Concept:Light encourages the growth of algae, which can disturb a water culture experiment.
Explanation:In a water culture experiment, plants grow with their roots in a nutrient solution.
When this solution is exposed to light, green algae can multiply rapidly.
These algae compete with the experimental plant for dissolved nutrients and oxygen.
They also release waste products, which may alter the nutrient balance of the solution.
This interference reduces the reliability and accuracy of the experiment.
To avoid these problems, the culture vessel is kept dark or covered.
Excluding light prevents algal growth without affecting the plant's roots.
The roots still receive minerals and water, and they are not overheated in the dark.
Excluding light does not cause roots to grow straight down by itself.
It also does not prevent the ionization of water molecules in the solution.
Therefore, the main purpose of excluding light is to stop the growth of algae.
Answer:D. prevent the growth of algae