• 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) 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) 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

b) Both assertion(A) and reason (R) are true; R does not explain A

a) Both assertion (A) and reason(R) are true; R explains A

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.