12.1 Respiration

Extended Only

Yeast can respire aerobically and anaerobically.

State the balanced chemical equation for aerobic respiration.

When yeast respires anaerobically, ethanol is produced.

Ethanol is a type of sustainable resource that can be made from a wide range of crop plants.

It can be used as a biofuel.

Table 1 summarises some information about crop plants that are used to make biofuel.

Table 1

A country has a mean temperature range of 12 °C to 24 °C. The country has a mean annual rainfall of 1000 mm.

Suggest and explain which crop plant would be the most suitable crop to grow to produce biofuel in the country.

Use the information in Table 1 to support your choice.

Respiration releases energy.

Write the word equation for aerobic respiration.

Fig. 1 shows the average daily energy requirement of different groups of males and females.

Fig. 1

[1]

An eleven-year-old male received only 8000 kJ per day for four months.

Use the data in Fig. 1 to suggest two ways this could affect him.

Use the data in Fig. 1 to make three comparisons between the energy requirements of individuals aged 17 years and adults.

Yeast cells can respire anaerobically.

Biotechnology makes use of this.

State two ways that the products of anaerobic respiration in yeast are used by humans.

Aerobic respiration increases during exercise.

State the name of the gas required for aerobic respiration.

[1]

State where aerobic respiration occurs in a cell.

[1]

Anaerobic respiration can occur when exercising vigorously.

State the word equation for anaerobic respiration in muscle cells.

[1]

State one advantage of using aerobic rather than anaerobic respiration in humans.

Researchers in the Czech Republic investigated oxygen consumption in horses.

They measured the oxygen consumption of the horses while they were exercising at four different paces: walking, trotting, cantering and galloping.

The results are shown in Fig. 1.

Fig. 1

Calculate the percentage increase in the average rate of oxygen consumption as the horses change from walking to trotting.

Show your working.

 ____________% 

Extended Only

The researchers also calculated the oxygen debt for each type of exercise.

They found that the horses developed a larger oxygen debt when they exercised by galloping and cantering rather than when they walked.

Explain why the horses developed an oxygen debt when they exercised.

Extended Only

Describe how the horses would recover from an oxygen debt when they stop exercising.

Aerobic respiration increases during exercise.

Use the words from the list to complete the definition of aerobic respiration.

Each word or phrase may be used once, more than once or not at all.

cells                  carbon dioxide                    DNA                    oxygen

the heart                     the brain                    nutrient 

Aerobic respiration is the chemical reactions in ....................................... that use ....................................... to break down ....................................... molecules to release energy.

Fig. 1 shows an adult fly, Chrysomya megacephala.

Fig. 1

State three visible features from Fig. 1 that could be used to distinguish adult insects from other arthropods.

A respirometer is shown in Fig. 2. It can be used to estimate an organism’s rate of respiration.

Fig. 2

Complete the sentences:

A respirometer can be used to calculate the ............................. of oxygen used by the fly larvae by measuring the ............................. the droplet of oil moves in one minute. A water-bath is used to ............................. the temperature of the apparatus.

[3]

The soda lime in the respirometer absorbs carbon dioxide.

Explain why this is important in this investigation. 

[1]

Fly larvae respire to release energy.

State two uses of energy in a fly larva.

[2]

Extended only

A student used a respirometer to investigate the effect of temperature on the rate of respiration of germinating seeds.

Predict the results of this investigation and explain your prediction.

Extended only

Students investigated the rate of respiration of crickets (a type of insect) using a carbon dioxide sensor and laptop as shown in Fig. 1. The sensor was fitted inside an airtight glass jar. The apparatus was set up in a room with a constant temperature of 17°C.

Fig. 1

The students found that the concentration of carbon dioxide inside the jar increased by 50ppm in 120 seconds.

Calculate the rate of carbon dioxide production as ppm per second.

Show your working and express your answer to two significant figures.

Give your answer in ppm s^-1.

Extended only

After 10 minutes, the students opened the jar by removing the sensor. They left the jar open for 5 minutes but made sure that the crickets remained in the jar. They then replaced the sensor and took more readings for another 10 minutes.

State and explain one reason for opening the jar after 10 minutes

During the investigation the temperature inside the jar increased. The temperature outside the jar remained constant.

Explain why the temperature inside the jar increased.

Researchers in Chile also investigated the rate of respiration in crickets.

They investigated the effect of temperature and body mass on the rate of respiration. They measured the rate of oxygen consumption in crickets with different body masses, at different temperatures.

The researchers’ results are shown in Fig. 2.

Fig. 2

State two conclusions that can be made from the data in Fig. 2 and support each conclusion with evidence from the graph.