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How is the brain structured and studied, and how does the eye work and fail?

Describe the structures and functions of the brain and how brain function is investigated with CT and PET scanning, the limitations of treating nervous-system damage, and the structure of the eye and its common defects and their correction.

A focused answer to Edexcel GCSE Biology 2.10B to 2.17B, covering the cerebellum, cerebral hemispheres and medulla, CT and PET scans, treatment limitations, the structure and function of the eye, and the correction of eye defects.

Generated by Claude Opus 4.810 min answer

Reviewed by: AI editorial process; not yet individually human-reviewed

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  1. What this dot point is asking
  2. The brain
  3. Investigating the brain
  4. Treating nervous-system damage
  5. The structure of the eye
  6. Eye defects and their correction
  7. Try this

What this dot point is asking

Edexcel statements 2.10B to 2.17B are Biology only. They want you to describe the main brain regions and their functions, explain how CT and PET scans investigate brain function, explain why brain and spinal damage is hard to treat, describe the structure of the eye and how it focuses (accommodation), and explain common eye defects and their correction.

The brain

Investigating the brain

Because the brain is encased in the hard skull, it is difficult and risky to access. Doctors use scanning instead:

  • A CT (computerised tomography) scan uses X-rays to build a detailed image of brain structure, helping to locate tumours or damage.
  • A PET (positron emission tomography) scan shows which parts of the brain are active, by detecting where a radioactive tracer is being used, helping to study brain function and diagnose disease.

These scans let scientists link regions of the brain to particular functions without surgery.

Treating nervous-system damage

Treating damage to the brain and spinal cord is difficult and limited because nervous tissue does not readily repair itself, the tissue is delicate and surrounded by the skull or backbone, and operating risks damaging healthy areas. This is why spinal injuries can cause permanent paralysis and why some brain tumours are hard to remove.

The structure of the eye

The eye is a sense organ that detects light. Light enters through the transparent cornea, passes through the pupil (the gap controlled by the coloured iris), and is focused by the lens onto the retina at the back. The retina contains light receptors, which send impulses along the optic nerve to the brain.

Eye defects and their correction

Try this

Q1. State the function of the cerebellum. [1 mark]

  • Cue. It coordinates muscular movement, balance and posture.

Q2. A person's eyeball is too long. State the defect and the lens used to correct it. [2 marks]

  • Cue. Short-sightedness, corrected with a concave (diverging) lens.

Exam-style practice questions

Practice questions written in the style of Pearson Edexcel exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.

Edexcel 20194 marksExplain how the eye focuses light from a distant object onto the retina.
Show worked answer →

A 4-mark explain question rewards the steps of accommodation for distant vision.

  1. To focus on a distant object, the ciliary muscles relax.
  2. This makes the suspensory ligaments pull tight.
  3. The lens is pulled thin (less curved).
  4. The thin lens refracts (bends) the light less, so the light from the distant object is focused sharply onto the retina.

Markers reward ciliary muscles relax, suspensory ligaments tighten, lens becomes thin, and light focused on the retina. Reversing this (which describes near vision) loses the marks.

Edexcel 20213 marksA person is long-sighted. Explain what causes long-sightedness and how it can be corrected.
Show worked answer →

A 3-mark explain question rewards the cause and the correcting lens.

In long-sightedness, the eyeball is too short, or the lens cannot become curved (thick) enough, so light from near objects is focused behind the retina, making close objects look blurred.

It is corrected with a converging (convex) lens, which brings the light together more before it enters the eye, so it focuses on the retina.

Markers reward light focusing behind the retina and a converging (convex) lens as the correction. Naming the wrong lens, or saying the eyeball is too long (which is short-sightedness), loses marks.

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