Brain development, nature and nurtureEdexcel A-Level Biology A: Mind map

Exam questions on Brain development, nature and nurture

1. Researchers sutured shut one eye of young kittens for their first three months of life and then reopened it. Later, recordings from the visual cortex showed that almost no neurones responded to light entering the previously closed eye, and the kittens behaved as if blind in that eye, although its retina and optic nerve were normal. The same procedure carried out on adult cats for three months caused no loss of vision.
   Explain how the results of the experiment on the kittens show that nurture, as well as nature, influences brain development.2 marks
2. A baby is born with a cataract that makes the lens of one eye cloudy. Surgeons recommend that the lens is replaced within the first few months of life, rather than waiting until the child is older.
   Explain why replacing the lens after the critical period would not restore normal vision in the affected eye.2 marks
3. A researcher compared scores on a test of spatial reasoning in pairs of twins. The scores of identical twins brought up together were very similar (correlation 0.85). The scores of non-identical twins brought up together were less similar (correlation 0.60). Identical twins who had been brought up in different homes were also very similar (correlation 0.75).
   Explain what the correlations suggest about the influence of genes and environment on spatial reasoning.3 marks