Explore the essential process of respiration in organisms with our detailed Class 7 Science notes on ‘Respiration in Organisms’!

Chapter 6: Respiration in Organisms

Overview of the Chapter

Understanding the Chapter

This chapter explains the process of respiration in different organisms, the types of respiration, the respiratory system in humans, and the importance of respiration for survival. It also covers the concept of aerobic and anaerobic respiration and how organisms obtain energy.

What is Respiration?

Definition and Importance

Definition: Respiration is the process by which organisms take in oxygen and release carbon dioxide to produce energy from food.
Importance: It provides the necessary energy for all life processes.

Types of Respiration

Aerobic Respiration

Definition: Respiration that occurs in the presence of oxygen.
Equation:
    Glucose + Oxygen → Carbon Dioxide + Water + Energy
    
Example: Most animals and plants.

Anaerobic Respiration

Definition: Respiration that occurs in the absence of oxygen.
Equation:
    Glucose → Lactic Acid + Energy
    
(in muscle cells)
    Glucose → Alcohol + Carbon Dioxide + Energy
    
(in yeast cells)
Example: Yeasts and some bacteria.

Human Respiratory System

Organs and Functions

Nose and Nasal Cavity: Filters, warms, and moistens air.
Pharynx: Passageway for air and food.
Larynx: Voice box, produces sound.
Trachea: Windpipe that filters air and leads to bronchi.
Bronchi and Bronchioles: Air passages that lead to the lungs.
Lungs: Main organs of respiration, where gas exchange occurs.
Alveoli: Tiny air sacs in the lungs where oxygen and carbon dioxide are exchanged.

Breathing Process

Inhalation and Exhalation

Inhalation: The process of taking in air rich in oxygen.
Exhalation: The process of expelling air rich in carbon dioxide.

Mechanism of Breathing

Diaphragm and Intercostal Muscles

Diaphragm: A domeshaped muscle that contracts and flattens during inhalation, increasing the chest cavity volume.
Intercostal Muscles: Muscles between the ribs that contract to lift the ribcage during inhalation.

Cellular Respiration

Process in Cells

Definition: Cellular respiration is the process by which cells produce energy from glucose.
Stages: Glycolysis, Krebs cycle, and Electron transport chain.

Anaerobic Respiration in Muscles

Lactic Acid Fermentation

Process: During vigorous exercise, muscles may not get enough oxygen and switch to anaerobic respiration, producing lactic acid.
Effect: Causes muscle fatigue and cramps.

Respiration in Other Organisms

Respiration in Fish

Gill Function: Fish breathe through gills which extract oxygen from water and expel carbon dioxide.
Process: Water enters through the mouth, passes over the gills, and exits through gill slits.

Respiration in Cockroaches

Tracheal System: Cockroaches breathe through a network of tubes called tracheae.
Spiracles: Openings on the sides of the body that allow air to enter and exit the tracheal system.

Respiration in Earthworms

Skin Respiration: Earthworms breathe through their moist skin.
Diffusion: Oxygen diffuses directly through the skin into the bloodstream, and carbon dioxide diffuses out.

Respiration in Plants

Process: Plants respire through stomata in leaves and lenticels in stems.
Equation: Similar to aerobic respiration in animals.

Fungi and Bacteria

Yeasts: Undergo anaerobic respiration to produce alcohol and carbon dioxide.
Bacteria: Some bacteria can respire anaerobically.

Importance of Respiration

Energy Production

Function: Provides energy for growth, repair, and maintenance of body functions.
Importance: Essential for survival and all life processes.

Conclusion

Summary of the Chapter

Respiration is crucial for energy production in organisms.

Aerobic respiration occurs in the presence of oxygen, while anaerobic respiration occurs without oxygen.

The human respiratory system consists of organs that facilitate the exchange of gases.

Cellular respiration takes place in cells to produce energy.

Different organisms have varied methods of respiration.

Additional Information

Key Terms and Concepts

Respiration: The process of exchanging gases to produce energy.
Aerobic Respiration: Respiration with oxygen.
Anaerobic Respiration: Respiration without oxygen.
Cellular Respiration: Energy production within cells.

Important Examples and Cases

Human Respiratory System: Involves organs like the lungs and diaphragm.

Human Respiratory System

Nasal Cavity Pharynx Larynx Trachea Left Bronchus Right Bronchus Left Lung Right Lung Diaphragm

Anaerobic Respiration in Yeast

Used in baking and brewing industries.

Notable Observations

Effect of Exercise: Vigorous exercise can lead to anaerobic respiration in muscles.
Respiration in Plants: Similar to animals but through different structures like stomata and lenticels.
1.  What is respiration?

Respiration is the process by which organisms take in oxygen and release carbon dioxide to produce energy from food.

2.  Why is respiration important?

Respiration provides the necessary energy for all life processes, including growth, repair, and maintenance of body functions.

3.  What is the difference between aerobic and anaerobic respiration?

Aerobic respiration occurs in the presence of oxygen, while anaerobic respiration occurs without oxygen.

4.What is the role of intercostal muscles in breathing?

Intercostal muscles are located between the ribs and help lift the ribcage during inhalation, increasing the chest cavity volume and aiding in breathing.

5.How do bacteria respire?

Some bacteria respire aerobically using oxygen, while others respire anaerobically, using substances other than oxygen to produce energy.

6.Why is the exchange of gases important in respiration?

The exchange of gases is important in respiration because it allows oxygen to enter the bloodstream for cellular respiration and removes carbon dioxide, a waste product of metabolism, from the body.

7.  What is the role of alveoli in the human respiratory system?

Alveoli are tiny air sacs in the lungs where oxygen and carbon dioxide are exchanged.

8.  What happens during inhalation?

During inhalation, air rich in oxygen is taken into the lungs.

9.  What happens during exhalation?

During exhalation, air rich in carbon dioxide is expelled from the lungs.

10.What is the function of the diaphragm in breathing?

The diaphragm is a dome-shaped muscle that contracts and flattens during inhalation, increasing the chest cavity volume.

11.  What are the stages of cellular respiration?

The stages of cellular respiration are glycolysis, Krebs cycle, and the electron transport chain.

12.  What causes muscle fatigue and cramps during vigorous exercise?

Muscle fatigue and cramps during vigorous exercise are caused by the accumulation of lactic acid from anaerobic respiration.

13.  How do fish respire?

Fish respire through gills, which extract oxygen from water and expel carbon dioxide.

14.  How do cockroaches breathe?

Cockroaches breathe through a network of tubes called tracheae, with openings called spiracles.

15.  How do earthworms respire?

Earthworms respire through their moist skin, where oxygen diffuses directly into the bloodstream and carbon dioxide diffuses out.

16.  How do plants respire?

Plants respire through stomata in leaves and lenticels in stems, similar to aerobic respiration in animals.

17.  What is the role of stomata in plant respiration?

Stomata are small openings on the surface of leaves that allow gas exchange for respiration.

18.  How do yeasts respire anaerobically?

Yeasts respire anaerobically by converting glucose into alcohol and carbon dioxide, producing energy.

19.  What are the main organs of the human respiratory system?

The main organs of the human respiratory system are the nose, pharynx, larynx, trachea, bronchi, bronchioles, and lungs.

20.  What is the function of the trachea?

The trachea, or windpipe, filters air and leads it to the bronchi.

21.  How does aerobic respiration benefit organisms?

Aerobic respiration provides a large amount of energy by breaking down glucose in the presence of oxygen.

22.  Why is anaerobic respiration important for certain organisms?

Anaerobic respiration allows certain organisms to produce energy in environments lacking oxygen.

23.  What is the significance of cellular respiration?

Cellular respiration is crucial for producing energy within cells to power various biological processes.

24.  How does the human body adapt during vigorous exercise to meet energy demands?

During vigorous exercise, the body increases the rate of breathing and heart rate to supply more oxygen for aerobic respiration and may switch to anaerobic respiration when oxygen is insufficient.

25.  What is the Krebs cycle?

The Krebs cycle is a series of chemical reactions in cellular respiration that generate energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins.

MCQs

Chapter 6: Respiration in Organisms MCQs

1. What is respiration?

2. What is the main organ of respiration in humans?

3. Which equation represents aerobic respiration?

4. What is produced during anaerobic respiration in muscle cells?

5. What are the tiny air sacs in the lungs where gas exchange occurs?

MCQs

6. How does a cockroach breathe?

7. What is the function of the diaphragm in breathing?

8. Which process describes the release of energy from glucose in the absence of oxygen?

9. How do earthworms respire?

10. What are the main products of aerobic respiration?

MCQs

11. Which stage is NOT part of cellular respiration?

12. Why do muscles sometimes produce lactic acid?

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