Question

The total number of species of plants, animals and microorganisms living on Earth is called as
A. Biodiversity
B. Flora
C. Fauna
D. Ecosystem

Answer 1

Hint:- Many varieties of living organisms are found on earth. They include organisms ranging from invisible microorganisms to large living organisms. All of these organisms are interrelated with each other and with their surrounding environment in one or the other way. This interrelationship forms the ecological diversity of the earth.

Complete answer: The total number of plants found in a particular area is referred to as flora. Flora provides the index, name, and actual account of the habitat and distribution of the plants of a particular area.
Correspondingly, the total number of animals found in a particular area or habitat is referred to as the Fauna.
The living organisms are dependent on abiotic (non-living) factors such as water, air, and sunlight for their survival.
The living factors (biotic), as well as the non-living factors (abiotic) of the environment present in a particular area, are collectively referred to as the Ecosystem.
The term Biodiversity is used to describe the combined diversity at all levels of the biological organization. Thus the total number of plant species, animal species as well as the microbial species are referred to as the Biodiversity.
Biodiversity can be described at various levels as-

Genetic diversity - A single species shows diversity at the genetic level, over its distributional range. For example, India has more than 50,000 genetically different strains of rice.
Species diversity - It is the diversity found at the species level. For example, Western ghats have a greater number of diverse amphibian species than eastern ghats.
Ecological diversity - It is the diversity at the ecosystem level. For example, India has a greater diversity (deserts, rainforests, Westlands, etc.) when compared to Norway.

Thus the correct answer is option A.

Additional information:

There are more than 20,000 species of ants, 3000 species of beetles, 28,000 species of birds, and 28,000 species of orchids present all over the earth.

Note: The diversity of plants and animals is not uniform throughout the world, rather it shows an uneven distribution based on the latitude of the area. The species diversity decreases as we move away from the equator towards the polar regions. The large tropical Amazon rainforest of South Africa has the greatest biodiversity on earth. Nowadays, the loss of biodiversity is occurring due to deforestation (habitat loss), overexploitation of the species, and due to natural and manmade extinctions. For a healthy ecosystem, it's biodiversity must be balanced.