There are four plants:?

Question

There are four plants: Green Bean, butter bean, rye grass and a sunflower. These plants grow rather quickly. The green bean plant is placed under white light and is used as the control. The butter bean is placed under green light, the rye grass plant under red light and the sunflower under blue light. All the plants are watered one cup of water ever other day and kept under the light the same amount of time. At the end of 4 weeks, the sunflower plant grows the most. What is wrong with this experiment? Explain.

Answer 1

Too many variables to determine the cause of the growth.

Answer 2

Regular lights do not have the wavelenghts that are required for growing plants in an experiment. Reguardless of color painted over the bulb there is no real diffence. A UV bulb is required to do growing experiments or a Grow bulb.

At the end of 4 weeks, the sunflower plant grows the most. Sunflower plants also are the tallest by default. You would need to use 4 of the same plant.

Answer 3

The problem is that you have two independent variables, both changing across your experiment. Even though all four plants "grow rather quickly" they do not all grow at the same speed. Noticing that a sunflower grew fastest under blue light doesn't prove anything about the blue light, nor about the sunflower.

A better experiment would be to set up all sixteen combinations: all four plants under each of the four light colors. Then, you could see if one color light really made them grow better or not. Or possibly that each plant had a favorite color.

Answer 4

All the plants need to be the same variety, because different plants have different growth rates. You can only test one variable at a time, in thiscase, I assume it's the color of light, so everything else has to be the same.

Answer 5

In order to understand the effect of a variable, you have to separate out the variable....

If you're studying how light color effects plants, you'd grow the same type of plant under different lights.

If you're studying which plant grows fastest, you'd plant different plants under the same kind of light.