(a) (i) Which part of the eye carries impulses to the brain? A cornea B iris C lens D optic nerve (ii) Name the structure within the eye that controls the amount of light entering the eye - Edexcel - GCSE Biology - Question 7 - 2020 - Paper 1

The structure within the eye that controls the amount of light entering is the iris. The iris adjusts the size of the pupil, thereby regulating the amount of light that enters the eye.

The two types of cells in the retina that detect light are rods and cones.

1. Rods are sensitive to low light levels and are responsible for night vision (scotopic vision). They do not detect color but are crucial for peripheral vision and detecting motion.

2. Cones function in bright light and enable color vision (photopic vision). There are three types of cones, each sensitive to different wavelengths of light (red, green, and blue), allowing us to perceive a broad spectrum of colors.

The type of drug used to treat infections caused by bacteria is called antibiotics. Antibiotics are designed to kill or inhibit the growth of bacteria and are commonly prescribed for bacterial infections.

Short-sightedness (Myopia):

• The eyeball is too long or the cornea is too curved, causing light rays to focus in front of the retina.
• The lens may be too curved or too convex, leading to excessive refraction of light.

Long-sightedness (Hyperopia):

• The eyeball is too short, or the cornea is not curved enough, resulting in light rays being focused behind the retina.
• The lens may be too thin or not convex enough to properly refract light onto the retina.