. Explain with the help of an activity how germinating seeds respire to release carbon dioxide. What will
happen if the same activity is performed with boiled seeds?
4. Demonstrate anaerobic respiration in yeast with the help of an activity. Will your observations differ if you
do not use oil in this activity? How?
Answers
Answer:
Explanation:
Aim
To experimentally demonstrate that carbon dioxide is released during the process of respiration.
Principle/Theory
The process of respiration is biochemically carried out wherein food, glucose to be precise is oxidized and energy is released. In this experiment, gram seeds (moistened) are used. The purpose of using these seeds is that they release carbon dioxide and are respiring actively. The released carbon dioxide is consumed by the solution of KOH.
Material Required
Soaked gram seeds
U-shaped delivery tube
Conical flask
Blotting paper (moist) /cotton wool
Thread
Water
Beaker
Test tube
Rubber cork with a single hole
Freshly prepared KOH solution (20%)
Vaseline
Procedure
Germinate close to 25 seeds. This can be done by wrapping them in moist blotting paper or cotton wool for around 3 to 4 days
Set up the germinated or sprouted seeds in the conical flask. Spray some water into the flask to dampen the seeds
With the help of a thread, suspend the conical flask containing the test tube having a freshly prepared 20% KOH solution.
Use the rubber cork to seal the opening of the conical flask.
One edge of the U-shaped glass delivery tube present in the conical flask should be inserted through the hole in the rubber cork. The other edge should be placed into a beaker that is saturated with water
All attachments of the set-up should be sealed. This can be done using vaseline to create an air-tight environment
The initial water level present in the U-shaped delivery tube needs to be marked.
Leave the experimental set-up uninterrupted for 1 to 2 hours. Observe the fluctuations in the water level in the tube.
Observation
Careful observation after a certain period of time reveals that the water level in the U-shaped delivery tube has risen in the beaker.
Conclusions
The rise in level water indicates that carbon dioxide is released as a result of germinating gram seeds during the process of respiration in the conical flask. The carbon dioxide that is released in the process is absorbed or consumed by the KOH solution that is suspended in the test tube in the conical flask, creating a vacuum or a void in the flask resulting in the upward water movement in the tube. Hence, the water level in the tube changes.
Precautions
The seeds that are to be germinated needs to be moistened
Air-tight environment for all the connections in the experimental set-up
The KOH solution that is used needs to be freshly prepared
Care needs to be taken to ensure that one end of the delivery tube is placed in the conical flask. The other edge is submerged in the water of the beaker
The tube that contains the KOH solution needs to be suspended carefully