The effect the surface area of an organism has on the rate of heat loss.

Biology coursework write-up:

Introduction

The surface area: volume ratio of an organism gets larger as the organism gets smaller. As the surface area of an organism is what affects heat loss, you are unlikely to get small animals such as insects in the North Pole and large animals such as polar bears in the desert but you do get large animals such as elephants in the desert and small animals such as rabbits in the arctic. BUT: These are warm blooded animals so can control their body temperature where as lizards are cold blooded and do not have the ability to control it. Therefore to make the experiment easier I will use water to represent a cold blooded animal as water being an inanimate object, does not have the ability to control its temperature like a cold blooded animal.

Aim

The aim of this experiment is to find out the relationship between surface area and rate of heat loss.

Variables

Prediction

As the volume of water increases, the rate of heat loss will decrease.

This is because the surface area to volume ratio of the higher volumes is much lower than that of the smaller volumes, therefore the smaller volumes will drop 100C very quickly compared to the higher volumes.

Method

I will use volumes 20,30,40,50,60,70,80,90 and 100cm3 of water at 700C

The water will be put in a beaker and the ...

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Aim

The aim of this experiment is to find out the relationship between surface area and rate of heat loss.

Variables

Prediction

As the volume of water increases, the rate of heat loss will decrease.

Method

I will use volumes 20,30,40,50,60,70,80,90 and 100cm3 of water at 700C

The water will be put in a beaker and the time for the temperature to drop from 70-600C will be recorded. To start at 700C I will allow the water at a higher temperature to cool.

Apparatus

Boiling tubes

Thermometers

Kettle (to heat water)

Stopwatches

Amendments

As the boiling tubes only hold 50cm3 I will use 10, 20, 30, 40 and 50cm3 of water to take results.

RESULTS

Time taken is given in minutes and seconds.

Volume Time taken 1 Time taken 2 Average Volume:surface area ratio

10 4:14 4:35 4:24.5 0.1

20 4:43 5:06 4:54.5 0.2

30 5:11 5:11 5:11 0.3

40 5:22 5:24 5:23 0.4

50 5:37 5:41 5:39 0.5

Volume: surface area ratio Rate of heat loss (0C per minute)

0.1 0.425

0.2 0.455

0.3 0.511

0.4 0.523

0.5 0.539

Conclusion

As the volume to surface area ratio increased, the rate of heat loss decreased. This agrees with my prediction.

Analysis

The results for the experiment could have been slightly inaccurate as room temperature increased by 20C during the experiment. I think using real animals could prove the prediction and this experiment only shows results for animals without the ability to control their body temperature, e.g. cold-blooded animals. Using warm-blooded animals or a source of heat could be done as a follow up experiment.