Respiration (Cambridge O Level Biology)

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]

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.

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.

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.