7a) Respiration :- ~ CHiz0g + 602 >

- Glo2 + 6H20
+gy >
-
stored
• Respiration is the process by which food is burnt in the cells of the body with
the help of oxygen to release energy. It takes place in the mitochondria of the
cells.
• The energy released during respiration is used to make ATP molecules
(Adenosine tri phosphate) from ADP molecules (Adenosine di phosphate) and
inorganic phosphate.
Energy
ADP + Phosphate ATP (storing energy]
from respiration
• Energy is stored in the cells in the form of ATP molecules. When the cells
need energy, ATP is broken down in the presence of water to form ADP and
energy is released.
• water
• ATP ADP + Energy [whenever energy
+ is needed]
Phosphate
Glucose >
- CO2 + 120
+y
a

break ,this
an
(ATP)
triphosphate
Adenosine

energy
En ever easd

Pi AT-
ADD +

denosine
-g
2

2 *TP

ATP- > ADD + Pi +

c be used

by 211s -
 38 AT&
Presence of
(MITOCHONDRIFY CO2 + Ho
en
+

M
AEROBIC

(GC)
rost--ATE
(3C) Absence of
CMUSCLE CELLS)
02
LACTIC ACET] -

L
-
-

(Cytoplasm) Kytoplasm)
ANAEROBI
Castoplasm)
&
C accumulation causes
cramps
muscle
fatigue

CALCOHOL
Absence
FERMENTATIONY
of 02 & ATP
YEAST CELLS

ANAEROBIC
Ethanol + CO2 +
E
energy

Cytoplasms
b) Types of respiration :-
• There are two main types of respiration. They are aerobic and anaerobic respiration.
i) Aerobic respiration :- takes place in the presence of oxygen. It produces more energy. The end
products are carbon dioxide, water and energy. It takes place in most organisms.
• In aerobic respiration glucose is converted into pyruvate in the cytoplasm in the presence of
oxygen and then in the presence of oxygen, pyruvate is converted into carbon dioxide, water and
energy in the mitochondria.
presence of oxygen presence of oxygen
Glucose Pyruvate CO2 + H2O + Energy
in cytoplasm in mitochondria
ii) Anaerobic respiration :- takes place in the absence of oxygen. It produces less energy. The end
products are lactic acid or ethanol, carbon dioxide, and energy. It takes place in muscle cells and
yeast.

• In anaerobic respiration in muscle cells, glucose is converted into pyruvate and in the absence of
oxygen pyruvate is converted into lactic acid and energy.
presence of oxygen absence of oxygen
•Glucose Pyruvate Lactic acid + Energy
in cytoplasm in muscle cells
• In anaerobic respiration in yeast, glucose is converted into pyruvate and in the absence of oxygen
pyruvate is converted into ethanol, carbon dioxide and energy. This process is called fermentation.
presence of oxygen absence of oxygen
•Glucose Pyruvate Ethanol + CO2 + Energy
in cytoplasm in yeast
 Breakdown of glucose by various pathways :-

presence
of oxygen
CO2 + H2O + Energy
(in mitochondria)

absence
of oxygen
•Glucose Pyruvate Lactic acid + Energy
in cytoplasm + (in muscle
Energy cells)

absence
of oxygen
Ethanol + CO2 + Energy
(in yeast)
b) Respiration in Humans :-
• The main organs of the respiratory system are nostrils, nasal cavity,
pharynx, larynx, trachea, bronchi, bronchioles, lungs and diaphragm.

NAREURL
-
• Air enter through the nostrils. The hairs and mucous traps the dust particles. It then
passes through the phraynx, larynx, trachea, bronchi and enters the lungs. The trachea
has rings of cartilage which prevents it from collapsing when there is no air in the
trachea. The bronchi divides into smaller tubes called bronchioles which ends in tiny air
sacs called alveoli. The alveoli is supplied with blood vessels through which exchange of
gases takes place. The alveoli helps to increase the surface area for the exchange of
gases.
valued
surface
exchange gases
aea

~
provides
w >
-

Oa
Mecahanism of breathing :-
• When we breathe in air, the muscles of the diaphragm contracts and
moves downward and the chest cavity expands and air enters into the
lungs.
• When we breathe out air, the muscles of the diaphragm relaxes and
moves upward and the chest cavity contracts and air goes out of the
lungs.