AP BIOLOGY

Detailed explanation-1: -Lower surfaces are not directly exposed to sun. This tends to reduce excessive water loss. It is a beneficial adaptation to check water loss in plants. Thus, the underside of leaves have more stomata.

Detailed explanation-2: -In most cases, the lower epidermis contains more stomata than the upper epidermis because the bottom of the leaf is cooler and less prone to water loss.

Detailed explanation-3: -Some plants limit water loss by closing their stomata when conditions are unfavorable. For example, when the humidity is low, water is more likely to evaporate quickly from the leaf surface, and plants often close or partially close their stomata to maintain a stable water balance in the leaf.

Detailed explanation-4: -Stomata regulate the loss of water and the exchange of gas by opening and closing. They allow water vapour and oxygen out of the leaf and into the leaf with carbon dioxide. The guard cells lose water in low light and allow the stomata to close.

Detailed explanation-5: -Almost all water used for plant growth is lost to the atmosphere by transpiration through stomatal pores on the leaf epidermis. By altering stomatal pore apertures, plants are able to optimize their CO2 uptake for photosynthesis while minimizing water loss.