Class 7 Science Respiration in Organisms Notes

Class 7 Science Respiration in Organisms Notes

Introduction:
The chapter “Respiration in Organisms” introduces students to the essential process of respiration that occurs in all living organisms. Respiration is the process by which organisms obtain energy from food. Unlike breathing, which involves the intake of air, respiration involves the breakdown of food to release energy. This chapter explains how different organisms, from humans to plants to microorganisms, perform respiration, the role of oxygen and carbon dioxide, and the importance of respiration in sustaining life.

Key Concepts Covered:

  1. What is Respiration?
    • Respiration is a biochemical process in which organisms break down food (usually glucose) to release energy. This process is necessary for growth, repair, movement, and other life functions.
    • Respiration occurs in the mitochondria of cells, where glucose and oxygen react to produce energy, carbon dioxide, and water.
    General Formula for Respiration: Glucose (C6H12O6)+Oxygen (O2)→Energy (ATP)+Carbon dioxide (CO2)+Water (H2O)\text{Glucose (C}_6\text{H}_{12}\text{O}_6) + \text{Oxygen (O}_2) \rightarrow \text{Energy (ATP)} + \text{Carbon dioxide (CO}_2) + \text{Water (H}_2\text{O)}Glucose (C6​H12​O6​)+Oxygen (O2​)→Energy (ATP)+Carbon dioxide (CO2​)+Water (H2​O)
  2. Types of Respiration:
    • Aerobic Respiration:
      • This type of respiration occurs in the presence of oxygen.
      • It produces a large amount of energy.
      • The general equation is: Glucose+Oxygen→Energy (ATP)+Carbon dioxide+Water\text{Glucose} + \text{Oxygen} \rightarrow \text{Energy (ATP)} + \text{Carbon dioxide} + \text{Water}Glucose+Oxygen→Energy (ATP)+Carbon dioxide+Water
      • Example: Humans and animals use aerobic respiration.
    • Anaerobic Respiration:
      • This type of respiration occurs in the absence of oxygen.
      • It produces a small amount of energy.
      • The general equation is: Glucose→Energy+Lactic acid (in animals) or Alcohol (in plants, yeast)\text{Glucose} \rightarrow \text{Energy} + \text{Lactic acid (in animals)} \text{ or } \text{Alcohol (in plants, yeast)}Glucose→Energy+Lactic acid (in animals) or Alcohol (in plants, yeast)
      • Example: Yeast cells carry out anaerobic respiration, leading to fermentation (used in making bread and alcohol).
  3. Breathing vs. Respiration:
    • Breathing is the physical process of taking in oxygen and expelling carbon dioxide from the lungs.
    • Respiration is the chemical process of breaking down food molecules (like glucose) to release energy. It occurs in all living cells, not just in the lungs.
    • Thus, breathing is just one part of the process that facilitates aerobic respiration by bringing in oxygen.
  4. Respiration in Different Organisms:
    • In Humans and Animals: Oxygen is taken in through the lungs (breathing), transported by the blood to cells, and used in the mitochondria for aerobic respiration.
    • In Plants: Plants perform aerobic respiration like animals but do so through stomata (small pores in leaves) for gas exchange. During the day, plants also perform photosynthesis, which produces oxygen and glucose, aiding in respiration.
    • In Microorganisms: Some microorganisms (like yeast) can perform anaerobic respiration, using glucose to release energy in the absence of oxygen, resulting in products like alcohol or lactic acid.
  5. Importance of Respiration:
    • Respiration provides the energy required for all life processes, including movement, growth, reproduction, and maintenance of body functions.
    • The energy produced is stored in the form of ATP (Adenosine Triphosphate), which is used for various cellular activities.
    • Respiration also helps in maintaining the carbon dioxide-oxygen balance in the environment.
  6. The Respiratory System in Humans:
    • Nose: Air enters through the nostrils.
    • Trachea (windpipe): Transports air to the lungs.
    • Lungs: The site where oxygen is exchanged for carbon dioxide through the alveoli (tiny air sacs).
    • Diaphragm: Helps in the expansion and contraction of the lungs during breathing.
  7. The Role of Oxygen and Carbon Dioxide:
    • Oxygen is required by organisms to perform aerobic respiration.
    • Carbon dioxide is produced as a waste product of respiration and is expelled from the body during breathing.

Important Questions with Answers:

  1. What is the difference between breathing and respiration?
    • Answer: Breathing is the process of taking in oxygen and releasing carbon dioxide, while respiration is the biochemical process that occurs inside cells to release energy from food, usually with oxygen.
  2. What is aerobic respiration?
    • Answer: Aerobic respiration is the process of breaking down glucose in the presence of oxygen to produce energy, carbon dioxide, and water.
  3. Where does respiration occur in the human body?
    • Answer: Respiration occurs in the mitochondria of the cells in the human body.
  4. What is anaerobic respiration?
    • Answer: Anaerobic respiration occurs without oxygen and produces less energy. It results in the formation of products like lactic acid (in animals) or alcohol (in plants, yeast).
  5. Why do we breathe in oxygen?
    • Answer: Oxygen is required for aerobic respiration, which releases energy from glucose and powers various cellular activities.
  6. What is the waste product of aerobic respiration?
    • Answer: The waste products of aerobic respiration are carbon dioxide and water.
  7. How is respiration different in plants and animals?
    • Answer: Both plants and animals perform aerobic respiration, but plants also carry out photosynthesis, which produces oxygen and glucose, which helps in respiration.
  8. What is the role of mitochondria in respiration?
    • Answer: The mitochondria are the sites of aerobic respiration in the cell, where glucose is broken down to release energy.