Control and Coordination
Control and Coordination asks about the neuron, reflex action, the human brain, hormones and plant movements. Expect short explanations and which-gland-which-hormone matching items.
Nervous system
A neuron has dendrites, a cell body and an axon; the gap between neurons is the synapse, crossed by chemicals. Reflex arcs let the spinal cord act before the brain registers pain: receptor, sensory neuron, spinal cord, motor neuron, effector. Brain parts: cerebrum for thinking and memory, cerebellum for posture and balance, medulla for involuntary actions such as breathing.
Hormones
Pituitary is the master gland, secreting growth hormone; thyroxine from the thyroid needs iodine and controls metabolism; insulin from the pancreas lowers blood sugar; adrenaline from the adrenal glands prepares the body for emergencies; testes and ovaries secrete testosterone and oestrogen.
Plants
Auxin, gibberellin, cytokinin and abscisic acid regulate growth. The shoot is negatively geotropic and positively phototropic; the root is positively geotropic.
Worked example
You touch a hot pan and pull back before you feel pain. Heat receptors in the skin generate an impulse; the sensory neuron carries it to the spinal cord, which immediately sends a motor impulse to the arm muscle. The signal reaches the brain a moment later, which is why withdrawal is faster than the sensation of pain.
Traps
Ignoring the spinal cord's role in reflexes; saying insulin raises blood sugar; mixing up cerebrum and cerebellum; calling a tropism a learned behaviour.