Which vitamin is essential for the clotting of blood?
- A.Vitamin A
- B.Vitamin C
- C.Vitamin D
- D.Vitamin K
Correct answer
Explanation
The correct answer is D, vitamin K. 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. Option A, vitamin A, is needed for the pigment of the retina, and its deficiency causes night blindness and xerophthalmia. Option B, vitamin C, is needed for collagen, and its deficiency causes scurvy with bleeding gums, which makes it a plausible wrong answer since bleeding is involved, but it has no role in the clotting cascade. Option C, vitamin D, governs the absorption of calcium, and its deficiency causes rickets in children and osteomalacia in adults. Calcium ions are themselves needed for clotting, so the two often appear in the same question.
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 →Edward Jenner is remembered for developing a vaccine against which disease?
- A.Rabies
- B.Smallpox
- C.Tuberculosis
- D.Polio
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In 1796 Edward Jenner used matter from a cowpox sore to protect a boy against smallpox, the first vaccination in the modern sense, and the word vaccine comes from vacca, the Latin for cow.
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