Atmospheric CO2 has been increasing rapidly since the late 1800s,...

Question

Atmospheric CO2 has been increasing rapidly since the late 1800s, largely due to human activities. Recall that CO2 enters leaves through stomata and can then be used for photosynthesis. However, transpiration occurs as a result of water evaporating through stomata. How have plants responded to elevated CO2 levels? The amount of water that evaporates from stomata over a period of time is referred to as stomatal conductance, which is determined largely by the number of stomata in a given area of leaf surface. Researchers obtained specimens from preserved collections and measured stomatal conductance in leaves from oak trees and pine trees that grew at various times under different CO2 levels. The data are shown in the following graph. In general, is the maximum stomatal conductance rate in plants more or less than it was a century ago?

Accepted Answer

Hello everyone here's our next question. It says to model conductance is the rate of evaporation of water from Tamara. Which of the following leaves shows the maximum model conductance rate. When we talk about the rate of evaporation of water from this tomato. We have kind of two factors governing that one would be um the degree the Samata are open. So the guard cells around this tomato can cause them to be more open and more closed. And the other would be the surface area of the leaf because a greater surface area means more stamina our present and that means higher. Still model conductance because obviously the more smarter there are the more water will evaporate from them. So since our answer choices involved four different types of leaves from four different plants. When we're comparing different types of plants. Um what we'll see here, we'll be looking at what is the surface area of those different leaves and the leaf was the greatest surface area will have the maximal model conductance rate. So our choices are a pine leaves, be oak leaves, see cactus leaves, de aloe vera leaves well right away we know pine leaves and cactus leaves are needle shaped and therefore will definitely have the lowest surface area. So we can eliminate a pine leaves and c cactus leaves right away. We're left with oak leaves and aloe vera leaves. Well aloe vera leaves and aloe vera is a succulent and its leaves tend to be very long and narrow. Like other succulents, it's adapted to minimize water loss for dry conditions. So choice D. Is also not our answer, So we're left with Choice B. Oak leaves. Oak leaves are much broader, wider and they do have the greatest surface area of all these leaves, so which leaves will have the maximum model conductance rate be oak leaves. And this definitely makes sense because the pine cactus and aloe vera all have adaptations allowing them to survive in dry climates, including the low surface area leaf, causing fewer Samata and therefore minimizing water loss in those dry conditions. See you in the next video.

Watch next