NCERT Class 11 Biology Biology: Chapter 14 — Breathing and Exchange of Gases
This chapter, 'Breathing and Exchange of Gases,' is part of the Human Physiology unit in the NCERT Class 11 Biology textbook. It introduces the concept of physiological processes being studied through both organismic and reductionist approaches, highlighting the rise of molecular biology and the subsequent realization of systems biology. The chapter emphasizes that emergent properties arise from interactions within biological systems at various levels, from molecules to populations. It sets the stage for detailed discussions on key human physiological functions like gas exchange, circulation, and movement, examined at cellular and molecular levels, with later chapters focusing on organismic coordination and regulation. The introductory section also briefly mentions the Italian anatomist Alfonso Corti and his significant contribution to understanding the auditory system.
Quick info
| Board | CBSE / NCERT |
|---|---|
| Class | Class 11 |
| Subject | Biology |
| Book | Biology |
| Chapter | Chapter 14 — Breathing and Exchange of Gases |
| Language | English |
| PDF type | NCERT Textbook |
| Session | CBSE 2026 |
| Reading time | 2 minutes |
| Word count | 279 |
Learning outcomes
- Understand the different approaches to studying life forms, including reductionist and systems biology.
- Recognize the importance of physico-chemical concepts in understanding biological processes.
- Identify the scope of the Human Physiology unit, focusing on gas exchange and other vital functions.
- Appreciate the historical context of physiological discoveries through figures like Alfonso Corti.
Vocabulary
| Word | Meaning |
|---|---|
| Reductionist approach | Studying complex systems by breaking them down into simpler components. |
| Physico-chemical concepts | Principles and techniques derived from physics and chemistry applied to biology. |
| Cell-free systems | Biological experiments conducted using components isolated from cells, without living cells. |
| Molecular biology | The branch of biology that deals with the structure and function of genes and proteins at the molecular level. |
| Biochemistry | The study of chemical processes within and relating to living organisms. |
| Biophysics | The application of the methods of physics to the study of biological systems. |
| Systems biology | A field of study that aims to understand the emergent properties of biological systems that arise from the interactions of their components. |
| Emergent properties | Properties of a complex system that cannot be predicted from the properties of its individual components. |
| Organismic level | The level of study focusing on the entire organism. |
| Cochlea | The spiral cavity of the inner ear containing the organ of Corti, which produces nerve impulses in response to sound vibrations. |
| Organ of Corti | The sensory organ of hearing located in the cochlea. |
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Practice questions
- What is the 'reductionist approach' in the study of life forms? Answer: The reductionist approach involves breaking down complex biological systems into their simpler components to study them.
- What is 'systems biology'? Answer: Systems biology studies emergent properties that arise from the interaction of components within a biological system at various levels.
- Who was Alfonso Corti and what is he known for? Answer: Alfonso Corti was an Italian anatomist known for describing the organ of Corti in the mammalian auditory system, which converts sound vibrations into nerve impulses.
Frequently asked questions
What is the main focus of the Human Physiology unit in Class 11 Biology?
The Human Physiology unit covers major human physiological processes like gas exchange, circulation, locomotion, and neural/chemical coordination.
How has the study of life forms evolved?
The study has evolved from organismic approaches to reductionist molecular studies, and now increasingly towards systems biology, recognizing emergent properties from interactions.
What are emergent properties in biology?
Emergent properties are characteristics of a system that arise from the interactions between its components and are not present in the components themselves.
What is the significance of the organ of Corti?
The organ of Corti, located in the inner ear, is crucial for hearing as it converts sound vibrations into nerve impulses.
Who discovered the organ of Corti?
The organ of Corti was described by the Italian anatomist Alfonso Corti.
Related resources
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Topics covered
NCERT Class 11 Biology — Biology — Chapter 14 — Breathing and Exchange of Gases. Verified by NCERT Help Editorial Team. Reviewed on 29 Jul 2026. Last updated 10 Aug 2026.