AQA GCSE COMBINED SCIENCE: TRILOGY
8464/B/2H HIGHER TIER BIOLOGY PAPER
2H 2022 COMPREHENSIVE STUDY GUIDE
2026 FULL QUESTIONS AND SOLUTIONS
GRADED A+
◍ aerobic respiration.
Answer: an exothermic reaction in which glucose is broken down using
oxygen to produce carbon dioxide and water and release energy for the cells
◍ Give examples of conditions maintained by homeostasis in the body.
Answer: ● Blood glucose concentration ● Body temperature ● Water levels
◍ What two types of responses are used in body control systems?.
Answer: Nervous and chemical
◍ What three components do all control systems have?.
Answer: ● Receptors ● Coordination centres ● Effectors
◍ What is the function of a receptor?.
Answer: Receptors detect changes in the environment (stimuli).
◍ anaerobic respiration.
Answer: an exothermic reaction in which glucose is broken down in the
absence of oxygen to produce lactic acid in animals and ethanol and carbon
dioxide in plants and yeast. A small amount of energy is transferred for the
cells
◍ What is the function of a coordination centre?.
Answer: Coordination centres obtain and process information from
receptors.
,◍ What is the function of an effector?.
Answer: Effectors (muscles or glands) bring about responses to stimuli.
◍ Glucagon.
Answer: A hormone secreted by the pancreatic alpha cells that increases
blood glucose concentration
◍ exothermic reaction.
Answer: a reaction that transfers energy to the environment
◍ glycogen.
Answer: carbohydrate store in animals
◍ What is the function of the nervous system?.
Answer: The nervous system allows the body to react to its surroundings
and coordinate an appropriate response.
◍ lactic acid.
Answer: the end product of anaerobic respiration in animal cells
◍ oxygen debt.
Answer: the extra oxygen that must be taken into the body after exercise has
stopped to complete the aerobic respiration of lactic acid
◍ Mitochondria.
Answer: Organelle that is the site of respiration
◍ Responses to exercise.
Answer: Heart rate increases, Breathing rate increases, glycogen in muscles
is converted to glucose
◍ endothermic reaction.
Answer: a reaction that requires a transfer of energy from the environment
◍ How does a stimulus lead to a response being carried out by the body?.
Answer: ● Stimulus is converted into an electrical impulse by the receptors.
● The electrical impulse passes along sensory neurones to the central
nervous system (CNS). ● The CNS coordinates an appropriate response and
, an electrical impulse is sent along motor neurones to the effector, which
carries out the response.
◍ What sequence of events describes how the nervous system works?.
Answer: Stimulus → receptor → coordinator → effector → response
◍ glucose.
Answer: a simple sugar
◍ limiting factors.
Answer: limit the rate of a reaction, for example photosynthesis
◍ photosynthesis.
Answer: the process by which plants make food using carbon dioxide, water,
and light
◍ Reactants for photosynthesis.
Answer: water and carbon dioxide
◍ Products of photosynthesis.
Answer: glucose and oxygen
◍ What is a reflex action?.
Answer: A reflex action is an automatic and rapid response which does not
involve any conscious input from the brain.
◍ Chloroplast.
Answer: Site of photosynthesis
◍ white blood cells.
Answer: Blood cells that perform the function of destroying disease-causing
microorganisms
◍ Why are reflex actions important?.
Answer: Reflex actions aid survival by preventing harm to the body.
◍ Describe how a reflex action occurs via a reflex arc.
Answer: ● The stimulus is detected by a receptor. ● An electrical impulse
passes along a sensory neurone to the spinal cord (part of the CNS). ● At a
, synapse between a sensory neurone and a relay neurone, a chemical diffuses
across the gap and stimulates a new impulse which passes along the relay
neurone. ● The same process occurs at a synapse between a relay neurone
and a motor neurone. ● At the effector, an appropriate response is carried
out.
◍ Sperm cells.
Answer: It has a long tail and a streamlined head to help it swim. There are a
lot of mitochondria in the cell to provide the energy needed. It also carries
enzymes in its head to digest through the egg cell membrane.
◍ What is the difference between a reflex pathway and a conscious pathway?.
Answer: Within a reflex pathway, the coordination centre is a relay neurone
found in the spinal cord/unconscious parts of the brain. In a conscious
pathway, the coordination centre is in the conscious part of the brain.
◍ Where is body temperature controlled in the body?.
Answer: Body temperature is controlled by the thermoregulatory centre in
the hypothalamus of the brain.
◍ light.
Answer: energy source for photosynthesis
◍ How is temperature monitored by the body?.
Answer: ● Thermoregulatory centre has receptors sensitive to blood
temperature. ● Skin has receptors sensitive to skin temperature - sends
impulses to thermoregulatory centre.
◍ What physiological changes occur when the body temperature is too high?.
Answer: ● Vasodilation - blood vessels near the surface of the skin dilate -
more heat is radiated away. ● Sweating - evaporation of water takes away
heat energy from the surface of the skin.
◍ What physiological changes occur when the body temperature is too low?.
Answer: ● Vasoconstriction - blood vessels near the surface of the skin
constrict - less heat radiated away. ● Shivering - respiration allows muscles
to contract. It is an exothermic process, so heat energy is released. ●
8464/B/2H HIGHER TIER BIOLOGY PAPER
2H 2022 COMPREHENSIVE STUDY GUIDE
2026 FULL QUESTIONS AND SOLUTIONS
GRADED A+
◍ aerobic respiration.
Answer: an exothermic reaction in which glucose is broken down using
oxygen to produce carbon dioxide and water and release energy for the cells
◍ Give examples of conditions maintained by homeostasis in the body.
Answer: ● Blood glucose concentration ● Body temperature ● Water levels
◍ What two types of responses are used in body control systems?.
Answer: Nervous and chemical
◍ What three components do all control systems have?.
Answer: ● Receptors ● Coordination centres ● Effectors
◍ What is the function of a receptor?.
Answer: Receptors detect changes in the environment (stimuli).
◍ anaerobic respiration.
Answer: an exothermic reaction in which glucose is broken down in the
absence of oxygen to produce lactic acid in animals and ethanol and carbon
dioxide in plants and yeast. A small amount of energy is transferred for the
cells
◍ What is the function of a coordination centre?.
Answer: Coordination centres obtain and process information from
receptors.
,◍ What is the function of an effector?.
Answer: Effectors (muscles or glands) bring about responses to stimuli.
◍ Glucagon.
Answer: A hormone secreted by the pancreatic alpha cells that increases
blood glucose concentration
◍ exothermic reaction.
Answer: a reaction that transfers energy to the environment
◍ glycogen.
Answer: carbohydrate store in animals
◍ What is the function of the nervous system?.
Answer: The nervous system allows the body to react to its surroundings
and coordinate an appropriate response.
◍ lactic acid.
Answer: the end product of anaerobic respiration in animal cells
◍ oxygen debt.
Answer: the extra oxygen that must be taken into the body after exercise has
stopped to complete the aerobic respiration of lactic acid
◍ Mitochondria.
Answer: Organelle that is the site of respiration
◍ Responses to exercise.
Answer: Heart rate increases, Breathing rate increases, glycogen in muscles
is converted to glucose
◍ endothermic reaction.
Answer: a reaction that requires a transfer of energy from the environment
◍ How does a stimulus lead to a response being carried out by the body?.
Answer: ● Stimulus is converted into an electrical impulse by the receptors.
● The electrical impulse passes along sensory neurones to the central
nervous system (CNS). ● The CNS coordinates an appropriate response and
, an electrical impulse is sent along motor neurones to the effector, which
carries out the response.
◍ What sequence of events describes how the nervous system works?.
Answer: Stimulus → receptor → coordinator → effector → response
◍ glucose.
Answer: a simple sugar
◍ limiting factors.
Answer: limit the rate of a reaction, for example photosynthesis
◍ photosynthesis.
Answer: the process by which plants make food using carbon dioxide, water,
and light
◍ Reactants for photosynthesis.
Answer: water and carbon dioxide
◍ Products of photosynthesis.
Answer: glucose and oxygen
◍ What is a reflex action?.
Answer: A reflex action is an automatic and rapid response which does not
involve any conscious input from the brain.
◍ Chloroplast.
Answer: Site of photosynthesis
◍ white blood cells.
Answer: Blood cells that perform the function of destroying disease-causing
microorganisms
◍ Why are reflex actions important?.
Answer: Reflex actions aid survival by preventing harm to the body.
◍ Describe how a reflex action occurs via a reflex arc.
Answer: ● The stimulus is detected by a receptor. ● An electrical impulse
passes along a sensory neurone to the spinal cord (part of the CNS). ● At a
, synapse between a sensory neurone and a relay neurone, a chemical diffuses
across the gap and stimulates a new impulse which passes along the relay
neurone. ● The same process occurs at a synapse between a relay neurone
and a motor neurone. ● At the effector, an appropriate response is carried
out.
◍ Sperm cells.
Answer: It has a long tail and a streamlined head to help it swim. There are a
lot of mitochondria in the cell to provide the energy needed. It also carries
enzymes in its head to digest through the egg cell membrane.
◍ What is the difference between a reflex pathway and a conscious pathway?.
Answer: Within a reflex pathway, the coordination centre is a relay neurone
found in the spinal cord/unconscious parts of the brain. In a conscious
pathway, the coordination centre is in the conscious part of the brain.
◍ Where is body temperature controlled in the body?.
Answer: Body temperature is controlled by the thermoregulatory centre in
the hypothalamus of the brain.
◍ light.
Answer: energy source for photosynthesis
◍ How is temperature monitored by the body?.
Answer: ● Thermoregulatory centre has receptors sensitive to blood
temperature. ● Skin has receptors sensitive to skin temperature - sends
impulses to thermoregulatory centre.
◍ What physiological changes occur when the body temperature is too high?.
Answer: ● Vasodilation - blood vessels near the surface of the skin dilate -
more heat is radiated away. ● Sweating - evaporation of water takes away
heat energy from the surface of the skin.
◍ What physiological changes occur when the body temperature is too low?.
Answer: ● Vasoconstriction - blood vessels near the surface of the skin
constrict - less heat radiated away. ● Shivering - respiration allows muscles
to contract. It is an exothermic process, so heat energy is released. ●
