Chapter Notes 2- Chapter 10: Respiration in Organisms, Class 7, Science | EduRev Notes

Science Class 7

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Class 7 : Chapter Notes 2- Chapter 10: Respiration in Organisms, Class 7, Science | EduRev Notes

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Respiration in Organism - Chapter Notes

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: 

Chapter Notes 2- Chapter 10: Respiration in Organisms, Class 7, Science | EduRev Notes 

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:

Chapter Notes 2- Chapter 10: Respiration in Organisms, Class 7, Science | EduRev NotesChapter Notes 2- Chapter 10: Respiration in Organisms, Class 7, Science | EduRev Notes 

  • 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. 

Review Questions 

Questions.1 What is respiration?

Answer: Respiration is a biological process in which food is utilized to produce energy. 

Questions.2 What is the end product of respiration in most of the organisms?

Answer: Carbon dioxide and water

Questions.3 What is the end product of anaerobic respiration in muscle cells?

Answer: Lactic Acid 


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 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. 

Chapter Notes 2- Chapter 10: Respiration in Organisms, Class 7, Science | EduRev Notes     

       Chapter Notes 2- Chapter 10: Respiration in Organisms, Class 7, Science | EduRev Notes 

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. 

Review Questions:   

Questions.1 What is breathing?

Answer: The process of taking in and giving out air; for respiration; is called breathing.

Questions.2 What is the respiratory organ in humans?

Answer: Lungs

Questions.3 Which membrane controls the movement of lungs?

Answer: Diaphragm


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. 

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. 

Review Questions: 

Questions.1 What is the respiratory organ in fish? 
Answer: Gills 

Questions.2 What is the respiratory organ in cockroach?
Answer: Spiracles and tracheae 
Questions.3 Which organ is used by a frog for breathing under water?
Answer: Skin

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