Transpiration in Plants

The rate of transpiration increases with higher light intensity.

Higher temperatures lead to faster water evaporation from mesophyll cells, increasing the concentration gradient for water vapor diffusion.

Still air allows water vapor to accumulate around stomata, decreasing the concentration gradient and slowing down transpiration.

Increased wind speed removes water vapor from around stomata, maintaining a larger concentration gradient, and thus increasing transpiration.

A waxy layer covering the leaf surface that helps prevent excessive water loss.

Tiny pores on the leaf surface that regulate gas exchange and water vapor release.

Specialized cells surrounding stomata that control their opening and closing, regulating gas exchange and water loss.

The process of water movement through a plant and its evaporation from aerial parts, primarily leaves.

The force that pulls water upwards from the roots to the leaves due to the evaporation of water from the leaves.

The upper surface of the leaves that face the sun, usually with fewer stomata to reduce water loss.

The lower surface of the leaves, typically with more stomata to facilitate gas exchange.

The closure of stomata during the night to reduce water loss through transpiration when photosynthesis is not occurring.

Wind increases the rate of transpiration by creating a steeper concentration gradient of water vapor between the leaf's air spaces and the surrounding air, leading to faster diffusion of water vapor out of the leaves.

Strong wind can cause excessive water loss, prompting the plant to close its stomata to reduce transpiration, leading to a decreased rate of transpiration.

High relative humidity decreases the concentration gradient of water vapor, slowing down the diffusion of water vapor out of the leaves and reducing the rate of transpiration.

The surface area of leaves plays a role in transpiration rate because a larger surface area exposes more stomata to the environment, facilitating increased water vapor loss.

A thinner cuticle allows for faster diffusion of water vapor from the leaf's internal tissues to the atmosphere, enhancing the rate of transpiration.

Higher stomatal density increases the number of openings for water vapor loss, contributing to a higher rate of transpiration.

Represents the net water loss of the plant during the daytime (0600-1600).

Represents the net water uptake of the plant over a full 24-hour period.

The outermost layer of a root, protecting it and aiding in water and mineral absorption.

Tiny hair-like projections extending from the root epidermis, increasing surface area for water and mineral absorption.

The layer of cells just beneath the epidermis, storing water and nutrients absorbed by the root hairs.

A central core in the root, composed of xylem and phloem, responsible for transporting water and nutrients throughout the plant.

The tissue in the vascular bundle transporting water upward from the roots to the rest of the plant.

The tissue in the vascular bundle transporting sugars and other nutrients produced in the leaves throughout the plant.

The process by which water moves from the soil into root hair cells along a water potential gradient.

The movement of water through the cell walls of the cortex, providing a faster and less resistive path for water transport.

Water absorption and turgor pressure in thin-walled cells provide support to plants. When sufficient water is available, these cells become turgid (swollen), pushing against each other and creating structural rigidity.

Xylem vessels, formed of thick-walled cells reinforced with lignin, provide structural support to plants. This support is independent of water content, unlike support provided by turgid cells.

The deposition of lignin in xylem cells increases with age, leading to the formation of wood. This process adds significant strength and support to the plant, particularly in woody plants.

The primary function of stems is to support leaves, flowers, and fruits. This allows for optimal light absorption for photosynthesis, facilitates pollination, and aids in the dispersal of seeds.

The main supporting tissue in young dicot stems is the cortex, which is composed of parenchyma cells. These cells have thin walls and rely on turgor pressure for support.

The opening and closing of stomata is controlled by the turgor pressure of guard cells. When guard cells absorb water, they become turgid, leading to the opening of stomata. Conversely, when guard cells lose water, they become flaccid, causing the stomata to close.

The thicker inner wall of a guard cell prevents it from expanding as much as the thinner outer wall when water is absorbed. This uneven expansion causes the guard cell to bend, opening the stomata.

When a plant experiences water stress (deficit in water), the guard cells lose water, becoming flaccid, which leads to the closure of stomata, reducing water loss through transpiration.

The cuticle, a waxy layer on the leaf surface, helps reduce water loss through transpiration by minimizing the evaporation of water. This is especially important for terrestrial plants living in dry environments.

The lower epidermis of terrestrial dicot leaves has a higher density of stomata than the upper epidermis. This helps reduce water loss by transpiration, as the upper surface is more exposed to sunlight and higher temperatures.

Terrestrial monocot leaves have stomata distributed nearly equally on both sides because their leaves are vertically oriented, exposing both sides to similar sunlight intensities. This ensures consistent water loss from both sides.

Submerged plants do not have cuticles and have few or no stomata on their leaves. This is because they absorb water and gases directly from the surrounding water through their entire surface.

Floating plants have adaptations that allow them to survive on the surface of water, such as a thicker cuticle and a waxy upper surface to reduce water loss. They may have stomata concentrated on their lower surface, exposed to the air.