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.

To investigate whether light intensity affects the rate of transpiration

Answer

Problem statement:

How does the light intensity affect the rate of transpiration?

Objective:

To investigate whether light intensity affects the rate of transpiration.

Hypothesis:

The higher the light intensity, the higher the rate of transpiration.

Variable

-Manipulated variable: Light intensity

-Responding variable : Time taken for the air bubble to travel 10 cm

-Fixed variable: air movement, temperature and relative humidity

Materials:

2 Hibiscus plant of similar size, tissue paper, vaseline

Apparatus:

Capillary tube (about 30 cm long), retort stand, 500 ml

beaker, basin, scalpel, rubber tubing (about 6 cm long), stop watch, ruler, thread

Technique:

Measure and record the time taken for the air bubble to travel 10 cm using astopwatch and the rate of transpiration is calculated using the formula: Distance traveled by air bubble/time.

Procedure

1. The leafy shoot is immersed in a basin containing water, and its stem is cut diagonally.

2. The leafy shoot is placed upright in the potometer’s capillary tube, through a stopper cork.

3. All equipment connection points are wiped with vaseline.

4. To trap an air bubble, the end of the capillary tube is removed from the basin, and then put back into the water.

5. A length of 10 cm is marked on the potometer.

6. The potometer is placed in the shade and using a stopwatch, record the time taken (in minutes) for the air bubble to move from point A to point B (10cm).

7. To reset the potometer, squeeze the rubber tubing so that the air bubble escapes into the beaker of water.

8. Repeat step 4 to 7 to get three readings with the same shoot in the shade and under strong sunlight respectively.

9. The average and the rate of transpiration measurement are recorded in the table.

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.

Result:

Environmental condition of experiment	Time taken for air bubble to move from 10 cm (minutes)				Rate of transpiration (cm/min)
	First reading	Second reading	Third reading	Average
Shady (lower light intensity)
Strong sunlight (higher light intensity)

Conclusion:

Hypothesis is accepted. The higher the light intensity, the higher the rate of transpiration.

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.

To study different food contains different energy value

Objective	To determine the energy value in food samples.
Problem statement	What is the energy value in cashew nut and groundnuts?
Hypothesis	Cashews nuts have higher energy value than ground nuts.
Variables	Manipulated : Types of food sample: Cashew nut and ground nut
	Responding : The rise in temperature of water//Energy value
	Constant : Volume of distilled water
Apparatus and materials	Apparatus (A): Boiling tubes, retort stand, plasticine, long pins, thermometer, electronic weighing scale, 25ml measuring cylinder Materials (M) :Fresh ground nuts, fresh cashews nuts, distilled water and matches
Technique	Measure and record the rise in temperature by using a thermometer// Calculate the energy value using the formula: Energy value = 4.2 (Jg-1 oC-1) x mass of water (g) x increase in temperature(oC) Mass of peanut(g)
Procedure	Weigh the cashew nut and record its weight. Fill a boiling tube with 20ml of distilled water. Clamped the boiling tube to a retort stand. Record the initial temperature of the distilled water. The pointed end of a long pin is poked into the cashew nut. The other end of the pin is poked into with a piece of plasticine. The cashew nut is ignited by using a match stick and immediately placed under the boiling tube. The flame from the cashew nut is allowed to heat up the water. The water is stirred gently by using a thermometer to distribute the heat evenly. At the same time the rise in temperature is observed. Measure and record the final temperature using the thermometer. Record the final temperature of the water in a table. The energy value of the cashew nut is calculated using the formula : Energy value = 4.2 (Jg-1 oC-1) x mass of water (g) x increase in temperature (oC)/ Mass of peanut(g) 10. Steps 1 to 9 are repeated by using a groundnut. 11. Precaution : a) Make sure that the nut is fully burnt. b) A shield is put around the nut to prevent heat loss to the surrounding.
Recording data/ result	Food sample Cashew nut Groundnut Weight(g) Initial temperature of water (oC) Final temperature of water (oC) Rise in temperature (oC) Energy value (J)
Conclusion	Cashew nut has a higher energy value than groundnut. The hypothesis is accepted.

To investigate the effect of change in pH value on the population growth rate of Lemna sp. plants.

Problem statement	What is the effect of change in pH value on the population growth rate of Lemna sp.?
Aim	To investigate the effect of change in pH value on the population growth rate of Lemna sp. plants.
Hypothesis	The population growth rate of Lemna sp. plants is the highest in the pH 7 compared to pH 2 and pH 14.
Variables	Manipulated variable: Different pH value // pH 2, pH 7and pH 14 Responding variable: The population growth rate of Lemna sp. plants. Controlled variable: Species of Lemna sp. // plant /volume of water /intensity / time
Material & Apparatus	Materials: Lemna sp. plants, distilled water / dilute hydrochloric acid / sodium hydroxide solution, culture solution / pond water. Apparatus: Beaker // petri dish // container, measuring cylinder, pH paper / meter.
Technique	Count and record the number of Lemna sp. after 5 days. Or Calculate the population growth rate of Lemna sp. by using a formula : The population growth rate of Lemna sp. = Number of Lemna sp. 5 days

Procedure

1. Choose Lemna sp. plants of the same size.

2. Choose // take three petri dishes of the same size.

3. Label the petri dishes as A, B and C.

4. Pour 5 ml of distilled water into petri dish A, 5 ml of hydrochloric acid into petri dish B and 5 ml of sodium hydroxide solution into petri dish C.

5. Test the pH value of each solution using pH paper (and record in a table).

6. Pour 5 ml of culture solution / pond water into each petri dish.

7. Put 5 Lemna sp. plants into each petri dish.

8. Record in a table.

9. Place the petri dishes on the table / near the window in the laboratory.

10. Change the solution in the petri dishes everyday.

11. Count the number of Lemna sp. plants after 5 days.

12. Calculate the population growth rate of Lemna sp. plants.

13. Repeat the experiment / steps 1 until 11 to get the average result.

14. Observe and record the result.

15. Precaution : Change the solution in the petri dishes everyday.

Data	pH value Number of Lemna sp. plants The population growth rate of Lemna sp. plants (number/ 5 days) Day-1 Day-5 Increase / Decrease Neutral Asidic Alkali

Conclusion

The population growth rate of Lemna sp. plants is the highest in the pH 7 compared to pH 2 and pH 14. Hypothesis is accepted.