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My name is Poon Cheng Moh. I have been teaching biology in SMK(P) Raja Zarina, Port Klang for 24 years. I sincerely hope that this blog on SPM Biology will be useful to both teachers and students.

Thursday, November 11, 2010

To investigate the effect of changes in air movement on the rate of transpiration of a plant.

ANSWER

Objective

To investigate the effect of changes in air movement on the rate of transpiraton of a plant.

Problem statement

What are the effects of the air movement on the rate of transpiration of a plant?

Hypothesis

The faster the air movement, the greater/higher the rate of transpiration of a plant.



Variables

Manipulated : Air movement

Responding : The distance traveled by air bubble in 10 minutes//Rate of transpiration

Constant : Surrounding temperature / light intensity/ relative humidity/ type and size of plant used/ time

Apparatus and materials

Apparatus (A)

Potometer, beakers, knife, basin, stopwatch

Materials (M)

Leafy shoot, colour water, vaseline

Technique

Measure and record the distance traveled by the air bubble in potometer in 10 minutes using a ruler// Calculate the rate of transpiration using the formula : Distance traveled by air bubble÷time (cm/min)

Procedure

1. Setup the apparatus as shown in diagram above.

2. Choose a leafy shoot and cut the shoot end in water.

3. Insert cut stem in the potometer.

4. Adjust and mark the initial position of the air bubble.

5. Dry the surface of the leaves before the start of the experiment.

6. The light intensity / temperature of the surrounding must be maintained throughout the experiment.

7. Measure the distance traveled by the air bubble in 10 minutes for each condition of air movement

8. Carry out the experiment in still air, slow and fast moving fan.

9. Use the same type and length of leafy shoot for all 3 experiments.

Precaution

1. The joint end of the stem and apparatus is smeared with vaseline to ensure no water leakage and the apparatus is airtight.

2. The surface of the leaves must be dry before the start of the experiment.

Recording data/ result

Condition of air/Speed of fan

Distance traveled by air bubble in 10 min

(cm)

Rate of transpiration :

Distance traveled by air bubble/Time

(cm/min)

Still air (Fan speed 0)



Slow moving air (Fan speed 1)



Fast moving air (Fan speed 3)



Conclusion

Hypothesis is accepted. The faster the air movement, the greater/higher the rate of transpiration of a plant.

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