A 20-kilogram river otter (a tertiary consumer) requires the energy harnessed by about kg of primary producers. Assume that 90% of the energy at each trophic level is lost as heat.

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.

that scientist would be robert hooke