Everything Life Sciences Grade 10

Observations:

Write down anything you observed about the plants, the plastic bags and the rate of water

loss from the plant.

Conclusions:

What can you conclude regarding the rate of transpiration at different light intensities? Was

there higher or lower water loss when you left the plant overnight compared to when you

monitored it throughout the day?

Questions:

How can you improve this experiment to determine the effects of different light intensities

on transpiration?

In this experiment what are the key variables we are controlling for? Have we properly

controlled for these?

Further tasks

• If you have a microscope, dissect the leaf surfaces before and after the experiment to
  see how the stomata have changed.


• Do this experiment with a variety of species in order to determine how transpiration
  changes across species.


• Calculate the average leaf surface area of all the leaves on a single plant. Work out
  the average amount of water loss per leaf surface area for the experiment you have just
  completed.

Advantages of transpiration Disadvantages of transpiration

Cools the plant down Excessive water loss causes the plant to

wilt

Assists in the transport of water from the

soil

Important for transport of water through

the xylem

Regulates the concentration of cell sap

Distribution of salts and minerals in the

plant

Table 6.1: Table comparing the advantages and disadvantages of transpiration

Structural adaptations of plants to reduce rate of transpiration DUMMY

When the rate of transpiration is too high, it can have detrimental effects on the plant, as you

will see in the next section on wilting and guttation. For this reason, plants have developed

structural adaptations to minimise the amount of water loss.

• Position of stomata:Stomata are found on both surfaces of the leaf but there are usually

176 6.3. Transpiration