Life On The Earth

Option (B) is correct because biosphere include all living and non living organisms. Biosphere is a global ecosystem composed of living organism and non living organism from which they derive energy and nutrients.

Option (A) is not correct because biosphere means a global ecosystem and only plants cannot make a global ecosystem.

Option (C) is not correct because only animal cannot form an ecosystem and on earth only animals are not present.

Option (D) is not correct because living organisms depends on non living organisms for energy and nutrient.

Option (B) is correct because tropical grasslands are also known as the savannas. It is a terrestrial biome that features vast open spaces consisting of scattered small shrubs and trees.

Option (A) is not correct because temperate grasslands are known as prairies in North America.

Option (C) is not correct because the Eurasian grasslands are known as steppes.

Option (D) is not correct because the appropriate answer is the savannas.

Option (C) is correct because oxygen combines with iron found in the rocks to form iron oxides. Rust is another name for iron oxide. When iron or an alloy that contains iron is exposed to oxygen and moisture for a long period of time, a new compound is formed called iron oxide.

Option (A) is not correct because carbon dioxide combines with iron to form iron carbonate. It occurs naturally as the mineral siderite.

Option (B) is not correct because nitrogen combines with iron to form iron nitrites.

Option (D) is not correct because sulphur combines with iron to form iron sulphate. It is a salt and soluble in water.

Option (C) is correct because during photosynthesis, carbon dioxide combines with water in the presence of sunlight to form carbohydrates. Photosynthesis is a process in which light energy is converted into chemical energy. This chemical energy is stored in carbohydrate molecules such as sugars.

Option (A) is not correct because protein is formed by protein synthesis. Protein synthesis is the process in which biological cells generate new proteins.

Option (B) is not correct because amino acids are formed by the Transamination reaction.

Option (D) is not correct because vitamins are made by living things. Vitamins are molecules made from the elements.

(i) Ecology is the branch of biology which studies the interaction of organisms with their physical environment and with each other. It is the study of ecosystems. The term ecology is derived from the Greek word ‘oikos’ meaning house, combined with the word ‘logy’ meaning the ‘study of’. We can study ecology at many different levels. For example, we may study organisms, populations, ecosystems and the biosphere in ecology. It is the study of interactions of biotic and abiotic factors.

(ii) Ecological system is a system consists of biotic and abiotic components. It includes all of the living things in a given area that interact with each other, as well as the non-living environments. The living and physical components are linked together through nutrient cycles and energy flows.

The major types of ecosystems in the world are:

*Terrestrial ecosystem: It is a type of ecosystem found only on biomes.

*Aquatic ecosystem: Communities of plants and animals living in water are known as aquatic ecosystems.

(iii) Food chain is the transfers of matter and energy in the form of form of food from one level to another. Each level of a food chain represents a different trophic level. Two types of food chain are: Grazing food chain and detritus food chain. Grazing food chain starts with plant as producers, herbivores are the intermediate level and ends with carnivores as consumers. Detritus food chain begins with dead organic matter. Example of grazing food chain is grass (producer) is eaten by goat (primary consumer) is eaten by man (secondary consumer). Grass is the first level, goat is the intermediate level and man is the last level.

(iv) Food web is a network of many different food chains. It is an important ecological concept. It represents feeding relationships within a community. Food webs are constructed to describe species interactions. Food web is also known as consumer resource system. For example, a mouse feeding on grain may be eaten by different secondary consumers (carnivores) and these carnivores may be eaten by other different tertiary consumers (top carnivores).

(v) A biome is a plant and animal community that covers a large geographical area. They can be found over a range of continents. They cover large areas. They comprise a variety of habitats. They are a way to divide the Earth’s surface. These divisions are based on the climate patterns, soil types, and the animals and plants that inhabit an area. There are five major biomes- forest, desert, grassland, altitudinal and aquatic biomes. Major biomes of India are tropical rain forest, deciduous forest, and desert.

(i) The movement of nutrient elements through the various components of an ecosystem is called biogeochemical cycle. Another name of biogeochemical cycle is nutrient cycle. Biogeochemical cycles are of two types: the gaseous and the sedimentary cycle. Example of gaseous cycle is nitrogen and carbon cycle. Example of sedimentary cycle is sulphur and phosphorus cycle.

The reservoir for gaseous type of nutrient cycle exists in the atmosphere and the reservoir for sedimentary cycle exists in the Earth’s crust.

Nitrogen is a major constituent of the atmosphere comprising about seventy eight percent of the atmospheric gases. Nitrogen fixation is a process by which nitrogen in the air is converted into ammonia or related nitrogenous compounds. The principal source of free nitrogen is the action of soil micro organisms and associated plant roots on atmospheric nitrogen found in pore spaces of the soil. Nitrogen is fixed into the atmosphere by lighting and cosmic radiation. Nitrogen fixation is essential to life because fixed inorganic nitrogen compounds are required for the biosynthesis of all nitrogen containing organic compounds, such as amino acids, proteins and nucleic acids.

(ii) Ecological balance is a term used to describe the equilibrium between living organisms such as human being, plants, and animals as well as their environment. It is a state of stability where species coexist with other species and with their environment. This occurs through competition and cooperation between different organisms where population remains stable. It is important because it leads to the continuous existence of the organisms. It ensures that no particular species is exploited or overused. Ecological imbalance is a disturbance in the balance of an ecosystem. It may be disturbed due to the introduction of new species, natural hazards or human causes.

The important measures needed to prevent ecological imbalances are:

*Creating awareness: Government should make aware people about the use of eco friendly practises through media.

*Population control: Controlling the human will reduce the strain on the ecosystem by reducing the rate at which people consume natural resources.

*Proper management of natural resources: A strong effort to use natural resources in a sustainable and efficient manner will help to protect and maintain ecological balance.

*Conservation of natural resources: Recycle to prevent the exploitation of natural resources.

*Afforestation: Plant more and more trees and stop deforestation. This will help in reducing the pressure on our ecosystem.

Characteristics of each biomes are:

*Tundra: Tundra is a type of biome where the tree growth is hindered by low temperatures and short growing seasons. It is coldest of all biomes. It is known for large stretches of bare ground and rock and for patchy mantles of low vegetation such as mosses, lichens, herbs and small shrubs. Climates vary considerably. Temperatures fluctuate from 4 degree celsius in midsummer to -32 degree celsius during the winter months in the Arctic region. Tundra soils are classified as Gelisols or Cryosols.

*Northern Coniferous forest: It is also known as boreal forest or taiga. Compare to tundra it has warmer season. Soil moisture is high. The diversity of tree species is quite low. Evergreen conifers like pine, fur etc are present.

*Tropical Rainforest: It is a hot, moist biome where it rains all year long. It is known for its dense canopies of vegetation that form three different layers. It receive 60 to 160 inches of precipitation that is fairly evenly distributed throughtout the year. Temperature is 20- 25 degree that is evenly distributed.

Temperate deciduous forest: It is also known as temperate broad leaf forests. They lose their leaves each year. They are found in areas with warm moist summers and cool winters.

*Mountains: Mountains are a large landform that rises above the surrounding land in a limited area, usually in the form of a peak. Temperature and precipitation vary depending upon latitudinal zone. Higher elevations on mountains produce colder climates than at sea level.

*Tropical Grassland (Savanna Biome): The climate in savanna biome varies depending on the season. It has a distinct wet and dry season. The savanna biome has a characteristics range of 68 to 86 degree Fahrenheit or 20 to 30 degree Celsius.

*Temperate Grassland: It has hot summers and cold winter. Rainfall is 500-900 mm. It has thin flocculated soil rich in bases.

*Desert: Deserts are formed by weathering processes. They get less than 25 cm of rainfall a year. It is a very dry biome.

*Chaparral: It is a shrubland. It is found in regions with a climate similar to that of the Mediterranean area, characterized by hot, dry summers and mild, wet winters.

*Tropical Scrub Forest: Tropical scrub forest is one of the biomes that make up aridland. It is an area of little precipitation, plenty of continuous winds and medium to poor soil quality.

Tree is defined as a woody perennial plant having a single stem or trunk growing to a considerable height. It provides habitat for many species of animals. It provides shade and shelter, timber for construction, fuel for cooking and heating.

Shrub is a small or medium sized perennial woody plant having multiple stems and shorter height, less than 6 m tall. They are a source of foodstuffs such as fruits, leaves, shoots and roots. They are also used in landscapes.

Perennial plants are the plant that lives for more than two years. Perennial plants are also known as herbaceous plants.

Types of birds which come to the garden are:

*Parrot

*Pigeon

*Crow

*Sparrow

*Eagle

*Woodpecker

Tropics are home to the greatest biodiversity of birds. Birds are bipedal, warm blooded, and egg laying vertebrates with about 10,000 living species. Birds evolved from theropod dinosaurs 200 to 150 million years ago. Globally, 1,223 species of birds, or about 12 percent of the total of 9,998 extant described bird species, were deemed endangered or threatened with extinction by IUCN’s 2009 Red List. Birds are crucial to maintain the balance of many ecosystems by providing various ecological services.