IBBiologyDPHLExam QuestionsInteraction & InterdependenceChemical Signalling

Chemical Signalling (DP IB Biology: HL): Exam Questions

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Chemical Signalling

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11 mark

Which of the following signalling molecules functions as a neurotransmitter?

  • Calcium ions

  • Cytokines

  • Amines

  • Steroids

Choose your answer

21 mark

Figure 1 shows the cascade of events that occurs in a cell triggered by the binding of adrenaline to a receptor in the cell surface membrane. 

Diagram of the cell membrane showing binding of adrenaline to a receptor activating an enzyme cascade.

Figure 1

Which is the second messenger shown in this response?

  • ATP

  • cAMP

  • Adrenaline

  • Adenyl cyclase

Choose your answer

31 mark

Which of the following gives an example of positive feedback?

  • Thermoregulation

  • Regulation of blood glucose

  • Osmoregulation

  • Cervix dilation during childbirth

Choose your answer

11 mark

Which of the following correctly describes the order of events after acetylcholine successfully binds to a receptor on the postsynaptic membrane?

  • Calcium ion channels open and calcium moves across the postsynaptic membrane triggering an action potential.

  • Positively charged ions diffuse through ion channels across the membrane causing a change in voltage across the plasma membrane.

  • An action potential is triggered when a threshold level of acetylcholine receptors are occupied.

  • Sodium ions are actively pumped across the membrane to initiate an action potential in the postsynaptic neurone.

Choose your answer

21 mark

Which features are characteristic of transmembrane receptor proteins?

 

External ligand binding site

Hydrophilic amino acids

Hydrophobic phospholipid tails

Non-polar

Intracellular domains

A

✓

✓

✓

✗

✓

B

✗

✓

✓

✗

✗

C

✓

✗

✗

✓

✓

D

✓

✓

✗

✗

✓

    Choose your answer

    31 mark

    Which of the following statements correctly describes the mechanism of action and effects of the steroid hormones oestradiol and progesterone on their respective target cells?

    • Oestradiol binds to receptors in hypothalamic cells, activating gonadotropin-releasing hormone (GnRH) secretion, by preventing the receptor from binding to specific DNA sequences and halting transcription of inhibitory genes.

    • Progesterone binds to intracellular receptors in endometrial cells, promoting gene transcription that supports endometrial thickening by binding to specific DNA sequences.

    • Oestradiol binds to receptors in endometrial cells, activating gene transcription to promote thickening of the uterine lining.

    • Progesterone binds to receptors in hypothalamic cells, promoting the release of GnRH by directly activating receptors on the plasma membrane.

    Choose your answer

    41 mark

    A group of scientists wanted to investigate insulin production in mice. They fed one group of mice with a normal diet and another group with a ‘high fat’ diet (containing a high level of both fat and sugar) for three weeks beforehand. They then measured their blood insulin levels after a meal.  Their results are shown in Figure 2 below.

    lKzizRCf_2

    Figure 2. Graph to show insulin production over time in two different groups of mice.

    Which of the following conclusions cannot be drawn from the data given?

    • Consuming a 'high-fat' diet leads to a significantly higher peak in blood insulin levels in mice.

    • Insulin production is faster for the normal diet group in the first 10 minutes after consuming a meal.

    • Insulin production drops more rapidly for the normal diet group between 30 and 90 minutes after a meal.

    • Between 30 and 90 minutes after a meal, there was approximately a 90% decrease in insulin levels in the blood for mice on a 'high-fat' diet.

    Choose your answer