science revision
cells
plant cell and animal cell
sperm cell and egg cell
animal cell has a cell wall but an animal cell does not
Animal cells each have a chromosome and lysosomes, whereas plant cells do not
Mutation
Being exposed to radiation and specific chemicals which causes the DNA to break down
When the cells repairs the DNA it can not repair properly causing a mutation.
DNA does not copy itself properly when the cells multiply
Chromeosones
X + X = Girl
X + Y = Boy
DNA
C + G always together
A + T always together
there can not be a y + Y because the mother has a x chromosome and the dad has either but it can no be possible.
they can not be paired with anyother.