21. Since fibrinogen is always present in the blood but the blood does not clot,

Question

21. Since fibrinogen is always present in the blood but the blood does not clot, _____________ must normally be absent.

a. prothrombin   b. thrombin c. calcium

d. red blood cells e. platelets

34. which of the following statements about human chorionic gonadotropin is incorrect?

a. it is secreted by placenta

b. It maintains the corpus luteum of pregnancy

c. It is secreted by the corpus luteum of pregnancy

d. the presence of chorionic gonadotropin in the urine is the basis of the pregnancy diagnosis tests

e. It is secreted primarily during the first ten weeks of gestation

44. during inspiration,

a. the intra-alveolar pressure falls below atmospheric pressure

b. the diaphragm contracts

c. the internal intercostal muscles contract

d. both a & b are correc

t e. all of the above

47. The number of primary oocytes in a female

a. is decreased continually throughout her reproductive life from puberty to

menopause.

b. is maintained constant during her reproductive life because those that are lost are

continuously replaced by an equal number of new primary oocytes.

c. increases at the time of menopause.

d. Both (a) and (c) above.

e. Both (b) and (c) above.

Explanation / Answer

21. ANS: b. Thrombin

Fibrinogen is always present in the blood but the blood does not clot, because the thrombin must normally be absent. The thrombin system consists of several blood proteins that, when bleeding occurs, become activated. The activated clotting proteins engage in a cascade of chemical reactions that finally produce a substance called fibrin.

34. ANS: c.It is secreted by the corpus luteum of pregnancy.

Human chorionic gonadotropin is secreted by placenta.

44. ANS: d. both a & b are correct

During inspiration, air flows from the higher pressure at the mouth down the lungs into the lower pressure in the alveoli.

Breathing In (Inhalation) when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward.

47. ANS: a. is decreased continually throughout her reproductive life from puberty to menopause.

Oogenesis is not a continuous process throughout the life of a female, unlike spermatogenesis in the male. oogenesis begins with the formation of primary oocytes in a process known as oocytogenesis. This occurs before birth.

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