Respiration in Organisms
Science Class Seven
WHY DO WE RESPIRE?
Our body does many types of works, such as walking, reading, talking, running, speaking, etc. All of these works require energy. Even while sleeping we need energy.
Our body requires more energy when we work more than normal, such as running, doing exercise, walking faster, etc.
Our body requires energy continuously even while sleeping, as our body has to perform many works even in sleeping, such as the continuous beating of the heart.
We get energy from the food that we eat. After digestion and assimilation, the nutrients of food are sent to every cell of our body. The cells of our body burn these nutrients and produce energy. Cells require oxygen to burn the nutrients which produce energy.
To get this oxygen that requires the burning of nutrients, we breathe. In breathing, we take oxygen in and expel carbon dioxide out. In the condition of working than normal, we require more oxygen, which forces our body to start breathing faster.
The process of producing energy by burning food in our body is called respiration.
The burning of food in our body using oxygen is called oxidisation of food.
Since respiration takes place in cells so it is also called cellular respiration.
In other words, the releasing of energy from the burning of food in the cells is called RESPIRATION or CELLULAR RESPIRATION.
How do we get energy in Respiration?
In the course of respiration, the glucose, we get from food, is broken down into carbon dioxide and water using oxygen and gives energy to our body.
The Reaction takes place in the Respiration
The reaction takes place during the respiration can be represented as follows:
Glucose + Oxygen ⇒ Carbon Dioxide + Water + Energy
C6H12O6 (Glucose) + 6O2 (Oxygen) ⇒ + 6CO2 (Carbon dioxide) + 6H2O (Water) + Energy
Types of Respiration
After observing the reactions takes place in respiration, it becomes evident that the burning of food takes place using oxygen and energy is released.
In majority of living organism respiration takes place in the presence of oxygen. But in some organisms and in some parts our body itself respiration takes place in the absence of oxygen also. Based on use of oxygen respiration is of two types:
(a) Aerobic Respiration
(b) Anaerobic Respiration
(a) Aerobic Respiration
The burning of glucose in our cells in the presence of oxygen is known as Aerobic Respiration.
In the course of respiration, along with energy, carbon dioxide and water are also formed. Carbon dioxide so formed is expelled out while breathing out.
In aerobic respiration glucose is oxidized completely and a higher amount of energy is released. Aerobic Respiration is a better mode of respiration in terms of efficiency or releasing energy. Carbon dioxide is produced as the bi product in respiration which is expelled out while breathing out. The oxygen we breathe in is used in oxidation of glucose. That’s why we breathe in and out continuously. The breathing in and breathing out is known as simply breathing. Aerobic Respiration occurs in most of the cell in our body.
Breathing takes place in all living organism, whether it is plant or an animal. Breathing is also known as exchange of gases.
(b) Anaerobic Respiration
Burning of oxygen in the absence of oxygen to release energy is called Anaerobic Respiration.
"An + aerobic" means "in absence of oxygen".
In the process of anaerobic respiration glucose is not oxidized completely resulting a less amount of energy is released compare to aerobic respiration. In anaerobic respiration Ethyl alcohol or lactic acid is produced as the bi product besides carbon dioxide and energy.
The reaction involved in an anaerobic respiration can be represented as follows:
Glucose (In the absence of air) → Lactic Acid + Carbon dioxide + energy
Anaerobic Respiration in Human Muscles
Sometimes we may have experienced a throbbing pain and or cramp in our calf muscles after running, cycling, long walking, or doing more exercise than normal.
In the course of more than normal physical work, our muscles demand extra energy. Demand of this extra energy is fulfilled by anaerobic respiration. In anaerobic respiration, lactic acid is produced along with the release of energy and gets accumulated in muscle cells. The accumulation of lactic acid resulted in throbbing pain or cramp in muscles.
The pain usually subsides after some rest, after taking a hot bath, or message. After taking a rest, taking a hot water bath, or massage, the circulation of blood in our muscles improves. This increases the supply of oxygen to the muscle. The increase in the supply of oxygen to the cells breaks down the lactic acid into carbon dioxide and water completely and we get relaxed of muscles' cramp or throbbing pain.
Anaerobic respiration takes place in our muscles, especially in the muscles of our legs. In anaerobic respiration lactic acid is produced as a by-product that causes cramp and or pain especially in our calf muscles. Calf muscles are present between the ankle and knee at the inner side of the legs.
The reaction involved in an anaerobic respiration can be represented as follows:
Glucose (In the absence of air) → Lactic Acid + Carbon dioxide + energy
Anaerobic Respiration in Microorganisms
In most of the microorganisms Anaerobic Respiration takes place.
This is the cause the microorganisms are called Anaerobes also.
In the case of anaerobic respiration in microorganisms, ethyl alcohol is produced as the end product, for example, anaerobic respiration in yeast. Yeast, which is a microorganism, gets energy through anaerobic respiration i.e. in the absence of oxygen. This quality enables yeast survival in the absence of oxygen.
This property of anaerobic respiration in microorganisms is used for many purposes.
The reaction involved in an anaerobic respiration can be represented as follows:
Glucose (In the absence of air) → Alcohol (Ethyl Alcohol) + Carbon dioxide + energy
Uses of Anaerobic Respiration
Anaerobic Respiration In the fermentation of batter
Jalebi; a famous sweet, idli; a famous South Indian dish, pakoda; a famous snack, etc. are made from the fermented batter. For the fermentation, the batter is left in a warm place for some time. This allows microorganisms to produce ethyl alcohol. The process of producing ethyl alcohol by microorganisms in food items is called fermentation. Because of fermentation we get special taste and consistency in these dishes.
Anaerobic Respiration In wineries
Molasses or fruit juice is left for fermentation in large tanks. The fermentation produces alcohol which is the main constituent of wine or liquor.
Anaerobic Respiration In making vinegar
Vinegar is produced by the fermentation of sugar cane juice. The juices of other fruits are also used to make vinegar. The juice is left sometimes in a warm place, which allows the microorganisms to produce ethyl alcohol by the process of anaerobic respiration. The production of ethyl alcohol converts the juice into vinegar.
Anaerobic Respiration In Dairy
Curd and cheese are made because of fermentation. There is a bacterium called Lacto Bacillus, which converts the milk into curd. A small amount of lacto-bacillus is added to warm milk as a starter. The warmth condition of milk helps in the multiplication of bacterium in which anaerobic respiration takes place. This converts the milk into curd.
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