DP Biology (last assessment 2024)
Question 19M.3.HL.TZ1.b
| Date | May 2019 | Marks available | [Maximum mark: 1] | Reference code | 19M.3.HL.TZ1.b |
| Level | HL | Paper | 3 | Time zone | TZ1 |
| Command term | Outline | Question number | b | Adapted from | N/A |
b.
[Maximum mark: 1]
19M.3.HL.TZ1.b
The diagram shows the bacterium Helicobacter pylori attacking the gastric mucosa of the stomach.
[Source: Reproduced from Gut, B A Hills, 34, 588–593, 1993 with permission from BMJ Publishing Group Ltd.]
The bacterium secretes an enzyme that breaks down urea, resulting in an increase in pH. Outline how this would help the bacterium survive in the stomach.
[1]
Markscheme
neutralizes the acid the stomach secretes that kills bacteria ✔
Examiners report
While most students achieved this mark, many seem to think that “higher pH values” indicate greater acidity.
