2 The process of keeping things
constant and balanced in the body is
3 Sodium and chloride levels in the blood are controlled
by the kidneys. These are lost when we sweat. They
produce urine which contains excess salts and water
that the body does not need.
4 The Menstrual Cycle- after 7 days of menstruation, FSH is released from the pituitary gland
which starts the development of follicles in the ovaries. Oestrogen is released to line the
uterus and LH causes the egg cell to be released from the ovary. Progesterone maintains
uterus lining. Egg is not fertilised so lining breaks down. Another 7 day menstruation and the
cycle starts again.
5 Contraceptive pill contains oestrogen and progesterone or just
progesterone. The progesterone pill has fewer side effects but has to be
taken punctually.Combined pill is more reliable.
6 Infertility can be treated
by injecting FSH into the
blood which stimulates the
maturation of eggs.
7 IVF- obtain eggs from the ovary before they are
released. The eggs are fertilised with sperm
outside of the body and the egg cells are
allowed to divide into embryos. Then the
embryos are inserted back into the womb.
8 If plants grow towards the light it is called
9 auxins are hormones
which stimulate the
growth of cells in stems.
10 Stems grow against the force of gravity
soare negatively gravitrophic. Roots are
positively gravitrophic because they grow
in the direction of the force of gravity.
11 If a root good grow towards water or gravity, it would grow
towards water. This would make it positively hydrotrophic.
12 The weedkiller 2,4-D causes rapid growth of
the weeds as they absorb the weedkiller by the
roots.The rapid growth causes the plant to die
as it is so abnormal