Show answer
Ammonium sulphide is an unstable, foul-smelling compound that breaks down to release ammonia and toxic hydrogen sulphide, so it is not used as a fertiliser.
Read the full explanation →The focal length of the objective lens of a telescope is 50 cm. If the magnification of the telescope is 25, then the focal length of the eye-piece is
- A.12.5 cm
- B.5 cm
- C.2 cm
- D.10 cm
Show answer
For an astronomical telescope in normal adjustment the magnifying power equals the focal length of the objective divided by that of the eyepiece, so the eyepiece focal length is 50 ÷ 25 = 2 cm.
Read the full explanation →The major source of vitamins and minerals for vegetarians is
- A.black gram and wheat.
- B.rice and mustard.
- C.vegetables and fruits.
- D.soya bean and milk.
Show answer
Vegetables and fruits supply most of the vitamins and minerals in a vegetarian diet, which is why they are called protective foods.
Read the full explanation →