Respiration in Organisms for Class 7

Respiration in living organisms is a fundamental biological process for the survival of all living beings. It is the process of releasing energy from food. This energy is necessary for growth, repair, and other essential functions. Respiration should not be confused with breathing, which is only one of the steps that occur in respiration. There are various forms of respiration in different species, namely, humans, plants, fishes, and insects, etc. Let's understand more about this.

What is Respiration in Organisms?

Respiration is the biological process of food energy release. This energy is necessary for growth, repair, and other essential functions. Respiration should not be confused with breathing, which is only one of the steps that occur in respiration.

Fun Fact: All living cells in your body do respiration, so it's a universal energy-making process.

Difference Between Breathing and Cellular Respiration

 

Cellular respiration produces about 36 ATP molecules from one glucose molecule in aerobic conditions.

Types of Respiration

Based on the presence or absence of oxygen, respiration in organisms is classified as:

Aerobic Respiration:

• Takes place in the presence of oxygen.

• The full oxidation of glucose leads to carbon dioxide and water.

• Generates a huge amount of energy.

Real-Life Example: Humans and many other animals perform aerobic respiration for energy.

Anaerobic Respiration:

• Takes place under anaerobic conditions.

• Glucose is broken down partly to lactic acid or to alcohol and carbon dioxide.

• Also produces less energy than aerobic respiration.
  
  

Real-life example: Yeast performing anaerobic respiration is used during the making of different kinds of bread and the production of beer.

 

Yeast cells perform anaerobic respiration, also known as alcoholic fermentation, to produce alcohol and carbon dioxide, which is why they are used in bread and beer production.

Respiration in Human Beings

Humans inhale oxygen and exhale carbon dioxide using a respiratory system. The main organs affected are the pharynx, larynx, trachea and bronchi, and the lungs. The respiration (Exchanging of gases) which are breathing and cellular respiration.

Mechanism of Breathing:

1. Inhalation: The process of taking in air rich in oxygen.

2. Exhalation: The process of expelling air rich in carbon dioxide.
   
   

Composition of Inhaled and Exhaled Air:

 

Fun Fact: Your lungs contain around 300 million alveoli, which provide a surface area the size of a tennis court for gas exchange.

 

Respiratory System

The human respiratory system is an organ system and process in humans that enables all of us to inhale air and exhale air out of the body. Let us take a closer look at its major components:

1. Pharynx: Muscular tube running from the nasal cavity to the larynx. It is a shared passageway for air and food.

• Fun Fact: The Pharynx is also used for making sounds while speaking.

2. Larynx: The larynx or voice box is where the vocal cords are located and is responsible for the production of speech.

• Real-life example: Screaming or singing causes your larynx to vibrate and create different sounds.

3. Trachea and Bronchi: The trachea (or windpipe) divides into two bronchi that supply air to the lungs. These are coated with cilia, which snag dust and other detritus.

• Fun Fact: Your Trachea Is 11 cm Long and Stays Open with Cartilage Rings in Place to Prevent It from Collapsing.

4. Lungs: The lungs are the gas-exchange organs. They hold millions of alveoli that absorb oxygen into the blood and release carbon dioxide.

• Real-life example: The atmosphere at high altitudes contains less oxygen, so athletes train at those altitudes to increase their lungs' capacity.

5. Muscles: Your diaphragm and intercostal muscles help you inhale and exhale. The diaphragm contracts downward to draw air into the lungs, then relaxes to expel it.

• Fun Fact: Your diaphragm pulls up and down around 20,000+ times per day and allows you to breathe without much difficulty.
  
  

Mechanism of Gas Exchange in Alveoli

The alveoli are tiny air pockets in the lungs where gas exchange occurs. The oxygen from the air inhaled diffuses into the blood while CO2 diffuses in the opposite direction from the blood into the alveoli to be exhaled.

Real-life example: Smokers often damage their alveoli, reducing the efficiency of their respiratory system.

Respiration in Plants

Plants also respire to get energy. They do it with the help of their leaves, stems, and roots.

Respiration by Leaves

Leaves have small pores or stomata through which gas exchange occurs. In the leaves, during respiration, oxygen passes through the stomata, and carbon dioxide is released.

Real-life example: During the night, when photosynthesis ceases, plants depend solely on respiration for energy production.

Respiration by Stems

Lenticels on the stem surface in woody plants allow for gas exchange. These tiny pores allow oxygen to enter and carbon dioxide to leave.

Real-life example: Stems of sugarcane plants also respire as a necessity for their growth and energy.

Respiration by Roots

Roots absorb oxygen from the air spaces in the soil. This oxygen then diffuses into the root cells to be used for energy production. Soil with poor aeration can interfere with these processes.

Real-life example: If plants are overwatered, roots may suffocate as it decreases oxygen availability in the soil.

 

Fun fact: Although photosynthesis happens during the day, plants still need energy in the form of ATP, so they carry out respiration even in the daytime.

 

Respiration in Animals

Various kinds of animals adapted different kinds of lungs based on their habitats.

Respiration in Fish

Fish extract oxygen using their gills underwater. Oxygen is taken up into the blood while carbon dioxide is released as water flows across the gill filaments.

Real-Life Example: Sharks must swim continuously so that air can pass over their gills to breathe.

Respiration in Earthworms

Respiration in earthworms occurs through moist skin, which serves as a respiratory surface. Oxygen diffuses into their bloodstream through their skin.

Real-Life Example: Earthworms adapt to moist soil as dry soil can inhibit their respiration.

Respiration in Frogs

Unlike us humans, frogs have a dual respiratory system because they can respire through breathing via lungs at the same time through their skin and also through the lining of their mouth. This allows them to survive not only in water but also on land.

Real-Life Example: Frogs hibernate in mud in winter and can breathe through their skin (cutaneous respiration).

Respiration in Insects

Insects breathe through a network of tiny tubes called tracheae. They take in oxygen through tiny openings called spiracles, which is sent directly to their tissues.

Real-Life Example: Insects, like grasshoppers, will rhythmically move their bodies to create air movement through their tracheal system.

Fun Fact: One single goldfish can absorb way more oxygen from the water than a human can from the air.

Lactic Acid Fermentation

In muscle activity through strenuous action, human muscles may not get sufficient O2. Anaerobic respiration takes place, which results in the formation of lactic acid that leads to muscle fatigue in such situations.

After a long workout, athletes feel cramps in their muscles as an outcome of lactic acid deposition.

Alcoholic Fermentation

Yeasts, as well as some bacteria, undergo alcoholic fermentation to generate alcohol and carbon dioxide without oxygen.

Fun Fact: The carbon dioxide that makes your soda birate comes from fermentation.

Tree Respiration

Trees absorb oxygen and release carbon dioxide through lenticels in their bark and stomata in their leaves. They also produce oxygen through photosynthesis.

It is considered an essential substance for the survival of an organism through a process called respiration. The breathing mechanics evolved from plants to humans, and other animals adapted to different environments and requirements. Learning respiration teaches us about the complex mechanisms that power the lives of organisms.

Things you have learned!

• By respiration, you release energy from food molecules.
• Humans have a respiratory system that contains organs such as the lungs, trachea, and diaphragm.
• The respiration of plants occurs through their leaves, stems, and roots.
• Aquatic animals developed specialised organs like gills, while terrestrial animals such as insects devised a network of air tubes called tracheae.
• Respiration happens in two forms: aerobic (with oxygen) and anaerobic (without oxygen).