How Can You Prove that Heat is Liberated During Respiration

A very essential part of ATP formation is respiration as it constitutes one of the most fundamental processes of living organisms. Respiration refers to the process through which living organisms obtain energy in the form of ATP (Adenosine triphosphate) by taking in oxygen and taking out carbon(iv)oxide from the oxidation of complex organic compounds.

It is a metabolic activity that happens in all living organisms. In the process of respiration, ATP is manufactured by the disintegration of glucose which is utilized by cell for different functions.

Plant cells respire just like animal cells respire. If respiration stops, life stops. Respiration and breathing are two different things. Breathing is a part of the respiration process.

Respiration is not one hundred per cent efficient. There is a liberation of heat as respiration takes place in animals. This heat is then transferred around the body which helps to maintain a static internal temperature.

Types of respiration

1. Aerobic respiration

2. Anaerobic respiration

Aerobic respiration

This uses glucose and it occurs in the presence of oxygen to manufacture energy. It occurs in the cells of plants and animals and it is a continuous process.

Anaerobic respiration

This type of cellular respiration uses only glucose and it occurs in the absence of oxygen to manufacture energy in the form of ATP. 

Phases of Respiration 

There are three phases of respiration:

  • Glycolysis
  • Oxidative phosphorylation
  • Citric acid cycle

1. Glycolysis: Glycolysis refers to a sequence of processes that absorb energy from glucose by dividing it into two, three molecules of carbon known as pyruvate.  During the glycolysis process, two molecules of NADH and ATP are produced. Oxygen is not involved in glycolysis and that means that living organisms that do not require oxygen (anaerobic organisms) also exhibit glycolysis. 


The process of glycolysis occurs in the cytosol of the cell. It can be divided into the energy-requiring phase and the energy-releasing phase.

  • Energy-requiring phase: The glucose molecule gets repositioned in this phase of glycolysis. Two phosphate groups are joined to it. Phosphate groups make up modified sugar.
  • Energy-releasing phase: This phase involves the conversion of a three-carbon sugar into another three-carbon molecule by a sequence of processes. In this phase, one molecule of NADH and two molecules of ATP are formed.

2. Oxidative phosphorylation: This happens in the mitochondria of the cell. In this process, there is a transfer of electrons from electron donors to electron acceptors. During this process, energy is released in the form of ATP.

3. Citric acid cycle: This is also referred to as the tricarboxylic acid or Kreb’s cycle. It is a principal pathway which enables a merging point for many metabolites.

How Important is Respiration

1. Makes it possible to inhale and exhale (breathing): The act of breathing is also known as pulmonary ventilation. The nose and the mouth take in air, and it flows via the pharynx, larynx and oesophagus into the lungs. The air is then taken out via the same pathway it followed when inhaling. Alterations to the air pressure and volume in the lungs cause breathing.

2. Allows for talking: During the process of releasing air out of the body, air moves from the lungs through the larynx (otherwise known as the “voice box”). Anytime you talk, the muscles in the larynx move the arytenoid cartilage which moves the vocal cord together. When the vocal cords are moved together, the passage of air between them, makes them vibrate, thereby creating sound. 

3. There is a gaseous exchange between the lungs and the bloodstream: There is an exchange of oxygen in the lungs for carbon(iv)oxide waste in what is termed as “external respiration”. This process happens through the alveoli. 

4. Exchange of gas occurs between the body tissues and the bloodstream: This process is known as “internal respiration”. Oxygen is transferred to the cells by the bloodstream. This removes carbon(iv)oxide. Oxygen is taken in from the lungs around the body by the action of the vasculature. Red blood cells release oxygen as soon as the oxygenated blood gets to the narrow capillaries.

Conducting Experiment To Prove That Heat Is Liberated During Respiration

Aim: To confirm that heat is given out during respiration

Required materials: Germinating seeds, thermos flask, thermometer, cooler


1. Get a thermos flask and use the thermos flask opening to create a proper hole cork with the thermocool.

2. Then use a thin sharp-pointed object to form a thin hole in the thermocool.

3. After that, insert the thermometer into the thin hole created

4. Put some germinating seeds in the thermos flask and then seal the flask with the cork.

5. Note down the previous temperature on the thermometer.

6. Note down the temperature recorded every two hours.

Observation: You will observe that the temperature is slowly increased, this shows that heat is given out during the process of respiration from germinating seeds present in the thermos flask.

Inference: This infers that heat is liberated during respiration.