| Date | May 2012 | Marks available | 1 | Reference code | 12M.3.HL.TZ2.14 |
| Level | Higher level | Paper | Paper 3 | Time zone | Time zone 2 |
| Command term | State | Question number | 14 | Adapted from | N/A |
Question
State one example of a steroid hormone.
State one example of a hormone that is a tyrosine derivative.
Outline the hormonal control of digestive juice secretion in the stomach.
Outline how exercise causes an increase in the ventilation rate.
Markscheme
estrogen / testosterone / progesterone
Accept other verifiable examples.
thyroxine/thyroid hormones / epinephrine / adrenaline / noradrenaline
Accept other verifiable examples
gastrin is secreted when food is in the stomach/chemoreceptors/stretch receptors are stimulated;
stimulates gastric acid/pepsinogen production;
when pH drops too low, gastrin secretion is inhibited by (secretin and somatostatin) hormones;
exercise uses energy/ATP/increases metabolic rate/aerobic respiration;
which causes increased CO2 which lowers blood pH;
detected by chemosensors in aorta/carotid arteries;
stimulate medulla/breathing centre of brain;
nerve impulses to diaphragm and intercostal muscles increase contraction (rate);
Examiners report
Most candidates had no difficulty to state the required factual information.
Most candidates had no difficulty to state the required factual information in part (a).
Most gained marks in part (b) as well, but some parts of answers were irrelevant (e.g. smell and taste) whereas other answers lacked precision (e.g. hormone instead of gastrin; gastric juice instead of HCl/pepsin).
It was similar in part (c), where some candidates had difficulty incorporating enough precision to gain some of the marks, for instance mentioning aerobic cell respiration, chemosensors in aorta or carotid arteries, naming the medulla of the breathing center instead of the brain only, the appropriate respiratory muscles, etc.
