Mammalian Sense Organs (Cambridge O Level Biology)

The image below shows some of the structures in the eye. 

The circular and radial muscles can control the size of the pupil in the eye. 

How would they respond in the eye of a person walking from a brightly lit room into a dark one?

	radial muscles	circular muscles	pupil
A	relaxes	contracts	constricts
B	relaxes	contracts	dilated
C	contracts	relaxes	dilated
D	contracts	relaxes	constricts

Which changes occur in the eye when viewing a distant object? 

1	The ciliary muscles contract.
2	The ciliary muscles relax.
3	The suspensory ligaments are pulled tight.
4	The suspensory ligaments are slackened.

A person is reading a book in a room with low light intensity.

Which row shows the state of the eye muscles?

	ciliary muscles	iris circular muscles	iris radial muscles
A	contracted	contracted	relaxed
B	contracted	relaxed	contracted
C	relaxed	contracted	relaxed
D	relaxed	relaxed	contracted

The image below shows the density of the two types of photoreceptor across a horizontal section of the retina. 

Which row of the table below correctly identifies the structures present in the eye according to the image above? 

	P	Q	R	S
A	cone cells	rod cells	retina	cone cells
B	rod cells	cone cells	fovea	rod cells
C	cone cells	rod cells	fovea	cone cells
D	rod cells	cone cells	retina	rod cells

Which row of the table best summarises the ways that the eye adjusts to different stimuli?

	looking at near objects	looking at far objects	bright light	dim light
A	lens becomes flat	suspensory ligaments loosen	circular muscles relax	radial muscles contract
B	suspensory ligaments loosen	ciliary muscles relax	circular muscles contract	radial muscles contract
C	suspensory ligaments tighten	suspensory ligaments tighten	circular muscles relax	radial muscles contract
D	lens becomes round	ciliary muscles contract	circular muscles contract	circular muscles relax