To investigate the effect of the number of leaves on the rate of transpiration in a hibiscus plant.

Transpiration is the loss of water vapour from plants, especially in leaves. Transpiration occurs mostly through the stomata. The amount of water lost by a plant depends on its size, surrounding light intensity, temperature, humidity and wind speed. Design an experiment to be conducted in the laboratory to investigate the effect of the number of leaves on the rate of transpiration in a hibiscus plant.
Objective	To investigate the effect of the number of leaves on the rate of transpiration in a hibiscus plant.
Problem statement	What is the relationship between the number of leaves and the rate of transpiration (in a hibiscus plant)?
Hypothesis	The more the number of leaves, the higher rate of transpiration.
Variables	Manipulated : Number of leaves / stomata
	Responding : Distance travelled by air bubble (in ten minutes) // The 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, ruler, capillary tube + rubber tubing, stoppered conical flask, beaker / basin, (sharp) knife, stopwatch, string Materials (M) Leafy shoot, vaseline, tissue paper / filter paper.
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 hisbiscus 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/air movement/humidity of the surrounding must be maintained throughout the experiment. 7. Measure the distance traveled by the air bubble in 10 minutes. 8. By using the same plant, repeat the experiment by removing two leaves each time. 9. Use the same plant for all experiments. 10. Calculate the rate of transpiration. 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	Number of leaves Distance traveled by air bubble in 10 min (cm) Rate of transpiration : Distance traveled by air bubble/Time (cm/min) 1st 2nd 3rd Average
Conclusion	Hypothesis is accepted. The more the number of leaves, the higher rate of transpiration.