transpiration and adaptations of plants

transpiration

the evaporation of water from a plant’s leaves

transpiration stream

the movement of water from roots to leaves

factors affecting transpiration (4)

-light intensity

→increasing light intensity, increases transpiration

→this is bcs the stomata open to allow more water vapour to escape

-temperature

→increasing temperature, increases transpiration

→this is bcs the rate of evaporation increases as the water molecules have more kinetic energy

-wind/ air movement

→increased air movement, increases transpiration

→this is bcs water vapour around the stomata is blown away. This reduces water vapour potential around stomata. This increases the water potential gradient, increasing rate of transpiration

-humidity

→decreased humidity, increases transpiration

→this is bcs when the air is less humid, the water potential gradient is increased

how can we measure transpiration?

use a potometer

-types of plants (2)

→adapted to what environment

→examples

→how are they adapted to their conditions?

xerophytes

→they’re adapted to live in dry environments

→e.g. cacti and marram grass

→ -thick waxy cuticle→reduces water loss through evaporation bcs it’s waterproof

-hair on leaves→ traps moist air, reducing the water potential gradient for evaporation

-sunken stomata→traps moist air, reducing the water potential gradient for evaporation

-rolled leaves→ traps moist air, reducing the water potential gradient for evaporation

→reduces surface area so less water is lost by evaporation

hydrophytes

→they’re adapted to live in wet environments

→e.g. water lilies

→ -air spaces→allows plant to float and receive more light for photosynthesis

-stomata on the upper surface → allow gas exchange as the lower surface is in water

-flexible leaves→ prevent damage from water currents