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Respiration
Master Respiration in Minutes: Let's Explore how living cells break down food molecules to release energy and convert it into a usable form (ATP). Learn the differences between aerobic and anaerobic pathways, the human respiratory setup, and gaseous exchange mechanisms across various organisms without complex formula blocks.
1.0Learning Outcomes
After completing this lesson, you will be able to:
- Define cellular respiration and distinguish it clearly from breathing.
- Differentiate between aerobic and anaerobic respiration pathways.
- Explain the causes and relief mechanisms of muscle cramps during strenuous exercise.
- Trace the human respiratory pathway and explain the mechanics of inhalation and exhalation.
- Compare respiratory organs across different animals (fish, insects, earthworms).
- Describe how plants achieve gaseous exchange via stomata, lenticels, and root surfaces.
Respiration in Organisms
"The process of releasing energy from food is called respiration."
2.0Introduction
All organisms are made of small, microscopic units called cells. A cell is the smallest structural and functional unit of an organism. Each cell of an organism performs certain functions such as nutrition, transportation, excretion and reproduction. To perform these functions, the cell needs energy. Even when we are eating, sleeping or reading we require energy. The food has stored energy, which is released during respiration. Therefore, all living organisms respire to get energy from food.
3.0Respiration
The metabolic process by which organisms obtain energy from oxidation of food (organic molecules). During breathing, we breath in air. You know that air contains oxygen. We breathe out air which is rich in carbon dioxide. The air we breathe in is transported to all parts of the body and ultimately to each cell. In the cells, oxygen helps in the breakdown of food.
Cellular respiration
Cellular respiration takes place in the cells of all organisms. It is an intracellular process in which glucose is oxidized and the energy is used to make ATP (adenosine triphosphate). It consists of many separate enzymatic reactions.
Types of cellular respiration
Cellular respiration is of two types - (i) Aerobic respiration (ii) Anaerobic respiration. (i) Aerobic respiration: The glucose and oxygen react together in the cells to produce carbon dioxide, water and energy is released. The reaction is called aerobic espiration because oxygen from the air is needed for it to work. Here is the word equation for aerobic respiration: (ii) Anaerobic respiration: When the food is broken down without using oxygen it is known as anaerobic respiration. In this type of respiration incomplete oxidation of food takes place and in comparison to aerobic respiration, much less amount of energy is produced.
- (a) Anaerobic respiration in yeast cell: Yeast can survive in the absence of air. They are called anaerobes. They get energy through anaerobic respiration. The glucose breaks down into alcohol and carbon dioxide in the absence of oxygen. The reaction is called anaerobic respiration or fermentation. Here is the word equation for anaerobic respiration: Glu cose (without the use of oxygen) Alcohol + Carbon dioxide + Energy
- (b) Anaerobic respiration in muscle cells: Our muscle cells can also respire anaerobically but only for a short time when there is a temporary deficiency of oxygen. During heavy exercise, fast running, cycling, walking for many hours or heavy weightlifting, the demand for energy is high but the supply of oxygen to produce the energy is limited. Then anaerobic respiration takes places in the muscle cells to fulfil the demand of energy. Glucose (without the use of oxygen) Alcohol + Carbon dioxide + Energy We get relief from cramps after a hot water bath or a massage. Hot water bath or massage improves circulation of blood. As a result, the supply of oxygen to the muscle cells increases. The increase in the supply of oxygen results in the complete breakdown of lactic acid into carbon dioxide and water.
Breathing
We require oxygen for oxidation of food and breathing is essential for this purpose. Breathing means taking in air rich in oxygen and giving out air rich in carbon dioxide with the help of respiratory organs. It is a continuous process which goes on all the time and throughout the life of an organism.
Breathing includes inhalation and exhalation. On an average, an adult human being at rest breathes in and out 15-18 times in a minute. During heavy exercise, the breathing rate can increase upto 25 times per minute. While we exercise, not only do we breathe fast, but we also take deep breaths and thus inhale more oxygen.
Inhalation:
The process of taking in air rich in oxygen into the body is called inhalation.
Exhalation:
The process of giving out of air rich in carbon dioxide is known as exhalation.
Breathing rate:
The number of times a person breathes in a minute is termed as the breathing rate. A breath means one inhalation and one exhalation. During breathing, inhalation and exhalation take place alternately.
4.0Respiratory organs in animals
Most animals use specialized organs or organ system such as lungs, trachea, or gills for external respiration. In all cases, exchange of gases between the environment and an animal occurs by diffusion through a surface which is permeable to oxygen and carbon dioxide.
Skin:
Earthworms breathe through their skins. The skin of an earthworm feels moist and slimy on touching. Gases can easily pass through them. Though frogs have pair of lungs like human beings, they can also breathe through their skin which is moist and slippery.
Earthworm
Trachea:
Cockroach, grasshopper and other insects have small openings on the sides of its body. These openings are called spiracles. Insects have a network of air tubes called tracheae for gas exchange. Oxygen rich air rushes through spiracles into the tracheal tubes, diffuses into the body tissue and reaches every cell of the body. Similarly, carbon dioxide from the cells goes into the tracheal tubes and moves out through spiracles.
Tracheal system
Gills:
Gills are projections of the skin and they help in breathing in fishes. Gills are well supplied with blood vessels for exchange of gases.
Animals with gills or lungs take up oxygen and transport oxygen-rich blood throughout the body. They transport carbon dioxide-rich blood from the body back into the respiratory organs where it is expelled.
Lungs:
Animals such as frogs, lizards, snakes, birds, elephants, lions, cows, goats have lungs in their chest cavities like the human beings.
5.0Human respiratory system
When we inhale air, it passes through our nostrils into the nasal cavity. From the nasal cavity, the air reaches our lungs through the windpipe. Lungs are present in the chest cavity. This cavity is surrounded by ribs on the sides. A large, muscular sheet called diaphragm forms the floor of the chest cavity. Breathing involves the movement of the diaphragm and the rib cage.
6.0 Human respiratory system
Mechanism of breathing
During inhalation, ribs move up and outwards and diaphragm moves down. This movement increases space in our chest cavity and air rushes into the lungs. The lungs get filled with air. During exhalation, ribs move down and inwards, while diaphragm moves up to its former position. This reduces the size of the chest cavity and air is pushed out of the lungs. These movements in our body can be felt easily.
Mechanism of breathing
7.0Gaseous exchange in plants
The process of respiration is similar in all organisms, whether plants or animals. Carbon dioxide is given out and oxygen is used up, and a lot of energy is produced.
In plants, specific organs for breathing are absent. The exchange of gases, however, occurs by the process of diffusion. Diffusion of gases (oxygen and carbon dioxide) occurs through following:
Through stomata (singular stoma), the minute openings on the surface of leaves.
During day, generated during respiration is used up for photosynthesis hence there is no release instead oxygen release in the atmosphere is the major event. Rate of photosynthesis is more as compared to respiration during day time. During night, stomata is closed and photosynthesis does not occur. elimination is the major exchange activity going on because liberation during respiration is not used in photosynthesis.
8.0 Structure of stomata
Through general surface of the roots.
The roots take up oxygen from the air spaces present between the soil particles. In aquatic plants, gases diffuse through the body surface.
Through lenticels of stem.
The living cells are organised in a thin layer inside and beneath the bark. They also have opening called lenticels.
9.0Building Concepts
Can cell survive in the absence of oxygen?
- Yes, some cells can survive in the absence of oxygen. For example, yeast and most of bacteria can survive in anaerobic conditions. Thus, all the cells do not use oxygen to produce energy.
Why we get muscle cramps after heavy exercise?
- The cramps occur when muscle cells respire anaerobically. The partial breakdown of glucose produces lactic acid. The accumulation of lactic acid causes muscle cramps.
Why do fishes die when taken out of water?
- Fishes have gills as respiratory structures which can take in only dissolved oxygen from water. So, outside water they cannot respire and therefore die.
Why we should cover our nose while sneezing?
- The air around us has various types of unwanted particles, such as smoke, dust, pollens etc. When we inhale, the particles get trapped in the hair present in our nasal cavity. However, sometimes these particles may get past the hairs in the nasal cavity. Then they irritate the lining of the cavity, as a result of which we sneeze. Sneezing expels these foreign particles from the inhaled air and a dust-free, clean air enters our body.
10.0Biology Diagrams made Easy
11.0Chapter at a Glance
12.0SOME BASIC TERMS
- Aerobic respiration: The glucose and oxygen react together in the cells to produce carbon dioxide, water and energy is released.
- Anaerobic respiration: When the food is broken down without using oxygen, it is known as anaerobic respiration.
- Cellular respiration: It is an intracellular process in which glucose is oxidized and the energy is used to make ATP.
- Diaphragm: A large, muscular sheet forming the floor of the chest cavity called diaphragm.
- Gills: Gills are projections of the skin and they help in exchange of gases in fishes.
- Ribs: Curved bones present in the chest.
- Inhalation : The process of taking in air rich in oxygen into the body is called inhalation.
- Exhalation : The process of giving out of air rich in carbon dioxide is known as exhalation.
- Spiracles: Insects have small openings on the sides of its body known as spiracles.
- Tracheae: Insects have a network of air tubes called tracheae for gas exchange.
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14.0Supporting Study Materials
This study material, CBSE Notes and NCERT Solutions for the Chapter "Life Processes" on respiration topics, is designed according to the latest CBSE Class 10 Science syllabus and NCERT guidelines. It provides clear explanations of key concepts, definitions, examples, and important questions to help students understand aerobic and anaerobic respirations and prepare effectively for examinations.
15.0PREVIOUS YEAR QUESTIONS (PYQs)
Q1. Write the three distinct pathways of glucose breakdown in living organisms. (CBSE Board)
Answer: The initial step in all three pathways involves breaking down 6-carbon glucose in the cell cytoplasm into 3-carbon pyruvate. The three subsequent pathways are:
- In the presence of oxygen (Aerobic): Pyruvate breaks down completely inside the mitochondria to yield Carbon dioxide, Water, and a large amount of energy (ATP).
- In the lack of oxygen (Human Muscle cells): During sudden heavy exercise, pyruvate converts into Lactic acid and releases a low amount of energy.
- In the absence of oxygen (Yeast Fermentation): Pyruvate breaks down into Ethanol (alcohol), Carbon dioxide, and a low amount of energy.
Q2. How are alveoli designed in human beings to maximize the efficiency of gas exchange? (CBSE Board)
Answer: Alveoli maximize gas exchange efficiency through the following design adaptations:
- Massive Surface Area: Millions of tiny, balloon-like alveoli cluster together inside the lungs, providing an enormous total surface area for diffusion.
- Extremely Thin Walls: The walls of the alveoli are only one-cell thick, which allows oxygen and carbon dioxide to pass through smoothly and rapidly.
- Rich Blood Supply: Alveoli are thoroughly wrapped in a dense network of blood capillaries, ensuring that oxygen is instantly carried away to body tissues and carbon dioxide is continuously brought to the lungs to be exhaled.
16.030-Second Revision
- Respiration = Breaking down glucose inside cells to form ATP.
- Aerobic = Complete breakdown in mitochondria with oxygen; gives high energy.
- Anaerobic (Yeast) = Yields Ethanol and Carbon dioxide (Fermentation).
- Anaerobic (Muscles) = Yields Lactic acid, causing muscle cramps.
- Alveoli = Microscopic balloon-like structures where gas exchange takes place.
- Inhalation = Diaphragm moves down, ribs move up and out.
- Plant Respiration = Occurs via stomata (leaves), lenticels (stems), and root hairs (soil).
17.0Recommended Next Topics
- Human Circulatory System (Heart and Blood)
- Transportation in Plants (Xylem and Phloem)
- Excretion in Human Beings
- Photosynthesis Deep Dive