NCERT Class 12 Biology Biology: Chapter 11 — Organisms and Populations
This chapter introduces ecology as a unifying thread in biology, explaining how organisms interact with each other and their physical environments to form organized wholes like populations, communities, and ecosystems. It highlights the importance of understanding these interactions for a holistic biological perspective. The chapter also touches upon anthropogenic environmental degradation and related socio-political issues. It begins by defining ecology and its scope, emphasizing the study of organisms in relation to their environment. The text introduces Ramdeo Misra, revered as the Father of Ecology in India, detailing his contributions to establishing ecology teaching and research in India, his foundational research on tropical communities and ecosystems, and his role in the formation of environmental planning bodies. This chapter sets the stage for understanding ecological principles and their application.
Quick info
| Board | CBSE / NCERT |
|---|---|
| Class | Class 12 |
| Subject | Biology |
| Book | Biology |
| Chapter | Chapter 11 — Organisms and Populations |
| Language | English |
| PDF type | NCERT Textbook |
| Session | CBSE 2026 |
| Reading time | 1 minute |
| Word count | 165 |
Learning outcomes
- Understand ecology as a unifying principle in biology.
- Recognize the interactions between organisms and their environments.
- Learn about different levels of biological organization (population, community, ecosystem).
- Appreciate the contributions of Ramdeo Misra to Indian ecology.
- Gain awareness of environmental issues and their socio-political context.
Vocabulary
| Word | Meaning |
|---|---|
| Ecology | The study of how organisms interact with each other and their physical environment. |
| Population | A group of individuals of the same species living in a particular area. |
| Community | All the populations of different species living and interacting in a particular area. |
| Ecosystem | A community of living organisms interacting with their physical environment. |
| Biosphere | The sum of all ecosystems on Earth; the part of Earth where life exists. |
| Anthropogenic | Originating in human activity. |
| Succession | The process by which the structure of a biological community evolves over time. |
| Productivity | The rate at which biomass is generated by producers in an ecosystem. |
| Nutrient cycling | The movement and exchange of organic and inorganic matter back into the process of life. |
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Practice questions
- Who is revered as the Father of Ecology in India? Answer: Ramdeo Misra is revered as the Father of Ecology in India.
- What is the essence of biological understanding as described in the text? Answer: The essence is to know how organisms, as individuals and groups, interact with other organisms and physical habitats.
- What are some of the areas Ramdeo Misra's research laid foundations for? Answer: His research laid foundations for understanding tropical communities and their succession, environmental responses of plant populations, and productivity and nutrient cycling in tropical ecosystems.
- What is ecology? Answer: Ecology is the study of how organisms interact with each other and their physical habitats.
Practice MCQs
Q1. Which of the following is NOT mentioned as a level of biological organization discussed in the chapter?
Explanation: The text mentions population, community, and ecosystem as levels of organization, along with the biosphere. Biome is not explicitly listed in this introductory paragraph.
Q2. Ramdeo Misra established teaching and research in ecology at which university?
Explanation: The text states that Ramdeo Misra established teaching and research in ecology at the Department of Botany of the Banaras Hindu University, Varanasi.
Q3. The chapter introduces ecology as a thread that provides a ______ perspective to biology.
Explanation: The text explicitly mentions that ecology is a thread which gives us a holistic perspective to biology.
Q4. Ramdeo Misra obtained his Ph.D. in Ecology from which university?
Explanation: Ramdeo Misra obtained his Ph.D. in Ecology (1937) under Prof. W. H. Pearsall, FRS, from Leeds University in UK.
Q5. The establishment of the Ministry of Environment and Forests in India was paved by efforts related to:
Explanation: Due to Ramdeo Misra's efforts, the Government of India established the National Committee for Environmental Planning and Coordination (1972), which later paved the way for the Ministry of Environment and Forests.
Frequently asked questions
What is the main focus of Chapter 11, 'Organisms and Populations'?
Chapter 11 introduces ecology as a unifying principle in biology, focusing on how organisms interact with each other and their physical environments at various levels like populations and communities.
Who is considered the Father of Ecology in India, and what were his key contributions?
Ramdeo Misra is revered as the Father of Ecology in India. He established ecology teaching and research in India, particularly at Banaras Hindu University, and conducted foundational research on tropical ecosystems.
How does ecology provide a holistic perspective to biology?
Ecology explains how individual organisms interact with their environment and other organisms, forming organized wholes like populations and communities, thus offering a comprehensive view of life.
What role did Ramdeo Misra play in environmental policy in India?
His efforts led to the establishment of the National Committee for Environmental Planning and Coordination, which later paved the way for the Ministry of Environment and Forests.
What broader issues does the chapter touch upon besides ecological principles?
The chapter also addresses anthropogenic environmental degradation and the socio-political issues that arise from it.
Related resources
Important topics
Topics covered
NCERT Class 12 Biology — Biology — Chapter 11 — Organisms and Populations. Verified by NCERT Help Editorial Team. Reviewed on 29 Jul 2026. Last updated 10 Aug 2026.