What do stomata regulate in plants?

Stomata are specialized structures found on the surfaces of leaves that play a critical role in regulating both water loss and gas exchange in plants. These tiny openings allow carbon dioxide to enter the leaf for photosynthesis — the process by which plants convert light energy into chemical energy — while simultaneously enabling oxygen and water vapor to exit.

By opening and closing, stomata control the rate of transpiration, which is the process of water loss from the plant to the atmosphere. This water loss is an essential part of maintaining the plant's internal water balance and helps in nutrient transport. Additionally, the regulation of gas exchange through stomata ensures that the plant has enough carbon dioxide for photosynthesis while minimizing excessive water loss, especially during hot or dry conditions.

The other options are less accurate because they either focus on a single aspect, like photosynthesis alone, which does not encompass the full breadth of functions stomata provide, or refer to processes like nutrient absorption and plant growth, which are associated with roots and other parts of the plant, rather than being directly regulated by stomata. Thus, the correct understanding of stomata’s functions highlights their dual role in maintaining water balance and facilitating necessary gas exchange.