A toxin in the venom of some spiders makes the vesicles in an axon terminal release neurotransmitter into a synapse, even when no impulse has arrived.
Which statement explains what happens at the synapse when the toxin is present?
No impulse starts in the next neurone, because an electrical impulse must cross the gap first.
Neurotransmitter diffuses across the gap and binds to receptor molecules, so an impulse starts in the next neurone.
Neurotransmitter is broken down as soon as it is released, so no impulse starts in the next neurone.
Neurotransmitter binds to the first neurone, so an impulse travels backwards along its axon.
135 exam-style questions on OCR GCSE Biology 3.1 Coordination and control – the nervous system, covering 3.1.1 Structure of the nervous system, 3.1.2 Coordinated response, 3.1.3 The reflex arc, 3.1.4 Structure of the eye, 3.1.5 Defects of the eye, 3.1.6 Structure and function of the brain, 3.1.7 Difficulties of investigating brain function, and 3.1.8 Limitations in treating nervous system damage. Each one has a worked solution and a mark scheme showing where the marks go.