Question 1: Define the term 'pupil' and explain its role in controlling the amount of light entering the eye.

Answer: The pupil is the opening in the centre of the iris that regulates the amount of light entering the eye by dilating or constricting.

Question 2: Describe the function of the retina in the process of vision.

Answer: The retina contains light-sensitive cells that detect light and convert it into nerve impulses sent to the brain for visual recognition.

Question 3: Explain how the iris adjusts to different light conditions.

Answer: The iris adjusts the size of the pupil by contracting or relaxing in response to light intensity, controlling the amount of light entering the eye.

Question 4: What is the role of the cornea in the eye?

Answer: The cornea refracts (bends) light to help focus it onto the retina.

Question 5: Identify two structures in the eye responsible for focusing light.

Answer: The cornea and the lens.

Question 1: The diameter of a pupil in bright light is 2 mm, and in dim light is 6 mm. Calculate the ratio of the pupil areas in bright and dim conditions. (Use the formula for area of a circle: A = πr²).

Answer: The ratio of areas is approximately 1:9.

Question 2: If the light intensity increases by 1000 lux, and causes the pupil to constrict from 6 mm to 3 mm, what is the percentage decrease in pupil area?

Answer: The pupil area decreases by approximately 75%.

Question 1: Outline the steps involved in testing pupil size response to a bright light source in a controlled environment.

Answer: First, measure the baseline pupil size in a dimly lit room using a ruler or pupilometer. Then, shine a bright light at a fixed distance onto the eye for a set duration. Measure the pupil size again immediately after exposure. Repeat the process multiple times to ensure accuracy. Variables include light intensity, distance, and duration. Safety precautions involve avoiding direct staring into bright lights and ensuring the participant's comfort.

Question 1: A group of students measured their pupil diameters in two conditions: dim lighting (4 mm) and bright lighting (2 mm). Calculate the percentage decrease in pupil size when moving from dim to bright conditions.

Answer: The pupil size decreased by 50%.

Question 2: Based on the data, explain how the pupil's response helps protect the retina from damage caused by excessive light.

Answer: The pupil constricts in bright light to reduce the amount of light reaching the retina, preventing damage and improving visual clarity. This reflex helps maintain optimal conditions for vision and protects the sensitive cells in the retina from excessive light exposure.

Question 1: Describe how the structure of the eye enables it to focus on objects at different distances. Include the roles of the cornea, lens, and ciliary muscles in your explanation. Your answer should be detailed and include the mechanisms involved. (6 marks)

Answer: The eye focuses on objects at different distances through a process called accommodation. The cornea refracts light to begin focusing it. The lens further adjusts its shape via the ciliary muscles to fine-tune focus; when viewing close objects, the ciliary muscles contract, making the lens thicker. For distant objects, the muscles relax, and the lens becomes thinner. This coordinated action allows the eye to focus images clearly onto the retina regardless of object distance.

Question 1: Explain how knowledge of the eye’s structure has contributed to the development of corrective lenses and laser eye surgery.

Answer: Understanding the eye's anatomy has enabled the design of corrective lenses to compensate for refractive errors like myopia and hyperopia. Laser eye surgery uses precise laser technology to reshape the cornea, correcting focus issues and reducing dependence on glasses or contact lenses.