Biodiversity revision notes for CBSE 12th Biology Term 2 Exam 2022

Have you ever noticed the diversity around you? What role do they play in the biosphere? And what is their importance? Our biosphere is full of diversities. The variety of animals, plants, fungi, and even microorganisms like bacteria are responsible for making our natural world. Each species and organisms work together in ecosystems to maintain the balance and support life. Biodiversity supports everything in nature that you need to survive.

According to the CBSE marking scheme of the Class 12 Term 2 Biology board exam, Unit- Ecology and Environment consists of 12 marks in total. Students can gain this perfect score as this unit is the easiest to revise in a short time compared to others. In this article, let us have a quick revision on the Biodiversity and Conservation chapter for Class 12 Term 2 board exam preparations.

Biodiversity

All the different kinds of life you can find in one area are known as Biodiversity. There are various types of diversities in nature. They are a precious wealth of nature that needs to be conserved. In recent centuries, due to human activities, we have lost millions of species, and many species reached the level of extinction. And it takes millions of years to accumulate this rich diversity in nature. Therefore, it is necessary to conserve them.

Types of Biodiversity

The term ‘biodiversity’ was popularised by the socio-biologist Edward Wilson. Some important biodiversities are-

1. Genetic Diversity

A single species might show high diversity at the genetic level over its distributional range. For example, the genetic variation of the medicinal plant Rauwolfia vomitoria.

2. Species Diversity

It is the diversity at the species level. For example, the Western Ghats or the Eastern Ghats in India.

3. Ecological Diversity

It is the diversity at the ecosystem level. For example- deserts, rainforests, etc.

Number of Species on Earth And in India

• There are more than 1.5 million plants and animal species recorded globally. Nearly 45,000 plants and more than twice as many animals are recorded in India.
• More than 70% of all species recorded are animals, while 30% are plant species.
• The number of fungi species recorded in the world is more than the combined total of the species of fishes, amphibians, reptiles, and mammals.
• India is one of the twelve mega biodiversity countries of the world. It has only 2.4% of the world’s land area and 8.1% of the global species biodiversity.

Pattern of Biodiversities

So far from the records, Biodiversity has shown two types of patterns:

1. Latitudinal gradients

The plants and animals are unevenly distributed throughout the world. This distribution pattern is along the latitudinal gradient in diversity in the world. The species diversity is more in tropical regions than in temperate or polar areas. It is because tropical regions have a long evolutionary time for species diversification, various seasonal environments, and the availability of more solar energy.

2. Species – Area relationships

Alexander Von Humboldt observed that species richness gets increased within a region when an explored area is increased, but only up to a limit. A straight line was obtained when the relationship between species richness and area was drawn using a logarithmic scale. And the equation is written as

log S = log C + Z log A

Where S= species

A= Area

Z= slope of the line

C= Y-intercept

Importance of Species Diversity To The Ecosystem

The number of species directly affects the ecosystem of that area. More the species, the more stable the area is compared to those with fewer species. A stable community should not show too much variation in productivity from year to year. It is considered that rich biodiversity is essential for ecosystem health and imperative for the very survival of the human race on this planet. It is observed that the plots with more species showed less year-to-year variation in total biomass, and increased diversity contributed to higher productivity.

Loss of Biodiversity

The presence of various species on the Earth is a precious biological wealth. And human activities are the biggest reason for the continuous loss of this wealth. Loss of biodiversity in a region leads to a decline in plant production, an increase in drought, flood, environmental problems, and increased water use, disease, productivity, etc.

The IUCN Red List (2004) documents enlist the extinction of 784 species (including 338 vertebrates, 359 invertebrates, and 87 plants) in the last 500 years. Some examples of recent extinctions include the dodo (Mauritius), quagga (Africa), thylacine (Australia), Steller’s Sea Cow (Russia), and three subspecies (Bali, Javan, Caspian) of the tiger. in the last 20 years, 27 species have been disappeared.

Need For Conserving Biodiversity

There are many reasons for conserving biodiversity, and broadly they are classified under three categories:

1. Narrowly Utilitarian

Humans obtain countless direct economic benefits from nature like food, firewood, fibres, construction material, medicinal plants, and industrial products. And more such resources result in enormous benefits.

2. Broadly Utilitarian

Biodiversity plays a major role in the ecosystem services that nature provides. Production of oxygen by trees, pollination of flowers leads to the growth of trees, and delight in using nature’s benefits are priceless treasures.

3. Ethical

The ethical argument for conserving biodiversity relates to what we owe to millions of plant, animal, and microbe species with whom we share this planet. Our moral duty is to care for this treasure and pass on our biological legacy in good order to future generations.

Ways To Conserve Biodiversity

We can conserve biodiversity in two ways-

1. In-situ ( on-site) conservation

Protecting biodiversity at all levels by conserving and protecting the whole ecosystem is called in situ conservation. In this conservation process, species are conserved and protected in their natural habitat. Biosphere reserves, national parks, wildlife sanctuaries, hotspots, wild forests, etc., are included under In-situ conservation. There are 34 biodiversity hotspots in the world. India has 14 biosphere reserves, 90 national parks, and 448 wildlife sanctuaries.

2. Ex-situ (off-site) conservation

The process in which endangered and threatened animals are saved by taking urgent measures is called Ex-situ conservation. In this method, threatened animals and plants are taken out from their natural habitat and placed in special settings where they are protected and given special care. Zoological parks, botanical gardens, wildlife safari, aquariums, gene banks, etc., are included under Ex-situ conservation.

It is a serious issue that we are losing our biological wealth at a rate visible to naked eyes. If this continues for a long time, then one day, our future generation will not be able to see this beauty of nature on our Earth. And we will be responsible for this.

We hope that this article can help all Biology students of Class 12 with a quick revision on the Biodiversity topic. You can take help from NCERT Solutions for the Class 12 Biology book for more information.

FAQs

1. What are the causes of biodiversity losses?
2. Many causes result in the loss of biodiversity. The biggest reason is due to human activities. Some of the causes are-
3. Humans have used a lot of land space for their use and snatched the natural habitat of many species. It results in the extinction of various genetic species.
4. Over-exploitation results in the degradation of natural resources. And it affects the biodiversity of that area.
5. When alien species enter new areas, they start to exploit them. It results in damaging the diversity of that region.
6. When a species becomes extinct, the plant and animal species also become extinct.

1. How can biosphere reserves help us in conserving biodiversity?
2. Biosphere reserves are protected areas that are used for multi-purposes. They help us in conserving biodiversity in the following ways-
3. They are created to protect genetic diversity and unique biological communities.
4. They help protect wildlife animals and provide them with natural habitats.
5. It helps in preserving the traditional lifestyle of tribals.
6. It preserves domesticated plants and animals’ genetic resources.
7. Its inner zones are completely restricted for human activities to protect wildlife.

1. Why is there a need for wildlife conservation?
2. There are a lot of reasons for conserving wildlife. Some of them are-
3. There is a need to balance the ecosystem, and without conserving wildlife, this balance can not be maintained.
4. Wildlife has a commercial value as they are sold for zoos and parks. And this process helps in earning foreign exchanges.
5. They are important for biological studies. Many zoologists and biologists study different behaviour of biological species.
6. Although hunting animals and cutting innumerable trees are prohibited, animals are used in various sports and other activities, and medicinal plants are useful for humans.

1. What is the importance of biodiversity?
2. Biodiversity or biological wealth is very valuable for us. Various reasons make it important for everyone.
3. We get food from plants and animals. Without food, we can’t do anything. And plants and animals are the parts of biodiversity.
4. We get fats and oils from the different sources of biodiversity.
5. The major sources of fibres are cotton, jute, flax, etc. These are the parts of biodiversity.
6. Several drugs and medicines are based on plants.
7. Biodiversity features a lot of values in terms of aesthetics.
8. Biodiversity must maintain and utilise the products obtained from nature.

1. What is the importance of biosphere reserves?
2. Biosphere reserves help in conserving biodiversity in many ways. Some of them are-
3. They help in the restoration of reduced ecosystems and habitats.
4. They promote studying natural science and ecosystems.
5. They help in the regular monitoring process that leads to the development and conservation of species.
6. They help in maintaining social, cultural, and ecological sanctity.
7. They help conserve various genetic diversity species, animals, ecosystems, and landscapes.

1. What are the threats to biodiversity?
2. Biodiversity is facing a huge threat due to various human activities. The world is facing the extinction of many species due to this. The major threats are-
3. Due to overpopulation, urbanisation, and industrialization, many species lose their natural habitat, and many animals are forced to migrate. In this process of migration, many species face the crisis of death.
4. Excessive exploitation of species results in poor conditions, and this situation becomes vulnerable because of the increasing population.
5. Various species exist with the support of other species. So, if there is extinction in one species, it results in the co-extinction of other species.