To study and demonstrate the rate at which respiration takes place in flowering buds or in leaf tissue or in germinating seeds.
The rate of respiration can be estimated with the help of a Ganong’s respirometer as shown in the figure.
The apparatus comprises three levelling parts of the tube:
- For the respiring material, there is a bulb that terminates in a 10% KOH win small bulb at the base. The big bulb has a stopper with a lateral hole in it. It is through this hole that the atmospheric association is made through stopper regulation.
- Graduated manometer embedded with the bulb.
- A levelling tube fastened to the manometer using a rubber tubing. The complete set-up is secured on a stand.
- 10% KOH solution.
- Ganong’s respirometer.
- Germinating seeds or Flower petals or a Leaf Tissue.
- Measure 2ml of respiring material such as flower petals or germinating seeds and place it into the big bulb of the respirometer.
- Into the manometer tube, add 10% KOH solution.
- Initially, through regulation of the bulb stopper, atmospheric air around the respiring material is moved to the atmospheric pressure. The regulation continues till the neck of the bulb and the hole are coinciding.
- The reservoir tube which is placed on the right is levelled in a way that the KOH solution inside the tube reaches the mark of 100ml at the base of the manometer.
- Now the respiring material is enclosed by a setup of 100ml air.
- To start the experiment, turn the glass stopper located at the top. This causes the atmospheric air to be cut off.
- Observe the changes taking place.
Also Refer: Seed Germination
- The changes taking place within the apparatus are noted.
- The solution within the manometer tube is observed to be rising eventually. This is because respiration occurs inside the closed apparatus.
- Readings for the experiment should be taken up till 80ml mark, i.e., Volume: 20ml(as aerial oxygen is 20%). The readings should be taken at an interlude of 10 minutes.
- Every time the liquid needs to be brought to the same mark in both the tubes, i.e., the liquid within the closed tube is made to come under the atmospheric pressure.
- The outcome can be measured as the amount of carbon dioxide that evolves in millimetre which comes out of the respiring material that is used.
- When the liberated carbon dioxide comes in contact with the KOH solution, it is consumed by it. Oxygen is absorbed hence the KOH solution raises in the manometer tube.
- The rate at which the KOH solution rises is estimated from the rate at which aerobic respiration takes place, measured in terms of consumption of oxygen volume per unit time per 2ml of the respiring material.
- 1/5th of the volume of the atmospheric air is oxygen. Therefore out of 100ml of the contained air inside the respirometer, 20ml of it is oxygen.
- This is why readings are taken up to 20ml rise in the volume of the KOH solution. Post this anaerobic respiration is initiated.
To compare the rate of respiration in various parts of the plants.
- Different parts of the plant such as roots, flower buds, and leaves of appropriate herbaceous plants are selected.
- Take 2ml of plant part. It can be measured using the water displacement method.
- Place the sample in bulbs of 3 separate Ganong’s respirometers.
- The rate at which respiration takes place is demonstrated using the above-mentioned experiment.
- In an interlude of 10minutes, the volume of carbon dioxide that is liberated is noted in each scenario.
- Rate of respiration is plotted geographically for every sample taken from different parts of the plant. Comparison is made.
- The respiration rate is higher always in younger and actively growing meristematic tissues in comparison with the mature and older parts of the plant.
- Protoplasm quantity and respiration rate are directly related. The higher the amount of protoplasm, the more is the rate of respiration.
- Young cells always have a greater quantity of respiratory enzymes and hydration of protoplasm in comparison with vacuolated and mature cells. This is the reason why the rate of respiration is always greater in younger cells that are protoplasm-rich.
- If the space around root hair and roots is supplied with adequate oxygen supply, respiration takes place actively.
- Maximum respiration rate is observed when the experiment is carried out with flower buds as compared to leaves and roots.
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