Aerobic respiration

Plants and animals have adaptations that help them survive.

A stingray is an animal that lives in the sea. Seagrass is a plant that grows on the sea floor.

Figure 8 shows a stingray swimming above seagrass.

Draw one line from each adaptation of seagrass to how the adaptation helps the seagrass survive.

In the stingray, gas exchange takes place in the gills.

Name the organs where gas exchange takes place in humans.

Gills are adapted to maximise gas exchange.

Which two features of gills help to maximise gas exchange?

Tick () two boxes.

Stingrays rest on the sea floor.

Table 4 shows information about the metabolic rate of a stingray.

Calculate how many times greater the metabolic rate of the stingray is when swimming compared with when resting.

Give your answer to the nearest whole number.

When the metabolic rate of the stingray increases, the rate of aerobic respiration in the stingray increases.

Complete the word equation for aerobic respiration.

Choose answers from the box.

Explain why the rate of respiration in the stingray increases when the stingray starts to swim.

Some plants can use anaerobic respiration.

Which two substances are produced during anaerobic respiration in plants?

Tick () two boxes.

This question is about the human circulatory system.

Blood plasma transports blood cells around the body.

Give one other function of blood plasma.

Do not refer to oxygen in your answer.

Figure 5 shows a red blood cell.

The image of the red blood cell in Figure 5 is magnified 7200 times.

Calculate the real diameter of the red blood cell.

Give your answer in micrometres (µm).

Figure 6 shows the heart.

Blood pressure is a measure of the force of the blood against the walls of the blood vessels.

Table 5 shows information about the different types of blood vessel shown in Figure 6.

Complete Table 5 using the correct letters from Figure 6.

One row has been completed for you.

Name blood vessel D in Figure 6.

Describe the structure of the walls of an artery.

An athlete ran on a running machine.

The athlete:

• reached their maximum intensity of exercise and then stopped exercising

• had their use of oxygen recorded

• had the lactic acid concentration in their blood recorded.

During the exercise the athlete respired aerobically and anaerobically.

Explain why anaerobic respiration is less efficient than aerobic respiration.

Figure 7 shows the athlete’s use of oxygen and the lactic acid concentration of blood during exercise and after exercise.

Explain why the use of oxygen remained high after the athlete stopped exercising.

Some athletes regularly exercise in conditions that increase the number of red blood cells.

Explain why having an increased number of red blood cells is an advantage to an athlete.

Diffusion is important for gas exchange.

Define the term ‘diffusion’.

Fish exchange gases through gills.

Oxygen from the water enters the blood of a fish through the gills.

Figure 8 shows part of a gill.

Explain how gills are adapted to maximise the exchange of oxygen between the water and the blood.

Some fish rest on the sea floor.

Explain why the metabolic rate of a fish is higher when swimming compared with when resting.

Cystic fibrosis (CF) is an inherited disorder caused by a faulty gene.

Where in a cell would the CF gene be found?

CF affects many organs in the body.

The main organs affected are:

• the lungs

• the pancreas

• the small intestine.

Figure 7 shows organs of the human body.

Which letters in Figure 7 show the lungs, the pancreas and the small intestine?

Tick () one box.

The pancreas produces several digestive enzymes.

CF reduces the amount of each enzyme that reaches the small intestine.

Explain why a person with CF has:

• difficulty digesting food

• difficulty gaining body mass.

Gas exchange happens in the alveoli in the lungs.

Describe three features of the alveoli that help maximise gas exchange.

CF reduces the amount of oxygen that can enter the blood from the alveoli.

Explain how a reduced amount of oxygen entering the blood will affect the human body.

Cystic fibrosis (CF) is an inherited disorder caused by a faulty gene.

Where in a cell would the CF gene be found?

CF affects many organs in the body.

The main organs affected are:

• the lungs

• the pancreas

• the small intestine.

Figure 2 shows organs of the human body.

Which letters in Figure 2 show the lungs, the pancreas and the small intestine?

Tick (✓) one box.

The pancreas produces several digestive enzymes.

CF reduces the amount of each enzyme that reaches the small intestine.

Explain why a person with CF has:

• difficulty digesting food

• difficulty gaining body mass.

Gas exchange happens in the alveoli in the lungs.

Describe three features of the alveoli that help maximise gas exchange.

CF reduces the amount of oxygen that can enter the blood from the alveoli.

Explain how a reduced amount of oxygen entering the blood will affect the human body.

Photosynthesis produces oxygen.

Complete the word equation for photosynthesis.

Choose answers from the box.

_____________________ + _____________________ → _____________________ + oxygen

Explain how oxygen is used in cells.

A student investigated the effect of light from different coloured light bulbs on photosynthesis.

The student:

• used pondweed in a beaker of water

• used different coloured light bulbs in a lamp

• counted the number of bubbles of oxygen the pondweed produced in 2 minutes for each colour of light bulb.

Give one hazard the student would need to consider when using the apparatus in this investigation.

Give the risk the hazard would cause.

The student needed to keep the temperature of the water in the beaker the same throughout the investigation.

Describe how the student could keep the temperature of the water the same.

The beaker of water contained the pondweed.

Explain why the temperature of the water in the beaker needed to be kept the same throughout the investigation.

Table 3 shows the results.

Which colour of light caused the highest rate of photosynthesis in the pondweed?

Tick (✓) one box.

What is the best way to display the data in Table 3 ?

Tick (✓) one box.

The student wanted to measure the volume of oxygen the pondweed produced in 2 minutes.

Name one piece of apparatus the student could use to measure the volume of oxygen.

Another student investigated the effect of light intensity on the rate of photosynthesis.

Figure 1 shows the results.

Describe what Figure 1 shows about the relationship between light intensity and the rate of photosynthesis.

All living organisms respire.

What is the chemical equation for aerobic respiration?

Tick (✓) one box.

Name the sub-cellular structures where aerobic respiration takes place.

Energy is released in respiration.

Give two uses of the energy released in respiration.

Describe two differences between aerobic and anaerobic respiration in humans.

Do not refer to oxygen in your answer.

What are the two products of anaerobic respiration in plant cells?

Tick (✓) two boxes.

A scientist investigated respiration and photosynthesis using some pondweed and a

pond snail. Figure 6 shows the apparatus used.

The apparatus was left in a well-lit room for 5 days.

The data logger recorded the concentration of carbon dioxide continuously.

After 5 days, the scientist completely covered the boiling tube with black paper.

The data logger continued to record the concentration of carbon dioxide.

Figure 7 shows the concentration of carbon dioxide inside the boiling tube over

15 days.

Explain why the concentration of carbon dioxide in the tube stayed the same between day 0 and day 5.

Suggest why the concentration of carbon dioxide increased between day 5 and day 10.

On day 10, the pond snail died.

Explain why the death of the pond snail caused the concentration of carbon dioxide to increase after day 10.

A student investigated respiration in yeast.

This is the method used.

1. Add 5 cm³ of a yeast and water mixture to each measuring cylinder.

2. Add different masses of sugar to each measuring cylinder.

3. Mix the contents of each measuring cylinder gently for 5 seconds.

4. Put the measuring cylinders in a water bath at 25 °C

5. Over the next 20 minutes, record the maximum volume the foam reaches in each measuring cylinder.

Figure 8 shows the student’s results.

Which two variables did the student control in the method?

Tick (✓) two boxes.

Table 3 shows the results.

What is value X in Table 3 ?

Use Figure 8.

In the investigation, the yeast respires and releases a gas which causes the foam to rise.

Which gas causes the foam to rise?

Tick (✓) one box.

What conclusion can you make about the relationship between the mass of sugar used and the volume of gas produced?

Why was no foam produced in the mixture with 0 g of sugar?

Why was the measuring cylinder with 0 g of sugar included in the investigation?

The top of the mixture can be covered with a layer of oil after step 3 in the method.

Suggest why the layer of oil stops the yeast respiring aerobically.

What other substance is produced during anaerobic respiration in yeast?

Tick (✓) one box.