Date | November 2019 | Marks available | 2 | Reference code | 19N.3.SL.TZ0.17 |
Level | Standard level | Paper | Paper 3 | Time zone | TZ0 / no time zone |
Command term | Outline | Question number | 17 | Adapted from | N/A |
Question
The stomach secretes hydrochloric acid into its lumen.
The electron micrograph below shows part of an epithelial cell from the digestive system.
[Source: Louisa Howard, Katherine Connollly – Dartmouth Electron Microscope Facility]
State one mechanism that controls gastric secretion.
State the type of gland that secretes juices into the digestive system.
State where this type of cell can be found in the digestive system.
Outline two adaptations of this cell to its function that are visible in this electron micrograph.
Markscheme
sight/smell of food
OR
negative/positive feedback
OR
nervous control/vagus/parasympathetic nerve stimulation
OR
hormonal control / gastrin / secretin / somatostatin ✔
exocrine ✔
Do not accept name of specific digestive gland.
small intestine/duodenum/ileum/jejunum ✔
Villi alone not acceptable. Accept intestinal villi.
a. microvilli increase the surface area for absorption ✔ Each adaptation needs function stated. Do not accept villi, microvilli is required.
b. many mitochondria produce ATP/energy «for active transport» ✔
c. vesicles resulting from endocytosis ✔