Advertisement

Release Of Co2 In Respiration Class 10th Science Lab Manual CBSE Solution

Class 10th Science Lab Manual CBSE Solution

Lab Experiment 7
Question 1.

AIM

To show that carbon dioxide is given out during respiration.


Answer:

MATERIALS REQUIRED


Conical flask, U-shaped delivery tube (tube bent twice at right angles), cotton wool or moist blotting paper, water, thread, beaker, test tube, rubber cork with one hole, 20% freshly prepared KOH solution, Vaseline, soaked gram seeds.


THEORY


1. Respiration is a catabolic process during which food (glucose) is oxidized to liberate energy.


2. In the experiment, moist gram seeds are taken as they are actively respiring and releasing carbon dioxide.


3. The carbon oxide released is absorbed by KOH and forms K2CO3.


4. The reaction is given below:



PROCEDURE


1. Take about 20-30 gram of gram seed and germinate these seeds by placing them on moist cotton cloth or moist blotting paper for at least 3-4 days.


2. Place the germinated seeds into a conical flask and add some water in the flask to moist the seeds.


3. Prepare a 20% KOH solution in a test tube and hang it in the conical flask with the help of thread, as shown in the figure:



4. The mouth of the conical flask should be blocked by placing a rubber cork on the mouth of the conical flask.


5. Through the hole in the rubber cork, insert one end of the U-shaped glass delivery tube in the conical flask and place the other end into a beaker filled with water.


6. vaseline must be applied to all the connections of the set-up to make the connection air-tight.


7. Also, mark the initial level of water in the U-shaped delivery tube.


8. Keep the apparatus undisturbed for 2-3 hours and then note the change in the level of water in the delivery tube.


OBSERVATIONS


After some time, the water level in U-shaped delivery tube dipped in water of the beaker rises.


RESULT

1. The CO2 is released by the germinated gram seeds during respiration.

2. The CO2 released is absorbed by KOH present in the hanging test tube in a conical flask.

3. The absorption of CO2 creates a vacuum in the conical flask which causes an upward movement of water in the delivery tube leading to a change in the level of water in the delivery tube.

PRECAUTIONS

1. Seeds should be kept under a moist condition to undergo germination.

2. The test tube containing KOH must be hung carefully inside the flask.

3. Freshly prepared KOH solution should be used.




Viva Questions
Question 1.

What is respiration?


Answer:

Respiration is a biochemical process during which food is oxidized to liberate energy. The food is broken down into simple substances such as CO2, and the energy is released in the process.



Question 2.

What is anaerobic respiration?


Answer:

In this types of respiration the food is oxidized in the absence of oxygen. As a result of incomplete combustion lesser amount of energy is released during the oxidation process. The end products are CO2 and water.



Question 3.

What is aerobic respiration?


Answer:

The aerobic respiration is a type of respiration in which the oxygen is utilized. As a result, maximum amount of energy is released.



Question 4.

Give the reaction for aerobic respiration?


Answer:

Aerobic respiration involves the complete oxidation and breakdown of glucose into the end products CO2 and water. Hence, aerobic respiration released 38ATP.

The reaction is given below:




Question 5.

Give the reaction for anaerobic respiration?


Answer:

Anaerobic respiration involves the incomplete or partial breakdown of glucose. Hence only 2 ATP are released. The reaction is given below:



Question 6.

What are the steps involved in aerobic respiration?


Answer:

The steps include are

1. Glycolysis: It converts one six-carbon molecule of glucose into two three-carbon molecules of pyruvate.


2. Krebs cycle: It is a series of cycles Krebs (also known as citric acid cycle) which takes in acetyl CoA and produces carbon dioxide, NADH, FADH2, and ATP or GTP


3. ETS and Oxidative phosphorylation. Here, the co-enzymes like NADH can lead to the production of ATP through oxidative phosphorylation.



Question 7.

Name the energy unit of the cell ?


Answer:

ATP(Adenosine triphosphate)



Question 8.

What is the compensation point?


Answer:

Compensation point is when the rate of photosynthesis is just equivalent to the rate of respiration.



Question 9.

How does KOH help to show CO2 is released?


Answer:

The KOH will absorb CO2 which creates a partial vacuum pressure in a conical flask, causing a rise in water level in u- the tube which shows CO2 is released during respiration.



Question 10.

Why is Vaseline used in the experiment?


Answer:

Vaseline is involved in all the joints in the experimental setup , thereby making the set-up air-tight.



Question 11.

Suggest an alternate apparatus to show that CO2 is released during respiration?


Answer:

Using lime water instead of water, since lime water turns milky when reacts with CO2 thus conforming CO2 formation during respiration.



Question 12.

Where does the glycolysis and kreb’s cycle take place inside the cell?


Answer:

Glycolysis takes place inside the cytolplasm of the cell. Kreb’s cycle takes place in the mitochondria of the cell.



Question 13.

Why CO2 is called respiratory gas ?


Answer:

The gas involved in respiration are called respiratory gases, and CO2 is released during respiration.



Question 14.

What is fermentation?


Answer:

The anaerobic respiration carried out by some microorganisms like Yeast is called fermentation.



Question 15.

Why respiration is a catabolic process?


Answer:

Respiration involves the breakdown of a big molecule into the smaller molecule. Hence respiration is a catabolic process.



Question 16.

What will happen if the seeds are not kept moist during the experiment?


Answer:

The germinating seeds require water for growth. If no water is sprinkled on the seeds, then they will dry up and the rate of respiratrion will decrease.



Question 17.

Can we use non-germinated seeds for this experiment?


Answer:

We use germinated seeds as the rate of germination is faster in these as compared to normal seeds.



Question 18.

What will happen if no KOH solution test tube is hung in the conical flask?


Answer:

If no KOH solution is hung, then the water level will not rise. The KOH solution absorbs the CO2. If CO2 is not absorbed, then there will be no vaccum and the water level will not rise.



Question 19.

How do germinating seeds respire?


Answer:

The germinating seeds respire aerobically to produce CO2 as the end product.



Question 20.

Can you give an alternative apparatus for this experiment?


Answer:

We can use lime water in place of water and NaOH in place of KOH. Lime water will turn milky when it reacts with CO2 released by the germinating seeds.