bio lab report Transpiration
Introduction
Transpiration is a process which is similar to the evaporation.
Water is lost at the surface of the plant such as leaves, stems, roots and flowers in the form of water vapor. It creates a pulling.
Force which causes continuous upward movement of water and mineral salts and this force is called transpiration pull.
Apart from to water, gas like carbon dioxides from the air can also pass through by the pore of the surface of the plants for photosynthesis.
But in this experiment, we would like to focus on the negative pressure which can pull the water up through the xylem but not the CO2.
Principle:
The Cohesion-Tension Theory is one of the force which cause the movement of water and hence the transpiration. As water evaporates into the air space, the drop in water potential in the mesophyll cells causes water to be drawn from neighbouring cells along the gradient of water potential and finally from the xylem through the apopast and symplastic pathways.
In the experiment, we would like to take a look at two factors which can affect the rate of the transpiration. They are light intensity and the air movement. We will perform 4 experiments and two of them are as the control experiments. After putting the plants in different conditions, the pressure inside the tube will be changed as the presence of transpiration. This can be detected by the pressure sensor and the data will be collected by the data logger. It is reminded that the slope of the graphs is the rate of the transpiration.
Results:
Graph :The Pressure Change with time in different environmental
Expt.
Condition
Time/min
Slope
1
Ambient
0-10
-0.061
2
Ambient + Fan
10-20
-0.076
3
Ambient + Lamp
20-30
-0.070
4
Lamp + Fan
30-40
-0.063
Discussion:
Qi Compare the rates for the 4 conditions you used.
We can find that the rate of transpiration is directly proportional to the slope and the negative
Transpiration is a process which is similar to the evaporation.
Water is lost at the surface of the plant such as leaves, stems, roots and flowers in the form of water vapor. It creates a pulling.
Force which causes continuous upward movement of water and mineral salts and this force is called transpiration pull.
Apart from to water, gas like carbon dioxides from the air can also pass through by the pore of the surface of the plants for photosynthesis.
But in this experiment, we would like to focus on the negative pressure which can pull the water up through the xylem but not the CO2.
Principle:
The Cohesion-Tension Theory is one of the force which cause the movement of water and hence the transpiration. As water evaporates into the air space, the drop in water potential in the mesophyll cells causes water to be drawn from neighbouring cells along the gradient of water potential and finally from the xylem through the apopast and symplastic pathways.
In the experiment, we would like to take a look at two factors which can affect the rate of the transpiration. They are light intensity and the air movement. We will perform 4 experiments and two of them are as the control experiments. After putting the plants in different conditions, the pressure inside the tube will be changed as the presence of transpiration. This can be detected by the pressure sensor and the data will be collected by the data logger. It is reminded that the slope of the graphs is the rate of the transpiration.
Results:
Graph :The Pressure Change with time in different environmental
Expt.
Condition
Time/min
Slope
1
Ambient
0-10
-0.061
2
Ambient + Fan
10-20
-0.076
3
Ambient + Lamp
20-30
-0.070
4
Lamp + Fan
30-40
-0.063
Discussion:
Qi Compare the rates for the 4 conditions you used.
We can find that the rate of transpiration is directly proportional to the slope and the negative