Suggest and explain how the interaction between the muscles labelled in Figure 1 could cause the pupil to constrict (narrow). - AQA - A-Level Biology - Question 1 - 2020 - Paper 2

When the circular muscle in the iris contracts, it causes the pupil to constrict. Concurrently, the radial muscle relaxes, facilitating this process. The contraction of the circular muscles reduces the size of the pupil, which helps to limit the amount of light entering the eye, protecting the retina in bright conditions.