Aqa Gcse Biology 8464 1H Higher Tier Paper One Official Marking Script 2026

AQA GCSE BIOLOGY 8464 1H HIGHER TIER
PAPER ONE OFFICIAL MARKING SCRIPT 2026
◉ What is a stimulus? 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? Answer: Detect the stimulus or change in
environment.


◉ What happens after the receptors? Answer: Receptors send messages
to the CNS via the sensory neurone.


◉ What makes up the central nervous system? Answer: The brain or
spinal cord


◉ What is an effector? Answer: Muscles or glands that bring about a
response.


◉ What do the muscles and glands do in response to stimuli? Answer:
Muscles contract and glands secrete chemical substances(hormones).


◉ What is a sensory neurone? Answer: A neurone that carry information
from the receptors to the CNS.

,◉ What is a relay neurone? Answer: Neurones that carry impulses from
the sensory neurone to the motor neurone.


◉ What is a motor neurone? Answer: Neurones that carry information
from the CNS to the effectors.


◉ What is the nervous system? Answer: It is a system that allows you to
react to your surroundings.


◉ How do signals travel across a synapse? 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? Answer: A gap between two neurones.


◉ What is the thermoregulatory centre of the brain? Answer: Near the
hypothalamus, monitors the temperature of blood.


◉ Describe the stages in a reflex arc. Answer: Stimulus->Receptor-
>sensory neurone->CNS (relay neurone) -> motor neurone -> effector ->
response


◉ Name responses that reduce body temperature. Answer: Hairs lie flat,
sweat and blood vessels get wider(vasodilation)

,◉ What happens during vasodilation? Answer: The blood vessels
supplying the skin dilate (widen). This helps to transfer energy to the
environment.


◉ Name responses that increase body temperature. Answer: Hairs stand
up, no sweat, shivering and blood vessels constrict(vasoconstriction)


◉ What happens during vasoconstriction? Answer: The blood vessels
supplying the skin constrict to close off the skins blood supply.


◉ What is the body's core temp? Answer: 37 degrees Celsius


◉ What are hormones? Answer: Chemical messengers that travel in the
blood to target organs.


◉ Compare and Contrast the endocrine (hormone) system and the
nervous system. 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? Answer: Produces thyroxine which
is involved in regulating metabolism.

, ◉ What do the adrenal glands do? Answer: Produce adrenaline which is
used to prepare the body for fight or flight.


◉ What is the role of the pancreas? 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. Answer:
Insulin


◉ What does insulin do? 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. Answer:
Glucagon


◉ What does glucagon do? HINT GLU-COSE-GONE Answer: It makes
the liver convert glycogen to glucose. This causes the blood glucose
level to increase.


◉ What is type I diabetes? Answer: When the pancreas produces little or
no insulin.