What function is maintained as a result of the release of HCG?

A. Production of milk by the mammary glands

B. Release of oxytocin by the posterior pituitary gland

C. Production of FSH by the anterior pituitary gland

D. Production of progesterone by the ovary

D

Some G2 forms commented that the distinction between anterior and posterior pituitary gland appears only in the Options. However, the distinction between the anterior and posterior pituitary was not necessary to answer the question. In Section 6.5 (Hormones, homeostasis and reproduction), the candidates are required to understand that 'The menstrual cycle is controlled by negative and positive feedback mechanisms involving ovarian and pituitary hormones'. This should have been sufficient knowledge to answer the question correctly.

What sequence shows the route taken by nitrogenous wastes in insects from their production in body cells to their removal from the insect’s body?

A. Hemolymph → Malpighian tubule → hindgut → rectum

B. Hindgut → hemolymph → kidney tubule → bladder

C. Malpighian corpuscle → nephron → ureter → bladder

D. Neonicotinoid → rectum → antagonistic muscles → anus

A

Which hormone is inhibited during pregnancy in order to prevent contractions of the uterus?

A. Oxytocin

B. Progesterone

C. Estrogen

D. FSH

A

The diagram represents a sarcomere. Which structure is myosin?

[Source: MPI of Molecular Plant Physiology. [Sarcomere]. [diagram online] Available at: http://www.macroevolution.net/sarcomere.html [accessed 4 April 2019]. Source adapted.]

B

Which kidney adaptation would be expected in the desert kangaroo rat (Dipodomys deserti)?

A. Increased nephron density
B. Longer proximal convoluted tubule
C. Longer loop of Henle
D. Increased ADH receptors on the collecting duct

 

C

Hybridoma cells are produced in laboratories for medical diagnostics and treatments. Which two cells are fused to produce a hybridoma cell?

A. Gametes from two phenotypically different parents

B. Two different antigen-secreting cells

C. Two different tumour cells

D. A plasma cell and a tumour cell

D

Hormones maintain the thickness of the endometrium during pregnancy. However, insufficient levels of hormones in early pregnancy may cause the breakdown of the endometrium, which leads to miscarriage. What could be a cause of miscarriage in early pregnancy?

A. The embryo does not produce enough HCG.

B. The pituitary gland does not produce enough FSH.

C. The endometrium does not produce enough progesterone.

D. The ovarian follicle does not produce enough estrogen.

A

The pregnancy test for humans is based on detection of the hormone HCG. What is the reason for detection of this hormone indicating pregnancy?

A. HCG is involved in milk production.

B. HCG production is blocked by negative feedback during menstruation.

C. HCG is produced by an embryo.

D. HCG is released during the acrosome reaction.

C

The basis for this question was an Application in 11.1 (Antibody production and vaccination). Even if candidates did not know that it is the embryo that secretes HCG, they should have been able to eliminate the three distractors and then realise that HCG production by embryos must be the answer.

The micrograph shows a glomerulus and Bowman’s capsule, where ultrafiltration takes place in the kidney.

[Source: MICROSCAPE/SCIENCE PHOTO LIBRARY.]

What facilitates the formation of glomerular filtrate?

A. Many fenestrations in walls of capillaries in the glomerulus

B. High pressure in the Bowman’s capsule

C. ADH secreted by the pituitary gland

D. Osmosis caused by a high concentration of urea in the blood

A

What is the role of calcium in muscle contraction?

A. To release tropomyosin from myosin

B. To bind to troponin so myosin-binding sites on actin are exposed

C. To bind to tropomyosin so ATP can bind to actin

D. To release ATP from actin so myosin can bind to troponin

B

The image shows a flow chart.

Which sequence would correspond to the stages shown in the flow chart?

C

If the ovaries of a pregnant woman have to be removed during the first five months of pregnancy, a miscarriage results and the pregnancy fails. If the ovaries are removed in the last four months of pregnancy, the miscarriage does not occur. What is the reason for this?

A.  After the fifth month, the ovaries can regenerate rapidly.

B.  The pituitary gland takes over the function of sustaining the pregnancy.

C.  The placenta produces sufficient hormones to sustain the pregnancy.

D.  Before removal the ovaries produce sufficient hormones to sustain the pregnancy.

C

The diagram shows the female reproductive system.

[Source: © International Baccalaureate Organization 2017]

Which structures do K and L identify?

B