Neuronal and Hormonal Communication (5.1.3–5.1.4): OCR A Level Biology Exam Questions by Topic

OCRCommunication, Homeostasis and EnergyExam Questions
Written by Tom Whitburn

These two spec points cover the body's two communication systems. Spec point 5.1.3 is about nerves: how sensory receptors act as transducers, the structure of sensory, relay and motor neurones, how resting and action potentials are set up and passed along a myelinated axon, and how synapses work. Spec point 5.1.4 moves on to hormones: endocrine glands, the adrenal glands, the histology of the pancreas, how insulin and glucagon control blood glucose, Type 1 and Type 2 diabetes and how diabetes is treated.

The marks are lost on detail. Students say no sodium ions enter when the answer is fewer, describe vesicles crossing the synaptic cleft, write that the impulse can't jump between nodes without saying the whole axon must depolarise, mix up the jobs of cortisol and aldosterone, or say ‘healthy diet’ when the mark needs less carbohydrate. In evaluation questions on diabetes treatment, many describe treatments but never weigh them up.

Work through the twenty questions below in order. They start with recall of synapses, glands and the pancreas, move on to applying what you know to toxins, unusual animals and patients, and finish with an experiment on calcium ions at a synapse and a six-mark evaluation of diabetes treatments. If you'd like to go through questions like these with me each week, my OCR A masterclasses run on Wednesdays at 5.15pm for Year 12 and on Tuesdays at 6.30pm or Thursdays at 5.15pm for Year 13.

Want help with this topic? It comes up in my weekly OCR A masterclasses. See the timetable →

What you need from GCSE

Each question on this page assumes you're secure on these GCSE ideas. If any of them feels shaky, look it up before you start.

  • The nervous system uses electrical impulses carried by sensory, relay and motor neurones from receptors to effectors.
  • A synapse is the gap between two neurones; a chemical diffuses across it to start an impulse in the next neurone.
  • Hormones are chemicals secreted by endocrine glands into the blood, which carries them to target organs.
  • Adrenaline from the adrenal glands prepares the body for ‘fight or flight’.
  • Insulin from the pancreas lowers blood glucose and glucagon raises it; Type 1 diabetes is treated with insulin and Type 2 with diet, exercise and drugs.

Key terms

These words come up in the questions and mark schemes. Examiners expect you to use them exactly.

  • Transducer: a sensory receptor that converts the energy of a stimulus into the electrical energy of a nerve impulse.
  • Generator potential: a small depolarisation of a receptor membrane; if it reaches threshold, an action potential is produced.
  • Resting potential: about −70 mV across the axon membrane, kept by sodium-potassium pumps and the membrane's greater permeability to potassium ions.
  • Depolarisation: the inside of the neurone becoming more positive than the outside as voltage-gated sodium ion channels open and Na+ floods in; the opening of more channels is positive feedback.
  • Saltatory conduction: in myelinated neurones, depolarisation happens only at the nodes of Ranvier, so the action potential travels faster.
  • Synaptic cleft: the gap between the presynaptic and postsynaptic membranes, which the neurotransmitter diffuses across.
  • Endocrine gland: a ductless gland that secretes hormones directly into the blood; an exocrine gland secretes into a duct.
  • Adrenal cortex and medulla: the cortex secretes steroid hormones such as cortisol and aldosterone; the medulla secretes adrenaline and noradrenaline.
  • Islets of Langerhans: the endocrine tissue of the pancreas: alpha cells secrete glucagon and beta cells secrete insulin.
  • Type 1 and Type 2 diabetes: in Type 1 the beta cells don't produce insulin; in Type 2 insulin is produced but target cells respond less to it.

What these questions cover (OCR 5.1.3 and 5.1.4)

The questions test these learning outcomes from the OCR A Level Biology A specification (H420):

  • 5.1.3(a) the roles of mammalian sensory receptors in converting different types of stimuli into nerve impulses (including the Pacinian corpuscle and receptors as transducers)
  • 5.1.3(b) the structure and functions of sensory, relay and motor neurones (including myelinated and non-myelinated neurones)
  • 5.1.3(c) the generation and transmission of nerve impulses in mammals (resting potential, action potential and saltatory conduction)
  • 5.1.3(d) the structure and roles of synapses in neurotransmission (cholinergic synapses, summation, inhibitory and excitatory synapses)
  • 5.1.4(a) endocrine communication by hormones
  • 5.1.4(b) the structure and functions of the adrenal glands (hormones of the cortex and medulla and their functions)
  • 5.1.4(c)(i) the histology of the pancreas
  • 5.1.4(c)(ii) the examination and drawing of stained sections of the pancreas to show the histology of the endocrine tissues
  • 5.1.4(d) how blood glucose concentration is regulated (insulin, glucagon, the liver, and the control of insulin secretion by beta cells)
  • 5.1.4(e) the differences between Type 1 and Type 2 diabetes mellitus
  • 5.1.4(f) the potential treatments for diabetes mellitus (insulin from GM bacteria and the potential use of stem cells)

How to use this page

Write your answer on paper before you open the mark scheme. Allow about 1.2 minutes per mark: the 20 questions are worth 43 marks, so about 52 minutes in total. Then mark your answer strictly against the mark scheme and read the examiners' tip underneath it. If you'd rather print the questions, download the PDF pack.

Recall

Question 1

A level Paper 1 · June 2023 · Q18(a)(i) · 1 mark · Easy

Name the region labelled B on an electron micrograph of a synapse.

Electron micrograph of the junction between two neurones, with A and C labelling the two neurones and B labelling the narrow gap between them.
Show the mark scheme Mark scheme: synaptic cleft or gap. "Synapse" ignored.

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From the examiners' report: Be precise: B is the synaptic cleft. "Synapse" on its own is the whole junction, so it doesn't score.

Question 2

A level Paper 1 · June 2023 · Q18(a)(ii) · 1 mark · Medium

Decide whether A or C is the first neurone, using evidence from the micrograph.

Question asking whether structure A or structure C in the electron micrograph is the first neurone in the pathway, with one piece of visible evidence.
Show the mark scheme Mark scheme: A, because it contains vesicles (fused with the membrane) or shows exocytosis of neurotransmitter. Must name A and give a reason.

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From the examiners' report: Say A, because you can see vesicles in it. Vesicles fuse with the presynaptic membrane and release neurotransmitter; they never move across the cleft.

Question 3

A level Paper 1 · June 2022 · Q21(a)(i) · 2 marks · Medium

Describe what is meant by an endocrine gland.

Question stating that glands can be endocrine or exocrine and asking what is meant by an endocrine gland.
Show the mark scheme Mark scheme: a group of cells that secretes hormones, directly into the blood (ductless). "Excretes" not allowed.

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From the examiners' report: Give both points: it secretes hormones, and it releases them directly into the blood (it has no duct). Don't say excretes.

Question 4

A level Paper 1 · June 2022 · Q21(a)(ii) · 1 mark · Medium

Suggest why pancreas cells that make digestive enzymes are called exocrine.

Question stating that the pancreas contains endocrine islets of Langerhans and cells that produce digestive enzymes, asking why the latter are exocrine.
Show the mark scheme Mark scheme: the digestive enzymes are released into ducts, not directly into the blood.

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From the examiners' report: Answer with where the enzymes go: into ducts, not into the blood. Saying they are secreted from the cells, or work outside them, doesn't explain exocrine.

Question 5

A level Paper 1 · June 2022 · Q21(b) · 2 marks · Easy

Suggest where the receptors for steroid hormones are, and why.

Question stating that hormones are steroid or non-steroid and that steroids are lipid soluble, asking for the location of steroid hormone receptors with a reason.
Show the mark scheme Mark scheme: inside the cell, in the cytoplasm or nucleus, because steroids can cross the cell surface membrane (phospholipid bilayer).

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From the examiners' report: Lipid-soluble steroids pass through the phospholipid bilayer, so their receptors are inside the cell. Use the term cell surface membrane or plasma membrane, not just "cell membrane".

Question 6

A level Paper 3 · June 2024 · Q5(b) · 3 marks · Easy

Identify an islet, a duct and a blood vessel on a photomicrograph of pancreatic tissue.

Photomicrograph of stained pancreatic tissue with label A on a pale islet of Langerhans, B on a duct and C on a blood vessel containing red blood cells.
Show the mark scheme Mark scheme: A, islet of Langerhans (or alpha or beta cell); B, a pancreatic duct; C, a blood vessel such as an arteriole or venule. "Capillary" not allowed.

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From the examiners' report: C contains too many red blood cells to be a capillary, so call it a blood vessel, arteriole or venule. It's pancreatic tissue, so don't name hepatic vessels.

Question 7

A level Paper 1 · June 2018 · Q16(a)(i) · 2 marks · Medium

Say which type of diabetes gestational diabetes is most like, and explain.

Question explaining that gestational diabetes causes high blood glucose in pregnancy even though normal levels of insulin are produced, asking which type of diabetes it is most like.
Show the mark scheme Mark scheme: Type 2, because insulin is still produced and the beta cells still work, but cells no longer respond to insulin (insulin resistance or fewer receptors).

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From the examiners' report: Say Type 2 and explain that insulin is still made but the target cells, not "the body", don't respond to it.

Question 8

A level Paper 1 · June 2018 · Q16(a)(ii) · 2 marks · Medium

Suggest two ways a woman with gestational diabetes can manage her condition.

Question asking for two ways a woman with gestational diabetes could manage her condition, with two numbered answer lines.
Show the mark scheme Mark scheme: low carbohydrate or sugar diet; exercise; managing weight gain; drugs such as metformin or insulin. "Healthy" or "balanced" diet ignored.

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From the examiners' report: Be specific about diet: a low-sugar or low-carbohydrate diet scores, but a "healthy diet" doesn't.

Question 9

A level Paper 1 · June 2018 · Q16(b)(i) · 1 mark · Medium

Name the other main tissue, besides skeletal muscle, that removes glucose from the blood in response to insulin.

Question stating that skeletal muscle is one of the main tissues where glucose is removed from the blood in response to insulin and asking for the other.
Show the mark scheme Mark scheme: liver (hepatic) tissue. Hepatocytes or cells ignored; other muscle ignored.

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From the examiners' report: The answer is liver tissue. The question asks for a tissue, so naming cells such as hepatocytes, or another type of muscle, didn't score.

Applying what you know

Question 10

A level Paper 3 · June 2019 · Q2(b)(i) · 2 marks · Medium

Use a diagram of ion channels to suggest why naked mole rats don't feel pain from acid.

Diagram comparing pain receptors: in naked mole rats the acid-sensing Na+ channel opens with H+ but the voltage-gated Na+ channel is blocked by H+; in other mammals the acid-sensing channel opens and the voltage-gated channel is unaffected.
Show the mark scheme Mark scheme: no or fewer action potentials along sensory neurones to the CNS, because few voltage-gated sodium channels open and there is less depolarisation. "No depolarisation" and "no Na+ enter" not allowed.

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From the examiners' report: Separate the generator potential (acid-sensing channels) from the action potential (voltage-gated channels). Say fewer sodium ions enter and fewer action potentials are sent, not none, and use "action potential" rather than "message".

Question 11

A level Paper 3 · June 2019 · Q2(b)(ii) · 1 mark · Easy

Explain how a pain receptor is an example of a transducer.

Question asking how a pain receptor is an example of a transducer.
Show the mark scheme Mark scheme: it converts a chemical (or other) stimulus into an electrical impulse or action potential. "Sensory information" ignored.

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From the examiners' report: Don't just define a transducer: apply it. Name the stimulus energy, such as chemical (H+ ions), and say the receptor converts it into electrical impulses.

Question 12

A level Paper 1 · June 2018 · Q21(a)(i) · 4 marks · Medium

Explain how tetrodotoxin, which stops voltage-gated sodium channels opening, affects neurones.

Passage about the blue-ringed octopus: its toxin TTX binds to voltage-gated sodium ion channels in the axon membrane, changes their tertiary structure and stops them opening.
Show the mark scheme Mark scheme: Na+ cannot enter; no depolarisation; membrane stays at resting potential; no action potential; no impulse conducted; no neurotransmitter released. Max 3 if only normal function is described.

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From the examiners' report: Describe what happens with TTX present, not how a normal neurone works, and say it is the axon membrane that isn't depolarised.

Question 13

A level Paper 1 · June 2018 · Q21(b) · 1 mark · Medium

Explain why action potentials travel more slowly along unmyelinated neurones.

Question stating that molluscs have unmyelinated neurones in which saltatory conduction cannot occur, asking why transmission along the axon is slower.
Show the mark scheme Mark scheme: no nodes of Ranvier; shorter local currents; the whole axon membrane must be depolarised. Jumping between nodes ignored.

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From the examiners' report: Don't repeat the stem about not jumping from node to node. Say the whole length of the axon membrane has to be depolarised.

Question 14

A level Paper 1 · June 2022 · Q21(c)(i) · 2 marks · Hard

Explain the symptoms of adrenal failure.

Information from a patient booklet: adrenal failure means too little cortisol and aldosterone; ACTH from the pituitary stimulates the adrenal cortex; symptoms include fatigue, weakness, weight loss, low blood pressure and salt craving.
Show the mark scheme Mark scheme: cortisol (glucocorticoids) regulates carbohydrate metabolism; lack of aldosterone causes low blood pressure or salt craving, as it regulates ion concentrations.

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From the examiners' report: Match each hormone to its own symptoms: cortisol regulates carbohydrate metabolism, aldosterone regulates sodium and potassium ion concentrations. Say ions, not salts.

Question 15

A level Paper 1 · June 2022 · Q21(c)(ii) · 3 marks · Easy

Explain why patients with a pituitary tumour still respond normally to danger.

Question asking why patients with a pituitary tumour have adrenal failure but still respond normally to danger or excitement.
Show the mark scheme Mark scheme: ACTH only affects the adrenal cortex; adrenaline comes from the adrenal medulla; adrenaline brings about the fight or flight response; the sympathetic nervous system also mediates it.

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From the examiners' report: Link adrenaline to the adrenal medulla, which ACTH doesn't control. If you mention the sympathetic nervous system, say it also triggers the fight or flight response.

Question 16

A level Paper 1 · November 2021 · Q17(b)(i) · 1 mark · Hard

Name the cells that secrete insulin.

Passage describing pancreas cells in culture incubated in 3 then 20 mmol dm⁻³ glucose with or without nifedipine, and a table of mean insulin secreted: 7.8 ± 0.78% without and 0.8 ± 0.15% with nifedipine.
Show the mark scheme Mark scheme: beta (β) cells.

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Question 17

A level Paper 1 · November 2021 · Q17(b)(ii) · 2 marks · Hard

Explain why the glucose concentration was raised before insulin secretion was measured.

Question asking why the scientists increased the glucose concentration around the pancreas cells before measuring insulin secretion.
Show the mark scheme Mark scheme: glucose causes the release of insulin; the change in insulin secretion is then large enough to measure. Synthesis or production ignored.

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Question 18

A level Paper 1 · November 2021 · Q17(b)(v) · 2 marks · Hard

Explain how blocking calcium channels could inhibit insulin secretion.

Question stating that nifedipine blocks Ca²⁺ channels and asking how this could inhibit insulin secretion.
Show the mark scheme Mark scheme: calcium ions don't enter the beta cells, so there is less or no exocytosis (fewer vesicles move to and fuse with the membrane). "Vesicles not secreted" not allowed.

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Experiments and extended answers

Question 19

A level Paper 1 · November 2020 · Q18(b)(ii) · 4 marks · Medium

Evaluate the conclusion that a rise in presynaptic Ca²⁺ causes an action potential in the postsynaptic neurone.

Table of stimulation strength (low, medium, high), FURA-2 fluorescence in the synaptic bulb (low, medium, high) and highest postsynaptic membrane potential (−60, +40, +40 mV); fluorescence is proportional to Ca²⁺ concentration.
Show the mark scheme Mark scheme: valid, as Ca²⁺ rises with stimulus strength and low to medium Ca²⁺ gives an action potential; Ca²⁺ causes neurotransmitter release, which opens Na+ channels, and if threshold is reached the postsynaptic membrane depolarises; but Ca²⁺ may not be the cause, and medium to high Ca²⁺ gives no further change.

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From the examiners' report: Analyse the table first: Ca²⁺ concentration rises with stimulus strength. Then explain the link (Ca²⁺ causes neurotransmitter release) and give a point against, such as no change in potential from medium to high.

Question 20

A level Paper 1 · November 2021 · Q17(c) · 6 marks · Hard

Evaluate past, current and potential treatments for Type 1 diabetes (6 marks).

Six-mark level-of-response question stating that Type 1 diabetes has been treatable for many years but treatments keep improving, and asking for an evaluation of past, current and potential treatments.
Show the mark scheme Mark scheme, Level 3: insulin from animal pancreases and from GM bacteria, plus another treatment such as pancreas or islet transplants, stem cells or immunotherapy, with advantages and disadvantages of insulin and another treatment, e.g. purity, allergy, cost, ethics, immunosuppression, donor supply.

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From the examiners' report: Evaluating means giving advantages and disadvantages, not just describing treatments. For Level 3, weigh up insulin (animal and GM) and at least one other treatment, such as transplants or stem cells.

Where students lose marks (from OCR examiners' reports and mark schemes)

Each point below is followed by wording that gained marks.

  • Fewer sodium ions, not none: Explaining why naked mole rats feel no pain from acid, many said no sodium ions enter or no depolarisation occurs, or wrote about a "signal" or "message".

    ✔ Gains credit: "Fewer voltage-gated sodium channels open, so less depolarisation and fewer action potentials along sensory neurones to the CNS"; "no depolarisation" is not allowed.

  • Vesicles fuse; they don't cross the cleft: Some students lost the mark by saying they could see vesicles moving across the synaptic cleft.

    ✔ Gains credit: "Structure A, because it contains vesicles fused with the membrane" (neurotransmitter is released by exocytosis).

  • Unmyelinated means the whole axon depolarises: Most answers repeated that the impulse can't jump from node to node, which was already in the question.

    ✔ Gains credit: "There are no nodes of Ranvier, so the whole axon membrane has to be depolarised".

  • Describe TTX at work, not a normal neurone: Weaker answers described normal nerve transmission instead of the effect of TTX, and didn't say it is the axon membrane that fails to depolarise.

    ✔ Gains credit: "Na+ cannot enter, so the axon membrane is not depolarised and stays at resting potential; no action potential is generated".

  • Cortisol for carbohydrates, aldosterone for ions: Many students didn't say cortisol regulates carbohydrate metabolism, wrote about salts instead of ions, or gave both hormones every symptom.

    ✔ Gains credit: "Cortisol regulates carbohydrate metabolism" and "lack of aldosterone causes low blood pressure because it regulates sodium ion concentration".

  • Steroid receptors sit inside the target cell: Some students said steroids can cross the membrane but still put the receptor on the membrane, or thought lipid solubility stops them getting in.

    ✔ Gains credit: "Inside the cell, in the cytoplasm or nucleus, because steroids can cross the cell surface membrane".

  • Low-carbohydrate diet, not a healthy diet: Suggesting how to manage gestational diabetes, answers that only said "maintain a healthy diet" weren't credited.

    ✔ Gains credit: "A low-carbohydrate or low-sugar diet" and "exercise".

  • Too many red cells for a capillary: Labelling pancreatic tissue, some students called structure C a capillary or named a hepatic blood vessel.

    ✔ Gains credit: "C = (named) blood vessel, e.g. arteriole or venule"; "capillary" is not allowed.

Download the questions

Download the PDF pack (20 questions, mark schemes at the end)

Keep practising

Questions, mark schemes and examiners' report extracts © OCR.

Tom Whitburn
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