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2.4 The eye

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Question 30

A control room uses two messages that an operator must be able to distinguish.

The table shows information about two types of retinal cell.

Cell typeMinimum light intensity needed for a response / arbitrary unitsDistinguishes colour
R4No
C65Yes

The normal light intensity in the control room is 90 arbitrary units. During a power failure, the light intensity falls to 20 arbitrary units.

Two display designs are considered.

  • Design P uses a red circle for one message and a green circle of the same size for the other message.
  • Design Q uses a large white circle for one message and a large white triangle for the other message.

Evaluate which display design should be used so that the operator can distinguish the messages in both lighting conditions.

[4]
Markscheme

2.4 The eye Questions

  1. GCSE
  2. /Biology
  3. /2.4 The eye

102 exam-style questions on Edexcel GCSE Biology 2.4 The eye, covering 2.4.1 Structure and function of the eye and 2.4.2 Eye defects and their correction. Each one has a worked solution and a mark scheme showing where the marks go.

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