When you investigated the effect of large plastic pollution on the ecosystem, the amount of microplastics increased.Explain why this prevented the investigation from being a fair test.

In a scientific investigation, a fair test is one in which only the independent variable has been allowed to affect the dependent variable. In this case, the independent variable is the large plastic pollution and the dependent variable is the ecosystem.

1. Introduction of Microplastics: If the amount of microplastics increased during the investigation, it means that another variable (microplastics) was introduced into the experiment. This could have affected the ecosystem, thus influencing the results of the investigation.

2. Uncontrolled Variable: The increase in microplastics represents an uncontrolled variable. In a fair test, all variables except the one you're testing (in this case, large plastic pollution) need to be kept constant. If other factors change and potentially affect the outcome, the test is no longer fair.

3. Impact on Results: Microplastics themselves can have a significant impact on the ecosystem, affecting both wildlife and plant life. They can be ingested by animals, leading to internal blockages, starvation, and even death. They can also absorb pollutants, which can then enter the food chain when the microplastics are consumed. This means that the changes observed in the ecosystem could be due to the increase in microplastics, rather than the large plastic pollution that was being investigated.

4. Conclusion: Therefore, the increase in microplastics prevented the investigation from being a fair test because it introduced an additional variable that was not controlled and could have affected the results. To ensure a fair test in the future, all forms of plastic pollution, including microplastics, would need to be accounted for and controlled.