Class T-shirt

This is the final design of our t-shirt!
Please pay up RM25 asap to SiWen (treasurer)
The sooner you pay, the sooner we will get it.
We'll wear it during Canteen Day!


<3 peifen

hey guys.. so sorry about that link part.. idk why it wont enter the spaces.. i cant make the font smaller. anyone who knows, do it ya.
hope you guys like the new template.

Happy Holidays :))

TRANSPIRATION

Aim : To study the effect of air movement on the rate of transpiration using bubbles potometer.

Problem statement : How does the movement of air affect the rate of transpiration?

Hypothesis : The faster the movement of air, the greater the rate of transpiration.

Variables : 

Manipulated : Air movement.

Responding : The distance travelled by the air bubble in 5 minutes.

Constant : Surrounding temperature, type of plant, light intensity.

Materials : A leafy shoot, vaseline, a piece of cloth and dilute eosin solution.

Apparatus : A rubber tubing (5cm), a capillary tube (40cm), a 250ml beaker, secateurs, a retort stand, a stopwatch, a stopwatch, a ruler and a basin of water.

Technique : Measure the distance travelled by an air bubble in a potometer in 5 minutes using a ruler.

A bubble potometer.

Procedure :

1. A leafy shoot is chosen from a plant. The shoot with secateurs is cut off and the cut end is immersed immediately into a basin of water.

2. About 1cm of the stem is cut obliquely under the water from the cut end of the shoot.

3. The rubber tubing is fix into the capillary tube under the water. The rubber tubing and capillary tube is filled with water. The air bubbles are make sure not trapped inside the capillary tube.

4. The stem is fix to the rubber tubing under the water. The leaves are make sure kept out of the water as much as possible.

5. The apparatus are removed from the water and set up as shown in the figure above.

6. The end of the capillary tube is immersed in a beaker of water.

7. The leaves and apparatus are wiped dry with dry cloth.

8. The joint between the stem and the potometer are smeared with Vaseline to prevent leakage of water and the apparatus are airtight.

9. The capillary tube are removed from the beaker and the rubber tubing are pressed to remove a drop of water from the capillary tube. A bubble of air are allowed to enter and the capillary tube are placed back into the beaker.

10. The potometer is placed in an enclosed room with no air movement.

11. A few minutes are allowed for the shoot to reach a steady state before taking any readings.

12. The stopwatch is started and the distance travelled by the air bubble in 5 minutes is recorded.

13. Repeat steps 11 and 12 by placing the potometer under fast moving fan.

14. The distance travelled by the air bubble under both conditions are recorded in the following table.

Precaution steps :

1. When you select the shoot, make sure the base of the shoot fits snugly into the stopper or rubber tubing of the potometer.

2. Choose a shoot with many leaves as the shoots with few leaves often give inadequate results.

3. Do not allow the air bubble to reach the end of the shoot.

Results :

Condition		Distance travelled by the air bubble in 5 minutes (cm)			Rate of transpiration (cm/minute)
	1st reading	2nd reading	3rd reading	Average
Non-windy (still air)	0.30	0.25	0.20	0.25	0.050
Windy (fast moving fan)	0.30	0.50	0.20	0.33	0.066

 

(maybe you all couldn't see the title)

Graph of rate of transpiration against condition

Discussion :

The leafy shoot must be cut under water to prevent air bubbles from forming inside the xylem vessels of the shoot. This ensures a continuous column of water inside the xylem vessels. The connection between the stem and the potometer is smeared with Vaseline so that the potometer airtight and no bubbles are formed inside the potometer.

The movement of the air bubble in the potometer indicates that transpiration is taking place. The potometer measures the rate of water uptake by an isolated leafy shoot. The rate of water uptake by a detached shoot is the rate of water evaporation from the leaves and stem into the atmosphere. Therefore, a potometer indirectly measures the rate of transpiration. In a potometer, the water in the xylem vessels in the shoot is continuous with the water filling the capillary tube that reaches the cut end of the stem.

From the graph, the movement of the air bubble in the potometer is placed under a fast moving fan represents the process of transpiration in an environment with high wind velocity. The rate of transpiration is higher when there is air movement (the potometer under a moving fan). The faster air movement helps to remove the water vapour which diffuses from the stomata and accumulates near the leaves surface.

The assumption made in this experiment is that the potometer measures the rate of transpiration because it is the same as the rate of water uptake by the shoot. The distance travelled by the air bubble in the given time gives the rate of water uptake by the plant. This is the indirect measurement of the rate of transpiration.

Conclusion :

The faster the movement of air, the greater the rate of transpiration. The hypothesis is accepted.

Homework During Chinese New Year :

BM - Karangan - Surat Rasmi (aduan), Laporan Aktiviti, Wawancara Tokoh

Math - Waja, Activity Book (chap 3-5)

Add Math - Waja (chap 1-3)

Chemistry - Text Book (exercise)

Biology - PEKA (above)

Moral - Folio, Work book (unit 5-9), Esei (unit 5&6)

Sejarah - Notes (chap 3)