The Endocrine System
Revise The Endocrine System for GCSE Biology with this free worksheet and full mark scheme — Foundation and Higher exam-style questions with worked answers for AQA, Edexcel and OCR. Hormones are chemical messengers carried in the blood, and the pituitary gland is often called the 'master gland'.
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These worksheets and mark schemes are original, written for Virtus Academy and checked against the current AQA, Edexcel and OCR specifications. Every worksheet comes with a full mark scheme.
Topic overview
The endocrine system is made of glands that secrete chemicals called hormones directly into the bloodstream. The blood carries them to a target organ where they produce an effect.
Hormonal responses differ from nervous ones in three consistent ways: they are slower to act, they last longer, and they act in a more general way rather than on a precise location. Those three contrasts are examined repeatedly.
The pituitary gland in the brain is the master gland. It secretes several hormones in response to body conditions, and many of these act on other glands to make them release further hormones — which is why it coordinates so much of the system.
Revision notes
How hormones work
Endocrine glands secrete hormones directly into the bloodstream.
The blood carries the hormone to a target organ, where it produces an effect. Because transport is by blood rather than by nerve, the effect is slower to begin but longer lasting.
The main glands
Pituitary: the master gland, secreting hormones that act on other glands. Thyroid: produces thyroxine, controlling metabolic rate.
Pancreas: produces insulin and glucagon. Adrenal glands: produce adrenaline. Ovaries: produce oestrogen. Testes: produce testosterone.
Nervous versus hormonal
Nervous: very fast, acts for a short time, acts on a precise area.
Hormonal: slower, acts for a longer time, acts in a more general way. Being able to state all three contrasts is worth several marks.
Key points
- Hormones are chemicals secreted into the bloodstream.
- They travel in the blood to a target organ.
- The pituitary is the master gland.
- Hormonal responses are slower than nervous ones.
- Hormonal responses last longer than nervous ones.
- Hormonal responses act more generally.
Worked examples
Example 1
State three ways hormonal responses differ from nervous responses. [3 marks]
Model answer
Hormonal responses are slower to take effect (1 mark). They last for a longer time (1 mark). They act in a more general way rather than on a precise location (1 mark).
Example 2
Explain why the pituitary gland is called the master gland. [2 marks]
Model answer
It secretes several hormones in response to body conditions (1 mark), and many of these act on other glands, causing them to release further hormones (1 mark).
Example 3
Name the gland that produces insulin and state one other hormone produced by the same gland. [2 marks]
Model answer
The pancreas (1 mark), which also produces glucagon (1 mark).
Common mistakes
Saying hormones travel along nerves.
They travel in the blood. Nerves carry electrical impulses.
Giving only one difference from nervous responses.
Three differences are examinable: speed, duration and precision.
Confusing glucagon with glycogen.
Glucagon is a hormone; glycogen is the storage carbohydrate.
Saying all glands are controlled by the pituitary.
It controls many, but not every hormone release depends on it.
Exam tips
- Learn the three nervous-versus-hormonal contrasts as a set.
- Say secreted into the bloodstream when defining a hormone.
- Learn which gland produces which hormone.
- Keep glucagon and glycogen distinct.
Key terms
- Hormone
- A chemical secreted by a gland into the bloodstream.
- Endocrine gland
- A gland that secretes hormones directly into the blood.
- Target organ
- The organ on which a hormone has its effect.
- Pituitary gland
- The master gland controlling many other glands.
Related topics
Written and reviewed against the current AQA, Edexcel and OCR specifications. Spotted an error? Let us know.