AQA GCSE Combined Science: Trilogy · 4.5

Homeostasis and response

50 revision questions with answers for 4.5 Homeostasis and response in AQA GCSE Combined Science: Trilogy (spec 8464). Practise with flashcards, a topic quiz, a random quiz across the course, 5 crosswords, or read every question and answer below.

All 50 questions and answers

Question 1 · Spec 4.5.1
What is homeostasis?
Answer:
Regulation of internal conditions to maintain optimum conditions for cell and enzyme function despite internal or external changes.
Question 2 · Spec 4.5.1
Name three internal conditions controlled by homeostasis.
Answer:
Blood glucose concentration, body temperature and water levels.
Question 3 · Spec 4.5.1
What is a receptor's role in a control system?
Answer:
It detects a stimulus: a change in internal or external conditions.
Question 4 · Spec 4.5.1
What does a coordination centre do?
Answer:
It receives and processes information from receptors and coordinates a response; examples include the brain, spinal cord and pancreas.
Question 5 · Spec 4.5.1
What are effectors?
Answer:
Muscles or glands that bring about responses, such as muscle contraction or hormone secretion.
Question 6 · Spec 4.5.2
What makes up the central nervous system?
Answer:
The brain and spinal cord.
Question 7 · Spec 4.5.2
How does information travel along a neurone?
Answer:
As an electrical impulse.
Question 8 · Spec 4.5.2
Put the main stages of a nervous response in order.
Answer:
Stimulus → receptor → coordination centre → effector → response.
Question 9 · Spec 4.5.2
What makes a reflex action different from a conscious response?
Answer:
A reflex is rapid and automatic and does not involve the conscious part of the brain.
Question 10 · Spec 4.5.2
State the neurone sequence in a simple spinal reflex arc.
Answer:
Sensory neurone → relay neurone in the spinal cord → motor neurone, leading to an effector.
Question 11 · Spec 4.5.2
What happens at a synapse?
Answer:
A chemical messenger diffuses across the gap between neurones and triggers an impulse in the next neurone.
Question 12 · Spec 4.5.2
Why are rapid reflexes useful?
Answer:
They help protect the body from harm by producing a response before conscious processing would occur.
Question 13 · Spec 4.5.2 · Required practical
Name an independent variable for a reaction-time investigation.
Answer:
For example, whether a participant performs a distraction task while responding to a falling ruler.
Question 14 · Spec 4.5.2 · Required practical
How does a ruler-drop test compare reaction times?
Answer:
Measure the distance a ruler falls before being caught. A greater distance corresponds to a longer reaction time.
Question 15 · Spec 4.5.2 · Required practical
Name three controls for a ruler-drop investigation.
Answer:
Use the same hand and starting finger position, the same release method and comparable conditions for each test.
Question 16 · Spec 4.5.2 · Required practical
Why should participants practise before reaction-time data are collected?
Answer:
Performance can improve through practice; familiarisation reduces learning effects during the measured trials.
Question 17 · Spec 4.5.2 · Required practical
Reaction times are 0.21, 0.19 and 0.20 s. Find the mean.
Answer:
Mean = (0.21 + 0.19 + 0.20) / 3 = 0.20 s.
Question 18 · Spec 4.5.3.1
How do endocrine glands communicate with target organs?
Answer:
They secrete hormones directly into the blood, which carries them to target organs where they have an effect.
Question 19 · Spec 4.5.3.1
Why is the pituitary sometimes called the master gland?
Answer:
It releases several hormones, including ones that stimulate other endocrine glands to release hormones.
Question 20 · Spec 4.5.3.1
Where are the pituitary, thyroid, pancreas and adrenal glands?
Answer:
Pituitary: in the brain; thyroid: neck; pancreas: abdomen; adrenal glands: above the kidneys.
Question 21 · Spec 4.5.3.1
Compare nervous and hormonal communication.
Answer:
Nervous responses are usually fast and short-lived; hormonal responses are usually slower and longer-lasting.
Question 22 · Spec 4.5.3.2
Which organ monitors and controls blood glucose concentration?
Answer:
The pancreas.
Question 23 · Spec 4.5.3.2
How does insulin reduce high blood glucose?
Answer:
It promotes glucose uptake into cells and conversion of excess glucose to glycogen in liver and muscle cells.
Question 24 · Spec 4.5.3.2
How is glycogen different from glucose?
Answer:
Glucose is a soluble sugar used in respiration. Glycogen is a large storage carbohydrate made from glucose units.
Question 25 · Spec 4.5.3.2
What causes Type 1 diabetes, and how is it usually treated?
Answer:
The pancreas produces insufficient insulin. Insulin injections help control blood glucose.
Question 26 · Spec 4.5.3.2
What causes Type 2 diabetes?
Answer:
Body cells become less responsive to insulin, so blood glucose is not regulated effectively.
Question 27 · Spec 4.5.3.2
How can Type 2 diabetes commonly be managed?
Answer:
A carbohydrate-controlled diet and exercise can help; treatment aims to improve blood glucose control.
Question 28 · Spec 4.5.3.2
How is obesity related to Type 2 diabetes?
Answer:
Obesity is a risk factor: it increases the likelihood of developing Type 2 diabetes, but does not mean every obese person develops it.
Question 29 · Spec 4.5.3.2 · Higher only
What happens when blood glucose is too low?
Answer:
The pancreas releases glucagon, which causes stored glycogen to be converted into glucose and released into the blood.
Question 30 · Spec 4.5.3.2 · Higher only
How do insulin and glucagon form a negative feedback system?
Answer:
Insulin lowers high glucose; glucagon raises low glucose. The responses reverse the original change, restoring glucose towards its normal range.
Question 31 · Spec 4.5.3.3
What causes secondary sexual characteristics to develop at puberty?
Answer:
Increased secretion of reproductive hormones.
Question 32 · Spec 4.5.3.3
Where is oestrogen produced, and what is one of its roles?
Answer:
It is produced in the ovaries and helps develop female secondary sexual characteristics and regulate the menstrual cycle.
Question 33 · Spec 4.5.3.3
Where is testosterone produced, and what does it stimulate?
Answer:
It is produced in the testes and stimulates sperm production and male secondary sexual characteristics.
Question 34 · Spec 4.5.3.3
What is ovulation?
Answer:
The release of a mature egg from an ovary, occurring about once per menstrual cycle.
Question 35 · Spec 4.5.3.3
What is the role of follicle stimulating hormone, FSH?
Answer:
It causes an egg to mature in the ovary.
Question 36 · Spec 4.5.3.3
What does luteinising hormone, LH, do?
Answer:
It stimulates ovulation: release of the mature egg.
Question 37 · Spec 4.5.3.3
Which two hormones help maintain the uterus lining?
Answer:
Oestrogen and progesterone.
Question 38 · Spec 4.5.3.3 · Higher only
How do oestrogen and progesterone interact with FSH and LH?
Answer:
Oestrogen inhibits FSH and stimulates an LH surge. Progesterone maintains the lining and inhibits FSH and LH.
Question 39 · Spec 4.5.3.3 · Higher only
A graph shows a sharp LH peak near the middle of a cycle. What event does it trigger?
Answer:
Ovulation, the release of an egg from an ovary.
Question 40 · Spec 4.5.3.4
How can oral hormonal contraceptives prevent egg maturation?
Answer:
They inhibit FSH production, so eggs do not mature.
Question 41 · Spec 4.5.3.4
How can a progesterone implant, injection or patch prevent pregnancy?
Answer:
Slow hormone release inhibits egg maturation and release for an extended period.
Question 42 · Spec 4.5.3.4
How do condoms and diaphragms prevent pregnancy?
Answer:
They form physical barriers that prevent sperm reaching an egg. Condoms also reduce transmission of some sexually transmitted infections.
Question 43 · Spec 4.5.3.4
How can an intrauterine device prevent pregnancy?
Answer:
Depending on the type, it prevents implantation or releases a hormone that reduces the chance of pregnancy.
Question 44 · Spec 4.5.3.4
Why is avoiding intercourse around ovulation less reliable than some other methods?
Answer:
The timing of ovulation varies, making the fertile period difficult to predict accurately.
Question 45 · Spec 4.5.3.4
How do spermicides and sterilisation work?
Answer:
Spermicides kill or disable sperm. Sterilisation blocks reproductive tubes, preventing sperm and egg meeting.
Question 46 · Spec 4.5.3.5 · Higher only
How can fertility drugs containing FSH and LH help conception?
Answer:
FSH stimulates egg maturation and LH stimulates ovulation, allowing fertilisation to occur after intercourse.
Question 47 · Spec 4.5.3.5 · Higher only
Describe the main stages of IVF.
Answer:
Hormones stimulate several eggs to mature; eggs are collected and fertilised in a laboratory; resulting early embryos are transferred to the uterus.
Question 48 · Spec 4.5.3.5 · Higher only
Give one benefit and two limitations of IVF.
Answer:
It offers a chance of pregnancy, but success is not guaranteed and treatment can be stressful; multiple births increase risks.
Question 49 · Spec 4.5.3.6 · Higher only
How does adrenaline prepare the body for fight or flight?
Answer:
Adrenal glands release it during fear or stress. It increases heart rate and delivery of oxygen and glucose to muscles and brain.
Question 50 · Spec 4.5.3.6 · Higher only
What does thyroxine do, and how is its level controlled?
Answer:
Thyroxine stimulates basal metabolic rate and supports growth and development. Negative feedback regulates its release from the thyroid.

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