IGNOU FST CHAPTER 1 Q13

Q)With an example explain the components that make up the method of science?
Ans)We are aware of the fact that plants make their own food by using sunlight carbon dioxide and water and give off oxygen in this process. Sunlight is make up of different colors visible to the eye which you might have seen in a rainbow. the question we may like to ask is whether light is equally effective in photosynthesis or light of any specific color is more effective than the others. We can have a set of hypothesis as

• Light of all colors is equally effective
• Light of one specific color is more effective than other color.

The nest step is to set up a hypothesis. The experiment can be easily set up. We take three twigs of a water plant like hydrilla, submerge them separately and cover them with bell jars. Then we wrap each bell jar with cellophane papers colored green yellow and red and put the three sets out in the sunlight. Thus each of these twigs is getting light of only one color.We assume that the amount of light reaching the twigs is the same. After some time we observe bubbles coming out of water in the bell jar.The rate at which bubbles come out indicates the rate at which plant is able to make its food. In this experiment there are four factors which are like to vary; the three twigs could be different, the amount of carbon dioxide in the three bell jars and the colors of light they could receive could vary. To test the effect of any of these factors we have to ensure that one of these remains the same.Thus if we are testing for the effect of light of different colors, the twigs, the amount of water and carbon dioxide in all the cases should remain the same in all the three cases. We can take similar twigs from the same plant and we can assume that carbon dioxide is same i each bell jar because they are of equal size. We can also assume that the amount of water  is same in each bell jar. Now if the rates at which gas bubbles come out in the three bell jars are different we can say that this is due to difference in colors.In this case we conclude that the rate is highest in the case of twig receiving red light. Thus we conclude that red light is more effective in food making by plants when compared with green or yellow colored light. This rejects the first hypothesis and gives us a partial proof for the second one. We could continue this experiment and test whether other colors like orange blue etc are more effective than red.