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Biology
The Eye (Section 6)
| Question | Answer |
|---|---|
| What does the conjunctiva do? | Lubricates and protects surface of the eye |
| What does the sclera do? | Tough outer layer that protects the eye |
| What does the cornea do? | Refracts light into the eye |
| What does the iris do? | Controls how much light enters the eye |
| What does the lens do? | Focuses the light onto the retina |
| What to rods do? | Sense light |
| What do cones do? | Sense colour |
| What does the optic nerve do? | Carries impulses from the receptors to the brain |
| What muscles contract to make the pupil smaller in bright light? | Circular muscles |
| What muscles contract to make the pupil bigger in dim light? | Radial muscles |
| How do the eyes adjust to look at distant objects? | 1. Ciliary muscles relax, allowing suspensory ligaments to pull tight 2. This makes lens go thin (less curved) 3. Light refracts by smaller amount |
| How do the eyes adjust to look at nearby objects? | 1. Ciliary muscles contract, loosening suspensory ligaments 2. Lens becomes more curved 3. Increases amount by which it refracts light |
| What occurs in the eye to make people short-sighted? | The cornea or lens bends light too much OR eyeball is too long, causing image to focus IN FRONT of the retina |
| What occurs in the eye to make people long-sighted? | Cornea or lens don’t bend light enough OR eyeball is too short, causing image to focus BEHIND the retina |
| Describe how the conjunctiva helps protects the eye from infection (2) | - Physical barrier between environment and inside of eye - Lysozyme on surface kills micro-organisms |
| Describe how the information detected by the retina is transmitted to the brain (2) | - Information transmitted as electrical signal - Signal travels along optic nerve to brain |
| Explain how cataracts are currently treated (2) | - Remove lens surgically - Replace with plastic lense |
| Describe the advantages of using eye drops to treat cataracts rather than the current treatment (2) | - Less risk of infection - Less risk of permanent damage |
| What kind of lens does a short-sighted person need? | Concave |
| What kind of lens does a far-sighted person need? | Convex |
| What is the part of the retina that light lands on called? | The fovea |
Created by:
JoeMather
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