GCSE BIOLOGY REVISION GUIDE COVERING CELLS
BODY SYSTEMS HEALTH GENETICS EVOLUTION
ECOLOGY AND PLANT RESPONSES
What is homeostasis? - The maintenance of a constant internal environment.✅✅✅
What is a stimulus? - A change in your environment than requires a response. e.g Light, sound,
touch, pressure, pain, chemical or temperature.✅✅✅
What do the receptors do? - Detect the stimulus or change in environment.✅✅✅
What happens after the receptors? - Receptors send messages to the CNS via the sensory
neurone.✅✅✅
What makes up the central nervous system? - The brain or spinal cord✅✅✅
What is an effector? - Muscles or glands that bring about a response.✅✅✅
What do the muscles and glands do in response to stimuli? - Muscles contract and glands secrete
chemical substances(hormones).✅✅✅
What is a sensory neurone? - A neurone that carry information from the receptors to the
CNS.✅✅✅
What is a relay neurone? - Neurones that carry impulses from the sensory neurone to the motor
neurone.✅✅✅
What is a motor neurone? - Neurones that carry information from the CNS to the
effectors.✅✅✅
What is the nervous system? - It is a system that allows you to react to your
surroundings.✅✅✅
How do signals travel across a synapse? - 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? - A gap between two neurones.✅✅✅
What is the thermoregulatory centre of the brain? - Near the hypothalamus, monitors the
temperature of blood.✅✅✅
,Describe the stages in a reflex arc. - Stimulus->Receptor->sensory neurone->CNS (relay
neurone) -> motor neurone -> effector -> response✅✅✅
Name responses that reduce body temperature. - Hairs lie flat, sweat and blood vessels get
wider(vasodilation)✅✅✅
What happens during vasodilation? - The blood vessels supplying the skin dilate (widen). This
helps to transfer energy to the environment.✅✅✅
Name responses that increase body temperature. - Hairs stand up, no sweat, shivering and blood
vessels constrict(vasoconstriction)✅✅✅
What happens during vasoconstriction? - The blood vessels supplying the skin constrict to close
off the skins blood supply.✅✅✅
What is the body's core temp? - 37 degrees Celsius✅✅✅
What are hormones? - Chemical messengers that travel in the blood to target organs.✅✅✅
Compare and Contrast the endocrine (hormone) system and the nervous system. - 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? - Produces thyroxine which is involved in regulating
metabolism.✅✅✅
What do the adrenal glands do? - Produce adrenaline which is used to prepare the body for fight
or flight.✅✅✅
What is the role of the pancreas? - 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. - Insulin✅✅✅
What does insulin do? - 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. - Glucagon✅✅✅
What does glucagon do? HINT GLU-COSE-GONE - It makes the liver convert glycogen to
glucose. This causes the blood glucose level to increase.✅✅✅
What is type I diabetes? - When the pancreas produces little or no insulin.✅✅✅
, What is type II diabetes? - 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? - Insulin injections, limiting intake of foods rich is simple
carbohydrates e.g. sugars and regular exercise.✅✅✅
How can type II diabetes be treated? - It can be controlled by eating a carbohydrate controlled
diet and getting regular exercise.✅✅✅
What is the role of the kidneys. - 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. - Glucose, water and
ions.✅✅✅
Name three things that are removed from the body in the urine. - Urea, water and ions.✅✅✅
What is deamination? - 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? - 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? - ADH✅✅✅
What happens when the concentration of water in the blood is too low. I.e. the Blood is MORE
concentrated. - 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. - 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? - 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.✅✅✅
BODY SYSTEMS HEALTH GENETICS EVOLUTION
ECOLOGY AND PLANT RESPONSES
What is homeostasis? - The maintenance of a constant internal environment.✅✅✅
What is a stimulus? - A change in your environment than requires a response. e.g Light, sound,
touch, pressure, pain, chemical or temperature.✅✅✅
What do the receptors do? - Detect the stimulus or change in environment.✅✅✅
What happens after the receptors? - Receptors send messages to the CNS via the sensory
neurone.✅✅✅
What makes up the central nervous system? - The brain or spinal cord✅✅✅
What is an effector? - Muscles or glands that bring about a response.✅✅✅
What do the muscles and glands do in response to stimuli? - Muscles contract and glands secrete
chemical substances(hormones).✅✅✅
What is a sensory neurone? - A neurone that carry information from the receptors to the
CNS.✅✅✅
What is a relay neurone? - Neurones that carry impulses from the sensory neurone to the motor
neurone.✅✅✅
What is a motor neurone? - Neurones that carry information from the CNS to the
effectors.✅✅✅
What is the nervous system? - It is a system that allows you to react to your
surroundings.✅✅✅
How do signals travel across a synapse? - 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? - A gap between two neurones.✅✅✅
What is the thermoregulatory centre of the brain? - Near the hypothalamus, monitors the
temperature of blood.✅✅✅
,Describe the stages in a reflex arc. - Stimulus->Receptor->sensory neurone->CNS (relay
neurone) -> motor neurone -> effector -> response✅✅✅
Name responses that reduce body temperature. - Hairs lie flat, sweat and blood vessels get
wider(vasodilation)✅✅✅
What happens during vasodilation? - The blood vessels supplying the skin dilate (widen). This
helps to transfer energy to the environment.✅✅✅
Name responses that increase body temperature. - Hairs stand up, no sweat, shivering and blood
vessels constrict(vasoconstriction)✅✅✅
What happens during vasoconstriction? - The blood vessels supplying the skin constrict to close
off the skins blood supply.✅✅✅
What is the body's core temp? - 37 degrees Celsius✅✅✅
What are hormones? - Chemical messengers that travel in the blood to target organs.✅✅✅
Compare and Contrast the endocrine (hormone) system and the nervous system. - 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? - Produces thyroxine which is involved in regulating
metabolism.✅✅✅
What do the adrenal glands do? - Produce adrenaline which is used to prepare the body for fight
or flight.✅✅✅
What is the role of the pancreas? - 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. - Insulin✅✅✅
What does insulin do? - 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. - Glucagon✅✅✅
What does glucagon do? HINT GLU-COSE-GONE - It makes the liver convert glycogen to
glucose. This causes the blood glucose level to increase.✅✅✅
What is type I diabetes? - When the pancreas produces little or no insulin.✅✅✅
, What is type II diabetes? - 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? - Insulin injections, limiting intake of foods rich is simple
carbohydrates e.g. sugars and regular exercise.✅✅✅
How can type II diabetes be treated? - It can be controlled by eating a carbohydrate controlled
diet and getting regular exercise.✅✅✅
What is the role of the kidneys. - 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. - Glucose, water and
ions.✅✅✅
Name three things that are removed from the body in the urine. - Urea, water and ions.✅✅✅
What is deamination? - 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? - 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? - ADH✅✅✅
What happens when the concentration of water in the blood is too low. I.e. the Blood is MORE
concentrated. - 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. - 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? - 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.✅✅✅
