internal assessment snail

VARIABLES

1. Manipulated variable
2. Responding variable
3. Controlled variable

MATERIALS AND APPARATUS

Table 1: Materials and apparatus needed for the experiment

PROCEDURE

Refer to the Biology HL Internal Assessment Handbook page 67.

DATA COLLECTION

1. Qualitative data

1. The snails move very slowly and they are very inactive.
2. The crickets move actively and jump energetically.
3. The colour of the potassium hydroxide remains colourless at the end of the experiment.
4. The crickets are more passive at the end of the experiment.

2. Quantitative data

Data Processing

Average =

Table 3: Amount of oxygen used and the weight of the animals

DISCUSSIONS

1. From the experiment, it was shown that cricket, which is a more active terrestrial animal than snail have higher rate of respiration. This means they consume oxygen and undergo cellular respiration more rapidly than snails at a given period of time.
2. Crickets, an organism from antraphoda family respires by exchanging gases through tracheal system where air reaches the tissue via trachea. They move a lot and produce sounds, thus a lot of oxygen gas must be consumed to break the food to form energy in the form of ATP that will be used in cellular respiration.
3. Snails, on the other hand move very slowly. Thus, only a small amount of oxygen is needed to break food to form energy in the form of ATP.
4. The equation for the aerobic respiration is:

                C6H12O6 + 6O2 → 6O2 + 6H2O + ATPs

5. KOH solution is used to absorb carbon dioxide produced by the animals. Filter paper is used to increase the area of KOH so that more carbon dioxide can be absorbed.

LIMITATIONS AND SUGGESTIONS

1. There are a number of limitation occur in this experiment that somehow disrupt or cause in accurate result.
2. Firstly both animals are trapped in the boiling tube. Consequently the animals don’t feel it like their environment and this may affect the rate of respiration. Therefore, a bigger container should be used to keep the animals. A bigger container may help to settle down better. Hence, respiration rate will be more accurate.
3. Secondly, the experiments are only done twice. Consequently, the result will be inaccurate. Therefore, in order to get better result, the experiments should be done more than that.
4. Thirdly, snails usually live in humid place. However, in the boiling tube, the humidity is different. Hence this will affect the rate of respiration because snails exchange the gaseous through the skin. Therefore, water should be dropped on the skin before starting the experiment.
5. Lastly, the usage of the manometer is not accurate to measure the change of the volume of carbon dioxide. Therefore, manometer should be replaced with respirometer which can give a better result.

CONCLUSION

The rate of respiration for cricket is higher compared to the rate of respiration for snail since cricket is more active compare to the snail.