Walls made of lignin
Consists of mainly vessels, It has pits which allow water and dissolved minerals to be transported sideways to other cells.
Stretches from roots to leaves
It has lignified walls to support the plant
It has a hollow lumen with no cross walls to let water pass through it easily
It is a dead structure with no protoplasm (hollow lumen)
Provide mechanical support for the plant
Transport water from the roots to the rest of the plant
Humidity of air, More Humid, slower rate of transpiration
Temperature of air, Higher temperature -> increases rate of evaporation of water vapor -> Transpiration is greater
Strong Wind, Stronger Wind, higher rate of transpiration
Light, Affects the size of stomata -> presence of light = increase of transpiration
What is wilting?, Leaf folds up because of excessive loss of water
Advantages, Rate of transpiration reduced, Leaf folds up to reduce surface exposed to sunlight, Causes guard cells to become flaccid (stomata will close) - to prevent water lost
Disadvantages, Rate of photosynthesis is reduced, Water becomes a limiting factor, Closed stomata cause the amount of carbon dioxide entering the leaf to reduce.
Holes in the sieve plates allows flow of the food substance (mainly sucrose) through sieve tube cells.
Transports food from the leaves to rest of the plant, The sucrose, amnio acids are also stored in fruits.
Has Sieve Cells which allow the food (Sucrose) using osmosis.
Companion Cells help in providing the energy for the sieve cells as the transportation of the food requires energy.