Homeostasis and response

Define homeostasis and name one internal condition that it regulates in humans.

Put these parts of an automatic control system into a logical sequence and describe each role: coordination centre, effector, receptor and response.

A runner becomes hot and loses water during a race. Explain why homeostatic control of both body temperature and water level is important, and identify the general components needed in each control system.

Complete the nervous-system pathway by placing these in order: effector, receptor, response, stimulus and coordinator.

A person touches a hot surface and rapidly pulls their hand away. Explain the pathway of the reflex action and why the response is important.

A student tests whether background music changes human reaction time by measuring one ruler-drop result with music and one without it. Evaluate this method and describe how to obtain more valid and reliable evidence.

For separate biology, match each brain region to its main function: cerebral cortex, cerebellum and medulla.

For separate biology, a patient has poor muscular coordination but can still understand speech. Suggest the brain region most likely affected and explain the evidence for your choice.

Higher tier: For separate biology, evaluate how evidence from a patient with localised brain damage, electrical stimulation and magnetic resonance imaging could be used to map brain function.

For separate biology, state the function of each eye structure: retina, optic nerve and iris.

For separate biology, compare accommodation when focusing on a near object with accommodation when focusing on a distant object.

For separate biology, a person's distant vision is blurred because light from a distant object focuses before the retina. Identify the defect and explain how two different treatments can correct it.

For separate biology, name the coordination centre for body temperature and state two sources of temperature information that it receives.

For separate biology, describe the responses when body temperature is too high and when it is too low.

Higher tier: For separate biology, explain how vasodilation and sweating lower an athlete's body temperature, and how vasoconstriction and shivering raise it in cold conditions.

Describe how a hormone travels from an endocrine gland to its target organ.

Compare hormonal coordination with nervous coordination.

A change in a body condition causes the pituitary gland to release a hormone that stimulates another gland. Explain why the pituitary is called a master gland and identify four other endocrine glands that could be shown on a body diagram.

Explain how insulin lowers a blood glucose concentration that is too high.

Two patients have different forms of diabetes. Explain the biological problem in each condition and how each is commonly managed.

Higher tier: Explain how insulin and glucagon form a negative-feedback system when blood glucose concentration rises above or falls below its optimum level.

For separate biology, describe how the kidneys form urine from blood without losing useful glucose.

For separate biology, evaluate dialysis and a kidney transplant as treatments for kidney failure.

Higher tier: For separate biology, after a person loses water their blood becomes more concentrated, and protein digestion has also produced excess amino acids. Explain how ADH controls water balance and how the excess nitrogen is made safe for excretion.

State the role of each reproductive hormone: testosterone, FSH, LH and progesterone.

Describe the roles of oestrogen, FSH and LH from the start of egg maturation to ovulation.

Higher tier: Explain the interactions among FSH, oestrogen, LH and progesterone that coordinate one menstrual cycle.

State how each contraceptive method reduces the chance of fertilisation: an oral hormonal contraceptive, a condom and a spermicide.

Compare an injection or implant containing slow-release progesterone with a diaphragm as methods of contraception.

A person wants a reversible contraceptive that does not need to be remembered every day. Evaluate suitable hormonal and non-hormonal options and explain why the final choice cannot be made from effectiveness alone.

Higher tier: State the roles of FSH and LH when they are used together as a fertility drug.

Higher tier: Describe the main stages of IVF from hormone treatment to embryo transfer.

Higher tier: Evaluate fertility drugs and IVF as treatments for infertility from the perspective of a patient deciding whether to proceed.

Higher tier: State the gland that produces adrenaline and give two effects of adrenaline during fear or stress.

Higher tier: Describe the source and roles of thyroxine, and explain why its concentration needs to be controlled.

Higher tier: A control diagram shows that a fall in blood thyroxine increases stimulation of the thyroid, while a rise in thyroxine reduces that stimulation. Explain why this is negative feedback and predict the response after each change.

For separate biology, define phototropism and gravitropism and name the hormone whose unequal distribution causes unequal growth in roots and shoots.

For separate biology, design an investigation into the effect of one-sided light on the growth of newly germinated seedlings.

Higher tier: For separate biology, compare the roles of auxin, gibberellins and ethene in plant control and coordination.

Higher tier: For separate biology, state one commercial use of auxin, one use of ethene and one use of gibberellins.

Higher tier: For separate biology, explain why a grower might use auxin rooting powder and then gibberellins at later stages of crop production.

Higher tier: For separate biology, evaluate the use of auxin weed killers and ethene-controlled ripening in commercial food production.