Question Video: Recalling When Guttation Is Most Likely to Occur Biology

Video Transcript

When is guttation most likely to occur? (A) When the rate of transpiration is at its lowest. (B) When the rate of transpiration is at its highest. (C) Constantly throughout daylight hours.

To answer this question, let’s start by understanding what the key terms guttation and transpiration mean.

Sometimes, plants need to remove excess water from their bodies. And there are two main processes that they can use to eliminate this water: transpiration and guttation. Transpiration is the evaporation of water from plant surfaces, like the leaves and stems, into the atmosphere. 90 percent of transpiration takes place through small pores on the leaves, which are called stomata. The stomata are usually open during the daytime to allow the diffusion of carbon dioxide into the leaves for photosynthesis. For this reason, transpiration and water loss is usually high during the daytime.

Guttation is the elimination of excess water from the plant through structures called hydathodes, which are found on the margins of leaves. Let’s take a closer look at this process.

Plants usually absorb water and mineral ions from soil into the roots. The absorption of fluids into roots creates an upward pressure through the xylem vessels, which transports these substances to the leaves, where any excess water can be removed through the hydathodes. When the rate of transpiration is high, the plant can get rid of excess water through the open stomata.

During this time, guttation is unlikely to happen, because there is not much buildup of water in the xylem. Guttation is most likely to happen when transpiration is at its lowest and the plant needs to eliminate large amounts of water. This is usually at night, when the stomata are closed. So guttation does not occur constantly throughout daylight hours.

Now we know that the correct answer to our question is (A). Guttation is most likely to occur when the rate of transpiration is at its lowest.