- Respiration is the biochemical process in which the cells of living organisms obtain energy by combining oxygen and glucose, resulting in the release of carbon dioxide, water, and ATP.
C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP
- Diverse organisms use oxygen to break-down glucose completely into carbon dioxide and water.
- The oxidation of glucose provides energy required for all cellular activities.
- In the absence of glucose, the cells break down proteins and fats to produce glucose. Further oxidation of this glucose fulfil the respiratory needs of the cell.
- At first, the six carbon glucose is broken down into two molecules of three carbon pyruvate (C3H4O3). This process takes place in the cytoplasm.
- Cellular respiration takes place in mitochondria. That’s why mitochondria are also known as the powerhouse of the cell.
Difference between breathing and respiration:
|It is a physical process.||It is a biochemical process.|
|In this process, we inhale and
exhale air in and out of our lungs.
|In this process, oxygen is used to
breakdown Glucose in order to
|It involves taking in oxygen from the
environment and removal of carbon
dioxide from the body.
|In this process chemical energy stored
in the food is released in the form of
ATP along with carbon dioxide and
|Breathing takes place in the respiratory
organs called as lungs.
|This takes place in the cells.|
|It is a voluntary process.||It is the involuntary process.|
|Breathing involves respiratory organs
and the cells called as alveoli.
|It involves cells in the body
and their organelles.
Types of respiration:
Different living organisms respire in different ways. Based on their respiration process either in presence or absence of oxygen there are two types of respiration:
- The respiration which takes place in absence of oxygen is called anaerobic respiration.
- Also, we can say it is the process of producing cellular energy without oxygen.
- There is no release of water in this process.
- Anaerobic respiration is a relatively fast reaction and produces 2 ATP, which is much less than aerobic process.
- Some examples include alcohol fermentation, lactic acid fermentation and in the decomposition of organic matter.
Glucose + Enzymes = Carbon Dioxide + Ethanol / Lactic acid
- Aerobic respiration is the breakdown of glucose in the presence of oxygen.
- This type has end products carbon dioxide, water and energy.
- The amount of energy released in aerobic respiration is very high i.e. 686 kcal or 38 ATP of chemical energy and 420 kcal of heat energy.
- Aerobic respiration is carried out in two stages that are: Glycolysis and Krebs cycle.
- It is mainly seen in multicellular organisms such as animals, plants, humans, several bacteria, fungi etc.
Difference between aerobic and anaerobic respiration:
|Aerobic Respiration||Anaerobic Respiration|
|The respiration which takes place in
the presence of oxygen is aerobic
|The respiration which takes place in
the absence of oxygen is anaerobic
|The end products of aerobic respiration
are carbon dioxide and water.
|The end products of anaerobic
process are carbon dioxide and
ethanol or lactic acid.
|In this process our brain receives
|This process helps in fermentation of
yeast to produce ethyl alcohol or
ethanol in the beverage industry.
|Aerobic respiration is carried on in two
stages call glycolysis and Krebs cycle.
|Anaerobic process is also carried on
in two stages called glycolysis and
|This type of respiration is mainly in
multicellular organisms such as
animals, plants, humans, etc.
|Anaerobic respiration is mainly seen in
unicellular organisms like bacteria,
fungi, protozoa, etc.
|Aerobic respiration which is carried out
in the lungs of humans, animals are
called pulmonary respiration.
|Anaerobic respiration uses bacteria
such as lactobacillus to convert pyruvic
acid into lactic acid. This bacteria
commonly used for making curd or
Respiration in plants:
- Every part of a plant carries respiration process.
- Stems, leaves and roots respire at very lower rate as compared to animals.
- The leaves of plants have tiny pores on their surface which are called stomata. Plants exchange gases by diffusion through the stomata during respiration.
- Oxygen from the air diffuses into a leaf and reaches all the cells.
- During respiration carbon dioxide produced is released into the air through the stomata.
- Plants respire during the day as well as during the night.
- During the day, plants respire the same oxygen produced during photosynthesis and the extra amount of oxygen is released through the stomata.
- The air present in the soil is taken up from roots.
- In stems, from either stomata or lenticels, the exchange of gases takes place.
Respiration in animals:
- In simple unicellular animals like Amoeba, respiration takes place by the simple diffusion of gases through the cell membrane.
- Earthworms use their skin to absorb oxygen from air and release carbon dioxide. So, skin is the respiratory organ in the earthworm.
- Fish, prawns and mussels are the aquatic animals which have gills as the respiratory organs. Gills absorbs oxygen dissolved in water and releases carbon dioxide out of the body.
- In the insects like grasshopper, cockroach, housefly and a mosquito, the tiny holes called spiracles on their body and the air tubes called tracheae are the respiratory organs.
- The land animals such as man (humans), birds, lizard, dog and frog etc. respire through the lungs. However, Frogs breathe both by lungs and skin.
Human Respiratory System:
The respiratory system in human beings consists of the nose, pharynx, larynx, trachea, bronchi, alveoli and pair of lungs.
- Air enters the body through nostrils.
- The air passing through the nostrils is filtered by fine hairs present inside the nostrils.
- Nostrils are also lined with mucus which prevents dust particles to enter inside.
- From here, it goes to pharynx which is a common passage for both the respiratory and digestive system. After that, it moves into the larynx (voice box).
- In the throat (trachea, which also known as wind-pipe and is 10-12 cm long tube with a diameter of 2-3 cm) there are rings of cartilage which ensures that the air-passage does not collapse.
- From here, the air passes through the throat and into the lungs.
- The lungs, which are a pair of spongy and elastic respiratory organs protected by a bony rib-cage.
- Inside lungs, the passage divides into smaller and smaller tubes which finally terminate in balloon-like structures called alveoli.
- The role of alveoli is to provide a surface where the exchange of gases can take place.
- The surface of the alveoli is reached with the extensive network of blood vessels.
- As air enters the lungs through nostrils, alveoli gets filled with air.
- The blood vessels present in alveoli absorbs all the oxygen.
- Haemoglobin (Present in RBC) present in blood has a great affinity towards oxygen.
- From here oxygen is transported to all the cells in the body.
- The blood brings carbon dioxide from the rest of the body cells and releases it into the alveoli.
- When there is breathing process, the lungs always contain a residual volume of air so that there is sufficient time for oxygen to be absorbed and for the carbon dioxide to be released.
- As we know that carbon dioxide is more soluble in water than oxygen and hence is mostly transported in the dissolved form in our blood.
|Nutrition in plants||Nutrition in animals|
|Respiration in plants||Control and coordination|
|Transportation in plants||Human circulatory system|