Bihar Board - Class 12 Biology - Chapter 15: Biodiversity and Conservation Long Answer Question

1. What do you mean by biodiversity? What are the different types of Biodiversity? 

Ans: Biodiversity can be defined as the totality of genes of species and ecosystem of a given particular region. Three types of Biodiversities are:- 

i) Genetic Biodiversity:- It refers to the diversity of genes within a species. The greater the genetic diversity among organisms of a species greater will be the sustainability it has against environmental perturbations. Whereas genetically uniform populations are highly prone to diseases or harsh environments. 

ii) Species Biodiversity:- It refers to the variety of species within a region. It has two important measures:- 

a) Species richness:- means the number of species per unit area. 

b) Species evenness:- means abundance with which each species is represented in an area. 

iii) Ecosystem Biodiversity:- It refers to the variety of habitats, community types, and abiotic environment present in an area. It is again divided into three types:- 

a) Alpha Diversity - It refers to the number of species in a given community. 

b) Beta Diversity - Biodiversity which appears in the range of communities due to the replacement of species with change in the community is called beta diversity. 

c) Gamma Diversity - It refers to the diversity of habitats over the total geographical area. 

2. What do you mean by latitudinal gradient? What could be the possible reasons for diversity between tropic and temperate regions? 

Ans: The latitudinal gradient in diversity means that species diversity usually decreases as we move away from the equator towards the poles. The Tropic area of the latitudinal range 23.50c harbors more species than the temperate or polar area. To explain this difference three hypotheses have been proposed, these are:-

i) Speciation is a function of time, which temperate regions were subjected to frequent glaciations in the past, the tropics have to remain unchanged and hence evolved more species diversity. 

ii) As compared to the temperate region, tropical environments are less seasonal, relatively more constant, and predictable. Niche specialization and greater species diversity have been promoted by such constant environments. 

iii) There is more solar radiation available in the tropical region which contributes directly to greater productivity and indirectly to greater species diversity. 

3. Why is it necessary to conserve biodiversity? 

Ans: Following are the reasons for conserving biodiversity that can be grouped into three categories. 

i) Narrow Utilitarian Reasons:- Several economic benefits have been derived by human beings. These benefits are food, fiber, firewood, industrial products, and medicinal products. 

ii) Broad Utilitarian Reasons:- Biodiversity plays a major role in providing ecosystem services like:- 

a) production of oxygen 

b) Pollination of flowers, without which seeds or fruits are impossible to be produced. 

c) Aesthetic pleasures which involve bird watching, watching the flowers of the spring season, walking through thick forest, working up to bulbul’s song, etc. 

iii) Ethical Reasons:- Every species has their intrinsic value even if they are not of any value to us economically. We have a moral duty to care for their well-being and pass on the biological legacy in a proper form to our future generation. 

4. What are the different approaches to biodiversity conservation in India? 

Ans: In India, there are two major approaches to the conservation of biodiversity. They are:- 

i) In-situ Conservation:- It is the process of protecting the endangered species of plant or animal in the natural habitat lay either protecting or cleaning up the habitat or by defending species from predators It includes:- 

a) Biosphere Reserves:- There are 425 biosphere reserves in the world of which 14 are in India. Hotspots have been identified for maximum protection to endemic or endangered species. 

b) National Park or Wildlife Sanctuaries:- India has about 90 national parks and 448 wildlife sanctuaries. 

c) Sacred Forests:- These are undisturbed forests without any human intervention and are surrounded by highly degraded landscapes. 

ii) Ex-situ Conservation:- It is the process by which the endangered species of plants or animals are given protection by removing them from threatened habitat and placing them under the care of humans. It includes:- 

a) Botanical garden, zoological park, and arboreta are conventional methods of ex-situ conservation 

b) Cryopreservation to the storage of materials at an ultra-low temperature either by rapid cooling or by gradual cooling and simultaneous dehydration at low temperature. 

5. What is the significance of Biodiversity to Human beings? 

Ans: Biodiversity provides numerous direct or indirect services to human beings. These are:

i) Source of food and improved varieties:- Biodiversity directly or indirectly add as the source of food, cloth, and shelter. 

ii) Fats and Oils:- A variety of plants are used to extract different kinds of oils. 

iii) Fibers:- A variety of plants eg. cotton, hemp, jute are the chief sources of fibers. 

iv) Resins:- Resins are sticky exudation of plants. 

v) Gums, Timber, Paper, Tannins, Dyes:- Plants species provide a variety of useful products such as gums, raisins, dyes, similarly animal species also provide leather, fur, honey, silk, pearl, etc. 

vi) Drugs and Medicines:- Living organisms also contain several therapeutically useful substances. 

vii) Stability of Ecosystem:- The food web, food chain energy flow in various trophic levels, and biochemical cycles occurs in natural ways without any hindrance if there is proper availability of diversified species 

viii) Aesthetic, Scientific and Recreational values:- Indian people grow many plants because they regard them as sacred. 

6. Why is the sobriquet ‘The Evil Quartet’ used in the context of biodiversity? Name the members of this quartet. Why do we grieve for the genes when a species is lost? 

Ans: The term ‘Evil Quartet’ is used to refer to the cause of the loss of biodiversity. The members of the quartet are:

(i) Habitat loss and fragmentation: When due to various human activities, large habitats are broken up into smaller fragments the animals requiring large territories such as elephants, birds, etc. are getting affected badly and their populations decline. 

(ii) Over-Exploitation: When the need for a resource becomes greed. e.g., overexploitation of passenger pigeons led to its extinction. Also marine fish are on the brink of being endangered due to overexploitation. 

(iii) Alien Species Invasion: Introduction of an intentional or unintentional species to a nearby area may disturb the harmony of existing species. e.g., Eichhornia after its introduction posed a big threat to the native species. 

(iv) Co-extinction: Extinction of one species invariably leads to the extinction of another when they are associated with each other in an obligatory way. E.g: When a host species becomes extinct, the obligate parasites that are dependent on it also die. 

7. Describe at least two approaches each for ex-situ conservation and in-situ conservation as a strategy for biodiversity conservation. 

Ans:  As a strategy for biodiversity conservation the two approaches for in-situ and ex-situ conservation is as follows: 

In situ conservation : 

(i) Identification and maximum protection should be provided to ‘hot spots.’

(ii) Legal protection to ecologically rich areas. 

(iii) Biosphere reserves, national parks, and sanctuaries. 

(iv) Sacred groves. 

Ex-situ Conservation : 

(i) Creation of zoological parks, botanical gardens, a wildlife sanctuary. 

(ii) Cryopreservation 

(iii) Seed bank.