In an investigation, plant cells are placed in water that has been tinted blue. The investigators observe the color of the cells changing to blue.

What additional observation would be evidence that the cells maintain homeostasis in response to this change?

A. The cells burst apart.

B. The cell membranes shrink away from the cell walls.

C. The central vacuole in the cells increases in size.

D. The cells pump out water by endocytosis.

E

The cells pump in additional water until they burst apart.

C

Explanation:

When plant cells take in water, the vacuole swells. A swollen vacuole indicates the plant cell has all the water it needs. This suggests that the plant is taking in water and is maintaining optimum conditions. This is an example of homeostasis.

If the cells burst apart, as in A and E, this would suggest the cell is not properly maintaining homeostasis, as the cell bursting suggests something has gone badly wrong. This suggests the cell has taken in too much water; the cell has not been able to maintain homeostasis and regulate water uptake to prevent this from happening.

In the reverse case, where the cells shrink apart (as in B), the cell would also not be properly maintaining homeostasis by failing to bring enough water into the cell to maintain a turgid state. This is also damaging for the cells.

Finally, D and E can also not be correct, because water can cross the cell membrane, and does not need to be pumped in or sent out by endocytosis.