Plant Transport

Need for transport in multicellular plants:

- Multicellular plants have too small surface area:volume ratio so diffusion is too slow to provide necessary molecules therefore requires a system to transport nnutrients and products around body

- If organism is small, then has a high surface area:volume ratio- all the necessary nutrients and respiratory gases can be taken in by diffusion across body surface.

Transpiration - the loss of water from the leaves of a plant

Factors affecting transpiration

Temperature

- increases kinetic energy of water molecules

- rate of diffusion and evaporation increases

- as temp increases, rate of transpiration increases

Light intensity

- stomata open at daylight to absorb CO2

- more H2O evaporates

- increases in light intensity increases rate of transpiration

Wind speed

- still air saturated with water vapour

- wind 'sweeps' water vapour away

- this increases water potential gradient between leaf and air

- increase in wind speed increases rate of transpiration

Humidity

- humid air saturated with water vapour

- shallow gradient between air and leaf

- increase in humidity decreases rate of transpiration

Xylem Vessel - structure and function

Hollow with no cell content

less ressistance to water

Large Lumen

less ressistance to water

Lack of end walls

- creates continous column of water

Pits-

…