Keeping the temperature the same will be difficult as the air-conditioning in the room will be on and off. I will need to put the test tube in the water bath and ensure that it is staying at a constant temperature.
I need to keep the seed type the same because some seed types might germinate under different conditions, and therefore it will give me inaccurate results. I need to keep the amount of water the same because water is one of the things needed for germination to occur. Oxygen is also needed for germination. Therefore I need to keep the amount of oxygen the same. It will be difficult to keep this the same, however, the oxygen saturation in the air should be the same for all the seeds, if they are in the same room, so as it varies; it will vary for all the test subjects. The amount of light to each seed would also be the same because they would all be kept in the same room. The weight of the seed also affects the rate of germination. The majority of the seed is the endosperm, which is the stored starch which the seed would use for germination. If the seed weighs more, it will have more stored starch, making it easier for it to germinate. I need to have my seeds all fresh and within 0.6g of the heaviest seed. For example, if the heaviest seed weighs 1g, the lightest seed I can have should be 0.4g.
Equipment:
I will require: Fresh Seeds*20
Thermometers*1
Measuring Cylinders*1
Test Tubes*12
Water Bath*3
Ruler*1
Cotton wool*30 (0.85g)
Refrigerator*1
Scales*1
I need to use the thermometer to test if the temperatures are accurate and not too hot or cold. This keeps the experiment fair and accurate. I need the measuring cylinder to accurately measure the amount of water which I put into the test tube. The water baths will be used to maintain the temperatures in the test tubes for the seeds to germinate. The ruler will be to measure the growth of the sprouts and to determine which of the seed had germinated best. I need the scales to weight the seeds and the cotton wool. The cotton wool has to be the same, because it affects the amount of light available to the seed.
Test Conditions:
Room Temp(23°c), 30°c, 40°c, 50°c, 60°c
Method:
- Measure 15ml of water in a measuring cylinder.
- Pour the water into a Test tube. Put 0.85g of cotton wool onto each test tube. Prepare 10 test tubes the same way.
- Place a seed into each individual test tube. Make sure they are embedded in the cotton wool.
- Place each test tube in the test conditions(varying temperatures)
- Observe the results and measure the growth of the radical and/or plumule after 3 days.
Modifications:
Room temperature will be changed by the air-con being on and off. I will need to place my room temperature test away from the air-con. However, the temperature will still change. However, the results in the end should be the same because all the tests are in the same room and therefore the temperature change will affect all the tests. I had to modify the amount of cotton wool in the test tubes form being 0.75g to 0.85g. This is because there would have been too little cotton wool in the test tube if I were to put in 0.75g. I changed the amount of water to be put into the test tube from 25ml to 15ml. This was because the seed would be completely submerged, thus not allowing it to have access to oxygen which it needs for respiration. By decreasing the amount of water, to only soak the cotton wool and slightly cover the seed, giving the seed the moisture it needs, and the oxygen, after the water evaporates a bit. I also changed the number of seeds which I needed. This is because if I put too many seeds in a boiling tube, there would be too little space to germinate and grow. Therefore I put two seeds in each test tube, and had two test tubes for each temperature. Therefore there is a higher chance at least one will germinate.
Diagrams:
Conclusion
The seedlings in the 40°c germinated the best, with the longest sprout out of all the tests. This is quite close to my prediction. I predicted the best temperature would have been 30°c. The best temperature for germination was 40°c. I think the germination was not as good in the room temperature (23°c) test as the 30°c or the 40°c because the rate of enzyme reaction would be lower. In the 40°c test, the enzymes reaction would have been higher. This is because the molecules would collide and move around more often at higher temperatures because they would have more kinetic energy. Over 40°c and the enzyme would become denatured and could no longer react with other molecules.
