FORM 5 : CHAPTER 1 – TRANSPIRATION

Objective: To investigate the effect of wind speed on the transpirations rate.

Problems statement: Does the increase in wind speed increase the rate of transpiration?

Hypothesis: The higher the speed of wind the higher the rate of transpiration .

Variables: Manipulate: wind speed Responding: the rate of transpiration Controlled: air temperature, plant shoot , light intensity

Apparatus: Potometer / capillary tube, beaker, ruler, stopwatch, stand fan, wire, cellophane tape, & Material retort stand.Fresh plant shoot, distilled water,vaselin.

Technique: Record the time taken for air bubble to move over a distance of 10 cm using a stopwatch and calculate the rate of absorption of water / transpiration.

Procedure: 1) Potometer is prepared as shown in the diagram, using fresh plant shoot

2) Two points , X and Y are marked on capillary tube with their distance apart is 10 cm.3) Potometer is placed under the fan and turn on the fan at minimum speed.4) The capillary tube is lift up to collect air bubble at the bottom.5) Time taken for the air bubble to move from X to Y is recorded 6) Step 4 and 5 are repeated for three times to get an average.7) Steps 3 ,4,5 and 6 are repeated by using the same shoot placed under the fan with medium speed

and then the maximum speed. 8) The data are recorded in the table as shown below.9) Transpiration rates at all the three wind speed are calculated.

Result:

Conclusion. The rate of the transpirations increases when the wind speed increases The hypothesis is accepted.

Air movement

Time taken for air bubble to move from X to Y (10 cm) /s

Transpiration Rate (cm s-1)

1 2 3 AverageLow speedMedium speed

High speed

Note :

Graph of the transpiration rate against air movement.

Air movement

From the bar chart, as the wind speed increases the rate of transpiration also increases.At lower speed of wind ,the rate of transpiration is low. At high speed of wind, the rate of transpiration is high.

Low speed

Medium speed

High speed