Which of the following pairs are the primary lymphoid organs of the human body?
- A.Spleen and lymph nodes
- B.Tonsils and appendix
- C.Bone marrow and thymus
- D.Liver and pancreas
Correct answer
Explanation
The correct answer is C, bone marrow and thymus. These are the organs in which lymphocytes are produced and in which they mature into cells able to tell self from non-self; the B cells complete this training in the bone marrow and the T cells in the thymus, a gland behind the breastbone that shrinks with age. Option A, the spleen and the lymph nodes, are secondary lymphoid organs, where the mature lymphocytes wait and meet the antigen; the spleen also filters blood and is called the graveyard of red blood cells. Option B, the tonsils and the appendix, are secondary lymphoid tissue as well, as are the Peyer's patches of the small intestine. Option D names two digestive glands with no lymphoid function of this kind, although the liver makes the plasma proteins and the clotting factors.
Read the full article: Blood Groups, Immunity and Vaccines: Notes for Exams
Practice Questions
View allWho discovered the ABO system of blood groups?
- A.Karl Landsteiner
- B.William Harvey
- C.Edward Jenner
- D.Alexander Fleming
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The correct answer is A, Karl Landsteiner, the Austrian physician who found in 1900 that human blood falls into groups according to the antigens on the red cells, which made safe transfusion possible, and who received the Nobel Prize in Physiology or Medicine for it in 1930; with Wiener he…
Read the full explanation →Which blood group is called the universal donor?
- A.A
- B.B
- C.AB
- D.O
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The red cells of group O carry neither the A antigen nor the B antigen, so when they are transfused the antibodies in the recipient's plasma find nothing to bind to and the cells are not destroyed, which is why group O, and strictly O negative, can be given to…
Read the full explanation →A person of which blood group has no antibody in the plasma and is therefore the universal recipient?
- A.O
- B.A
- C.B
- D.AB
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A person of group AB carries both the A and the B antigen on the red cells, and because the body does not make antibodies against its own antigens, the plasma carries neither anti-A nor anti-B; blood of any group can therefore be transfused into such a person, who is…
Read the full explanation →The Rh factor in human blood is named after
- A.a rhesus monkey
- B.a rabbit
- C.a river in Europe
- D.the scientist Rh. Weber
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Landsteiner and Wiener found the antigen in 1940 while working with the blood of the rhesus monkey, and the first two letters of rhesus gave the factor its name; a person with the D antigen on the red cells is Rh positive and one without it is Rh negative.
Read the full explanation →Which vitamin is essential for the clotting of blood?
- A.Vitamin A
- B.Vitamin C
- C.Vitamin D
- D.Vitamin K
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The liver needs vitamin K to make prothrombin and several other clotting factors, so a deficiency of it lengthens the clotting time and causes bleeding; this is why a newborn is given vitamin K and why the vitamin is sometimes called the anti-haemorrhagic vitamin.
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