The nervous system

Students used a reaction test card in an investigation.

The reaction test card can be used to test the reactions of car drivers.

Figure 4 shows the reaction test card.

Suggest why fast reactions are important for car drivers.

Students investigated the effect of number of hours of sleep on reaction time.

The students used the reaction test card shown in Figure 4 on page 11.

Figure 5 shows the method used.

This is the method used.

1. Record the number of hours of sleep student A had the night before the test.

2. Student B holds the lower edge of the card level with the top of student A ’s thumb.

3. Student A holds their thumb and forefinger slightly apart, with space for the card

to drop.

4. Student B drops the card.

5. Student A catches the card as quickly as possible.

6. Record the number shown at the top of student A ’s thumb.

7. Repeat steps 1 to 6 with seven other students.

Draw one line from each type of variable to the example of that variable in the investigation.

Figure 4 is repeated below.

A student said:

‘It would be better to use a ruler showing millimetres instead of the card in Figure 4.’

Why is the student correct?

Tick (✓) one box.

Figure 6 shows the results for the seven other students.

Student A had 8 hours and 30 minutes of sleep and a reaction score of 3

Plot the result for student A on Figure 6.

The mean number of hours of sleep for all students was 7.4

What was the mode for the number of hours of sleep?

A lower reaction score means a faster reaction.

What was the effect of increasing the number of hours of sleep on reaction time?

Use Figure 6.

Tick (✓) one box.

Suggest two ways the students could improve the investigation.

Do not refer to using a ruler in your answer.

Motor neurones are involved in reactions.

Figure 7 shows a motor neurone.

Figure 7

Explain one way the motor neurone cell is adapted for its function.

A student investigated the effect of either seeing a stimulus or hearing a stimulus on reaction time.

First, the student measured their reaction time to seeing a colour change. This is the method used.

1. Sit in front of a computer with a reaction timer program open.

2. Press a key on the keyboard as quickly as possible when the computer screen changes colour.

3. Record the reaction time.

4. Repeat steps 1 to 3 four more times and calculate the mean reaction time.

Next, the student measured their reaction time to hearing a sound. This is the method used.

5. Sit in front of a computer with a reaction timer program open.

6. Press a key on the keyboard as quickly as possible when the computer produces a sound.

7. Record the reaction time.

8. Repeat steps 5 to 7 four more times and calculate the mean reaction time.

Table 1 shows some variables in this investigation.

Identify each variable as an independent variable, a dependent variable or a control variable. Tick (✓) one box in each row on Table 1.

How could the method be improved? Tick (✓) one box.

A shorter reaction time means the student reacted faster. The student reacted faster as each test was repeated. Suggest one reason why the student’s reactions got faster.

Table 2 shows the results.

Complete Figure 2. You should:

• plot the data from Table 2 as a bar chart

• label each bar

• label the y-axis.

Compare the reaction time when seeing the stimulus with the reaction time when hearing the stimulus.

Caffeine is a drug that affects reaction time.

Coffee is a drink that contains caffeine.

Five students investigated the effect of drinking coffee on their reaction time.

Each student sat in front of a computer screen showing a reaction timer.

This is the method used.

1. Press any key on the keyboard when the colour of the screen changes to green.

2. Record the reaction time shown on the computer screen.

3. Drink coffee containing caffeine.

4. Wait 15 minutes then repeat steps 1 and 2.

What is the dependent variable in the investigation?

Tick (✓) one box.

Give two control variables the students should have used.

Why did the students wait 15 minutes after drinking the coffee before repeating the test?

Responding to the colour change of the screen involves a receptor in the student.

Where is the receptor in the student?

Tick (✓) one box.

Responding to the colour change of the screen involves an effector in the student.

What is the effector in the student?

Tick (✓) one box.

Table 1 shows the results.

What is the effect of drinking coffee on reaction time?

Use Table 1.

Which student had the smallest change in reaction time after drinking coffee?

Tick (✓) one box.

The students decided that one of the results was anomalous.

What should the students do with the anomalous result when calculating the mean change in reaction time?

Caffeine is a drug that decreases reaction time. A group of sixteen students investigated the effect of caffeine on reaction time. The students were all 15-year-old girls. The group was divided into 8 pairs of students. This is the method used.

1. Student A starts two stopwatches at the same time.

2. Student A then gives one of the stopwatches to Student B.

3. Student A says “stop” at the same time as stopping her stopwatch. Student B stops her stopwatch as quickly as possible after Student A says “stop”.

4. The difference in time shown on the two stopwatches is recorded. This is the reaction time of Student B.

5. Student B drinks a caffeinated drink.

6. The students wait 15 minutes and then repeat steps 1 to 4.

Suggest one control variable the students should have used in the investigation. Do not refer to age or sex in your answer.

Suggest two sources of random error when using this method to measure a person’s reaction time.

Table 1 shows the results.

Why can a mode not be determined for the data in Table 1 ?

The students decided the result from pair 8 was anomalous. The students calculated that the mean decrease in reaction time was 0.030 seconds. Describe how the students calculated the mean decrease in reaction time.

Caffeine causes the release of adrenaline. Adrenaline affects heart rate. Explain how the effect of adrenaline on heart rate might cause reaction time to decrease.

Adenosine is a different chemical made by the body.

Adenosine binds to receptors on relay neurones. Adenosine decreases the number of impulses in relay neurones. Figure 5 shows how caffeine binds to adenosine receptors on a relay neurone. When caffeine binds to adenosine receptors it blocks the receptor so adenosine cannot bind.

Label X shows the gap between the sensory neurone and the relay neurone. What is the name of the gap labelled X ?

Suggest why reaction time decreases when caffeine binds to adenosine receptors.

Human reactions are a response to an external change.

Reflex actions help to protect the body against damage. Figure 8 shows the nervous pathway for a reflex action.

A stimulus from the hot pan will cause the muscle in the arm to contract and move the finger away. Describe how the stimulus from the hot pan reaches the muscle in the arm.

A student investigated whether using the right hand or the left hand had an effect on reaction time. The student only tested right-handed people.

Describe a method for the student’s investigation. Include details of the test you would use for reaction time.

A different student carried out an investigation to see if playing tennis improved reaction time. The student used two groups of six people. Table 2 shows the results.

Calculate mean value X in Table 2.

What is the dependent variable in the student’s investigation?

The student concluded: ‘Playing tennis improves reaction time.’

Give one piece of evidence which supports the conclusion.

Give one piece of evidence which does not support the conclusion.

Human reactions are a response to an external change.

Reflex actions help to protect the body against damage. Figure 2 shows the nervous pathway for a reflex action.

A stimulus from the hot pan will cause the muscle in the arm to contract and move the finger away. Describe how the stimulus from the hot pan reaches the muscle in the arm.

A student investigated whether using the right hand or the left hand had an effect on reaction time. The student only tested right-handed people. Describe a method for the student’s investigation. Include details of the test you would use for reaction time.

A different student carried out an investigation to see if playing tennis improved reaction time. The student used two groups of six people. Table 1 shows the results.

Calculate mean value X in Table 1.

What is the dependent variable in the student’s investigation?

The student concluded: ‘Playing tennis improves reaction time.’

Give one piece of evidence which supports the conclusion.

Give one piece of evidence which does not support the conclusion.

Some students investigated the effect of drinking caffeine on reaction time.

They used a drink containing 32.25 mg of caffeine per 100 cm³

This is the method used.

1. Divide the students into four groups, A, B, C and D.

2. Measure and record the reaction time of each student using the ruler-drop test.

3. Students in:

group A drink 200 cm³ of water

group B drink 200 cm³ of the caffeine drink

group C drink 400 cm³ of the caffeine drink

group D drink 600 cm³ of the caffeine drink.

4. Repeat step 2 after 15 minutes.

Describe how to do the ruler-drop test.

Table 3 shows the mass of caffeine taken in by each student.

Calculate value X.

Why did group A drink water instead of the caffeine drink?

Table 4 was used to convert the results of the ruler-drop test into reaction times.

Estimate the reaction time for a student who recorded a distance of 23 cm

Students calculated the decrease in their reaction time after the drink compared with before the drink.

Figure 6 shows the results for each student.

Describe the effect of the mass of caffeine taken in on the decrease in reaction time.

For three students the decrease in reaction time was negative.

Give the reason why the value was negative.

What is the range of results for group C ?

Suggest two variables that should have been controlled in this investigation.

Explain why the ruler-drop test does not involve a reflex action.

Some students investigated the effect of drinking caffeine on reaction time. They used a drink containing 32.25 mg of caffeine per 100 cm³ This is the method used.

1. Divide the students into four groups, A, B, C and D.

2. Measure and record the reaction time of each student using the ruler-drop test.

3. Students in:

group A drink 200 cm³ of water

group B drink 200 cm³ of the caffeine drink

group C drink 400 cm³ of the caffeine drink

group D drink 600 cm³ of the caffeine drink.

4. Repeat step 2 after 15 minutes.

Describe how to do the ruler-drop test.

Table 1 shows the mass of caffeine taken in by each student.

Calculate value X.

Why did group A drink water instead of the caffeine drink?

Table 2 was used to convert the results of the ruler-drop test into reaction times.

Estimate the reaction time for a student who recorded a distance of 23 cm

Students calculated the decrease in their reaction time after the drink compared with before the drink. Figure 1 shows the results for each student.

Describe the effect of the mass of caffeine taken in on the decrease in reaction time.

For three students the decrease in reaction time was negative. Give the reason why the value was negative.

What is the range of results for group C ?

Suggest two variables that should have been controlled in this investigation.

Explain why the ruler-drop test does not involve a reflex action.

This question is about coordination in the human body.

Figure 2 shows a sensory neurone (nerve cell).

Which label is the cell nucleus?

Tick one box.

Which label is the receptor?

Tick one box.

Figure 3 shows the nerve pathway when a person touches a sharp pin.

Name structures A and B on Figure 3

When the finger touches the sharp pin, the muscle in the arm contracts to pull the arm away.

What type of action is this?

Tick one box.

Doctors tested people of different ages to time how long it took between touching a sharp pin and the arm muscle contracting.

At each age they tested five men and calculated a mean value for the time.

Table 1 shows the results.

How much longer does it take for the muscle to contract at 80 years of age compared to at 20 years of age?

Give your answer in seconds.

Figure 4 shows the position of some of the glands which release hormones.

Which label on Figure 4 shows the position of the pituitary gland?

Tick one box.

Luteinising hormone (LH) is a hormone released by the pituitary gland.

What is the function of LH?

Tick one box.

How does LH travel from the pituitary gland to its target organ?

Figure 5 shows the relative levels of sex hormones of three young people over 30 days.

One person is an 8-year-old girl, one is an 18-year-old boy and the other is an 18-year-old girl.

Which person is the 18-year-old boy?

Give one reason for your answer.

This question is about the nervous system. Figure 3 shows a reflex arc.

Name parts P and Q shown on Figure 3

Compare how information is transferred along a neurone with how information is transferred across gap P.

Why does a conscious action take longer than a reflex action?

Information travels at 120 metres per second in neurones. Calculate the time it would take for the information to travel 1.6 m along a neurone. Give your answer in milliseconds.

Doctors tested people of different ages to time how long it took between touching a sharp pin and the arm muscle contracting. Table 3 shows the results.

Describe the relationship between age in years and time for the muscle to contract.