The Germination of Vigna Radiata Affected by Water Pollution
IB Candidate Number: 001207-0020
IB Environmental Systems and Societies SL Y2
10/31/2015
The Germination of Vigna radiata Affected by Water Pollution
Background: Water pollution is the contamination of a body of water due to pollutants entering it at a magnitude greater than what can be retained naturally. This type of pollution is becoming a serious problem with the advent of developing technologies and increasing numbers of factories emitting pollutants through sewage. These polluted waters can adversely affect the growth of underwater and nearby plants, and further impact the subsequent tropic levels that feed on these plants. Industrial chemicals often make up these polluted waters, one of them being copper.
Aim: The aim of this experiment is to explore the effects of water pollution on the germination of Vigan radiata (Mung Beans), in order to fully understand the negative effects of pollution on plant growth. Copper sulfate in its pentahydrate form (CuSO4•5H2O ) will be used in this experiment to represent the copper components found in real-life polluted waters.
Research question: What effect does copper sulfate have on the growth of Vigna radiata?
Variables:
Independent variable:
Copper sulfate concentration in water | Copper sulfate was used to serve as the representation of a pollutant that contaminates water in real life. The cups were given water with five different concentrations of copper sulfate, including a controlled condition. The concentrations were: distilled, 0.005 mol/L, 0.01 mol/L, 0.02 mol/L, and 0.04 mol/L. |
Dependent variable:
Germination of Mung Beans | The number of seeds that germinated is a dependent variable, since this is determined by the copper sulfate concentration of the water. Copper is known as a micronutrient, only required in small doses for plants, so a large concentration will hinder the germination of the Mung Bean seeds. |
Length of radicle/root | The length of the radicle and the root of the seeds are affected by the copper sulfate concentration of the water. The more copper sulfate, the lengths of the radicles and roots will be generally shorter. |
Controlled variables:
Time | Each of the samples was left for 72 hours before the seeds were retrieved and measured. Even though there were time lags associated with placing the seeds into the 25 cups and later retrieving them, each procedure was done in a time frame of 10 minutes to minimize distortion of results. |
Light | The 25 cups were all placed under the identical lightstand, which gave the same amount of light to each of the seeds placed in the cups. The light source was constant for 72 hours. |
Position of Mung Bean seed | The Mung Bean seeds were placed in the cups so that the micropyle was facing up. This was done to ensure maximum growth and to prevent the germination from being hindered. |
Amount of oxygen and carbon dioxide | The cups were placed in the same room in a designated area, so the oxygen and carbon dioxide concentrations were kept constant. Furthermore, to limit evaporation, all the cups were sealed with another cup placed directly on top. |
Amount of water placed in the cups | Each of the cups was given 20 mL of water, whether it is distilled or containing copper sulfate. The same amount of water was given to ensure that there is a controlled amount of moisture in each of the cups. |
Miscellaneous materials | The materials used in the procedure for the cups were controlled and identical to one another. Such materials include: plastic cup type, usage of the same water source, paper towel, scotch tapes, and so on. The materials and other factors were kept constant in order to get rid of potential distortion of results or other confounding effect. |