[Nicolas Sanchez]

Up

0

Down

::

A lizard was placed in a chamber with a constant flow of air. The temperature of the chamber was varied between 25°C and 10 °C. Apart from temperature and time, all other variables were kept constant.
The carbon dioxide concentrations in the air leaving the chamber are shown in the graph.

[see graph below]

Which of the following statements is/are correct?

1 Between 25 °C and 10 °C the respiration rate of the lizard is inversely proportional to
the environmental temperature.
2 The data demonstrates that the lizard is only respiring aerobically.
3 The carbon dioxide could be detected by passing the air leaving the chamber through limewater.

A. none of them
B. 1 only
C. 2 only
D. 3 only
E. 1 and 2 only
F. 1 and 3 only
G. 2 and 3 only
H. 1, 2 and 3

Jump to the accepted answer

Discussion

[Paris]

Up

0

Down

::

This is a weird one so let’s take a look at the statements individually.

1. The environmental temperature decreases from 25 degrees to 10 degrees. The breathing rate of the lizard seems to be proportional to the lowering of the temperatures since the levels of carbon dioxide demonstrate the lizard’s aerobic respiration which gets slower and slower to preserve heat.

2. The carbon dioxide concentration only increases when carbon dioxide is released. Aerobic respiration, compared to anaerobic respiration, releases CO2. The fact that the carbon dioxide concentration increases does not guarantee the absence of anaerobic respiration taking place in the lizard. Therefore, this is false.

3. Limewater is famously used to test for carbon dioxide. This is correct.

The answer is D.