Respiration (Edexcel GCSE Biology)

Give a definition of the term 'respiration'.

In an investigation, a person ran at different speeds. 

The graph in Figure 1 shows the concentration of lactic acid in the runner's blood and the runner's heart rate during the run. 

When the running speed is 22 km h^-1, the stroke volume of the runner is 0.18 dm³.

Calculate the cardiac output of the runner using the equation. State the appropriate units. 

Referring to the data in Figure 1, state the concentration of lactic acid in the blood when the heart rate has reached its maximum level. 

Explain why the concentration of lactic acid changes at running speeds greater than 18 km h^-1.

In the absence of sufficient oxygen, cells respire anaerobically.

Identify the compounds X and Y to complete the word equation for anaerobic respiration in yeast cells.

Glucose → Compound X + Compound Y

State two industrial processes that make use of anaerobic respiration of yeast cells.

(2)

Compare anaerobic respiration in the muscle cell of an animal with anaerobic respiration in a yeast cell.

(3)

Identify three different ways in which animals use the energy released by aerobic respiration.

Figure 1 shows three respirometers set up for an investigation into respiration in peas. 

Figure 1

• Respirometer A contained germinating peas.
• Respirometer B contained peas that had been boiled and cooled before the experiment. 
• Respirometer C contained glass beads.
• All other aspects of each respirometer were kept constant. 

All three respirometers were placed in a water bath at 25°C for 30 minutes. The reduction in oxygen levels inside each respirometer was measured using a data logger. 

Explain why the respirometers were placed in a water bath at 25°C for 30 minutes.

The scientist carrying out the study recorded the change in oxygen levels within the 3 respirometers over a 30-minute period. 

The results are shown below

A  10 minutes (-0.8) cm³, 20 minutes (-1.6) cm³, 30 minutes (-2.4) cm³

B  10 minutes (-0.1) cm³, 20 minutes (-0.1) cm³, 30 minutes (-0.1) cm³

C  No change

Complete the table below with these results. 

Calculate the rate of oxygen consumption per second for the peas in Respirometer A.

The graph in Figure 1 shows the volume of oxygen an athlete absorbs at different running speeds.

(1)

A student investigated respiration in three different organisms.

Red hydrogencarbonate indicator was placed in each of three test tubes.

Gauze was placed in each test tube to hold the organisms.

In test tube 1 the student placed four germinating peas.

In test tube 2 the student placed four dried peas.

In test tube 3 the student placed four mealworms.

Bungs were added to each of the test tubes.

The three test tubes were left for one hour.

The equipment used is shown in Figure 1.

Figure 1

(2)

(2)

Hydrogencarbonate indicator changes from red to yellow when more carbon dioxide is present.

The results for this investigation are shown in Figure 2.

Figure 2

(2)

(1)

Explain why cellular respiration is essential for living organisms.

Some scientists wanted to investigate respiration rates in different areas of a plant. 

They measured carbon dioxide production in the roots and leaves of a plant at night time. 

Table 1 shows the rate of carbon dioxide production that they measured.

Calculate the percentage difference in carbon dioxide production in the leaves compared to the roots.

The carbon dioxide readings shown in Table 1 were all taken during the night-time.

Give a reason for this.

Suggest an explanation for the results shown in Table 1.

In order to collect the data about carbon dioxide produced by the roots of the plant, scientists took samples of the air from the soil around the plant roots and adjusted it to account for atmospheric carbon dioxide levels.

Suggest why the readings they took may still be higher than the actual rate of carbon dioxide production in the plant roots.

Compare the processes of aerobic and anaerobic respiration.

Figure 1 shows the oxygen and carbon dioxide composition of inhaled air and exhaled air from the lungs.

Figure 1

Describe and explain the differences between inhaled and exhaled air as shown in Figure 1.

The data in Table 2 shows the distribution of blood to different organs of the body before and after exercise.

Table 2

Explain the reason for the changes in distribution of blood to the arteries of the heart and muscles of the skeleton, as shown in Table 2.

Table 2 shows that blood flow to the skin increases significantly.

Explain why this is.

A student used the equipment shown in Figure 1 to investigate the rate of anaerobic respiration in yeast.

Figure 1

The student measured the volume of carbon dioxide produced by 5 g of yeast over 60 minutes. Their results are shown in Table 1.

Table 1

Calculate the rate of carbon dioxide production in cm³ g^-1min^-1 for the first 30 minutes of the investigation.

With reference to the data in Table 1, suggest why the rate of carbon dioxide production decreased between 50 and 60 minutes.

Suggest a reason for the layer of oil shown in Figure 1. 

With reference to Table 1:

(2)

A student wanted to investigate the rate of respiration in living organisms at different temperatures.

The student was provided with the following equipment shown in Figure 1:

Figure 1

Devise a plan for the student to complete this investigation.

Include a control and any variables that the student would need to consider.

Explain how the accuracy of the equipment shown in Figure 1 could be improved.