• Arctic Tundra Food Wed 

It is a well-balanced food web. This region gets slanting sunrays means very little sunlight in which lichens, grasses, and wildflowers grow and form the first trophic level as a producer. In the second trophic level herbivores who depend on the producers for survival like Arctic Hare, Musk ox, Lemming is the primary consumers. Carnivores who eat the herbivore are-Hawk, Polar Bear and Wolf. They are above the herbivores in a food pyramid. They are secondary consumers.

(i) of late, parts of the savanna grasslands are being converted into farmlands.
(ii) This pose a great threat to the wide range of fauna.
(iii) For Eg. The population of the big cats like cheetah, lion etc. are dwindling drastically.

(i) The Tropical Forest Biomes have very dense forests.
(ii) So human settlements are found scattered here.
(iii) They sustain their livelihood through food gathering, fishing, lumbering and shifting cultivation.

Hotspots in India are the Himalayas, Western Ghats, Indo Burma Region and Sundaland

An ecological region that has lost more than 70% of its original habitat is considered a hot spot.

(i) Terrestrial biomes is a group ofliving organisms that live and interact with one another on land.
(ii) They are mainly determined by temperature and rainfall.
(iii) Some of the major terrestrial biomes of the world are
a. Tropical Forest Biomes
b. Tropical Savanna Biomes
c. Desert Biomes
d. Temperate Grassland Biomes and
e. Tundra Biomes

(i) The extinction of species (flora and fauna) due to human and natural influences is called loss of biodiversity.
(ii) The biodiversity loss has a great impact on mankind and also affects land, water, air etc.
(iii) Habitat destruction due to deforestation, population explosion, pollution and global warming are the major cause for loss of biodiversity.
(iv) Sometimes, habitat loss is so severe or happens so quickly that it results in a species being eliminated from the planet.

(i) Bio diversity refers to a wide variety of Iiving organisms, which live in a habitat.
(ii) It is highly influenced by topography, climate as well as human activities.

(i) An ecosystem is a community, where all living organisms live and interact with one another and also with their non-living environment such as land, soil, air, water etc.
(ii) Ecosystems range in size from the smallest units (Eg: bark of a tree) that can sustain life to the global ecosystem or ecosphere. (Eg: Cropland, Pond ecosystem, Forest ecosystem, Desert ecosystem etc.).
(iii) Biosphere harbours all ecosystems on the earth and sustains life forms including mankind.

(i) Biosphere, the fourth sphere of the Earth, is a life supporting layer that exists on the earth's surface.
(ii) This layer on earth encompasses the Lithosphere, Hydrosphere and Atmosphere.
(iii) It includes flora and fauna that thrive on or near the earth's surface.
(iv) Biosphere harbours all ecosystems on the earth and sustains life forms including mankind

Aquatic biome is a group of living organisms that live and interact with one another and its aquatic environment for nutrients and shelter. It is broadly classified as fresh water biomes and marine biomes.
A. Fresh water Biomes:
(i) Fresh water biomes comprises lakes, ponds, rivers, streams, wetlands etc.
(ii) It is influenced by various abiotic components such as the volume of water, water flow, composition of oxygen, temperature, etc.
(iii) Humans rely on freshwater biomes for drinking water, crop irrigation, sanitation and industry.
(iv) Water lily, lotus, duck weeds etc. are the common plants found here.
(v) Trout, salmon, turtles, crocodiles etc. are the animals found here.
B. Marine Biomes:
(i) They are the largest aquatic biomes on earth.
(ii) They are continuous bodies of salt water and provide a wide range of habitats for marine plants and animals.
(ii) Coral reefs are a second kind of marine biomes within the ocean.
(iv) Estuaries, coastal areas where salt water and fresh water mix, form a third unique marine biome.
(v) As water provides maximum mobility to marine organisms, nutrients are circulated more quickly and efficiently here than the terrestrial biomes.
(vi) Apart from animals, plants such as kelp, algae, phytoplankton etc. also grow in water.
(vii) Some of the threats and issues to aquatic biomes are overfishing, pollution and rise in sea level.

(i) The living organisms form an interacting set of flora and fauna which are organized into trophic levels, food chains and food webs.
(ii) The functioning of an ecosystem depends on the pattern of the energy flow, as it helps in the distribution and circulation of the organic and inorganic matter within an ecosystem.
(iii) Energy flow generally takes place in a hierarchical order in an ecosystem through various levels.
(iv) These levels are called trophic levels.
(v) The chain of transformation of energy from one group of organisms to another, through various trophic levels is called a food chain.
(vi) A system of interlocking and interdependent food chains is called a food web.

(i) An ecosystem consists of three basic components, namely
a) Abiotic components,
b) Biotic components and,
c) Energy components
a) Abiotic Components
Abiotic components include the non-living, inorganic, physical and chemical factors in the environment. Eg. Land, Air ,Water, Calcium, Iron etc.
b) Biotic Components
(i) Biotic components include plants, animals and micro organisms.
(ii) Biotic components can be classified into three categories: (1) Producers, (2) Consumers and (3) Decomposers.
(iii) Producers are self nourishing components of the ecosystem. Hence they are called Autotrophs.
(iv) They are found both on land and water. Eg. Plants, Algae, Bacteria etc.
(v) Consumers are those that depend on producers, directly or indirectly. Hence they are called Heterotrophs.
(vi) Decomposers are some organisms that are incapable of preparing its own food. They live on dead and decaying plants and animals. Hence they are called Saprotrophs.
c) Energy Components
(i) All organisms in the biosphere use energy to work and convert one form of energy into another.
(ii) The Sun is the ultimate source of energy for the biosphere as a whole.
(iii) The producers, consumers and the decomposers contribute a lot to the energy flow in an ecosystem.