How does pondweed measure the rate of photosynthesis?
How does pondweed measure the rate of photosynthesis?
Method
- Set up the apparatus as in the diagram.
- Leave for five minutes for the pondweed to acclimatise to the new light intensity.
- Count the number of bubbles given off in one minute.
- Move the light 10 cm further back.
- Leave for five minutes for the pondweed to acclimatise again.
What does the rate at which the bubbles are released indicate?
of photosynthesis
The number of bubbles released in a given time can be counted as a measure of the rate of photosynthesis. The apparatus in the diagram shows how the volume of oxygen produced in a given time may be measured instead.
How does light intensity change as the distance of the pondweed from the light source is doubled?
the light intensity is related to distance – it will decrease as the distance away from the bulb increases – so light intensity for the investigation can be varied by changing the distance from the lamp to the plant.
What was the independent variable in the investigation power output of bulb?
Independent Variable: The potential difference across the bulb.
How do you set up a pondweed experiment?
How does light intensity affect photosynthesis in pondweed?
The effect of light intensity on photosynthesis can be investigated in water plants. the light intensity is related to distance – it will decrease as the distance away from the bulb increases – so light intensity for the investigation can be varied by changing the distance from the lamp to the plant.
When pondweed was left in a tube of the indicator for a day the solution went purple explain why?
Answer: When pondweed left in a tube of the indicator for a day, the solution went purple. This indicates that the pondweed is in low concentrations of carbon dioxide. Hope it is helpful.
Why is pondweed used for photosynthesis experiments?
Bright light provides more energy than dim light. Red light is more easily used by the pond weed than most other colours. This process of making sugar and oxygen is called photosynthesis. Pond weed uses the carbon dioxide which is dissolved in the water it is in.
How can you change the intensity of light reaching the pondweed?
Light will be provided by a lamp and its light intensity can be controlled by moving the light source further away from the pondweed and following the inverse square law. For a given light intensity, the rate of photosynthesis will be measured by measuring the volume of gas displaced in a set amount of time.
Why is the end of the pondweed cut off?
Like many other water plants, pondweed has specialised tissue called aerenchyma that allows oxygen to diffuse inside the plant. If you cut through the aerenchyma this gas can escape.
What gas is collected in the pondweed experiment?
carbon dioxide
Pond weed uses the carbon dioxide which is dissolved in the water it is in. The amount of dissolved carbon dioxide can be varied by adding sodium hydrogen carbonate (carbon dioxide solution) to the water. Many other plants take carbon dioxide from the air.
How does temperature affect photosynthesis in pondweed?
When the temperature rises the rate of photosynthesis rises also. There is an optimum temperature at which the rate of photosynthesis is maximum. Beyond this temperature, the reaction quickly comes to a halt. Place a pond weed Elodea upside in a test tube containing water at 25°C.
Why is my pondweed Bubbling?
When placed closer to a light source, the rate of bubbling will speed up, and as the pondweed is taken further away, the bubbles will slow down again – an instant and visual indicator of the importance of light intensity in photosynthesis.
What happens to the Elodea once the experiment is over?
-In order to be ethical, once the experiment is over, the Elodea will be recycled by releasing it back into its original habitat, a river or stream. -The capillary tube can be very fragile and breaks easily so take care whilst handling the glass.
What experiments can be done in the lab with plants?
There are several experiments that can be done in the lab that would complement this virtual experiment. For example, students can use elodea and measure the number of bubbles released when the plant is under a bright light. Algae beads can also be used to measure changes in pH as the plants consume carbon dioxide.
Is Elodea safe to use in pond water?
There is a slight risk of infection from pond water, so take sensible hygiene precautions, cover cuts and wash hands thoroughly after the work is complete. 1 Elodea can be stored in a fish tank on a windowsill, in the laboratory or prep room.
