DP Biology (last assessment 2024)

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Question 23M.3.HL.TZ2.5

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Date May 2023 Marks available [Maximum mark: 5] Reference code 23M.3.HL.TZ2.5
Level HL Paper 3 Time zone TZ2
Command term Describe, Label, State Question number 5 Adapted from N/A
5.
[Maximum mark: 5]
23M.3.HL.TZ2.5

Olfactory receptors are chemoreceptors in the nose that detect odorants. The diagram shows the cell organization of the main olfactory system.

(a)

On the diagram, label a chemoreceptor.

[1]

Markscheme

properly labelled chemoreceptor;

Accept label with lines pointing directly to any part of a receptor cell.

Examiners report

The majority correctly identified a chemoreceptor on the diagram.

(b)

Describe how olfactory chemoreceptors can detect different odorants.

[2]

Markscheme
  1. odorants are small/volatile molecules (with different chemical formulae);
  2. olfactory chemoreceptors have receptors (proteins) on surface membrane;
  3. each odorant attaches to its specific receptor;
Examiners report

It was very hard for them to describe how they could detect odorants in terms of membrane receptors and specificity.

(c)

State two types of receptors other than chemoreceptors.

1: 

2: 

[2]

Markscheme
  1. photoreceptor;
  2. proprioceptor/mechanoreceptor;
  3. thermoreceptor;
  4. baroreceptor;

If more than two receptors are written, mark only the first two.

Examiners report

Most could state two types of receptors, although a few used inappropriate terminology.