Respiration in Organisms Ncert Notes

Introduction to Respiration in Organisms

Respiration in Organisms- All living organisms require energy to perform their daily activities like moving, growing, and repairing their bodies. This energy comes from the food they consume. Respiration is the process by which organisms break down food (mainly glucose) to release energy. It is a vital life process that occurs in all living beings, including humans, animals, and plants.

Respiration involves taking in oxygen from the surroundings and releasing carbon dioxide and water as waste products. The energy released during respiration is stored in the form of ATP (Adenosine Triphosphate), which acts as the energy currency of the cell.

The general equation for respiration is: Glucose + Oxygen → Carbon Dioxide + Water + Energy

---

Types of Respiration

Respiration can be classified into two main types based on the presence or absence of oxygen:

1. Aerobic Respiration:
   • This type of respiration occurs in the presence of oxygen.
   • It takes place in the mitochondria of the cell, often called the “powerhouse” of the cell.
   • Glucose is completely broken down into carbon dioxide and water, releasing a large amount of energy.
   • Example: Humans, dogs, birds, and most animals perform aerobic respiration.
   • Equation:
     C₆H₁₂O₆ (Glucose) + 6O₂ (Oxygen) → 6CO₂ (Carbon Dioxide) + 6H₂O (Water) + Energy
2. Anaerobic Respiration:
   • This type of respiration occurs in the absence of oxygen.
   • It releases less energy compared to aerobic respiration because glucose is not fully broken down.
   • It takes place in the cytoplasm of the cell, not in the mitochondria.
   • Products vary depending on the organism:
     • In yeast: Glucose → Ethanol + Carbon Dioxide + Energy (this process is called fermentation).
     • In muscle cells (during heavy exercise): Glucose → Lactic Acid + Energy.
   • Example: Yeast (used in making bread and alcohol), some bacteria, and human muscle cells during intense activity.

---

Why Do We Respire?

Organisms respire to obtain energy for various functions:

• Growth and repair of tissues.
• Movement (e.g., running, flying, swimming).
• Maintaining body temperature (in warm-blooded animals like humans).
• Performing metabolic activities like digestion and excretion.

Without respiration, organisms cannot survive as they would lack the energy to carry out these essential processes.

---

Breathing vs. Respiration

• Breathing: The physical process of inhaling oxygen-rich air and exhaling carbon dioxide-rich air. It involves organs like the nose, trachea, and lungs in humans.
• Respiration: The biochemical process of breaking down food to release energy inside cells. Breathing is just one part of respiration, supplying oxygen for the process.

---

Respiration in Humans

Humans perform aerobic respiration, and the process involves a well-developed respiratory system.

1. Organs Involved:
   • Nose: Air enters through the nostrils, where it is filtered, warmed, and moistened.
   • Trachea (Windpipe): A tube that carries air to the lungs.
   • Lungs: The main respiratory organs where the exchange of gases occurs.
   • Diaphragm: A muscle below the lungs that helps in breathing by contracting and relaxing.
2. Mechanism of Breathing:
   • Inhalation: The diaphragm contracts and moves down, the chest cavity expands, and air (rich in oxygen) enters the lungs.
   • Exhalation: The diaphragm relaxes and moves up, the chest cavity contracts, and air (rich in carbon dioxide) is expelled from the lungs.
   • The exchange of gases happens in tiny air sacs called alveoli in the lungs. Oxygen from the air passes into the blood, and carbon dioxide from the blood is released into the alveoli to be exhaled.
3. Transportation of Gases:
   • Oxygen is carried by hemoglobin in red blood cells to all parts of the body.
   • Carbon dioxide produced during respiration is transported back to the lungs via blood and exhaled.
4. Breathing Rate:
   • The number of times a person breathes in a minute is called the breathing rate.
   • At rest, humans breathe about 15-18 times per minute. This rate increases during exercise because the body needs more oxygen and produces more carbon dioxide.

---

Respiration in Other Animals

Different animals have different respiratory organs depending on their habitat and body structure:

1. Earthworms: Respire through their moist skin. Oxygen dissolves in the moisture and diffuses into their blood.
2. Fish: Use gills to extract dissolved oxygen from water. Gills have a large surface area for efficient gas exchange.
3. Frogs: Respire through lungs on land and through moist skin in water.
4. Insects: Have a network of tiny tubes called tracheae. Air enters through small openings called spiracles and reaches the cells directly.
5. Birds: Have lungs and air sacs that allow a continuous flow of oxygen, supporting their high energy needs during flight.

---

Respiration in Plants

Plants also respire to release energy from glucose, but their process differs from animals:

• Plants take in oxygen and release carbon dioxide through tiny openings called stomata on leaves and stems.
• Respiration in plants occurs day and night, unlike photosynthesis, which happens only in the presence of sunlight.
• During the day, plants perform both photosynthesis (producing oxygen) and respiration (using oxygen). At night, only respiration occurs.
• Roots respire by taking oxygen from air spaces in the soil.

Key Difference:

• Photosynthesis uses carbon dioxide and water to produce glucose and oxygen, while respiration breaks down glucose using oxygen to release energy, carbon dioxide, and water.

---

Anaerobic Respiration in Everyday Life

1. Yeast Fermentation:
   • Yeast respires anaerobically to produce alcohol and carbon dioxide.
   • Used in baking (carbon dioxide makes dough rise) and brewing (alcohol production).
2. Muscle Cramps:
   • During intense exercise, when oxygen supply is low, muscles switch to anaerobic respiration, producing lactic acid. This causes cramps or fatigue.

---

Effects of Respiration

• Energy Production: Essential for survival and activities.
• Carbon Dioxide Release: A waste product that must be removed from the body.
• Heat Generation: In warm-blooded animals, respiration helps maintain body temperature.

---

Interesting Facts

1. Holding Breath: Humans can hold their breath for a short time, but respiration continues in cells using stored oxygen.
2. Sneezing and Coughing: These are reflexes to clear the respiratory passage of dust or irritants.
3. High Altitude: At higher altitudes, oxygen levels decrease, so breathing becomes faster to supply enough oxygen.

---

Summary

Respiration is a universal process that sustains life by providing energy. Aerobic respiration uses oxygen and is more efficient, while anaerobic respiration occurs without oxygen and releases less energy. Humans rely on a complex respiratory system, while other organisms like fish, insects, and plants use specialized structures suited to their environments. Understanding respiration helps us appreciate how living organisms adapt to survive and thrive.

Ch 06 Respiration In Organisms