Aerobic respiration

The heart is an organ that pumps blood around the body.

Figure 10 is a model of the heart and shows the direction of blood flow.

Draw one line from each blood vessel shown in Figure 10 to the name of the blood vessel.

Heart rate is controlled by a group of cells.

The group of cells acts as a pacemaker.

Where would the pacemaker be located in Figure 10 ?

Tick () one box.

Heart muscle cells contain many mitochondria.

Explain why heart muscle cells contain many mitochondria.

A small number of people are born with a ‘hole in the heart’.

Figure 11 shows the position of a hole in the heart.

The hole allows some blood from the right side of the heart to mix with blood in the left side of the heart.

Suggest two symptoms of having a hole in the heart.

In an operation to repair a hole in the heart:

• a flexible tube is inserted into a blood vessel and guided to the heart

• a mesh patch is passed down the tube

• the mesh patch covers the hole.

Heart tissue grows around the mesh and closes the hole.

Suggest two possible risks of this operation to repair a hole in the heart.

This question is about plants.

Some plants can respire anaerobically.

Which are the two products of anaerobic respiration in plants?

Tick () two boxes.

Figure 6 shows the structure of part of a leaf

What is the name of tissue A ?

Explain how tissue A is adapted to its function.

Plants absorb water from the soil.

Describe how water is transported from the soil through plant tissues to the atmosphere.

Light intensity varies during 24 hours.

Figure 6 shows the overall exchange of carbon dioxide and oxygen for a tree at three different light intensities.

Explain the overall exchange of carbon dioxide and oxygen at the three different light intensities.

Anaerobic respiration in yeast is called fermentation.

The equation for fermentation is:

glucose → ethanol + carbon dioxide

How does the equation show that fermentation is an anaerobic reaction?

Fermentation in yeast is used in the manufacture of beer, wine and bread.

Why is fermentation used when making beer and wine?

Explain why fermentation is used when making bread.

A student investigated fermentation in yeast.

Figure 3 shows the apparatus.

This is the method used.

1. Mix yeast with sugar solution in a flask.

2. Put the flask in a water bath at 35 °C.

3. After 10 minutes attach a gas syringe to the flask.

4. Record the volume of carbon dioxide collected every 5 minutes for 1 hour.

What volume of carbon dioxide has been collected in the gas syringe in Figure 3 ?

Why did the student wait 10 minutes before attaching the gas syringe?

Tick (✓) one box.

Figure 4 shows the results.

A and B are different parts of the graph in Figure 4.

Draw one line from each part of the graph to the description of the reaction.

Part of the graph
Description of the reaction

The equation for fermentation is repeated here.

glucose → ethanol + carbon dioxide

Suggest one reason why fermentation in the flask stopped.

Fermentation is controlled by enzymes.

The investigation was repeated at 2 °C and at 75 °C.

No carbon dioxide was produced at either of these temperatures.

Suggest why no carbon dioxide was produced at 2 °C or at 75 °C.

Reason at 2 °C

Reason at 75 °C

Anaerobic respiration also happens in animal cells.

Complete the equation for anaerobic respiration in animal cells.

Choose answers from the box.

Fermentation in yeast is used in the manufacture of bread and alcoholic drinks. The equation for fermentation is: glucose → ethanol + carbon dioxide

Fermentation is an exothermic reaction. What does exothermic mean?

A student investigated the effect of temperature on fermentation in yeast. Figure 3 shows the apparatus.

This is the method used.

1. Mix yeast with sugar solution in a flask.

2. Pour a layer of oil over the surface of the mixture.

3. Put the flask in a water bath at 2 °C and leave for 20 minutes.

4. Attach a gas syringe.

5. Record the volume of gas collected every 5 minutes for 30 minutes.

6. After 30 minutes move the flask to a water bath at 35 °C.

7. Continue to record the volume of gas collected every 5 minutes.

Suggest why a layer of oil was needed on the surface of the mixture.

Suggest why the mixture was left for 20 minutes before the gas syringe was attached.

Steps 1 to 4 of the method were repeated at 35 °C.

The volume of gas collected was recorded every 5 minutes for 45 minutes. Table 2 shows the results for both flasks for the first 30 minutes. Table 3 shows the results for the last 15 minutes, when both flasks were at 35 °C.

Explain the results from 0 minutes to 45 minutes for the flask that was at 2 °C and was then moved to 35 °C. Use Table 2 and Table 3.

Explain the results from 0 minutes to 45 minutes for the flask kept at 35 °C. Use Table 2 and Table 3.

Being overweight can affect the health and life expectancy of a person.

What is one lifestyle change a person could make to help them lose body mass? Tick (✓) one box.

Exercise has many health benefits. Give two health benefits of regular exercise. Do not refer to losing body mass in your answer.

During exercise, breathing rate increases to provide more oxygen for aerobic respiration.

What is the equation for aerobic respiration? Tick (✓) one box.

Figure 1 shows the human breathing system.

Where does gas exchange take place? Tick (✓) one box.

A scientist investigated the effect of exercise on the breathing rate of four people. This is the method used.

1. Measure the resting breathing rate.

2. Exercise for 10 minutes.

3. Measure the breathing rate as soon as exercise stops.

4. Record the time taken for the breathing rate to return to the resting rate.

Table 1 shows the results.

The scientist concluded that person B was the fittest. Give two reasons that support the scientist’s conclusion. Use Table 1.

Suggest two reasons why the scientist’s conclusion may not be valid.

Give two changes that happen in the body during aerobic exercise. Do not refer to increased breathing rate in your answer.

Muscles respire anaerobically during vigorous exercise. Complete the sentences. Choose answers from the box.

Muscles respire anaerobically if they do not have

Anaerobic respiration of glucose produces.

Being overweight can affect the health and life expectancy of a person.

Give one disease related to being overweight.

Body mass index (BMI) helps to show if a person has a healthy body mass for their height. BMI is calculated using the equation:

A woman has a BMI of 27 and a body mass of 68.1 kg Calculate the woman’s height in metres.

Figure 4 shows a height-body mass chart for adults.

Which weight category describes the woman in Question 03.2 ? Tick (✓) one box.

People are encouraged to control their body mass with diet and exercise. Describe how the balance between the mass of food eaten and the amount of exercise a person does controls body mass.

During long periods of vigorous exercise the body respires anaerobically. Explain the changes that happen in the body during and after vigorous exercise.