Writing about genes Four students were asked to explain why brothers and sisters are similar but not identical. They have each
made a mistake.
• Underline the incorrect sentence in each student’s work.
• Add comments to show how each piece of work could be improved.
Emma writes:
Brothers and sisters have the same blood so they look similar. They also inherit genes from their parents. The genes are in the nucleus of every cell. They decide things like what colour hair you have. Half your genes come from each parent so you look a bit like both of them.
Ali writes:
When people have children they give them half their genes. It is just luck which half they get. The genes are in every cell and show the cells how to grow. The father’s genes are stronger, especially in boys. Identical twins have exactly the same genes but everyone else has different genes so they look different.
Precious writes:
Brothers and sisters are similar because they get all their genes from the same two people. There are genes in every cell’s nucleus and genes decide what you look like by controlling things like your eye colour. Some genes change as you get older and others stay the same. Half your genes come from the egg, and the other half come from the sperm. Each egg and sperm contains a different collection of genes so every baby is different.
Madu writes:
Brothers and sisters look different because they both get genes for some features from their mum and genes for other features from their dad. Some of the genes they get are the same and some are different. The genes are copied every time a new cell is made. Every cell has a full set in its nucleus.