Transpiration And Translocation

the evaporation of water from plants

in the xylem tube which are vessels from the roots to leaves

• thick side walls and rings of lignin • dead cells have no cytoplasm • lack of cell walls between cells • tiny pores

keeps it strong

• holes in ends of cell walls • pores • very small amount of cytoplasm

• water travels up xylem tubes like a suction system • water travels to leaves • unbroken chain of water molecules held together by weak forces of attraction between molecules • as water from leaves evaporates, more is drawn into the roots

• light intensity • temperature • air flow or wind speed

• plants wilt as water sustains a plants structure. if little water, plant cant stand up properly • it helps photosynthesis be done in its optimum conditions,like controlling temp of plant

• with a potometer - it measures the movement of a bubble in a capillary tube

• if air flow if poor, water vapour just surrounds leaf and doesnt move away • this means that there is a high concentration of water particles outside the leaf as well as inside • so diffusion doesnt happen quickly

• the brighter the light, the greater the transpiration rate • stomata begin to close as it gets darker • as photosynthesis cant happen in the dark, so stomata dont need to be open to absorb CO2 • when stomata are closed, very little water can escape

the movement of sugars in a plant

• plants make sucrose from glucose after photosynthesis • its transported via translocation in the sieve tubes in the phloem • companion cells actively pump sucrose into and out of the sieve tubes

dead cells joined end to end with no walls between them and a hole in the middle

the movement of water from the roots, through the xylem and out of the leaves

columns of elongated living cells with small pores in the end walls to allow stuff to flow through

to transport food substances (mainly sucrose) made in the leaves to the rest of the plant for immediate use or for storage

• energy from respiration - as the transport goes in both directions

• if there is good air flow, rate of transpiration increases • because the water is swept away • which maintains a low concentration of water particles in the air outside the leaf • so diffusion from the leaves happens quickly, from an area of high concentration to an area of low concentration

• the warmer it is, the faster transpiration happens • when its warm the water particles have more energy • to evaporate and diffuse out of the stomata

distance moved / time taken

• water loss from the leaves - as the xylem tube is a continuously flowing source of water

• to form rigid tubes that wont burst or collapse - and provide support

to form an empty tube for water to flow through