4.1 Key findings
Plants thrive in normal conditions and grow at a slower pace in hazy conditions as compared to plants in a normal environment.
4.2 Explanation of key findings
Plants can be affected by the physical factors of its environment. Polluted air will affect the environment, and cause the plants to grow or react in a different way than in normal air conditions. As hazy conditions make the surroundings rather dark, only a small amount of light can pass through when it is very hazy. With less light, the plant’s stomata will react in a way that when the surrounding conditions looks like the night, the plant will close its stomata, which will hinder the plant’s growth. As haze scatters it absorbs solar radiation, which reduces the sunlight reaching the surface by a certain percentage, thus reducing amount of light absorbed and nutrition produced, which in turn hinders the plants growth. It will partially shut its stomata and will not allow much oxygen or carbon dioxide to enter, at the same time reducing the amount of sunlight absorbed by the plant, which reduces the rate of photosynthesis. With the haze around the plant all day long, the plant will shut its stomata at a partial amount as some light can pass through the haze. This could be one reason that affects the plant growth.
Haze affecting many parts of the world are aerosols composed of solid and liquid particles of varying sizes. Haze can be made out of pollutants like, carbon monoxide, sulfuric dioxide, nitric oxide, nitrogen dioxide and ethylene. Plants and humans both respire, these particles affect humans respiratory system and hinder their body processes, it will affect the plant in a similar way too
4.3 Evaluation of hypothesis
Based on our results collected, our hypothesis was proven. This is because the plants exposed to the polluted conditions grew at a much slower rate in comparison to the plants left in cleaner air.
4.4 Areas for improvement
1. Instead of using cotton wool to cover the top of the bell jar, we could use N95 masks, or cut out certain sections of it to cover the top, as the masks can prevent pollutants from escaping the jar at the same time allowing particles like oxygen, carbon dioxide in and out of the masks.
2. To prove that our results are reliable, we should not use only one type of seed, we should use a variety of seeds. This can make our findings for reliable and accurate, so we can find out whether the polluted air affects all types of plants, or only certain plants.
3. We can change the measurement unit for the soil from ml to grams. This will help to reduce human error as when measuring in ml, there may be air pockets within the soil that has been taken, thus the actual amount of soil may be lesser than others. Instead, we should use grams to measure as this would accurately measure the mass instead of the level of soil in the beaker, thus creating a more fair experiment.
4. We could use a flatter aluminium tray so that we can reduce the air pollutants from escaping the jars. This is so that the results of the experiment will be more accurate, as well as so that we can reduce human error of putting moist cotton wool to prevent the pollutants from escaping the jar bell.
5. We could also use either larger jar-bells, or smaller pots so that the pots and the tray holding the burning materials would be able to fit properly in the jar-bell, and reduce spilling of the ash, or spilling of the soil. Also, this will help to not tilt the pot, so that the plant will be able to grow straight and not affect the accuracy of the results of the experiment.