Outline the role of the skin in temperature regulation.

Outline the role of hormones in the process of birth in humans

Explain the principles of vaccination.

heat causes vasodilation of arterioles;
blood closer to surface so heat loss from skin;
heat causes sweating (from sweat glands);
evaporation of sweat leads to cooling;
cold causes vasoconstriction of arterioles;
less blood at surface so less heat loss from skin;
cold leads to less sweating/evaporation of water from skin / hair becomes erect and traps air/goose bumps appear;
temperature receptors in skin transmit impulses to the hypothalamus;

level of progesterone falls before birth;
oxytocin secreted;
from pituitary;
this stimulates contractions of uterus;
uterine contraction/stretching of cervix/vagina stimulates secretion of (more) oxytocin;
form of positive feedback;

vaccine is a modified/weakened/attenuated form of a pathogen / contains antigens from pathogens;
vaccine injected/ingested/introduced to patient;
pathogen/antigens stimulates specific immune response called primary/initial responses;
antigens stimulate macrophages/lymphocytes/T-cells;
which stimulate cloning of B-cells/plasma cells;
including development of memory (B-)cells;
that produce specific antibodies;
(upon second exposure) production of antibodies is much faster;
higher level of antibody production / person has immunity;
called secondary response;
labelled graph showing curve with higher slope/peak for secondary response than primary response;
may need booster shot to maintain immunity;
this is an example of active/artificial immunity;

Answers to part (a) were varied but mostly lacked precision of terms, using blood vessels instead of arterioles, etc. Some students still believe the arterioles move towards or away from the surface. The description of the role of sweating was often incomplete.

Part (b) was also poorly answered on the whole, with many students discussing hormonal changes throughout the pregnancy and/or confusing the names of the hormones involved in the birth process.

Part (c) of this question was very well answered by many candidates, showing good understanding of the processes involved in vaccination. Other candidates’ answers, however, were vague and confused and in some cases with poor use of terminology and the order of the processes. Others spent time writing at length about the ethics of the use of vaccinations.