Water Transport In Plants

Front 1

How Water Enters a Plant:

Back 1

1) Water has to get from the soil, through the root, and into the xylem.
2) Water is absorbed by the root hairs, which increase the root's surface area, speeding up water uptake.
3) Once absorbed, the water has to get through the cortex, including the endodermis, before reaching the xylem.

Front 2

The Symplast Pathway:

Back 2

1) The symplast pathway goes through the living parts of cells - the cytoplasm.
2) The cytoplasm of neighbouring cells connect through plasmodesmata.

Front 3

The Apoplast Pathway:

Back 3

1) The apoplast pathway goes through the non-living parts of the root - the cell walls.
2) The walls are very absorbent and water can simply diffuse through them.
3) When the water reaches the endodermis cells, its path is blocked by a waxy strip called the Casparian Strip. Here the water enters the symplast pathway.
4) The water must then pass through a cell membrane before moving into the xylem.
5) The apoplast pathway provides the least resistance.

Front 4

How Water Moves Up a Plant:

Back 4

1) Cohesion and tension help water to move up plants, from roots to leaves, against the force of gravity.
2) Water evaporates from the leaves, which creates tension, pulling more water into the leaf. Water molecules are cohesive, and so the whole column of water in the xylem moves upwards.
3) Root pressure also helps move the water upwards. When water is transported into the xylem in the roots, it creates a pressure and shoves water already in the xylem further upwards.

Front 5

Transpiration:

Back 5

1) Transpiration is the evaporation of water from a plant's surface, especially the leaves.
2) Water evaporates from the moist cell walls and accumulates in the spaces between cells in the leaf.
3) When the stomata open, it moves out of the leaf down the concentration gradient.

Front 6

Factors Affective Transpiration Rate:
1)
2)
3)
4)

Back 6

1) Light - the lighter it is, the faster the transpiration rate. This is because the stomata open in light.
2) Temperature - the higher the temperature, the faster the transpiration rate, due to evaporation and kinetic energy of water molecules.
3) Humidity - the lower the humidity, the faster the transpiration rate, due to the concentration gradient.
4) Wind - the windier it is, the faster the transpiration rate, due to the concentration gradient.