The Eye
Biology: Edexcel IGCSE, topic 3.5.11
Retina Scanning
Your retina is full of receptor cells, which are sensitive to both the brightness (light intensity) and the colour of light.
Scanning the retina
Retina scanning looks at the pattern of blood vessels in your retina to identify you.
The Eye
The iris controls pupil diameter and the quantity of light reaching the retina. If there isn't much light then the iris will make our pupils dilate (get bigger).
Pupil dilating
Test yourself on The Eye
Which of these are found in the eye?