Question

The use of Vaseline in the experiment to show that
CO, is given out during respiration, is to
(a) lubricate the joints
(b) make the set-up air-tight
(c) absorb oxygen
(d) absorb carbon dioxide
​

Answer 1

B) make the set up air tight.

Hope it helps

Answer 2

Explanation:

BASIC BUILDING CONCEPTS

Respiration is of two types – aerobic respiration and anaerobic respiration.

Aerobic respiration – In this type of respiration oxygen is utilised. As a result, complete oxidation of glucose takes place and maximum amount of energy is released. This type of respiration can be represented by the following equation:

cbse-class-10-science-practical-skills-co2-is-released-during-respiration-1

Aerobic respiration involves three stages-Glycolysis, Krebs cycle and ETS. All the events associated with glycolysis occur in cytoplasm and events associated with Kreb cycle and ETS take place in mitochondria.

Anaerobic respiration – In this type of respiration food is oxidised in the absence of oxygen. In this case, incomplete oxidation of glucose results in release of lesser amount of energy. The process of anaerobic respiration can be represented by the following equations:

cbse-class-10-science-practical-skills-co2-is-released-during-respiration-2

AIM

To show experimentally that carbon dioxide is given out during respiration,

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

Respiration is a biochemical process during which food (glucose) is oxidised to liberate energy. It is a catabolic process.

In the experiment, moist gram seeds are taken as they are actively respiring and releasing CO2. The CO2 released is absorbed by KOH and forms KgCO3.

cbse-class-10-science-practical-skills-co2-is-released-during-respiration-3

PROCEDURE

Take about 25-30 seeds of gram and germinate these seeds by placing them on moist cotton wool or moist blotting paper for 3-4 days.

Place the germinated seeds into a conical flask and sprinkle a little water in flask to moist the seeds.

Take freshly prepared 20% KOH solution in a test tube and hang it in conical flask with help of thread.

Close the mouth of conical flask by placing a rubber cork containing one hole. .

Through the hole of 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.

Seal all the connections of the experimental set-up with vaseline so as to make it air-tight.

Mark the initial level of water in the U-shaped delivery tube.

Keep the apparatus undisturbed for 1-2 hours and note the change in level of water in the delivery tube.

OBSERVATIONS

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

cbse-class-10-science-practical-skills-co2-is-released-during-respiration-4

RESULT

Germinated gram seeds in a conical flask release CO, during respiration. The C02 released is absorbed by KOH present in the hanging test tube in conical flask. This creates a vacuum in conical flask which causes upward movement of water in the delivery tube leading to change in level of water in the delivery tube.

PRECAUTIONS

Germinating seeds should be kept moist.

All connections of the set-up should be air-tight.

Freshly prepared KOH solution should be used.

Keep one end of U-shaped delivery tube in conical flask and the other end immersed in water of the beaker.

The test tube containing KOH should be hung carefully.

INTERACTIVE SESSION

Question 1.

What is respiration?

Answer:

Respiration is a biochemical process by which food material is broken down by cells into simple substances such as C02 and energy is released in the process.

Question 2.

What are the types of respiration?

Answer:

The types include-