B1 Revision

Sex Cells

What’s the chance of being male or female? Parent’s chromosomes are in pairs. When sex cells are made they only get one chromosome from each pair. So half a man’s sperm cells get an X chromosome and half get a Y chromosome. All a women’s egg cells get an X chromosome. When a sperm cell fertilises an egg cell the chances are 50% that it will be an X or a Y sperm. This means that there is a 50% chance that the baby will be a boy or a girl.

Huntington ’s disease and Pre-natal tests

Huntington’s Symptoms: memory problems, balance, they slur words so people think they…