Respiration is the process by which organisms produce energy from food through cellular respiration. It occurs in the mitochondria of cells and requires oxygen. There are two types of respiration: aerobic respiration, which uses oxygen and produces carbon dioxide and water, and anaerobic respiration, which occurs without oxygen and produces substances like alcohol or lactic acid. Breathing is the process of inhaling and exhaling air for respiration through organs like lungs, gills, or skin depending on the organism. The rate of breathing increases with physical activity and decreases at rest.

1. VIDYA BHARTI EDUCATIONAL INSTITUTIONS
SCIENCE NOTES CLASS 7TH
RESPIRATION IN ORGANISM
RESPIRATION: The biological process in which food is utilized to produce energy is
called respiration. Respiration is necessary for survival for the living beings. A living
being cannot survive even for a few seconds, without respiration. During respiration, it is
mainly the carbohydrate which is oxidized to produce energy. This can be shown by
following equation:
SITE OF RESPIRATION: Respiration happens inside the cells. As respiration happens
inside the cell, it is also called cellular respiration. A cell organelle; called mitochondria;
is the site of cellular respiration.
TYPES OF RESPIRATION
AEROBIC RESPIRATION: Aerobic respiration takes place in the presence of oxygen.
Carbon dioxide and water are the end products of aerobic respiration. Aerobic
respiration happens in most of the organisms.
ANAEROBIC RESPIRATION: Anaerobic respiration takes place in the absence of
oxygen. Anaerobic respiration usually happens in most of the microbes. Alcohol and
carbon dioxide are formed at the end of anaerobic respiration. In some cases, lactic
acid is formed at the end of anaerobic respiration.
Anaerobic respiration also happens in our muscle cells. When someone runs or walks
too fast, one may feel a throbbing pain in calf muscles. This happens because of
deposition of lactic acid; produced by anaerobic respiration. Once the person takes rest
for some time, the pain goes away.
BREATHING: The process of taking in and giving out air; for respiration; is called
breathing. Breathing involves two man steps, viz. inhalation and exhalation. During
inhalation, we breathe in air which is rich in oxygen. During exhalation, we breathe out
air which is rich in carbon dioxide.
RATE OF BREATHING: When we are doing normal activities, the rate of breathing is
normal. The rate of breathing increases when we do strenuous physical works; such as
CONTACT: 9654089891, 9811083910, 9953898004
HEAD OFFICE: 131/12 KRISHNA COLONY, STREET NO 4, NEAR SHIV MANDIR, GURGAON

2. VIDYA BHARTI EDUCATIONAL INSTITUTIONS
SCIENCE NOTES CLASS 7TH
RESPIRATION IN ORGANISM
running, swimming, jogging, etc. the rate of breathing decreases when we take rest or
when we are sleeping.
PROCESS OF BREATHING: The breathing is controlled by the movement of
diaphragm. Diaphragm is a membrane which is between the chest and abdomen. The
movement of diaphragm is controlled by a group of muscles; called intecostalis
muscles.
When the diaphragm moves down, the ribcage expands. This leads to the expansion
inside the lungs. As a result, the air moves into the lungs. This process is called
inspiration or inhalation.
When the diaphragm moves up, the ribcage contracts. This leads to contraction of the
lungs. As a result, the air moves out of the lungs. This process is called expiration or
exhalation.
To show that carbon dioxide is released during exhalation:
Carbon dioxide reacts with limewater to make calcium carbonate. This property is
utilized to show the evolution of carbon dioxide during respiration. For this, take a test
tube and pour some limewater in it. Dip a drinking straw in the test tube. Blow air in the
limewater through the drinking straw. It is observed that the limewater turns milky. This
shows that carbon dioxide is released during exhalation.
BREATHING IN OTHER ANIMALS
Animals, which belong to amphibia, reptilian, aves and mammalia, use the lungs for
breathing. Amphibians breathe through their skin, when they are in water. Smaller
animals have different organs for breathing.
CONTACT: 9654089891, 9811083910, 9953898004
HEAD OFFICE: 131/12 KRISHNA COLONY, STREET NO 4, NEAR SHIV MANDIR, GURGAON

3. VIDYA BHARTI EDUCATIONAL INSTITUTIONS
SCIENCE NOTES CLASS 7TH
RESPIRATION IN ORGANISM
BREATHING IN FISH: Fish have a pair of gills. The breathe air; dissolved in water;
through gills.
BREATHING IN COCKROACH: Cockroach and other insects breathe through spiracles
and tracheae. There is a network of hollow tubes running through the body of an insect.
These hollow tubes are called trachea. Each trachea opens on the body surface in the
form of very small pore. These pores are called spiracles.
BREATHING IN EARTHWORM: Earthworms breathe through their skin. The skin of
earthworm always remains moist, which helps in breathing.
Breathing in Unicellular Animals: Unicellular animals breathe through the cell
membrane.
BREATHING IN PLANTS: Plants can be of various sizes. Developing respiratory
organs could not be a fruitful solution for plants; because of their unlimited growth. Each
plant part breathes through its external layer of cells. Roots breathe through root hairs.
Stems breathe through epidermis. Leaves have numerous small pores; called stomata;
for breathing.
CONTACT: 9654089891, 9811083910, 9953898004
HEAD OFFICE: 131/12 KRISHNA COLONY, STREET NO 4, NEAR SHIV MANDIR, GURGAON