What modules would be contained in the two white pipes cleaners (backbones of dna)?

answer:

double helix. each dna strand within the double helix is a long, linear molecule made of smaller units called nucleotides that form a chain. the chemical backbones of the double helix are made up of sugar and phosphate molecules that are connected by chemical bonds, known as sugar-phosphate backbones.

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).

the menstrual cycle – higher tier. negative feedback mechanisms affect the production of hormones in the menstrual cycle. oestrogen also stimulates the release of lh (luteinising hormone) from the pituitary gland, which in turn controls the production of progesterone.