Date | May 2018 | Marks available | 1 | Reference code | 18M.3.SL.TZ1.18 |
Level | Standard level | Paper | Paper 3 | Time zone | Time zone 1 |
Command term | State | Question number | 18 | Adapted from | N/A |
Question
State one role of fibre in the diet.
Outline control of digestive juice secretion so that digestive juices are only secreted into the gut when there is food present.
Outline the role of intestinal villi.
Markscheme
aids peristalsis / reduces risk of intestinal disorders/cancer/constipation / reduces hunger
a. combination of nervous AND hormonal control
b. food in stomach stimulates chemoreceptors/stretch receptors / stretches the wall
c. causes production of gastrin
d. arrival of chyme to the small intestine triggers the release of hormones/secretin
e. volume and composition of gastric juices are controlled
a. villi/microvilli provide large surface area
b. capillary network for absorption and transport
c. lacteal for absorption and transport of lipids/fatty acids/glycerol / bile resorption
d. mitochondria in epithelial cells provide energy for absorption