What are sense organs?
Groups of receptor cells that respond to particular types of stimulus.
Cambridge IGCSE (9–1) Biology 0970 (Extended) (2026–2028) · 14.2
Revise Cambridge IGCSE (9–1) Biology 0970 (Extended) (2026–2028) specification point 14.2, Sense organs, with free active-recall flashcards. Flip through the set or review every question and answer below.
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What are sense organs?
Groups of receptor cells that respond to particular types of stimulus.
What type of stimulus do the eyes detect?
Light.
What type of stimulus do the ears detect?
Sound.
What two types of stimulus do receptors in the skin detect?
Touch and temperature.
What type of stimulus do receptors in the nose and tongue respond to?
Chemicals.
What does the cornea do to light entering the eye?
It refracts the light.
What is the pupil?
The opening surrounded by the iris through which light enters the eye.
What is the function of the iris?
It controls how much light enters through the pupil.
What is the function of the lens behind the iris?
It focuses light onto the retina at the back of the eye.
What receptors does the retina contain?
Light receptors, including some sensitive to light of different colours.
What is the function of the optic nerve?
It carries impulses from the eye to the brain.
Where is the blind spot in the eye?
At the point where the optic nerve leaves the eye.
Why can the blind spot not detect light?
This part of the retina has no light receptors.
What is the pupil reflex?
A change in pupil diameter in response to light intensity.
How does the pupil reflex reduce light entering the eye in bright light?
The iris narrows the pupil, reducing the amount of light entering the eye.
How does the pupil reflex increase light entering the eye in dim light?
The pupil widens, allowing more light to enter the eye.
How do the circular and radial iris muscles respond to bright light?
The circular muscles contract and the radial muscles relax.
How does pupil diameter change in bright light, and how does this affect light entry?
The pupil narrows, so less light enters the eye.
How do the circular and radial iris muscles respond to dim light?
The radial muscles contract and the circular muscles relax.
How does pupil diameter change in dim light, and how does this affect light entry?
The pupil widens, so more light enters the eye.
What is accommodation in the eye?
Changing the shape of the lens to focus light from objects at different distances on the retina.
How do the ciliary muscles change suspensory ligament tension when focusing on a near object?
They contract, reducing tension in the suspensory ligaments.
How does the lens change shape when focusing on a near object?
It becomes thicker and more curved.
How does the strength of refraction by the lens change when focusing on a near object?
The lens refracts light more strongly.
How do the ciliary muscles change suspensory ligament tension when focusing on a distant object?
They relax, allowing the suspensory ligaments to become taut.
How does the lens change shape when focusing on a distant object?
It is pulled thinner and less curved.
How does the strength of refraction by the lens change when focusing on a distant object?
The lens refracts light less strongly.
What are the two types of light receptor in the human retina?
Rods and cones.
Why do rods support vision in dim conditions?
They are more sensitive to light than cones.
Do rods provide colour vision?
No. Rods do not provide colour vision.
What is the fovea?
A small central region of the retina that provides the sharpest detailed vision.
How do the distributions of rods and cones differ in the retina?
How do cones enable colour vision?
There are three kinds of cones, which absorb light of different colours.