MP Board Class 12th Biology Solutions Chapter 14 Ecosystem
Ecosystem NCERT Text Book Questions and Answers
Question 1.
Fill in the Blanks:
- Plants are called…………….. because they fix carbon dioxide.
- In an ecosystem dominated by trees, the pyramid (of numbers) is ………………… type.
- In an aquatic ecosystem, the limiting factor for productivity is …………………….
- Common detritivores in our ecosystem are ………………………..
- The major reservoir of carbon on earth is ………………………
Answer:
- Producer
- Inverted
- Light
- Earthworm
- Ocean and Biosphere.
Question 2.
Which one of the following has the largest population in the food chain:
(a) Producers
(b) Primary consumers
(c) Secondary consumers
(d) Decomposers.
Answer:
(d) Decomposers.
Question 3.
The second trophic level in a lake is:
(a) Phytoplankton
(b) Zooplankton
(c) Benthos
(d) Fishes.
Answer:
(b) Zooplankton
Question 4.
Secondary producers are:
(a) Herbivores
(b) Producers
(c) Carnivores
(d) None of the above.
Answer:
(a) Herbivores
Question 5.
What is the percentage of photosynthetically active radiation (PAR) in the incident solar radiation:
(a) 100%
(b) 50%
(c) 1 – 5%
(d) 2 -10%.
Answer:
(b) 50%
Question 6.
Distinguish between:
(a) Grazing food chain and detritus food chain
(b) Production and decomposition
(c) Upright and inverted pyramid
(d) Food chain and Food web
(e) Litter and Detritus
(f) Primary and Secondary productivity.
Answer:
(a) Grazing food chain and detritus food chain
(b) Production and decomposition
(c) Upright and inverted pyramid
(d) Food chain and Food web
(e) Litter and Detritus
(f) Primary and Secondary productivity.
Question 7.
Describe the components of an ecosystem.
Answer:
An ecosystem has two types of components biotic and abiotic.
1. Biotic components:- There are living organisms present in an ecosystem. On the basis of their obtaining food, biotic components are of 3 types – produces, consumers and decomposers.
- Producers – They are autotrophic components that include phytoplankton, some algae floating, submerged, and marginal plants.
- The consumers are the organism like zooplankton, free-swimming animals, bottom-dwelling animals, etc consumes producers as their food.
- The decomposers are organisms (saprophytic) which obtain nourishment from organic remains they digest the organic remains by digestive enzyme and liberates inorganic nutrients. Because of this decomposers are called mineralizers.
2. Abiotic components:- They are factors and materials of the physical environment. The materials include inorganic nutrients and organic remains. The organic remains consist of human substances, carbohydrates, lipids, proteins, etc. The abiotic materials are air, water, and soil.
Question 8.
Define ecological pyramids and describe with examples, pyramids of number and biomass.
Answer:
Ecological Pyramid: The relation between producers and consumers in an ecosystem can be graphically represented in the form of a pyramid called an ecological pyramid. The base always represent the producers or the first trophic level and the apex represents top-level consumer or the lost trophic level ecological pyramids are of three types:
- Pyramid of number
- Pyramid of biomass
- Pyramid of energy
The biomass, i.e., the living weight of the organisms in the food-chain present at different trophic levels in an ecosystem forms the pyramid of biomass.
When biomass of consumers is greater than biomass of producer then pyramid is called as an inverted pyramid of biomass.eg., pyramid of biomass of pond ecosysyem is always inverted.
Ecosystem: The system resulting from the interaction between organisms and the environment is called an ecosystem.
Question 9.
What is primary productivity? Give a brief description of factors that affect primary productivity.
Answer:
Primary productivity:- It is the rate of synthesis of biomass by producers per unit time per unit area through, the process of photosynthesis.
Factors:- It depends up on sunlight, temperature moisture, nutrients and photosynthesis efficiency of producers.
- Sunlight:- In tropical regions maximum sunlight is available. It reduces towards the pole. Therefore more photosynthesis and high productivity occurs in tropics.
- Temperature:- Temperate forest have lesser productivity as compared to tropical forests due to the cold climate during winter. Alpine and arctic regions have very low productivity because of low temperatures almost throughout the year.
- Moisture:- Good rain and humidity increase productivity of the ecosystem with the fall in availability of water the productivity decreases.
- Nutrients:- A regular availability of nutrients is required for sustaining plant growth and hence the productivity of an ecosystem. Coral reefs and esturies are highly productive as the nutrient supply is rich.
- Photosynthetic efficiency:- Some plants are photosynthetically more efficient in trapping sunlight than others. eg: Sugarcane.
Question 10.
Define decomposition and describe the processes and products of decomposition.
Answer:
Decomposition is the process that involves the breakdown of complex organic matter or biomass from the body of dead plants and animals with the help of decomposers into inorganic raw materials such as carbon dioxide, water, and other nutrients.
The various processes involved in decomposition are as follows:
1. Fragmentation: It is the first step in the process of decomposition. It involves the breakdown of detritus into smaller pieces by the action of detritivores such as earthworms.
2. Leaching: It is a process where the water-soluble nutrients go down into the soil layers and get locked as unavailable salts.
3. Catabolism: It is a process in which bacteria and fungi degrade detritus through various enzymes into smaller pieces.
4. Humification: The next step is humification which leads to the formation of a dark coloured colloidal substance called humus, which acts as reservoir of nutrients for plants.
5. Mineralization: The humus is further degraded by the action of microbes, which finally leads to the release of inorganic nutrients into the soil. This process of releasing inorganic nutrients from the humus is known as mineralization. Decomposition produces a dark coloured, nutrient-rich substance called humus. Humus finally degrades and releases inorganic raw materials such as CO2, water, and other nutrient in the soil.
Question 11.
Given the account of Explain energy flow in ecosystem.
Answer:
Energy flow: In die ecosystem, energy is transferred in an orderly sequence. The flow of solar energy from producers to consumers and to decomposers subsequently in an ecosystem is known as energy flow. Energy flow is an ecosystem is always unidirectional. Sun is the sole source of solar energy in an ecosystem. Green plants utilize this energy in photosynthesis and convert it in the form of chemical energy and store it. Plants utilize the maximum part of this energy to do its biological functions. Some of it is converted into heat and released in the environment. The remaining part of the energy is stored in various components of the body.
When a consumer eats these producer plants, the energy is then transferred into its body. In any food-chain energy flows from primary producers to primary consumers, from primary consumers to secondary consumers and secondary consumers to tertiary consumers and so on. Because every organism of a trophic level continuously converts chemical energy into heat, there is always a loss of energy with each step in a food-chain. According to an estimate only 10% of the total energy obtained is transferred from one trophic level to another.
Question 12.
Write important features of a sedimentary cycle in an ecosystem.
Answer:
Sedimentary cycles have their reservoirs in the earth’s crust or rocks. Nutrient elements are found in the sediments of the earth. Elements such as sulphur, phosphorus, potassium, and calcium have sedimentary cycles.
Sedimentary cycles are very slow. They take a long time to complete their circulation and are considered as less perfect cycles. This is because during recycling, nutrient elements may get locked in the reservoir pool, thereby taking a very long time to come out and continue circulation. Thus, it usually goes out of circulation for a long time.
Question 13.
Outline salient features of carbon cycling in an ecosystem.
Answer:
Carbon constitutes 49 percent of the dry weight of organisms.
- 71 percent of the carbon is found dissolved in oceans which is responsible for its regulations in the atmosphere.
- The carbon cycle occurs through the atmosphere, oceans, and through the living and dead organisms.
- It is estimated that 4xl013 kg of Carbon is fixed in the biosphere through photosynthesis annually.
- Carbon is returned to the atmosphere as CO2 by animals and plants through respiration and the activities of decomposers.
- Some amount of fixed carbon is lost as sediments and removed from circulation.
- Burning of wood, forest fire, volcanic activity, and combustion of organic matter and fossil fuels are some essential sources for releasing CO2 into the atmosphere.
- Human activities like deforestation and vehicular burning of fossil fuels have caused an increase in the amount of CO2 in the atmosphere.
Ecosystem Other Important Questions and Answers
Ecosystem Objective Type Questions
Choose the Correct Answer
Question 1.
The position of man in the food chain of all ecosystem is as:
(a) Consumer
(b) Producer
(c) Producer and consumer
(d) Decomposer.
Answer:
(a) Consumer
Question 2.
The flow of energy in an ecosystem is:
(a) Unidirectional
(b) Bi-directional
(c) Three directional
(d) Quadri-directional.
Answer:
(a) Unidirectional
Question 3.
The word “ Ecosystem” was first used by :
(a) Tansley
(b) Odum
(c) Writer
(d) Mishra and Puri.
Answer:
(a) Tansley
Question 4.
The Source of energy in an ecosystem is:
(a) Solar energy
(b) Green plants
(c) Food substances
(d) All of the above.
Answer:
(a) Solar energy
Question 5.
Pyramid of number of trees in an ecosystem is always:
(a) Inverted
(b) Upward
(c) Both (a) and (b)
(d) None of these.
Answer:
(a) Inverted
Question 6.
Correct food chain is:
(a) Grass → Grasshopper → Frog Snake → Hawk
(b) Grass → Frog → Snake → Peacock
(c) Grass → Peacock → Grasshopper → Hawk
(d) Grass → Snake → Rabbit.
Answer:
(a) Grass → Grasshopper → Frog Snake → Hawk
Question 7.
Pyramid of biomass of an ecosystem of lake is:
(a) Upward
(b) Inverted
(c) Inverted and Upward both
(d) None of these.
Answer:
(b) Inverted
Question 8.
Man is:
(a) Producer
(b) Carnivore
(c) Herbivore
(d) Omnivorous.
Answer:
(d) Omnivorous.
Question 9.
Decomposer is:
(a) Rats
(b) Algae
(c) Bacteria and Fungi
(d) Goats.
Answer:
(c) Bacteria and Fungi
Question 10.
Man-made ecosystem is:
(a) Pond
(b) Aquarium
(c) Forest
(d) Lake.
Answer:
(b) Aquarium
Question 11.
Pyramid of energy is a forest ecosystem is:
(a) Always Inverted
(b) Always upward
(c) First upward than Inverted
(d) None of the above.
Answer:
(b) Always upward
Question 12.
Study of the ecosystem of species is called:
(a) Ecology
(b) Autecology
(c) Synecology
(d) None of these.
Answer:
(b) Autecology
Question 13.
Food chain starts from:
(a) Respiration
(b) Photosynthesis
(c) Decomposition
(d) Nitrogen fixation.
Answer:
(b) Photosynthesis
Question 14.
Flow of energy and food in a food web is:
(a) Unidirectional
(b) B i-directional
(c) Multidirectional
(d) None of these.
Answer:
(c) Multidirectional
Fill in the Blanks:
- The transitional zone between two adjacent communities is called ………………………
- The term ecosystem was proposed for the first time by ………………………..
- The brief source of energy in the ecosystem is …………………….
- Bacteria which fix the nitrogen is called ……………………
- All ecosystem are dependent on energy on …………………….
- Balance of ecosystem is called ………………………
- Pyramid of energy is always …………………………
- All the plant of a particular geographic area constitute ………………………. of the place.
Answer:
- Ecotone,
- Tansley,
- Sunlight,
- Rhizobium,
- Solar energy,
- Ecological balance,
- Upright,
- Flora.
3. Match the Following:
Answer:
- (b)
- (e)
- (d)
- (a)
- (c).
Answer:
- (b)
- (e)
- (d)
- (a)
- (c)
Question 4.
Answer in One Word/Sentence:
- Mention the two names of biotic components of the ecosystem.
- Who proposed the term ecosystem?
- Which ecosystem is more stable?
- Name the relatively loss stable ecosystem.
- Name the ecosystem showing maximum stratification.
- Give two examples of artificial ecosystems.
- Give the name of any two food chains.
- Write the name of the basic unit of ecology.
- Name the organisms found on the surface of water bodies.
- Name the transitional zone of two adjacent communities.
- Name the process of establishment of organisms in any new area.
- From where xerosere started?
- Who has proposed the term succession?
- Name the succession starting from the naked rock.
Answer:
- Biotic, Abiotic
- Tansley
- Ocean
- Desert
- Aquatic
- Aquarium, crop¬land
- Grazing, Detritus
- Producer
- Benthos
- Ecotone
- Succession
- Rocks
- Hult(1885)
- Lithosere.
Ecosystem Very Short Answer Type Questions
Question 1.
Name the process of soil formation.
Answer:
Pedogenesis.
Question 2.
What is the orientation of the pyramid of energy?
Answer:
Upright.
Question 3.
Which ecosystem is most established?
Answer:
Complex ecosystem.
Question 4.
When many food chains operates simultaneously and interlock such a pattern is formed.
Answer:
Food web.
Question 5.
Name the ecosystem which shows the most productivity.
Answer:
Tropical ecology.
Question 6.
What are fungi and bacteria called in an ecosystem?
Answer:
Micro consumer or Decomposer.
Question 7.
Which part of the energy is transferred from one trophic level to other in ecosystem?
Answer:
10 %.
Question 8.
Name the type of chemosynthetic bacteria.
Answer:
Autotrophic.
Question 9.
Name the word which is similar to ecosystem given by Pro. R. Mishra.
Answer:
Ecocosm.
Question 10.
Name the trophic level in which green plants are found.
Answer:
Primary trophic level.
Question 11.
Who gave the word transformer for producer?
Answer:
By E. J. kormondy.
Question 12.
Name any two sedimentary cycle.
Answer:
- Phosphorus cycle
- Sulpher cycle.
Question 13.
The energy pyramids are always.
Answer:
Upright.
Question 14.
Give examples of decomposers.
Answer:
Bacteria and Fungi.
Question 15.
Who gave 10% rule of energy?
Answer:
Lindeman.
Question 16.
Which form of nitrogen is absorbed by plants?
Answer:
In the form of nitrate ion (No3–).
Question 17.
Name two types of food chain.
Answer:
- Grazing food chain,
- Detritus food chain.
Ecosystem Short Answer Type Questions
Question 1.
Differentiate between food chain and food web.
Answer:
Question 2.
Write the names of important components of atmosphere.
Answer:
(A) Abiotic components:
- Energy: Light, temperature, energy of chemical substances.
- Materials: Water, soil, salts etc.
(B) Biotic components:
- Producers: e.g., green plants.
- Consumers: Primary, secondary and tertiary.
- Decomposers: Bacteria, fungi.
Question 3.
Write the name and ratio of different components of biosphere.
Answer:
Name and ratio of different components of biosphere is :
Some gases are also found in the biosphere e.g., Helium, Neon and Crypton are found in less quantity.
Question 4.
Differentiate between detritivore and decomposer.
Answer:
Detritivore is organisms which feed on detritus and break them into smaller particles, e.g., the earthworm. And decomposers are organisms which by secreting enzymes break down complex organic matter into organic substances e.g. some bacteria and fungi.
Question 5.
Name a dominant producer in a deep aquatic ecosystem. What other name could you give to a primary consumer, (AT 2007)
Answer:
Phytoplanktons or certain algae are the dominant producers in a deep aquatic ecosystem.
Primary consumers are known as herbivores.
Question 6.
Differentiate between biome and ecosystem.
Answer:
An ecosystem is the interaction of living and non-living things in an environment. A biome is a specific geographic area notable for the species living there.
Question 7.
Draw a pyramid of the energy of grassland in the ecosystem.
Answer:
Question 8.
Explain the nitrogen cycle in nature.
Answer:
Question 9.
Explain sulphur cycle by the diagram.
Answer:
Question 10.
Explain the effect of light on plants.
Answer:
Effect of light on plants: Light is the source of energy. It is essential for life. It is an important factor of an ecosystem. The existence of life on earth is because of light obtained from sun. Sunlight is essential for photosynthesis, help in the preparation of food for the whole living world. Light effects biological activities of plants by its intensity, period and duration. Plants are classified into the following two categories on the basis of the requirement of light intensity:
- Heliophytes: Plants, which can grow better in bright light are called heliophytes.
- Sciophytes: Plants, which require relatively less of light and they can grow better in shades are called sciophytes.
Question 11.
Explain the meaning of food web and draw its diagram.
Answer:
Food Web: In nature, food-chains are not isolated sequences, but are interrelated and interconnected with one another. When many food-chains operate simultaneously and interlock such pattern is termed as food web. Thus, the food web is a description of feeding connections between the organisms which make up a community. Energy passes through one trophic level to next via these food web links, e.g., a rat feeds on various kinds of grains, fruits, stems, roots, etc.
A rat in its turn is consumed by a snake which is eaten by a falcon. The snakes feed on both frogs and rats. Thus, a network of food-chains exists and this is called food web. The food web gets more complicated because of variability in taste and preference availability and compulsion and several other factors at each level. For example, tigers normally do not feed on fishes or crabs but in Sunderbans they are forced to eat them.
Question 12.
Explain Calcium cycle with well labelled diagram.
Answer:
Question 13.
Draw ecological pyramid of number of a tree ecosystem and grassland ecosystem.
Answer:
Question 14.
What do you mean by ecosystem? Describe the important components of a pond ecosystem.
Or
Write about role of decomposers in an ecosystem with example.
Answer:
Ecosystem: The system resulting from the interaction between organisms and their environment is called as ecosystem.
Components of a pond ecosystem:
A pond ecosystem should contain all components of ecosystems like:
(a) Producers: Organism, which can synthesize their own food are included under producers, e.g., Volvox, Pandorina, Oedogonium, Saggitaria, Utricularia, Azolla, Trapa, Lemna, Typha, Nymphaea etc. form the producer class of the pond ecosystem.
(b) Consumers:
- Primary consumer: Animals, which feed on producers are included into this category e.g., Daphnia, Cyclops, Paramoecium, Amoeba and small fishes.
- Secondary consumers: Primary consumers also serve as food for water sn’akdls, a few tortoise, few types of fish etc. hence, these are carnivores.
- Tertiary consumers : Secondary consumers also serve as food for aquatic birds like kingfisher, cranes, big fish and these together form a top class carnivorous group and called as tertiary consumers.
(c) Decomposers: All producers and consumers die and accumulate on the floor of the pond. Even the waste material and faeces of these animals get accumulated on the floor of the pond. Similarly, the floor of pond is also occupied by decomposers, which include bacteria and fungi. These decomposers decompose complex organic compounds of then- bodies into simpler forms which are finally mixed with soil of floor of ponds. These are again absorbed by the roots of producer plants and thus matter is recycled.
Question 15.
Explain pyramid of biomass of pond ecosystem.
Answer:
The biomass, i.e., the living weight of the organisms in the food-chain present at different trophic levels in an ecosystem forms the pyramid of biomass.
When biomass of consumers is greater than biomass of producer then pyramid is called as inverted pyramid of biomass. eg. pyramid of biomass of pond ecosysyem is always inverted.
Ecosystem: The system resulting from the interaction between organisms and the environment is called an ecosystem.
Ecosystem Long Answer Type Questions
Question 1.
What are ecological pyramids? Explain various types of ecological pyramids.
Answer:
Trophic level: In an ecosystem, the producer-consumer arrangement is a kind of structure known as trophic structure, and each food level in the food chain is called a trophic level or energy level. In other, words each level of food in the food chain is called its trophic level. The first trophic level (T,) in an ecosystem is occupied by producers. Herbivores (primary consumers) form the second trophic level (T2), secondary consumers form the third trophic level (T3), tertiary consumers form the fourth trophic level (T4) and decomposers form the fifth trophic level (T5) in an ecosystem.
Food or Ecological Pyramids: If we express the organisms of various trophic levels according to their number, biomass and ratio of energy stores within it, then we obtain ac6ne or pyramid-like structure which is known as food or ecological pyramid. Ecological pyramids represent the trophic structure and function of an ecosystem. In base and successive trophic levels the tiers which make up the apex. Ecological pyramids are of the following three types :
- Pyramid of Biomass
- Pyramid of number
- Pyramid of energy.
1. Pyramid of Biomass: Biomass is the dry weight of living organisms per unit of space. The ecological pyramid, which shows the quantitative relationship of the standing crop at each trophic level. The pyramid of biomass shows a gradual reduction in biomass at each trophic level from base to apex. The pyramid of biomass may be:
- Upright: e.g., all terrestrial ecosystems.
- Inverted: e.g., all aquatic ecosystems.
2. Pyramid of Number: The ecological pyramid shows the number of individual organisms at each trophic level. It represents the numerical relationship between the different trophic levels of a food chain. In this pyramid, more abundant species from the first trophic level and from the base of the pyramid and the less abundant species remain near the top. The pyramid of number may be:
- Upright: e.g. grassland, pond, forest ecosystem.
- Inverted: e.g. ecosystem of the tree.
3. Pyramid of Energy: It indicates the total amount of energy at each trophic level of the food chain. At each producer level, the total energy available is relatively more than at the higher trophic levels because of the loss of the energy at each trophic level. Thus, there is a gradual loss of energy at each trophic level. The pyramid of the energy of each type of ecosystem is always upright.
Question 2.
What is meant by terrestrial biomes? What are its types? Explain any one biomes in detail.
Answer:
Terrestrial Biome: Large areas occupying ecosystems in nature are called biomes. If biomes are on land then they are called Terrestrial biomes.
Terrestrial biomes may be:
(a) Forest Biomes: They may be as below;
- Topical rain forest
- Cold tropical forest
- Taiga forest.
(b) Grassland biomes: They may be as below:
- Tropical rain forest
- Cold tropical forest.
(c) Desert Biomes
(d) Tundra Biomes.
Grassland Biome or Ecosystem has long grasses, Its, land is fertile. It receives approximately 25 to 75 cm average rainfall. Its component is:
(a) Abiotic component: All organic, inorganic substances and climatic factors together form the abiotic component.
(b) Biotic component:
- Producers: Grasses, herb, shrubs.
- Primary consumers: Herbivore like a cow, buffalo, goats, sheep, deer, rabbit, rat insect.
- Secondary consumers: Carnivore animals which eat primary consumers-like snakes, birds, foxes, jackal, etc.
- Tertiary consumers: This organism eats secondary consumers because no other one eats them like Hawk, Peacock, etc.
- Decomposers: Micro-Fungus, Bacteria, actinomycetes are decomposers of grassland biomes and recycle the material back to the soil and used by producers.
Question 3.
What are Biogeochemical cycles? Write in short sulphur and calcium cycle.
Answer:
All living organisms get matter from the biosphere components i.e„ lithosphere, hydrosphere, and atmosphere. Essential elements or inorganic substances are provided by the earth and are required by organisms for their bodybuilding and metabolism, they are known as Biogeochemical or biogenetic nutrients.
Sulphur Cycle: Producers (green plants) need sulphur in the form of sulphates from soil or from water (aquatic plants). The animals get sulphur through food. Some animals get sulphur from water also. Sulphur is found in three amino acids hence, sulphur is a component of most proteins, some vitamins and enzymes. Plants pick up sulphur in the form of sulphates. They are converted to organic form mostly as components of some amino acids. It is found in nature as an element and also as sulphates in soil, water and rocks. After the death of plants and animals, they are decomposed by microbes like Aspergillus, Neurospora and Escherichia releasing hydrogen sulphide.
Calcium cycle: Calcium is slowly released from the rocks by water and wind action. These are either blown into the air or absorbed by plants through their roots. Animals obtain it directly as compounds and also from plants. Calcium is released from plant and animal bodies by decomposition after death. Mollusks and corals deposit a large quantity of calcium in their shells and skeletons making it unavailable for quick cycling.