Question 1: Define the term 'pupil' and explain its role in the eye.

Answer: The pupil is the opening in the centre of the eye that regulates the amount of light entering the eye. Its size adjusts to control light intake for optimal vision.

Question 2: Describe how the iris controls the size of the pupil.

Answer: The iris contains muscles that contract or relax to change the size of the pupil, making it larger in dim light and smaller in bright light.

Question 1: Calculate the focal length of a lens in the eye if its power is +60 dioptres (D). Use the formula: Focal length (m) = 1 / Power (D).

Answer: 0.0167

Question 2: If a person’s near point (closest point of clear vision) is 25 cm, what is the approximate eye power needed to focus at this distance? Use the formula: Power (D) = 100 / Distance (cm).

Answer: 400

Question 1: Design a simple experiment to test how pupil size varies with light intensity. What are the independent and dependent variables? List any safety precautions.

Answer: The independent variable is light intensity; the dependent variable is pupil size. Use a dimmer or torch to vary light, measure pupil size with a ruler or light meter, and ensure the participant is seated comfortably to avoid strain.

Question 1: A study measures pupil diameters in bright and dim lighting conditions. Pupils in bright light average 2 mm, while in dim light they average 4 mm. Explain the significance of these findings in terms of eye adaptation.

Answer: The pupils constrict in bright light to reduce light entry, protecting the retina, and dilate in dim light to allow more light in for better vision, demonstrating the eye's adaptation to different lighting conditions.

Question 1: Explain how the structure of the iris allows for the regulation of light entering the eye. (6 marks)

Answer: The iris contains two sets of muscles: the sphincter pupillae and dilator pupillae. The sphincter pupillae contracts to constrict the pupil in bright light, reducing light entry, while the dilator pupillae contracts to dilate the pupil in dim light, increasing light entry. This regulation helps protect the retina from damage and optimises vision.

Question 1: Discuss how knowledge of pupil reflexes is used in the development of diagnostic tools for neurological conditions.

Answer: Pupil reflexes are tested in neurological exams to assess brain and nerve function. Abnormal pupil responses can indicate issues such as brain injury or neurological diseases, helping in early diagnosis and treatment.