It involves:-
taking oxygen (or air) into the cell
↓
Using it for releasing energy by burning food
↓
Eliminating the waste product (CO2 and water) from the food
The reaction that takes place during respiration is:-
Food + O2 (g) ----> Energy + H2O (l) + CO2 (g) ↑
↓
(Glucose)
Note- The process of respiration takes place inside the cells of
the body that’s why it is called cellular respiration.
-> It is essential for life because it provides energy for carrying out all
the life process which is necessary to keep an organism alive.
Difference between breathing and respiration
In Muscle cells 
Q) When anaerobic respiration takes place in human
beings?
| Respiration | Breathing |
|---|---|
| * It includes breathing as well as oxidation of food in the cells to release energy. |
* It includes obtaining oxygen from the air and release CO2. |
| * It is a physical as well as the biochemical process of oxidation of food. | * It is a physical process. |
| * In this process, Lungs & Mitochondria are involved. | * In this process, only lungs are involved. |
| * Energy is released. | * Energy isn't released. |
| * Enzymes are used in this process. | * Enzymes aren't released in this process. |
The energy produced during respiration is stored in the form of ATP
molecules in the cells of the body.
it is used by the organism when required.
ADP ➝ Adenosine Diphosphate; low energy content
ATP ➝ Adenosine Triphosphate; high energy content
Pi ➝ inorganic phosphate
The energy released during respiration is used to make ATP molecules
from ADP and pi.
ADP + phosphate + energy ➝ ATP
↓ ↓ ↓
(low energy) (pi) (high energy)
Thus, energy is stored during respiration is in the form of ATP
molecules. when cells need energy then ATP gets breakdown using water to
released energy.
ATP + water ➝ ADP + phosphate + energy
↓
This released energy is equivalent to 30.5 KJ/mol.
Note- ATP is known as the energy currency of the cell.
-> Most cases, respiration takes place by
using oxygen however some organism exist which carry out respiration without using oxygen.
So,
In the presence of oxygen, there are two types of
respiration. i.e. aerobic & anaerobic.
Aerobic Respiration
-> The process of respiration which takes place in the presence of
oxygen is called aerobic respiration. In this process, the glucose (food) is completely breakdown into Co2 and water by oxidation. In this process, More energy is released as compared to anaerobic
respiration.
So,
it takes place in the cytoplasm and mitochondria. Mitochondria are known as the
sites of aerobic respiration.
End Products are -> 6CO2+6H2O+ 38 ATP
Note- Formula of Pyruvate is C3H4O3 or CH3-CO-COOH
↓
The primary function of the pyruvate molecule is to act as the
transport molecule that carries carbon atoms into the mitochondria
for complete oxidation to carbon dioxide.
Anaerobic Respiration
-> The process of respiration which takes place in the absence of
oxygen is called anaerobic respiration. In this process, incomplete
oxidation of glucose takes place. It only occurs in the cytoplasm. In this process, Less energy is released as compared to aerobic
respiration.
It occurs in certain bacteria, yeast, and certain tissues of the higher
organisms like human beings.
* Fermentation- The process by which microscopic organism like yeast & certain bacteria obtain energy by anaerobic respiration is
called fermentation.
In yeast
Ans->When the demand for oxygen is more than the
supply, muscle cells use anaerobic respiration for some time. So during vigorous exercise, Anaerobic
respiration takes place in human beings.
Note– Phosphate is necessary for the formation of
bone and teeth. Phosphate is also used as a building block
for several important substances, including those used by
the cell for energy, cell membranes, and DNA
(deoxyribonucleic acid).
| Plants | Animals |
|---|---|
| * All the parts of plants like roots, leaves, and stems perform this process individually. | * Animal performs respiration as a single unit. |
| * During respiration, there is a little transport of respiratory gases from one part to the other part of the plant. | * During respiration, Respiratory gases usually transported over long distances inside the animals. |
| * Respiration occurs at a slow rate. | * Respiration occurs at a fast rate. |
* Diffusion -> The net random movement of particles
(atoms, molecules or ions) from higher concentration to
lower concentration of a substance until the concentration
becomes uniform is called Diffusion.
It is a very slow process.
The diffusion rate depends on the following factors:-
i) On concentration- The rate of diffusion is directly
proportional to the concentration. Hence, when concentration
is higher, then the diffusion process is also higher and vice-versa.
ii) On surface area- The rate of diffusion is directly
proportional to the surface area. Hence, when the surface area is
greater, then the rate of diffusion is also greater and vice-versa.
* Plants use the diffusion process for respiration because they
have a branching shape, so they have a large surface area as
compared to their volume. Therefore, diffusion alone can
supply O2 to all the cells of a plant.
It is also a very important process for photosynthesis
because carbon dioxide diffuses into the leaves from the
stomata and finally goes into the cells of the plant.
* Diffusion occurs in the root, stem, and leaves of the plant.
Q) Why the process of diffusion is an
incomplete process to supply the oxygen in
multicellular organisms like human beings?
Ans- Human beings don’t use the diffusion process for
respiration because the body of human beings has a large
volume as compared to their surface area. So, diffusion alone
can’t provide oxygen to all the cells of the human body quickly.
Note- In the human body, RBC carries oxygen from the
lungs to all the parts of the body very effectively.
Respiration in roots
-> Air present in soil interspaces and roots hairs of the root are in direct contact with
them. Now, oxygen
present in the soil diffuses
in plants through root hair
and reaches to all the
internal cells of the root
for respiration. During this process, CO2 is released in the root cells which
diffuses in the opposite direction.
* In the absence of oxygen, soil air becomes deficient. As the result, the metabolic activity of the root gets disturbed and the plant may
wither (सुखना ).
Soil may be regarded as waterlogged soil when it is nearly
saturated with water much of the time such that its air phase
is restricted and anaerobic condition prevails (प्रबल ).
In other words, during agriculture, various
crops needed (especially oxygen) to a greater or lesser depth
of the soil. waterlogging of the soil stops
the air from getting in.
Respiration in stems
-> The stems of herbaceous plants have stomata. the oxygen
from the air diffuses into the stems of herbaceous plants through
stomata and reaches all the cells of the plant for respiration.
The CO2 gas produced during respiration diffuses out into the
air through the same stomata.
Note- In Woody stem, the bark has lenticels for gaseous
exchange.
↓
* Lenticels:- These are the pores of outer plant tissue
that provide a direct exchange of gases between internal
parts and the atmosphere. The bark is normally impermeable and the
exchange or release of internal gases would be Impossible
without the plant’s lenticels.
Here, Lenticel acts as a layer.
Respiration in leaves
-> Leaves respire through stomata. The exchange of respiratory
gases in the leaves take place by the process of diffusion
through stomata.
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