A person is finding it difficult to read road signs in the distance clearly, but has no trouble reading a book up close.

Describe the eye defect this person could have.

Suggest how this eye defect can be corrected.

Write down the role of the ciliary muscles in the eye.

Parkinson's disease is a progressive neurological condition where dopamine-producing neurones in the brain are lost. Clinical trials are investigating treatments using stem cells derived from the patient's own tissue (such as skin cells) to replace these lost neurones.

Suggest why using the patient's own stem cells is preferred in terms of the body's immune system response.