1 Some plants can be grown in water using the technique of hydroponics. The roots are in water and
supplied with the ions that they need at the concentrations that support maximum growth. Some
ions can be absorbed both by diffusion and by active transport.
(a) (i) State two features of diffusion that do not apply to active transport.

# Diffusion is a down hill process.(flow is from higher concentration to lower concentration)

# It does not require energy.

but,

# Active transport is a uphill process.(flow is from lower concentration to higher concentration)

# It requires energy.

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.