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Date November 2017 Marks available 2 Reference code 17N.3.HL.TZ0.05
Level Higher level Paper Paper 3 Time zone TZ0 / no time zone
Command term Explain Question number 05 Adapted from N/A

Question

A cataract is a clouding of the lens in the eye, resulting in blurred vision.

[Source: Cataract in Human Eye, Rakesh Ahuja, MD (https://en.wikipedia.org/wiki/Cataract#/media/File:Cataract_in_human_eye.png)]

Explain the use of a local anesthetic during surgery to remove the cataract.

[2]
b.

Describe red-green colour blindness.

[2]
c.

Markscheme

a. reduction/elimination of pain

    OR

    to block sensory perception

b. blocks synaptic transmission between «sensory neurons and CNS»

    OWTTE

c. allows patient to remain aware

d. prevent reflex causing blinking/eye movement

    OWTTE

[Max 2 Marks]

b.

a. sex/X-linked «genetic trait»

b. results from absent/defective cone cells

c. cannot distinguish between red and green

[Max 2 Marks]

c.

Examiners report

[N/A]
b.
[N/A]
c.

Syllabus sections

Option A: Neurobiology and behaviour » Option A: Neurobiology and behaviour (Additional higher level topics) » A.5 Neuropharmacology
Option A: Neurobiology and behaviour » Option A: Neurobiology and behaviour (Additional higher level topics)
Option A: Neurobiology and behaviour

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