A student wants to investigate heat loss from the outer surface of the bodies of two animals. She uses two test-tubes to represent the animals: - a large test-tube with a lower surface area to volume ratio, - a small test-tube with a higher surface area to volume ratio. - She pours hot water to almost fill each test-tube. Immediately she reads the temperature of the water in each test-tube and records the results. - She reads and records the temperature of the water in the…

Biology 5090/62 — May/June 2018

Cambridge O-Level · Alternative to Practical · worked solutions for every part, with the mark scheme

questions

marks

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Topics Observations and Measurements · Experimental Contexts · Planning Experiments and Investigations · Analysis, Conclusions and Evaluation · Microscopy and Biological Drawing · Use of Techniques, Apparatus and Materials

Q116MObservations and MeasurementsExperimental ContextsPlanning Experiments and InvestigationsAnalysis, Conclusions and EvaluationFree sample

A student wants to investigate heat loss from the outer surface of the bodies of two animals.

She uses two test-tubes to represent the animals:

a large test-tube with a lower surface area to volume ratio,
a small test-tube with a higher surface area to volume ratio.
She pours hot water to almost fill each test-tube. Immediately she reads the temperature of the water in each test-tube and records the results.
She reads and records the temperature of the water in the test-tubes every 2 minutes for the next 10 minutes.
Her results are shown in the table.

Time / minutes	Temperature / $^\circ\text{C}$
	Large test-tube	Small test-tube
0	85	85
2	77	66
4	71	51
6	66	45
8	61	41
10	58	38

(a)

(i)

State how her results could be made more reliable.

______

(ii)

State and explain one safety measure the student should take when carrying out this investigation.

______

(b)

(i)

On the grid below and using one set of axes, construct a graph with two lines to show the relationship between time and temperature of the water in the two test-tubes.

Join your points with ruled, straight lines.

Fig. 1.1

(ii)

Use your graph to determine the temperature of the water in the large test-tube at 3 minutes.

Show your working on your graph.

_____

(iii)

Describe what you can conclude about heat loss in large and small animals from the student's results.

______

(c)

Penguins are animals that need to maintain a constant body temperature. They can be found living in cold climates near the South Pole as well as in the warmer climate of New Zealand.

Using the results of this investigation, suggest and explain:

(i)

what difference there may be in the size of the penguins found in these two areas,

size = ______

explanation = ______

(ii)

why penguins stand very close together in groups when external temperatures are very low.

______

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Q2Microscopy and Biological Drawing · Experimental Contexts · Observations and Measurements · Use of Techniques, Apparatus and Materials · Planning Experiments and Investigations24M

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