Evidence indicates that plants increase the number of stomata in their leaves as atmospheric CO₂ levels decline.Increasing the number of stomata per unit surface area should have the effect of doing which of the following?
1) increasing dehydration of leaf tissues
2) decreasing dehydration of leaf tissues
3) countering the effect of declining CO₂ on photosynthesis
4) reinforcing the effect of declining CO₂ on photosynthesis
5) decreasing the O₂ content of air next to the leaves lower than it would otherwise be
6) increasing the O₂ content of air next to the leaves higher than it would otherwise be

Question

Quizplus · Accepted Answer

Increasing the number of stomata per unit surface area allows for increased gas exchange, which includes the uptake of CO2 for photosynthesis. Therefore, this would counter the effect of declining atmospheric CO2 on photosynthesis (choice 3) and increase the CO2 content of air next to the leaves (choice 6). However, since stomata also allow for water loss through transpiration, increasing the number of stomata would increase dehydration of leaf tissues (choice 1). It would not decrease dehydration (choice 2) or reinforce the effect of declining CO2 on photosynthesis (choice 4). Choice 5 is incorrect because increasing the number of stomata would not decrease the content of atmospheric oxygen (O2) next to the leaves.

Evidence Indicates That Plants Increase the Number of Stomata in Their