paper 1 exam questions

Question 1

describe how an impulse passes from the relay neurone to the motor neurone (3 marks)

Answer 1

• impulse in the relay neurone triggers release of neurotransmitters
• neurotransmitters diffuse across the synapse
• a new impulse is triggered in the motor neurone

Question 2

explain how impulses are transmitted at synapses (4 marks)

Answer 2

• synapse is a gap between neurones
• electrical impulse stimulates the release of chemical (neurotransmitter)
• neurotransmitters diffuse across the synapse
• this stimulates an electrical impulse in the next neurone

Question 3

explain the function of the reflex arc (2 marks)

Answer 3

• an involuntary process which occurs in response to danger

- bypasses brain which means faster reaction

Question 4

explain how a signal is transmitted at a synapse and how painkillers reduce the pain felt by the person (6 marks)

Answer 4

• synapse is a gap between 2 neurones
• neurones transmit electrical impulses which trigger the release of neurotransmitters
• neurotransmitters diffuse across the synapse and bind to the receptors on the next neurone
• this triggers an electrical impulse in the next neurone and the process repeats
• painkillers prevents neurotransmitters from binding to the receptors, meaning an electric impulse will not be triggered and the person will not feel any pain

Question 5

describe the changes in the eye that occur when a bright light is shone into the eye (2 marks)

Answer 5

• iris contracts (gets larger)
• pupil becomes smaller
• to reduce amount of light entering the eye

Question 6

reasons why the three domain classification system was proposed

Answer 6

• genetic analysis
• better microscopes = more knowledge
• based on DNA/genetics