This diagram shows the movement of water through the root
Water is found in the spaces between the soil particles. Water enters through
the cell wall and cell membrane of the root hair cell by osmosis. Water fillsthe vacuole of the root hair cell.
Water can now move across the parenchyma cells of the cortex in two ways:
Most of the water passes along the cell walls of the parenchyma cells by
diffusion. Movement of water and solutes between the intercellular spaceswithout crossing the plasma membrane is known as apoplastic movement.
Some of the water passes from the vacuole of one parenchyma cell to the vacuole
of the next cell by osmosis. Movement of water and solutes through the cells isknown as symplastic movement.
The water must pass through the endodermis to enter the xylem.
Once water is in the xylem of the root, it will pass up the xylem of the stem.
Transpiration and movement of water:
http://www.phschool.com/science/biology_place/l abbench /lab9/xylem.html
This website shows a diagram of how water moves up through the plant.
http://www.neok12.com/Plants.htm
This video shows plant transport and provides some interactive quiz games.
Investigation: water uptake by roots
Aim : To measure the uptake of water by roots
Apparatus
Plastic 2 litre Coke bottle
water
soil
scissors
measuring scale
tree or plant cuttings
ruler
Method
Remove the label from the Coke bottle. Cut the top of the bottle off 20cm from
the bottom of the bottle. Poke holes in the bottom of the bottle for drainage.Hold the plant cutting in the container while you fill the container with soil.
Leave one or two leaf buds about 5cm above the soil.
Weigh the container to get the total weight of the bottle, soil and plant.
Water the plant with enough water so that it starts to run out of the bottom of
the bottle through the holes.
Weigh the container again after the water has stopped running out and subtract
the total weight in step 2 from the weight in step 4 to get the weight of thewater. 1 litre of water is equal to 1 kilogram of water, therefore you can work
out exactly how much water is in the container.
Set the containers by the window where they will receive enough sunlight. Wait
for the leaves to start growing (1-3 weeks).
After the leaves are growing, weigh the containers every 1-3 days for 3 weeks.
Subtract the new weight from the weight calculated in step 4. The new number isthe amount of water that the plant is using. Water the plant as necessary (when
the soil becomes dry), but remember to reweigh the container when you add morewater so that you can still tell how much water the plant is taking up.
Draw a graph of the amount of water the plant is using. The X-axis should show
the number of days since the beginning of the experiment and the Y-axis shouldshow the amount of water that the plant has used.
Question on investigation – Surely as the plant grows it forms new leaves
etc which have mass? How do we subtract the mass of the new leaves to prevent
this making the mass of the entire container inaccurate in terms of how much
mass is
