Maharashtra Board Class 11 Environmental Science Chapter 3 Biodiversity PDF Download

Biodiversity

3.1 What Is Biodiversity?

The variety and range of life forms on the earth is termed as "Biological diversity" or "Biodiversity". In other words, biodiversity is made up of all living species, their genetic properties and the ecosystems of a region. Biodiversity is the outcome of 3000 million years of evolution.

The biosphere constitutes a vital life supports for man. Its existence in a healthy and functional state is essential for existence of human race. This diversity of living creatures form a support-system which has been utilized by each civilization for its growth and development. The variability in nature helped in utilization of the earth's biological wealth for the benefit of humanity and has been integral to the process of development.

Those that used this "bounty of nature" carefully survived. Those that over used or misused it disintegrated. At present we are losing accumulated heritage of millions of years at a very rapid rate. The very basis of our existence is being undermined. The onset of reduction in diversity of life forms is bound to have grave consequences for the entire living-world.

"Variation is the law of Nature."

Different living beings have different structures, shapes, defense mechanism, feeding habits and life cycle. Such variety is found in all forms of flora and fauna in your surroundings. Make a list.

Teacher's Note

Biodiversity means all different types of plants and animals living together. Just like your school has students of different heights and colors, nature has different plants and animals.

Exam Trick

Remember: Biodiversity = Bio (life) + Diversity (many different types). So it means many different types of living things in one place.

Points to Remember

Biodiversity is made of all living species and their homes.
It took 3000 million years to make all this biodiversity.
We are losing biodiversity very fast now.
Different animals have different shapes, sizes and habits.
Nature has the law of variation - nothing is exactly same.

3.2 Levels of Biodiversity

There are three hierarchical levels.

(a) Genetic diversity: This is the variability that is present in the individuals of a species due to differences in individuals genetic makeup.

It refers to variation of genes within species. Differences could be in entire genes or in structure of chromosomes. Genetic diversity enables a population to adapt to the environment. It is also responsible for speciation. Some variations are easy to see, such as; size, colours, taste and flavor. For example varieties of rice and wheat. Deliberate manipulation of genes by humans within a species produces new varieties of crops and new breeds of domestic animals.

(b) Species diversity:

It is the variability in the species richness within a specified area (habitat).

It refers to the variety of species in a given region.

It is largely the result of natural evolutionary process.

(c) Ecosystem diversity:

It is the variety of ecosystems that are present on the earth. some of them include forest, grassland, pond, river, marine ecosystems etc.

This variety in ecosystems is formed because of different climatic conditions and topographical features which are present on the earth.

Teacher's Note

There are three types of biodiversity. Genetic diversity is like different types of rice seeds your grandmother keeps. Species diversity is all the different animals in a jungle. Ecosystem diversity is all different habitats like forest, river, and desert.

Exam Trick

Remember: Genetic = genes inside one animal. Species = different animals. Ecosystem = different homes for animals. Think: Gene in family (genetic), Species in area (species), System in region (ecosystem).

Points to Remember

Genetic diversity means different genes in one type of animal.
Species diversity means different types of animals in one place.
Ecosystem diversity means different types of homes in different areas.
All three work together to make biodiversity.
Human farmers make new varieties using genetic diversity.

3.3 Values of Biodiversity

The world is inhabited by myriads of life forms, animals and plants. These life forms are of great diversity, living in diverse habitat and possessing diverse qualities which in themselves make very interesting studies. Moreover, these life forms are vital to human survival as they provide food and materials for shelter, clothing, tools and medicine.

Now a days, we possess modern technologies which can utilize the different genetic qualities in a variety of ways. Wild diversity can also be incorporated into crops and contribute to world agricultural development.

Why Is Biodiversity Important?

All species are interconnected. They depend on one another. With less biodiversity, these connections weaken and sometimes break, harming all the species in the ecosystem. Biodiversity is important to people in many ways As biodiversity decreases, these systems break down.

Teacher's Note

Biodiversity is important because all living things help each other. If bees die, flowers cannot make seeds. If flowers die, animals have no food. Everything is connected like a chain.

Exam Trick

Remember: Biodiversity = value. No bees = no flowers = no fruits = no food for animals. All are connected. So save all animals and plants.

Points to Remember

Biodiversity gives us food, clothes, and medicine.
All species depend on each other.
If one species dies, others are also affected.
Modern science can use biodiversity to make new crops.
Losing biodiversity harms all living things.

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