Grade 11 Zoology Note


Biodiversity:It is the total verity of the life on the earth. Scientist can only guess how many millions of species that exist on the planet. Biodiversity is the variability among living organism in all sources.  In other word, it encompasses the total number, variety and variability of life form, level and combinations existing within the living world. It is not the sum of all ecosystem, species and genetic material. Rather it includes diversity within species, between species and of ecosystem. The biodiversity mainly consist of three categories, they are

1. Ecosystem diversity: An ecosystem comprises a dynamic complex of plant, animal and micro-organism communities and their non-living environment which interact as a functional unit. Thus, ecosystem commonly exists within ecosystems. Ecosystem diversity refers to the variety and frequency of distinct ecosystems including the variety of habitats, biotic communities and their change in composition and structure over time and ecological processes in the biosphere.

2.Species diversity: Species is defined as a population of organism whose members able to interbreed freely under natural conditions. A species represents groups of organisms which has evolved distinct inheritable features and occupies a unique geographical area. Species diversity is used to describe the frequency and variety of species within a geographical area. The total number of species in a globe has been estimated to range from 5 to 30 million.

3. Genetic Diversity: Genes are the principle units of heredity which are passed from an organism to its offspring. These are composed of nucleic acid and are located along an organism’s chromosomes, in the plasmids of bacteria and other extra chromosomal forms as well. Genes, either individually or in groups contribute many different attributes to an organism such as its physical appearance, its ability to resist certain insects, or genes within living organisms, that is, the genetic differences among population of a single species and among individuals within a population.


Scope of Biodiversity:


1. Biological diversity is the main resource on which human beings depend. The existence of human is intimately related with the wide variety of plant and animal species found around us.

2. Biodiversity provides the vast majority of foodstuffs. Many kinds of animals and plants are lived and grow in different climate and geographical conditions. These plants and animals supply lots of food products such as fruits, cereals, nuts, mushroom, honey, meat, mike etc.

3. It is estimated that 80% of people in the developing world depend directly on traditional medicines derived from plants and animals.

4. More than 1500 plants of Nepal have medicinal value.

5. Biological diversity exerts direct influences on regional and local weather patterns.

6. Plant purifies the air and regulates the composition of the atmosphere, recycling oxygen and filtering harmful particles release due to industrial activities.

7. Biodiversity provides various raw materials for textile, leather, tannis, dyes, furniture industries.

8. Biological diversity is the main sources on which human beings depend. The existence of human is intimately related with the wide variety of plant and animal species found around us.

Faunal diversity of Nepal:

Nepal is a diversified country in geography low lands to 8 highest peaks
in the world like Mt. EVEREST, MT. DHAULAGIRI, MT. KANCHANJUNGA, etc. In
Nepal a lot of fauna species are found. A complete record of fauna and
flora is not reported yet. However, IUCN has published a checklist of
faunal diversity of Nepal. There are 4675 species of Mammals found worldwide and 185 mammals (3.95%) in Nepal. Out of 9799 Birds found worldwide, there are 874 (8.90%) life forms of Birds found in Nepal. 78 numbers (0.99%) of Reptiles are found in Nepal out of 7870 species of. Reptiles are found all around the world. Amphibians of 118 (4.47%) out of 4780 worldwide are present in Nepal. There live 10000 fishes worldwide and 187 (1.87%) of them are found in Nepal. Butterflies of 651 in numbers (3.72%) are in Nepal and 17000 species are found all over the world.160000 life forms of Moths including 785 (0.44%) in Nepal are found around the globe. 175 (0.44%) species of Spiders are found in Nepal out of 39490 lifeforms of them are found all around the world.

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