Calculate how many minutes the group mice are active between 21:00 and 00:00 at 8°C.

Outline the relationship between activity and temperature from 21:00 to 03:00 in all of the mice.

Animals which are active at night are nocturnal. Suggest one advantage for mice being nocturnal.

State the relationship between temperature and metabolic rate.

Compare the results for the single mice at 15°C with those for the group mice at 15°C.

Suggest one reason why the results differ for single mice and group mice.

Explain why oxygen consumption is used as a measure of metabolic rate.

Using the data from both graphs, evaluate the hypothesis that increased activity causes an increase in metabolic rate in mice.

90 (minutes)

as temperature increases activity increases/positive correlation.

avoid predators / less competition for food

as temperature increases metabolic rate decreases/negative correlation (accept converse)

metabolic rate of group mice is always less than single mice; (accept converse)
both follow similar pattern of increases/decreases/fluctuations at same time of day;
fluctuations greater in group mice;
both most active/higher metabolic rate during evening/21:00; (accept any reference to times between 18:00 and 00:00)

single mice need to produce more heat/have greater heat loss because of greater surface exposed to air / group mice huddle together to reduce the surface exposed to air
Allow any other reasonable answer.

oxygen is required for (aerobic) respiration;
respiration produces ATP/releases energy/heat in the mice;
metabolic rate is a measure of total energy released/consumed in the body / oxygen consumption is proportional to energy released/consumed in body/ proportional to metabolic rate;

metabolic activity high when mice more active supports the hypothesis;
activity is normally correlated with energy consumption;
but another factor may be causing both to increase at the same time / correlation does not always establish cause and effect;
grouping/environmental temperature also affect metabolic rate;

Part (a) was an easy start to the question and almost all candidates gave the correct value.

In (b) most students correctly identified the relationship between activity and temperature at the given time, although there was a low but significant number of students who only described the data without being able to state a trend or a relationship.

The most common answers in (c) were that they were more protected from predators or that there was less competition for food although some students said it was easier for them to find their prey at night (mice are rodents).

In (d) candidates were again asked to identify the relationship, this time between temperature and the metabolic rate. Most were able to do this although some inverted the relationship.

In part (e) of question 1, candidates were expected to compare the results of the single and group mice. However, many listed values without making the comparisons. 

In part (f) there were some correct answers related to the sharing of heat in a group of mice and thus a lower metabolic rate, but many referred to groups of mice having less oxygen or that the sharing of tasks diminished the metabolic rate or that the value was a mean, implying a lower value could be expected.

There was good general comprehension in (g) of the use of oxygen consumption to measure metabolic rate but many students had difficulty providing clear answers, although most gained at least one mark by saying that respiration requires oxygen.

Most students had difficulty in (h) relating the data on the two graphs. Some were able to see that both metabolic activity and activity increased at the same times but others were not able to do so, simply restating data. Many did not make any evaluation of the data. Many implied that temperature was a factor, but not with sufficient clarity.