Q. 1. Define Biosphere.
Ans. The Biosphere is that part of earth in which life forms exist.
Q. 2. Why is the biosphere important?
Ans. It is important because life of any kind is possible only in this layer.
Q. 3. Name two categories of organisms.
Ans. (i) Plant Kingdom
(ii) Animal Kingdom.
Q. 4. Define a ‘Homosapien’.
Ans. The earliest man on the earth is known as Homosapien.
Q. 5. Define the term ‘Ecology’.
Ans. The study of the interaction between organisms and their environment is called Ecology.
Q. 6. Name the two categories of components of an Ecosystem.
Ans. (a) Biotic such as plants and animals (living).
(b) Abiotic such as soil and water (non-living).
Q. 7. Name two sources of internal energy of the ecosystem.
Ans. (i) Matter.
Q. 8. Name three most abundant elements found in all living organisms.
Ans. (i) Carbon
Q. 9. Name the major nutrients found in Biosphere.
Ans. (i) Carbon, Oxygen, Nitrogen from Atmosphere.
(ii) Iron, sulphur, phosphorus, manganese from Lithosphere.
Q. 10. What makes natural cycles operational?
Ans. Energy, through solar radiation.
Q. 11. Divide the organisms into three groups.
Ans. The major groups of all organisms are :
Q. 12. Define the term ‘Photosynthesis.’
Ans. The process of energy conversion is known as photosynthesis. Plants use light energy to convert carbon dioxide and water to produce carbohydrates to support life. In simple words, photosynthesis means production of carbohydrates.
Q. 13. Define the term ‘Decomposers’.
Ans. The microscopic organisms and bacteria (Fungi and Earth-worms) who feed on the decomposed and decayed organic products are called decomposers.
Q. 14. Where is life found on earth?
Ans. Life on earth is found almost everywhere. Living organisms are found from the poles to the equator, from the bottom of the sea to several kilometres in the air, from freezing waters to dry valleys, from under the sea to underground water lying thousands of metres below the earth’s surface.
Q. 15. Where are most of organisms found in Biosphere?
Ans. The biosphere includes all the living components of the earth. It consists of all plants, animals including all micro-organisms that populate our planet earth and interact with their surrounding environment.
Most of the organisms exist on the lithosphere and/or the hydrosphere as well as atmosphere. There are also many organisms that move freely from one realm to another.
Q. 16. What are the effects of components of Biosphere?
Ans. The biosphere and its components are very significant elements of the environment. These elements interact with other components of the natural landscape such as land, water and soil.
They are also influenced by atmospheric elements such as temperature, rainfall, moisture and sunlight. The ineractions of biosphere with land, air and water are important to growth, development and evolution of the organism.
Q. 17. What is ecological system?
Ans. The interactions of a particular group of organisms with land, water and air, within a particular habitat results in a clearly defined energy flow and material cycle, is called an ecological system.
Q. 18. What is meant by Ecological adaptation?
Ans. When various plants and animal species have got adapted through evolution ; it is called ecological adaptation.
Q. 19. What is meant by water cycle?
Ans. The water cycle. All living organisms, the atmosphere and the lithosphere maintains between them a circulation of water in solid, liquid or gaseous form referred to as the water or hydrologic cycle.
Q. 20. What is meant by Photosynthesis?
Ans. Sun is the main source of energy on which all life depends. Photosynthesis is the process which supplies food and energy to the green plants. During photosynthesis carbon dioxide is converted to organic compounds and oxygen.
Q. 21. What do you mean by Ecology, Ecological adaptation and Ecological system?
Ans. Ecology. The environment is made up of the abiotic and biotic elements. It would be interesting to understand how the diversity of life forms is maintained to bring a kind of equilibrium or balance.
This balance is maintained in a particular proportion so that a healthy interaction between the biotic and the abiotic elements is found. The term ecology is derived from the Greek word ‘oikos’ meaning ‘house’, combined with the word ‘logy’ meaning the ‘science of’ or ‘the study of.’
Literally ecology is the study of the earth as a ‘household’, of plants, animals and micro-organisms. They all live together as interdependent components. A German zoologist Ernst Haeckel, who used the term as ‘oekologie’ in 1869, first coined the term ecology.
The study of interactions between lifeforms (biotic) and the physical environment (abiotic) is the science of ecology. Hence, ecology can be defined as a scientific study of the interactions of organisms with their physical environment and with each other.
Ecology is mainly concerned with the growth, development, distribution, behaviour and survival of organisms. Ecology is not only concerned with living organisms and their interactions but also with energy flows and material cycles that occur on land, water and air.
The interactions of a particular group of organisms with land, air and water (abiotic factors) within a particular habitat or habitats resulting in clearly defined energy flows and material cycles on land, water and air, are called ecological systems. A habitat in the ecological sense may be explained to be the totality of the physical and chemical factors that constitutes the general environment.
Different types of ecosystems exist with varying ranges of environmental conditions where various plants and animal species have not adapted through evolution. This phenomenon is known as ecological adaptation.
Q. 22. Describe the major types of Ecosystems.
Ans. Types of ecosystems. Ecosystems are of two major types— terrestrial and aquatic. Terrestrial ecosystem can further be classified into ‘biomes’. A biome is a plant and animal community that covers a large geographical area. The boundaries of different biomes on land are determined mainly by climate and weathering. Therefore a biome can be defined as the total assemblage of plant and animal species interacting within specific conditions.
These conditions include rainfall, temperature, humidity and soil conditions. Some of the major biomes of the world are—forest, grassland, desert and tundra biomes. Aquatic ecosystems can be classed as marine and freshwater ecosystems. Marine ecosystem includes oceans, coastal estuaries and coral reefs. Freshwater ecosystem includes lakes, ponds, streams, marshes and bogs.
Q. 23. What do you mean by ‘Ecology’?
Ans. Ecology is a combination of two Greek words (Oikos) and (Logy) meaning house and science. Ecology is the study of earth as home of plants, humans, animals and bacteria. These are interdependent. German zoologist Ernst Haeckel was the first to use this term in 1869. He is known as the father of ecology. The study of interactions between life forms (Biotic) and (Abiotic) is the science of ecology.
Q. 24. Describe the different types of Biomes.
Ans. A biome is a plant and animal community that covers a large geographical area. Therefore a biome is a total assemblage of plant and animal species. There are five major Biomes—forests, deserts, grassland, aquatic and altitudinal.
Q. 25. Describe the carbon cycle.
Ans. The carbon cycle. Carbon is one of the basic elements of all living organisms. It forms the basic constituent of all organic compounds. The biosphere contains over half a million carbon compounds in them. The carbon cycle is mainly the conversion of carbon dioxide. This conversion is initiated by the fixation of carbon dioxide from the atmosphere through photosynthesis. Such conversion results in the production of carbohydrate, glucose that may be converted to other organic compounds such as sucrose, starch, cellulose, etc.
Here, some of the carbohydrates are utilised directly by the plant itself. During this process more carbon dioxide is generated and is released through its leaves or roots during the day. The remaining carbohydrates not being utilised by the plant become part of the plant tissue. The plant tissues are either being eaten by the herbivorous animals or get decomposed by micro-organisms. The herbivores convert some of the consumed carbohydrates into carbon dioxide for release in to the air through respiration. The micro-organisms decompose the remaining carbohydrates after the animal dies.
Q. 26. Describe the mineral cycles.
Ans. Mineral cycles. Other than carbon, oxygen, nitrogen and hydrogen being the principal geochemical components of the biosphere many other minerals also occur as critical nutrients for plant and animal life. These mineral elements required by living organisms are obtained initially from inorganic sources such as phosphorus, sulphur, calcium and potassium. They usually occur as salts dissolved in soil water or lakes, streams and seas. Mineral salts come directly from the earth’s crust by weathering where the soluble salts enter the water cycle eventually reaching the sea.
Other salts are returned to the earth’s surface through sedimentation and after weathering they again enter the cycle. All living organisms fulfil their mineral requirements from mineral solutions in their environments. Other animals receive their mineral needs from the plants and animals they consume. After the death of living organisms the minerals are returned to the soil and water through decomposition and flow.
Q. 27. Describe the oxygen cycle.
Ans. The oxygen cycle. Oxygen is the main byproduct of photosynthesis. It is involved in the oxidation of carbohydrates with release of energy, carbon dioxide and water. The cycling of oxygen is a highly complex process.
Oxygen occurs in a number of chemical forms and combinations. It combines with nitrogen to form nitrates and with many other minerals and elements to form various oxides such as iron oxide, aluminium oxide and such others.
Much of oxygen is produced from the decomposition of water molecules by sunlight during photosynthesis and is released to the atmosphere through transpiration and respiration processes of plants.
Q. 28. Explain the term ‘‘Biosphere’’.
Ans. Biosphere is the realm of all living forms (human beings, plants, animals) that exist in hydrosphere, lithosphere, and atmosphere. In this way, natural environment includes man also. It is a thin life bearing layer above the earth’s surface. It extends vertically from the deep ocean to the higher layers of atmosphere.
The biosphere is the basis of life on the earth. Man tries to modify the environment and utilizes the resources of earth. Man tries to bring a totality of environment so that environment operates as a whole.
Q. 29. Examine the importance of Biosphere.
Ans. Biosphere is a thin layer which contains living things above the earth’s surface. It has a great significance for human life. The earth has a unique place in the solar system due to the presence of biosphere.
Organisms in the biosphere provide a variety of food for us. Plants provide us raw materials for clothing and shelter such as cotton and jute. Human existence and survival on the earth depends upon biosphere. Coal, mineral oil, wool, silk and many industrial raw materials are obtained from biosphere.
Q. 30. What do you understand by the term ‘‘Ecological Balance’’?
Ans. In nature, each geographical element has a life cycle. These features are born, grow to maturity and then die. Landforms, plants, and animals pass through this cycle. Landforms have a longer life cycle, but plants and animals change within short periods. After the final stage, there is no change in the composition of plants as a community. This stage is known as ecological balance.