Co-ordination & Response (Edexcel GCSE Combined Science: Biology): Exam Questions

Figure 1 shows the structures of two neurones, A and B. 

Figure 1

Identify the kind of neurone that Neurone A is.

Identify the destination of the impulse carried by Neurone B.

The boxes in Figure 2 show the structures and impulses that form part of a processed (voluntary) response. The stimulus is a person tapping another person on the shoulder. The second person decides to turn around (to see who tapped them on the shoulder) as their response. 

Figure 2

Place the boxes from Figure 2 into chronological order to describe the pattern of events in a processed response. The first one has been completed for you.

Describe two features of a processed response that distinguish it from a reflex response. 

Describe the differences between the structures and functions of a sensory neurone and a motor neurone.

The speed of a nervous impulse travelling along a myelinated axon is around 150 metres per second. 

A sensory impulse generated in a man's toe travels 1.5 metres along myelinated axons to his central nervous system, crossing 4 synapses on its journey.

The average time required for a synapse to transmit an impulse is 2 milliseconds, (or 2 × 10^-3 seconds).

Calculate the overall time taken for the nervous impulse to reach the man's central nervous system.

Suggest and explain how the time taken to transmit the impulse would differ if the impulse were to travel along unmyelinated axons. 

Figure 1 shows the number of neurones in the brain of different animals.

Figure 1

(i) Calculate the difference between the number of neurones in the brain of the rat and the brain of the frog.

Give your answer in standard form.

(2)

........................................ neurones

(ii) Most neurones in the brain are unmyelinated whereas motor neurones are myelinated.

Explain why myelination is needed on motor neurones but not on neurones in the brain.

(3)

Figure 2 shows a sensory neurone.

Figure 2

(i) Label the axon on Figure 2.

(1)

(ii) Describe the role of sensory neurones.

(2)

Explain how impulses are transmitted at synapses.

Figure 1 shows part of a reflex arc in the spinal cord.

Figure 1

(i) Describe how an impulse passes from the relay neurone to the motor neurone.

(3)

(ii) Explain the function of a reflex arc.

(2)

A scientist investigated the reaction times of five students using a computer program. The computer screen showed a blue square at the start. As soon as the blue square turned yellow, each student had to press a key on the keyboard as fast as possible. Figure 2 shows the results for the five students.

Figure 2

(i) Which is the median result for these students?

(1)

☐ A 200 milliseconds

☐ B 210 milliseconds

☐ C 215 milliseconds

☐ D 225 milliseconds

(ii) The scientist wanted to investigate if the colours of the squares used on the computer program affected reaction time.

The computer program started with blue squares that turned into yellow squares.

Describe how the scientist could compare the reaction times of these students when they respond to red squares turning into yellow squares.

(3)

Figure 1 shows a neurone found in the human nervous system.

Figure 1

(i) State the name of the type of neurone seen in Figure 1 and describe its role in the nervous system.

(2)

(ii) Label the dendrites on Figure 1.

(1)

The nervous system contains important structures called synapses. 

Explain how a signal is transmitted at a synapse.

Some painkillers work by reducing the ability of synapses to transmit signals.

One scientist investigated the effect of different painkillers on the amount of pain felt by the patient. They tested paracetamol, ibuprofen and a placebo (sugar tablet containing no medication).

The results are shown in Figure 2 below.

Figure 2

(i) State why the scientist decided to use a placebo in the experiment. 

(1)

(ii) A student concluded that paracetamol was the most effective painkiller. Evaluate this conclusion.

(4)

The human nervous system is responsible for detecting and responding to changes in our environment. 

Describe how impulses in the reflex arc are transmitted in order to decrease the chances of getting hurt when accidentally touching a hot saucepan. 

Two students decided to investigate the speed of transmission of electrical impulses in the nervous system. 

They decided to test how caffeine affected their reaction times. Student A drank a 330ml caffeinated sports drink while Student B drank a 330ml glass of water. They tested their reaction times every 5 minutes by dropping a ruler between their fingers and timing how long it took to catch the ruler.

The results of their experiment are shown in Table 1 below.

Table 1

(i) Plot a graph of these results.

(5)

(ii) The caffeinated sports drink manufacturer wants to advertise the effects of their sports  drink on reaction time.

Give two improvements that could be made to this experiment to make the results more reliable.

(2)

Impulses in neurones in the reflex arc can travel at 120 metres per second. 

The sensory neurone in a single reflex arc is 76mm long.

(i) Calculate the time an impulse takes to travel the length of this sensory neurone.

Use the equation:    

(3)

(ii) Multiple sclerosis (MS) is an autoimmune condition, caused when the body mistakes its own cells for foreign substances and this can trigger an immune response. The outcome of this is that the immune system attacks the nerve cells, and consequently the myelin sheath in the brain and nervous system becomes damaged. 

Explain the role of the myelin sheath and suggest why people with MS might have slower reactions than people without MS. 

(2)