Independent variable for
Exercise increases breathing rate

Dependent variable for
Exercise increases breathing rate

Controlled variable for
Exercise increases breathing rate

Independent: exercise

Dependent: breathing rate

Control: temperature is held constant throughout experiment

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explanation:

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.