AQA GCSE Biology Paper 2 perfect answers
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.
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 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.
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.
