A patient has a tumour deep within one of the cerebral hemispheres. Before treatment, the patient's speech is normal. Radiotherapy destroys the tumour, but afterwards the patient has difficulty speaking.
Which statement best explains this result?
The radiation damaged the cerebellum, which is the brain region that controls language.
Neurones controlling speech divide rapidly, so the radiation damaged them more than the tumour.
The tumour cells had been carrying impulses for speech, so destroying them stopped speech.
The radiation also damaged healthy neurones near the tumour, and these neurones are not replaced.
111 exam-style questions on Edexcel GCSE Biology 2.3 The nervous system and brain, covering 2.3.1 Structures and functions of the brain, 2.3.2 Imaging brain function with scanning, 2.3.3 Limitations in treating nervous system damage, 2.3.4 Neurones and impulse transmission, and 2.3.5 Structure and function of a reflex arc. Each one has a worked solution and a mark scheme showing where the marks go.