DP Biology (last assessment 2024)

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Question 23M.3.SL.TZ2.17

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Date May 2023 Marks available [Maximum mark: 6] Reference code 23M.3.SL.TZ2.17
Level SL Paper 3 Time zone TZ2
Command term Describe, Identify, State Question number 17 Adapted from N/A
17.
[Maximum mark: 6]
23M.3.SL.TZ2.17

The electron micrograph shows cells in the wall of the small intestine.

[Source: STEVE GSCHMEISSNER / SCIENCE PHOTO LIBRARY.]
(a.i)

State the name of the structures marked X.

[1]

Markscheme

microvilli / brush border;

Examiners report

Many identified the microvilli as villi.

(a.ii)

Describe how the structures marked X help the cells in the intestinal wall to carry out their function.

[1]

Markscheme
  1. (the many finger-like) projections increase the absorption by increased surface area/OWTTE;
Examiners report

Most could describe their function. 

(a.iii)

Identify with a reason the type of cell marked Y.

[1]

Markscheme
  1. goblet/exocrine/secretory cell as its products can be seen to be released into the intestine/OWTTE;
Examiners report

Very few candidates could identify the goblet cell.

(b)

Describe the cause of stomach ulcers.

[3]

Markscheme
  1. caused by the Helicobacter pylori/H.pylori;
  2. secretes a protease;
  3. cause breakdown of the inner protective/mucous lining;
  4. the acid/gastric juices can get through to the stomach wall;
  5. cause inflammation/open sore;
Examiners report

There were many good answers describing the cause of stomach ulcers.