Question

A group of students is trying to grow a kelp plant in a tank without any others animals. They use a temperature regulation system to keep the water temperature at about 12°C. They bury the holdfast below the soil that has been enriched with nutrients and place the plant near a window in direct sunlight. However, over a few weeks the kelp plant withers and dies. Why did this happen?

Answer 1

Kelp is very sensitive to temperature change. Placing the plant near the window and exposing it to direct sunlight will result in continuous warming of the water in which the kelp plant is growing. Research has shown that kelp plant degrades very quickly when temperature increases due to tissue loss.

Answer 2

I have read the question several times and I believe "A.The kelp draws nutrients from the water rather than the soil, which it does not have available." would actually be your answer.

Although it is true that kelp is temperature sensitive, the question states that "They use a temperature regulation system to keep the water temperature at about 12°C." So even with the added addition of sunlight, I think the temperature still stays generally the same. And as long as the temperature is between 5-20 C degrees, the kelp should be okay.

However, kelp does not work the same as most land plants, kelp does not have a root system. It instead has a "holdfast" anchoring system that does not transport nutrients. So how does kelp get nutrients? From the water directly. Since the question says nothing about nutrients in the water, and directly talks about nutrients in the soil, we can assume that their is no nutrients in the water (only in the soil). Making A our answer.

I know the question is old, but this is for anyone who still needs the answer.