20. Which defines a biome as a desert? a. A rate of evaporation higher than precipitation.
b. Annual rainfall less than 10 cm/yr.
c. Area with no organic matter in soil.
d. A region with few or no trees.

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.