Respiration in Organisms Class 7 Science Notes - Chapter 10
Respiration in Organisms Class 7 Science Notes - Chapter 10
Preview of the chapter
Energy is required for each cell in an organism to execute tasks like nourishment, transport, excretion, and reproduction. Energy that is included in our diet is released during breathing. We take in oxygen-rich air and exhale carbon dioxide-rich air when we breathe. This is the process of breathing. Each cell in the body eventually receives the oxygen-rich air that has been carried to every region of the body. The cell uses this oxygen for breathing. Cellular respiration is the term used to describe the process by which food is broken down in an organism's cells and energy is released.
Breathing vs. Respiration
Aerobic respiration
- When the breakdown of glucose occurs with the use of oxygen, it is called aerobic respiration.
- During aerobic respiration, glucose is completely broken down into carbon dioxide and water and energy is released.
- Aerobic respiration takes place in mitochondria.
- It can be shown by the following equation:
- Glucose(food) Oxygen−→−−−− Carbon dioxide + Water + Energy
Anaerobic respiration
- When a breakdown of glucose takes place without using oxygen, it is called anaerobic respiration.
- The glucose is not completely broken down into carbon dioxide and water.
- These organisms that carry out respiration in the absence of oxygen are called anaerobes.
Diffusion
- Diffusion is the process of movement of molecules from the area of its lower concentration to the area of its higher concentration without any application of energy.
- Diffusion is what happens when you put a drop of ink in water and it slowly mixes with the water uniformly.
- The same principle is used for the exchange of gases (breathing) in the animals.
Breathing
- It is the process in which air rich in oxygen is taken inside and air rich in CO2 is given out, with the help of respiratory organs.
- Thus, breathing involves two steps which take place alternately.
Inhalation:
Taking in of air rich in oxygen into our body is called inhalation.
Exhalation:
Giving out air rich in carbon dioxide from our body to the external environment is called exhalation.
Mechanism of Breathing
- When we breath air in (or inhale) two processes occur together, i.e. the muscles between the ribs contract causing the ribcage to move upward and outward, while the diaphragm contracts and moves downwards
- his upward and downward movement of ribcage and diaphragm respectively increases the space in the chest cavity and makes it larger.
- As the chest cavity becomes larger, it sucks air from outside the lungs and lungs get filled up with air and expand.
Breathing Out or Exhalation
- When we breath air out or exhale the reverse process takes place, i.e. the muscles of the ribs release causing the ribcage to move downward and inward, while diaphragm releases and moves upward.
- This downward movement of the rib cage and upward movement of diaphragm decreases the space in our chest cavity and makes it smaller.
- When the chest cavity becomes smaller, the air is pushed out of the lungs.
Breathing in Other Animals
Cockroaches
- spiracles on the body of insects are connected to a network of thin air tubes called tracheae which; spreads into the whole body of the insect, where the exchange of gases takes place.
- Air rich in oxygen rushes through spiracles into the tracheal tubes, diffuses into the body tissue and reaches every cell of body. Similarly,
- CO2 from the cells enters into tracheal tubes and moves out through spiracles.
Earthworm
Earthworms and leeches absorb the atmospheric oxygen through their moist and slimy skin because gases can easily pass through the moist and slimy skin. They absorb the atmospheric oxygen through their moist skin and transport it through the blood to all the cells.
Frog
A frog-like human possesses a pair of lungs but when they are in the water, they breathe through their moist and slippery skin. When they are on land they breathe through their nostrils and a pair of lungs. Breathing Under Water There are many organisms which live in water. They do also breathe underwater.
Respiration in Plants
Every living thing in the world, whether it be an animal or a plant, breathes. Along with emitting carbon dioxide, plants also absorb oxygen from the atmosphere. Additionally, they convert glucose into carbon dioxide and water, which releases energy for carrying out other tasks. Because plants breathe through their leaves, roots, etc., they breathe differently from animals. They perform independent respiration, which means that each plant component can independently take in oxygen from the air, use it to produce energy, and release CO2.
Respiration in Leaves
Plants have stomata, or microscopic pores, on the surface of their leaves. During respiration, stomata in the leaves allow for the exchange of gases, namely O2 and CO2. Through diffusion, oxygen from the surrounding air enters a leaf's stomata and permeates all of the leaf's cells, while CO2 produced during respiration also diffuses from the leaf through the stomata and into the surrounding air.
Respiration in Roots
Plants breathe through their roots underground. Additionally, they require oxygen for breathing, which releases energy for their own use. Air that is present in the gaps between soil particles provides oxygen to root cells.
The numerous microscopic hairs that cover plant roots are known as root hairs. In soil particles, oxygen from the air diffuses into root hair and eventually reaches the root's cells, where it is used for respiration.
Exchange of Gases
- The exchange of gases takes place in the plants all the time, but it is increased during day time.
- The leaves are more actively involved in photosynthesis during the day time in the presence of sunlight.
- The CO2 released during respiration is utilised by the plant during photosynthesis to produce its food.
- During photosynthesis, the O2 is released by plants which are taken up during respiration in plants.
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