AQA GCSE Biology Paper 2
What is homeostasis? ANS:The maintenance of a constant internal environment.
What is a stimulus? ANS:A change in your environment than requires a response. e.g Light, sound, touch, pressure, pain, chemical or temperature.
What do the receptors do? ANS:Detect the stimulus...
AQA GCSE Biology Paper 2
What is homeostasis? ANS:The maintenance of a constant internal environment.
What is a stimulus? ANS:A change in your environment than requires a response. e.g Light, sound,
touch, pressure, pain, chemical or temperature.
What do the receptors do? ANS:Detect the stimulus or change in environment.
What happens after the receptors? ANS:Receptors send messages to the CNS via the sensory neurone.
What makes up the central nervous system? ANS:The brain or spinal cord
What is an effector? ANS:Muscles or glands that bring about a response.
What do the muscles and glands do in response to stimuli? ANS:Muscles contract and glands secrete
chemical substances(hormones).
What is a sensory neurone? ANS:A neurone that carry information from the receptors to the CNS.
What is a relay neurone? ANS:Neurones that carry impulses from the sensory neurone to the motor
neurone.
What is a motor neurone? ANS:Neurones that carry information from the CNS to the effectors.
What is the nervous system? ANS:It is a system that allows you to react to your surroundings.
How do signals travel across a synapse? ANS:The chemical or neurotransmitter diffuses across the
synapse and binds to a complementary receptor on the neurone (postsynaptic). This causes an electrical
impulse to travel down the next neurone.
What is a synapse? ANS:A gap between two neurones.
What is the thermoregulatory centre of the brain? ANS:Near the hypothalamus, monitors the
temperature of blood.
Describe the stages in a reflex arc. ANS:Stimulus->Receptor->sensory neurone->CNS (relay neurone) ->
motor neurone -> effector -> response
Name responses that reduce body temperature. ANS:Hairs lie flat, sweat and blood vessels get
wider(vasodilation)
What happens during vasodilation? ANS:The blood vessels supplying the skin dilate (widen). This helps
to transfer energy to the environment.
,Name responses that increase body temperature. ANS:Hairs stand up, no sweat, shivering and blood
vessels constrict(vasoconstriction)
What happens during vasoconstriction? ANS:The blood vessels supplying the skin constrict to close off
the skins blood supply.
What is the body's core temp? ANS:37 degrees Celsius
What are hormones? ANS:Chemical messengers that travel in the blood to target organs.
Compare and Contrast the endocrine (hormone) system and the nervous system. ANS:Nervous is faster
acting than the endocrine system.
Hormones have longer lasting effects compared to electrical impulses. Nerves act on a very specific area
whereas hormones act more general.
What does the thyroid gland do? ANS:Produces thyroxine which is involved in regulating metabolism.
What do the adrenal glands do? ANS:Produce adrenaline which is used to prepare the body for fight or
flight.
What is the role of the pancreas? ANS:Produces glucagon and insulin which are involved in regulating
glucose levels in the blood.
Name the hormone that is released if blood sugar is too high. ANS:Insulin
What does insulin do? ANS:It makes the liver convert glucose into glycogen. This causes blood glucose
levels to decrease.
Name the hormone that is released if blood sugar is too low. ANS:Glucagon
What does glucagon do? HINT GLU-COSE-GONE ANS:It makes the liver convert glycogen to glucose. This
causes the blood glucose level to increase.
What is type I diabetes? ANS:When the pancreas produces little or no insulin.
What is type II diabetes? ANS:When a person becomes resistant to their own insulin. Being overweight
can increase your chances of type II diabetes.
How can type I diabetes be treated? ANS:Insulin injections, limiting intake of foods rich is simple
carbohydrates e.g. sugars and regular exercise.
How can type II diabetes be treated? ANS:It can be controlled by eating a carbohydrate controlled diet
and getting regular exercise.
What is the role of the kidneys. ANS:Kidneys make urine by taking unwanted waste products out of your
blood. They are involved in selective reabsorption.
, Name three things that are re-absorbed by the kidneys into the blood. ANS:Glucose, water and ions.
Name three things that are removed from the body in the urine. ANS:Urea, water and ions.
What is deamination? ANS:Proteins (excess amino acids) cannot be stored by the body. Excess amino
acids are converted to fats and carbohydrates. This occurs in the liver.
What is produced as a waste product of deamination? ANS:Ammonia is produced as a waste product.
Ammonia is toxic so it is converted into urea in the liver.
What hormone controls the amount of water absorbed by the kidneys? ANS:ADH
What happens when the concentration of water in the blood is too low. I.e. the Blood is MORE
concentrated. ANS:Receptors in the hypothalamus detects the water content is too low. The coordinator
in the brain receives the information and coordinates a response. The pituitary gland produces MORE
(Anti-diuretic hormone) ADH, which makes the kidney tubule MORE permeable. This means that MORE
water is reabsorbed into the bloodstream. The kidneys produce a small volume of concentrated urine.
What happens when the concentration of water in the blood is too high. I.e. the Blood is dilute/LESS
concentrated. ANS:Receptors in the hypothalamus detects the water content is too high. The
coordinator in the brain receives the information and coordinates a response. The pituitary gland
produced LESS ADH, which makes the kidney tubule LESS permeable. This means that LESS water is
reabsorbed into the bloodstream. The kidneys produce a large volume of dilute urine.
How does a dialysis machine work? ANS:In a dialysis machine the patients blood flows between a
partially permeable membrane surrounded by dialysis fluid. The dialysis fluid contains the same
concentration of dissolved ions and glucose as healthy blood. This means they won't be lost from the
blood during dialysis. Only wastes such as urea and excess ions and waters diffuse across the barrier.
What is the purpose of the partially permeable membrane in the dialysis machine. ANS:To only allow
small soluble molecules (e.g. urea, water and ions) to move into the dialysis fluid, not large molecules
like proteins.
What are the advantages and disadvantages of a kidney transplant over dialysis? ANS:Kidney transplants
are a cure, but they can be rejected. Patients are treated with immunosuppressants. People are not
always on the donor list, relatives have to agree to the donation. Transplants are cheaper than dialysis
to the NHS. Long waiting lists for transplants. Patients have to spend 3-4 hours a day, 3 x a week which
can have a negative impact on their quality of life.
What are the four stages of the menstrual cycle? ANS:1) Menstruation-the uterus lining breaks down
2) The uterus lining builds up again
3) Ovulation-Around day 14 a egg is released from an ovary.
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