Biodiversity – AHSEC Class 12 Swadesh Adhyayan Chapter 3

Here is a comprehensive guide to Chapter 3, “Biodiversity,” from the “Swadesh Adhyayan” textbook, created specifically for AHSEC Class 12 students. This guide includes a summary, complete textual answers, previous years’ AHSEC questions, and other important questions.

Chapter 3:

Biodiversity

Here is a comprehensive guide to Chapter 3 from the “Swadesh Adhyayan” textbook, created to help you prepare thoroughly for your upcoming AHSEC Class 12 exams. This guide includes a summary, complete textual answers, previous years’ AHSEC questions, and other important questions.

Summary Note

This chapter introduces the concept of “biodiversity,” a term derived from “biological diversity,” which refers to the variety and variability of life on Earth. It encompasses the diversity of species, the genetic diversity within those species, and the diversity of ecosystems they form. The chapter explains that biodiversity is a result of complex interactions between living organisms and physical factors like climate, soil, and topography.

The text outlines three primary types of biodiversity:

1. Species Diversity: The number and variety of different species in a given area.
2. Genetic Diversity: The variation of genes within a single species. This is crucial for agriculture and food security, as a lack of genetic diversity makes crops vulnerable to disease.
3. Ecosystem Diversity: The variety of different ecosystems, such as forests, deserts, wetlands, and oceans, across the planet.

The chapter highlights Assam’s status as a region rich in biodiversity, being part of the Northeast India biodiversity hotspot. This richness is due to its unique physiography, climate, soil types, and the vast network of the Brahmaputra river. Assam is home to numerous national parks and wildlife sanctuaries, and boasts a significant diversity of plants (flora) and animals (fauna), including many endemic species.

However, this rich biodiversity is under severe threat from problems like population growth, habitat destruction due to human activities (anthropogenic causes), overgrazing, poaching, and pollution. The chapter emphasizes the urgent “Need for Conservation,” arguing for it from both a human-centric view (our survival depends on these resources for food, medicine, etc.) and an ethical view (every species has a right to exist). The chapter concludes by introducing the concept of “Sustainable Development”—a way to meet human needs without compromising the environment for future generations—and lists the 17 Sustainable Development Goals (SDGs) adopted by the United Nations.

Complete Textual Question and Answer

Here are the answers to the “EXERCISE” questions from page 46 of the PDF.

1. What do you mean by biodiversity? What are its various types? Explain citing suitable examples.
Answer: Biodiversity, or biological diversity, refers to the variety and variability of all forms of life on Earth. It includes the diversity of species, the genetic differences within those species, and the variety of ecosystems they inhabit.
Its three main types are:

1. Species Diversity: This is the variety of different species found in a particular region. For example, a rainforest has high species diversity with its numerous types of trees, insects, birds, and mammals, whereas a desert has lower species diversity.
2. Genetic Diversity: This refers to the variation of genes within a single species. For example, the thousands of different breeds of dogs (like German Shepherds and Pugs) or the numerous varieties of roses and rice all demonstrate genetic diversity within their respective species.
3. Ecosystem Diversity: This is the variety of different habitats, biological communities, and ecological processes. For example, the range of ecosystems on Earth includes deserts, forests, grasslands, wetlands, and oceans, each with its own unique set of species and environmental conditions.

2. How can we measure biodiversity? Describe its different procedures.
Answer: Biodiversity is mathematically measured using two main components: richness and evenness.

• Richness: This is a simple count of how many different species exist in a given area.
• Evenness: This measures how equal the population sizes of each species are within a community.

To represent both richness and evenness in a single number, scientists use Diversity Indices. The two most widely used indices are:

1. Shannon Index (H): This is an information statistic index that is strongly influenced by species richness and the presence of rare species.
2. Simpson Index (D): This is a dominance index that gives more weight to common or dominant species and is less affected by rare ones.

Additionally, the biologist R. H. Whittaker proposed three other indices to measure biodiversity at different scales:

• Alpha Diversity: The number of species in a single, local community (species richness).
• Beta Diversity: The measure of change in species composition between different communities along an environmental gradient.
• Gamma Diversity: The total species diversity over a large geographical scale or landscape.

3. Prepare a note on the biodiversity of Assam.
Answer: Assam is one of the richest biodiversity states in India and is part of one of the two biodiversity hotspots in the country—Northeast India. Its rich biodiversity is due to several factors:

• Favourable Location and Climate: Its unique location, diversified topography, and ideal wet sub-tropical climatic conditions support a wide variety of life.
• River Systems: The vast network of the Brahmaputra and Barak rivers and their tributaries creates extensive wetland and grassland ecosystems.
• Forests: The state has an abundance of tropical evergreen, semi-evergreen, and deciduous forests.
• National Parks and Sanctuaries: Assam is home to 5 National Parks (like Kaziranga and Manas) and 18 Wildlife Sanctuaries, which protect its diverse fauna and flora.
• Animal and Plant Diversity: Assam has about 164 species of mammals, 958 species of birds (including 17 endemic species), and is particularly rich in non-human primates (9 out of 15 Indian species are found here). It also has a rich diversity of reptiles, amphibians, fish (185 species), and insects like butterflies. The state also has immense plant diversity, including 42 species of bamboo and 193 species of orchids.

4. Explain about the problem and prospects of biodiversity of Assam.
Answer:
Problems: The rich biodiversity of Assam is facing severe threats. The major problems are:

1. Population Growth and Density: Increasing human population puts immense pressure on natural resources.
2. Habitat Destruction: Forests and wetlands are being destroyed for settlement, agriculture, and unplanned development (anthropogenic causes).
3. Overgrazing: Excessive grazing by livestock degrades grasslands and forests.
4. Poaching: Illegal hunting threatens many species, such as the one-horned rhinoceros and elephants.
5. Flood and Bank Erosion: These natural disasters destroy habitats and affect both wildlife and human populations.
6. Loss of Traditional Knowledge: The traditional knowledge of conservation and sustainable use of resources is decreasing at an alarming rate.

Prospects: Despite the problems, Assam’s rich biodiversity offers significant prospects for economic development:

1. Ecotourism: The national parks and sanctuaries can be developed as major ecotourism hubs.
2. Fish Production: The vast wetlands and rivers have great potential for both commercial and ornamental fish production.
3. Bamboo-based Industries: With 42 species of bamboo, there is huge scope for developing bamboo-based industries.
4. Traditional Medicine: The state’s rich medicinal plants can be researched and utilized for developing traditional and modern medicines.

5. Prepare a note on the need of conservation of biodiversity.
Answer: The need for the conservation of biodiversity is felt globally for several crucial reasons. These can be seen from two main perspectives:

1. Human-centric View: Our survival is directly dependent on biodiversity. We rely on various plants and animals for essential resources like food, medicine, materials for shelter, and clean water. The enormous growth in the human population has put immense pressure on these resources, and we have already crossed the Earth’s carrying capacity. Therefore, conserving biodiversity is a must for ensuring the availability of these resources for our own survival.
2. Ethical View: This perspective holds that every species has an intrinsic right to exist, regardless of its usefulness to humans. We have an ethical obligation to protect other species and ensure their survival for future generations.
   Furthermore, damage to biodiversity is often irreversible. The extinction of a species is permanent. Conservation is necessary to maintain the diversity of organisms and the complexity of ecosystems, which are essential for the evolution of new species and the overall health of the planet.

6. What is pollution? Explain its various types.
Answer: Pollution is the introduction of harmful contaminants into the natural environment, which causes adverse change. These contaminants can harm human health, wildlife, and ecosystems.
The major types of pollution mentioned in the chapter are:

1. Air Pollution: The release of harmful chemicals and particulates into the atmosphere from industries and motor vehicles. Common pollutants include carbon monoxide, sulfur dioxide, and nitrogen oxides.
2. Noise Pollution: This includes excessive and harmful noise from roadways, aircraft, and industries.
3. Plastic Pollution: The accumulation of plastic products and microplastics in the environment, which adversely affects wildlife and humans.
4. Soil Contamination: This occurs when chemicals are released into the soil through spills or underground leakage. Major contaminants include hydrocarbons, heavy metals, and pesticides.
5. Radioactive Contamination: This results from activities related to atomic physics, such as nuclear power generation and weapons research.
6. Water Pollution: The discharge of wastewater from industries and untreated domestic sewage into rivers and other surface waters.

7. What is sustainable development? Explain the development of the concept of sustainable development.
Answer: Sustainable development is a form of development that aims to improve the quality of human life and meet the socio-economic needs of the present generation without damaging the environment or compromising the ability of future generations to meet their own needs. In essence, it is about finding a harmony between development and conservation.
The concept of sustainable development emerged as a major global concern after the World Summit held in Stockholm in 1972, where countries voiced their concern for the environment. The concept was formally defined and popularized by the Brundtland Report (titled “Our Common Future”) in 1987. This report outlined key strategies for achieving sustainable development, such as reviving economic growth, changing the quality of growth to be less resource-intensive, meeting essential human needs, and conserving the natural resource base. This led to the adoption of global goals, culminating in the 17 Sustainable Development Goals (SDGs) by the United Nations in 2015, which provide a roadmap for achieving a sustainable future by 2030.