The human eye | Biology | Quizalize & Oak National Academy

Starter quiz

What does the eye detect?

chemicals

light ✓

touch

heat
True or false? Muscles are effectors.

True ✓

False
True or false? The reflex arc is a lengthened neural pathway.

True

False ✓
Put the steps of this reflex arc in the correct order.

1

⇔

The stimulus is detected by the receptor.

2

⇔

A nerve impulse is sent along the sensory neurone.

3

⇔

In the spinal cord, a relay neurone transfers the impulse to the motor neurone.

4

⇔

This triggers the effector muscle to contract and produce the response.
What organ is not initially involved in a reflex response?

'The brain' ✓
How can the brain override some reflex responses?

By triggering the sensory neurone in the reflex arc.

By triggering the relay neurone in the reflex arc.

By triggering the motor neurone in the reflex arc. ✓

Exit quiz

Match the part of the eye to its name.

a

⇔

cornea ✓

b

⇔

iris ✓

c

⇔

lens ✓

d

⇔

ciliary muscles ✓
The ciliary muscles contract or relax to change the shape of the ...

'Lens' ✓
Which statement correctly describes the lens and ciliary muscles if you are focusing on an object that is far away?

The lens is short and fat in shape beacuse the ciliary muscles contract.

The lens is short and fat in shape because the ciliary muscles relax.

The lens is long and thin in shape because the ciliary muscles contract.

The lens is long and thin in shape because the ciliary muscles relax. ✓
Put the following steps in order to describe how we see.

1

⇔

Light enters the eye.

2

⇔

Light is refracted by the cornea.

3

⇔

Light is focused by the lens.

4

⇔

Light is sensed by the retina.
Which of the following responses happen to the eye in the dark?

circular muscles in the iris relax ✓

circular muscles in the iris contract

radial muscles in the iris relax

radial muscles in the iris contract ✓
How can we investigate the effect of light on pupil size?

Lucas: We can shine a bright torch in someones eyes to see the pupil change

Sofia: We can sit in the dark then turn on a light and see how the pupil changes ✓

Sam: We can look at different peoples eyes

Jacob: We can watch someones eyes to see if it changes

Worksheet

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Lesson Details

Key learning points

The human eye is a sense organ that detects light to enables us to see.
The functions of the cornea, iris, lens, ciliary muscles, retina and optic nerve.
Interpretation of ray diagrams showing refraction, to explain how the eye focuses light onto the retina.
The iris expands and contracts (a reflex response) to control the amount of light entering the eye through the pupil.
Use appropriate techniques to investigate the size of the pupil in different light levels.

Common misconception

There is often confusion between parts of the eye and their function, and that both the cornea and the lens refract light, but only the lens can focus light.

The parts of the eye and their function are covered carefully and in detail. The role of the cornea and lens in refracting and focusing light is examined in detail with simplified drawings to demonstrate.

Keywords

Lens - An object that can focus light rays. In the eye, it brings light rays to focus on the retina.
Refraction - Occurs when light travels from one transparent medium to another, causing a change in direction.
Focus - The process of bringing light rays together to converge at a single point creating a clear image.
Focal point - The point where rays of light meet after passing through a lens.
Reflex response - An involuntary, fast neural response to a situation.