True or false: enzymes are only good for one use, that is they get ‘used’ up.

The right answer is False.

An enzyme is a protein with catalytic properties. They catalyze chemical reactions in cells or outside the cells.

An enzyme specifically activate and accelerate the rate of a reaction. The enzyme is not modified during the reaction (it doesn't get used up). The initial molecules are the substrates of the enzyme, and the molecules formed from these substrates are the products of the reaction.

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.