AQA GCSE Biology Paper 2 Question And Correct Answers.

What is homeostasis? - correct answer The maintenance of a constant internal environment. What is a stimulus? - correct answer A change in your environment than requires a response. e.g Light, sound, touch, pressure, pain, chemical or temperature. What do the receptors do? - correct answer Detect the stimulus or change in environment. What happens after the receptors? - correct answer Receptors send messages to the CNS via the sensory neurone. What makes up the central nervous system? - correct answer The brain or spinal cord What is an effector? - correct answer Muscles or glands that bring about a response. What do the muscles and glands do in response to stimuli? - correct answer Muscles contract and glands secrete chemical substances(hormones). What is a sensory neurone? - correct answer A neurone that carry information from the receptors to the CNS. What is a relay neurone? - correct answer Neurones that carry impulses from the sensory neurone to the motor neurone. What is a motor neurone? - correct answer Neurones that carry information from the CNS to the effectors. What is the nervous system? - correct answer It is a system that allows you to react to your surroundings. How do signals travel across a synapse? - correct answer 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? - correct answer A gap between two neurones. What is the thermoregulatory centre of the brain? - correct answer Near the hypothalamus, monitors the temperature of blood. Describe the stages in a reflex arc. - correct answer Stimulus->Receptor->sensory neurone->CNS (relay neurone) -> motor neurone -> effector -> response Name responses that reduce body temperature. - correct answer Hairs lie flat, sweat and blood vessels get wider(vasodilation) What happens during vasodilation? - correct answer The blood vessels supplying the skin dilate (widen). This helps to transfer energy to the environment. Name responses that increase body temperature. - correct answer Hairs stand up, no sweat, shivering and blood vessels constrict(vasoconstriction) What happens during vasoconstriction? - correct answer The blood vessels supplying the skin constrict to close off the skins blood supply. What is the body's core temp? - correct answer 37 degrees Celsius What are hormones? - correct answer Chemical messengers that travel in the blood to target organs. Compare and Contrast the endocrine (hormone) system and the nervous system. - correct answer 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? - correct answer Produces thyroxine which is involved in regulating metabolism. What do the adrenal glands do? - correct answer Produce adrenaline which is used to prepare the body for fight or flight. What is the role of the pancreas? - correct answer 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. - correct answer Insulin What does insulin do? - correct answer 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. - correct answer Glucagon What does glucagon do? HINT GLU-COSE-GONE - correct answer It makes the liver convert glycogen to glucose. This causes the blood glucose level to increase. What is type I diabetes? - correct answer When the pancreas produces little or no insulin. What is type II diabetes? - correct answer 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? - correct answer Insulin injections, limiting intake of foods rich is simple carbohydrates e.g. sugars and regular exercise. How can type II diabetes be treated? - correct answer It can be controlled by eating a carbohydrate controlled diet and getting regular exercise. What is the role of the kidneys. - correct answer 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. - correct answer Glucose, water and ions. Name three things that are removed from the body in the urine. - correct answer Urea, water and ions. What is deamination? - correct answer 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? - correct answer 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? - correct answer ADH What happens when the concentration of water in the blood is too low. I.e. the Blood is MORE concentrated. - correct answer 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. - correct answer 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? - correct answer 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. - correct answer 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? - correct answer 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? - correct answer 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. 4) The wall is maintained for about 14 days until day 28. If the egg has not been fertilised and implanted into the uterus lining it breaks down. What is the role of FSH (Follicle stimulating hormone) in the menstrual cycle? - correct answer Made in the pituitary gland. Causes a egg to mature in one of the ovaries in a structure