To investigate the effect of air movement on the rate of transpiration of a hibiscus plant

Amali Book – Pg 4-6

Aim : To show the presence of xylem as a continous tube system to transport  water

Observations

Cross section of a balsam root

Cross section of a balsam stem

Discussion

1.       Xylem tissue

2.       Yes

3.       The vascular tissues in the stem are arranged in a circle with the phloem tissue located in the outer layer.  In the root, the xylem tissues are found in the centre and are shaped like a star whereas the phloem tissues are between the radii of the xylem.

4.       A long tube filled with coloured water. This tube is the xylem tissue as it forms a continuos tube system to transport water.

Conclusion

The xylem tissues form a continous tube system from the root to the stem and leaves in transporting water in a plant.

Amali Book – Pg 2-3

Aim	To correlate different sizes of cubes with total surface area/volume (TSA/V) ratio.
Hypothesis	The smaller the size of cube, the larger the TSA/V ratio; the higher the percentage of coloured area.
Variables	MV : Size of cubes RV : The percentage of coloured area FV : Temperature, time taken, type of potato

Side (cm)	T Surface area (cm2)	Volume (cm3)	TSA/V	Estimated Percentage of coloured area  (%)
2	24	8	3	60
3	54	27	2	40
4	96	64	1.5	30

Answer to Question

1.       A big object has a low TSA/V ratio in which the movement of solutes through diffusion is less.  The hypothesis is accepted.

Heart beat animation

How Blood flow through the heart

Answers to Hands-on Pg 10-16

1. C 2. C 3. D 4. D 5. B 6. C 7. A 8. B 9. D 10. C

11. D 12. C 13. B 14. A 15. A 16. D 17. D 18. C 19. D

1. (a) P : Erythrocyte

Q : Leucocyte

(b) (i) To transport oxygen from the lungs to the body tissue

(ii) Haemoglobin

(c) Cell P, erythrocyte, is filled with haemoglobin. Oxygen from the lungs diffuses into the red blood cells and combines with the haemoglobin to form oxyhaemoglobin.

Oxygen is carried to the body tissues in the form of oxyhaemoglobin. Upon reaching the tissues, oxygen readily detaches itself and diffuses into the body cells.

(d) Draw the 2 processes of phagocytosis from the Biology text book

(ii)Phagocytosis

(iii) Phagocytosis is carried out by neutrophil, a type of leucocyte.

The neutrophil will move towards a bacterium in an amoebic movement.

Upon coming into contact with the bacterium, a cup-shaped indentation is formed and the bacterium is taken into a vacuole where it is digested by lysosomes.

2. (a) To colour the xylem tissues

(b)

(c) (i) Xylem

(ii) Elongated tube which runs continuously from the roots to the leaves.

(d) When water vapour evaporates from the leaves, a transpirational pull is exerted to draw up water along the xylem vessels.

Cohesive forces between the water molecules prevent the water column in the xylem vessels from breaking.

Adhesive forces between the water molecules and the xylem vessel wall prevent the water molecules from falling back.

As a result of these forces, water molecules are pulled towards the leaves.

(e) Water molecules from the soil are drawn into the root hairs through osmosis. A force exists to ‘pull’ the water from the roots to the xylem vessels. This force is called root pressure, which is responsible for pushing the water from the roots to the stem.

This explains the increase in water level in the tube after one day.

Answers to Hands-on Pg 8-10

Aim : To study the effect of light intensity on the rate of transpiration.

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

MV : Light intensity

RV : Distance traveled by air bubble in 10 minutes

FV : Air movement/temperature/air humidity/type and size of plant

Method :

1. Setup the apparatus as shown in diagram above.

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

3. Insert cut stem in the potometer (capillary tube fitted with rubber tubing).

4. Lift the capillary tube to insert an air bubble.

5. Adjust and mark the initial position of the air bubble with a thread.

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

7. Make sure the apparatus is airtight by smearing the joints with vaseline.

8. The air movement / temperature /humidity of the surrounding/type and size of plant must be maintained throughout the experiment.

9. A table lamp was placed 50cm away from the potometer.

10. Measure and record the distance traveled by the air bubble in 10 minutes using a stopwatch.

11. Repeat the experiment by placing the lamp at different distances of 40cm, 30cm and 20 cm from the potometer.

12. Calculate the rate of transpiration using the formula : Distance traveled by air bubble/time.

13. Tabulate the results in a table.

Distance of light bulb (cm)	50	40	30	20
Distance traveled by air bubble in 10 min (cm)	4	8	11	15
Rate of transpiration (cm/s)	4/10 = 0.4	8/10 = 0.8	11/10 = 1.1	15/10 = 1.5

Discussion :

1. When the distance between the light source and the leafy shoot decreases, the light intensity increases.

2. Rate of transpiration is highest when the light source is 20cm from the leafy shoot.

3. Rate of transpiration is lowest when the light source is 50cm from the leafy shoot.

4. When light intensity increases, the stomata open more as photosynthesis increases. Therefore more water vapour is lost through the stomata. Hence the rate of transpiration increases.

Conclusion : The hypothesis is accepted. When light intensity increases, the rate of transpiration increases.

Answers to Hands-on Pg 6-8

Beginning of activity - Apparatus with a porous pot

End of activity - Apparatus with a porous pot

Beginning of activity - Apparatus with a leafy shoot

End of activity - Apparatus with a leafy shoot

Discussion:

1. Water evaporates from the surface of the porous pot, causing the water in the capillary tube to rise. This draws the mercury level up. Adhesive forces and cohesive forces enable the water column to be held together.
2. As the water evaporates from the leaf surface, the water in the xylem vessel rises, drawing the mercury up the capillary tube. Adhesive forces between water molecules and the capillary tube wall prevent the water molecules from falling back. Cohesive forces between the water molecules prevent the water column from breaking.

Conclusion :

Adhesive and cohesive forces cause the movement of water in plants.