You are interested in the effect of increased carbon dioxide versus normal air, and also in the effect of green light versus full sunlight on the growth of corn plants in a greenhouse. Although you can set up your experiment inside a greenhouse, it is possible that there will be plant growth effects due to effects that you do not know and may never know. Which of the following are important to ensure control of unknown variables?

A. An increase in carbon dioxide does not result in a substantial decrease of other necessary gases.
B. All seedlings are from one uniform strain.
C. The intensity or brightness of the green light equals the intensity of the full sunlight.
D. All temperatures and available water remain the same.
E. All of the choices are important.

The correct answer is option E.

Explanation:

The effect on the growth of the full sunlight and green light or the increased carbon dioxide and normal air. There are several effects that can affect the growth of the plant can be affected. Provided options are directly or indirectly affects the variables that are unknown but can affect the growth of plants.

Increased in carbon dioxide does not leads to the decrease of other essential gasses in substantial amount, common uniform strain of seedlings are also cause effects the experiment of plant growth in specific manner. Light is also one of influential and limitation factor that affects the growth of the plant.

Thus, the correct answer is is option E.

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the relative atomic mass of an element is the mass of one atom of that element, relative to 1/12th of the mass of a  1212c atom. to convert to an absolute mass in kg, it is necessary to multiply by  1.661×10−271.661×10−27.

the relative atomic mass is roughly equal to the number of neutrons, plus the number of protons, in the nucleus of the atom.

for elements with more than one stable isotope (different types of nucleus with different numbers of neutrons but the same number of protons), the quoted mass is usually the average mass, weighted by the relative abundance of the different isotopes.