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Date May 2019 Marks available 3 Reference code 19M.2.HL.TZ2.3
Level Higher level Paper Paper 2 Time zone Time zone 2
Command term Outline Question number 3 Adapted from N/A

Question

The graph shows blood pressure changes on the left side of the heart during one heartbeat. Identify the two parts of the circulatory system that produce traces I and II on the graph.

[Source: © International Baccalaureate Organization 2019]

[2]
a.

Outline the actions taken by the body to avoid infection when the skin is cut.

[3]
b.

Hormones are distributed throughout the body by the blood. Outline the roles of two reproductive hormones during the menstrual cycle in women.

[2]
c.

Markscheme

I. aorta ✔

II: «left» atrium ✔

a.

a. platelets/cut tissues release clotting factors ✔ Mp a requires student to identify source of clotting factors.

b. «clotting factors» activate thrombin «from prothrombin» ✔

c. thrombin converts fibrinogen to fibrin ✔

d. «fibrin» forms a clot/scab/mesh that seals the cut ✔

e. phagocytic white blood cells ingest pathogens ✔

b.

a. FSH/follicle stimulating hormone stimulates the development of follicles/follicle cell division in the ovary «to produce eggs» ✔ Two different hormones must be identified.

b. LH/luteinizing hormone triggers ovulation/development of the corpus luteum ✔

c. estrogen stimulates development of the uterine lining/endometrium ✔  Description of role required as well as name of hormone.

d. progesterone maintains the uterine lining/endometrium
OR
inhibits other hormones by negative feedback eg, FSH ✔

e. HCG stimulates ovary to produce progesterone «in early pregnancy» ✔

f. other verifiable hormone and roles relevant to the menstrual cycle ✔

c.

Examiners report

This question was poorly answered with most students earning either one mark or no marks. It was more common for candidates to correctly identify the atrium rather than the aorta. ß

a.

This question about clotting was well answered with most being able to correctly identify the roles of clotting factors, fibrinogen and thrombin, though in a number of cases, specific details were lacking.

b.

Students were able to correctly identify hormones that played a role in the menstrual cycle and were often successful in outlining their function. A common problem was distinguishing the role of progesterone from that of estrogen.

c.

Syllabus sections

Core » Topic 6: Human physiology » 6.3 Defence against infectious disease
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