Co-ordination & Response (Edexcel GCSE Biology)

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 an eye.

Figure 1

(i) When the eye changes from focusing on a distant object to focusing on a near object

(1)

☐ A the lens gets thinner to bend the light rays more 
☐ B the lens gets thicker to bend the light rays more
☐ C the lens gets thinner to bend the light rays less
☐ D the lens gets thicker to bend the light rays less

(ii) Give a reason why people who are short-sighted cannot see distant objects clearly.

(1)

(iii) State the type of lens that can be used to correct short-sightedness.

(1)

A student was given the hypothesis ‘People with brown eyes are more likely to be short-sighted than people with blue eyes.’

Devise a plan to test this hypothesis.

Figure 1 shows a picture seen through healthy eyes and the same picture seen through eyes affected by cataracts.

Figure 1 

(i)  In which part of the eye do cataracts form?

(1)

☐ A retina

☐ B iris

☐ C cornea

☐ D lens

(ii) Explain why the picture seen through eyes with cataracts is less clear.

(2)

Figure 2 shows the estimated number of people with cataracts in the world between 1980 and 2020.

Figure 2

Describe the change in the estimated number of people with cataracts between 1980 and 2020.

(i) Explain how cataracts are currently treated.

(2)

(ii) Scientists are developing a new treatment using eye drops for cataracts.

Describe the advantages of using eye drops to treat cataracts rather than the current treatment.

(2)

The effect of age on focusing distance was investigated.

Volunteers of different ages had their eyes tested.

Each volunteer was asked to read words from a book. The book was moved closer to their eyes.

When the words became out of focus, the distance was recorded.

Figure 1 shows the results.

Figure 1

(i) Calculate the mean distance for the volunteers aged 50.

Give your answer to three significant figures.

(3)

.......................................... mm

(ii) Give one conclusion that can be made from the data in Figure 1.

(1)

(iii) Give two improvements that are needed in this investigation before a valid conclusion can be made.

(2)

1................................................
2.................................................

Which part of the eye detects coloured light?

☐ A iris

☐ B lens

☐ C cones 

☐ D cornea

Figure 2 shows light rays entering the eye of a person with normal vision.

Figure 2

(i) Describe how light rays are focused to give normal vision.

(2)

(ii) Figure 3 shows light rays entering the eye of a person with an eye defect and two lenses that can be used to correct eye defects.

Figure 3

Explain which lens would correct the eye defect shown in Figure 3.

(2)

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 a diagram of the human eye.

Figure 1

(i) Which row in the table gives the function of structure X and structure Y?

(1)

(ii) Describe the changes that occur in the eye when a bright light is directed into the eye.

(2)

Higher Tier Only

Eye tests can detect some brain tumours.

(i) State one other way that brain tumours can be detected.

(1)

(ii) Describe why a brain tumour is difficult to treat.

(2)

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)

(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 the responses, A and B, of a human eye to differing environmental conditions. 

Figure 1

Suggest and explain the differing environmental conditions and their effects on the eye as shown in Figure 1.

Using your knowledge of the eye, suggest why Phrase A is more accurate than Phrase B below to describe the change of shape of the lens during a change of focus from a distant object to a close-up object. 

Phrase A The lens shape is changed to accommodate the angle of entry of light rays. 

Phrase B The lens changes its shape to accommodate the angle of entry of light rays. 

Age-related long-sightedness is a common feature of the ageing process and tends to affect people from around age 40 onwards. Sufferers are unable to focus on close-up objects such as when reading a book. 

Suggest and explain a possible reason for age-related long-sightedness and a remedy. You may use the sketches in Figure 2 to illustrate your answer. 

Figure 2

Name the eye condition that usually affects only males, and is hereditary and untreatable.

Higher Tier Only

Figure 1 shows a human brain with four regions labelled A - D. 

Figure 1

Identify regions A - D and give an example of a role of each region.

Higher Tier Only

Ancient scientists including Aristotle (4^th Century BCE) believed that the brain's main function was to allow excess heat to be radiated from the body. This has since been disproved by other scientists.

Suggest and explain an aspect of the brain's appearance that caused Aristotle to put forward this theory of the brain's function. 

Higher Tier only

In 1975, a woman standing on a railway station platform was hit from behind by the open carriage door of a moving train. Sadly, she sustained a serious injury to the back of her head and was blinded instantly.

Explain why the woman lost her sight after this incident. 

Higher Tier only

Sophisticated scanning techniques like CT and PET have allowed doctors to visualise brain function and diagnose disease, as an alternative to the use of invasive procedures like surgery. This has allowed information to be gathered much more safely and quickly in hospitals.

Contrast the techniques of CT and PET for providing information on brain function. 

A measles infection can cause inflammation of the brain.

Figure 1 shows a brain.

Figure 1

(i) Name the part of the brain labelled X.

(1)

(ii) The death rate from measles is 0.15%.

In 2015, 134 250 people died from measles.

Calculate the number of people infected with measles in 2015.

Give your answer in standard form.

(3)

..................................... people

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 optic nerve is responsible for carrying electrical impulses to the brain from the eye

The eye responds to changes in the environment, such as changing light levels. Figure 2 shows a section of the eye.

Figure 2

State the structure and function of parts A, B and C in Figure 2.

(3)

Astigmatism is an eye condition that causes blurred vision and short-sightedness.

(i) Explain, in terms of light entering the eye, how short-sightedness is caused.

(4)

(ii) Suggest what type of lens could be used to correct astigmatism and explain how this would work.

(3)

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 3 below.

Figure 3

(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)

Higher Tier Only

Advances in brain scanning mean that signs of MS can be picked up much earlier than in previous years. 

Magnetic Resonance Imaging (MRI) scans are the most effective way to detect changes in the brain tissue that highlight MS. The paler the appearance of the tissue, the greater the damage to the myelin sheath. 

Figure 1 shows an MRI scan comparing a brain of a person without MS to a brain of a person that has MS.

Figure 1

(i) Describe how the scan in Figure 1 allowed MS to be diagnosed.

(2)

(ii) State two advantages of MRI scanning to assess brain function compared to the use of electrodes during brain surgery.

(2)