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Date May 2019 Marks available 1 Reference code 19M.3.SL.TZ1.6
Level Standard level Paper Paper 3 Time zone Time zone 1
Command term Outline Question number 6 Adapted from N/A

Question

The diagram illustrates the sensitivity to sound frequencies, measured in Hz, of the different regions of the semicircular canal. The base is the region closest to the oval window.

[Source: © International Baccalaureate Organization 2019]

The diagram shows the human ear.

[Source: Didier Descouens, https://commons.wikimedia.org/wiki/Category:Human_middle_ear#/media/File:Place-desosselets-
Schema.jpg, licensed under CC BY-SA 3.0]

Outline the relationship between the distance from the oval window and the sound frequency detected.

[1]
a.

State the range of sound frequencies detected by the ear.

[1]
b.

Sensory receptors are divided into different categories. Hair cells in the cochlea are sensory receptors. State the category to which they belong.

[1]
c.

Identify the structure labelled Y in the diagram.

[1]
d.i.

Annotate the diagram with an X to show the internal location where a cochlear implant is placed.

[1]
d.ii.

Outline the function of the stapes.

[2]
e.

Markscheme

the further from the base, the lower the frequency detected ✔

Allow vice versa

a.

20 000 Hz «20 kHz» to 20 Hz ✔

Unit required. Allow 19 980 Hz.

b.

mechanoreceptor ✔

c.

auditory/cochlear/acoustic nerve ✔

d.i.

cochlea annotated with an X ✔

eg:

 

[Source: Didier Descouens, https://commons.wikimedia.org/wiki/Category:Human_middle_ear#/media/File:Place-desosselets-
Schema.jpg, licensed under CC BY-SA 3.0]

X can be anywhere in the spiral of the cochlea

d.ii.

a. connects the oval window to the eardrum/ossicles ✔

b. mechanical transmission of vibration of eardrum
OR
amplify vibration/sound ✔

c. moves oval window with frequency of the vibration/sound
OR
transmits vibration/sound to inner ear/cochlea ✔

e.

Examiners report

Most answered correctly.

a.

The correct frequency range was given but the unit was often omitted.

b.

Perhaps a third of candidates gave the correct term.

c.

Most correct answers were for auditory nerve rather than the alternatives.

d.i.

Most candidates placed the X in the correct region.

d.ii.

There were some good answers here, although connections to parts of the ear were sometimes confused. Amplification and transmission to the cochlear were frequent responses

e.

Syllabus sections

Option A: Neurobiology and behaviour » Option A: Neurobiology and behaviour (Core topics) » A.3 Perception of stimuli
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Option A: Neurobiology and behaviour » Option A: Neurobiology and behaviour (Core topics)
Option A: Neurobiology and behaviour

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