MP Board Class 12th Biology Solutions Chapter 14 Ecosystem

MP Board Class 12th Biology Solutions Chapter 14 Ecosystem

Ecosystem NCERT Text Book Questions and Answers

Question 1.
Fill in the Blanks:

1. Plants are called as …………….. because they fix carbon dioxide.
2. In an ecosystem dominated by trees, the pyramid (of numbers) is ………………… type.
3. In aquatic ecosystem, the limiting factor for the productivity is …………………….
4. Common detritivores in our ecosystem are ………………………..
5. The major reservoir of carbon on earth is ………………………
Answer:

1. Producer
2. Inverted
3. Light
4. Earthworm
5. 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) Herbivors
(b) Producers
(c) Carnivors
(d) None of the above.
Answer:
(a) Herbivors

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 ecocystem.
Answer:
Ecosystem: The system resulting from the interaction between organisms and their environment is called as ecosystem.

(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 8.
Define ecological pyramids and descirbe with examples, pyramids of number and biomass.
Answer:
Ecological Pyramid : The relation between producers and consumers in a ecosystem can be graphically represented in the form of a pyramid called 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 :

1. Pyramid of number
2. Pyramid of biomass
3. 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 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 as ecosystem.

Question 9.
What is primary productivity ? Give brief description of factors that affect primary productivity.
Answer:
The rate of biomass production is called productivity.
It is expressed in terms of g^-2yr^-1  or(Kcal-m^-2) yr^-1 to compare the productivity of ecosystems.
It can be divided into Gross Primary Productivity (GPP) and Net Primary Productivity (NFP).

Gross Primary Productivity of an ecosystem is the rate of production of organic matter during photosynthesis. A considerable amount of GPP is utilized by plants in respiration.

Gross primary productivity minus respiration losses (R), is the Net Primary Productivity (NPP). GPP – R=NPP.
Primary productivity depends on :

• The plant species inhabiting a particular area.
• The environmental factors.
• Availability of nutrients.
• Photosynthetic capacity of plants.

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 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 maximum part of this energy to do its biological functions. Some of it is converted into heat and released in the environment. 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 eosystem.
Answer:
Carbon constitutes 49 percent of dry weight Of an organisms.

• 71 percent of the carbon is found dissolved in oceans which is responsible for its regulations in atmosphere.
• The carbon cycle occurs through atmosphere, oceans and through living and dead organisms.
• It is estimated that 4xl013 kg of Carbon is fixed in the biosphere through photosynthesis annually.
• Carbon is returned to 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 organicjnatter and fossil fuels are some essential sources for releasing CO₂ in the atmosphere.
• Human activities like deforestation and vehicular burning or fossil fuels has caused in increase in the amount of CO₂ in atmosphere.

Ecosystem Other Important Questions and Answers

Ecosystem Objective Type Questions

Choose the Correct Answer

Question 1.
Position of man in food chain of all ecosystem is as :
(a) Consumer
(b) Producer
(c) Producer and consumer
(d) Decomposer.
Answer:
(a) Consumer

Question 2.
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)Writier
(d) Mishra and Puri.
Answer:
(a) Tansley

Question 4.
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) Omnivorus.
Answer:
(d) Omnivorus.

Question 9.
Decomposer are:
(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 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:

1. The transitional zone between two adjacent communities is called ………………………
2 The term ecosystem was proposed for the first time by ………………………..
3. The brief source of energy in ecosystem is …………………….
4. Bacteria which fix the nitrogen is called ……………………
5. All ecosystem are dependent of energy on …………………….
6. Balance of ecosystem is called ………………………
7. Pyramid of energy is always …………………………
8. All the plant of a particular geographic area constitute ………………………. of the place.
Answer:

1. Ecotone,
2. Tansley,
3. Sunlight,
4. Rhizobuim,
5. Solar energy,
6. Ecological balance,
7. Upright,
8. Flora.

3. Match the Following:


Answer:

1. (b)
2. (e)
3. (d)
4. (a)
5. (c).

Answer:

1. (b)
2. (e)
3. (d)
4. (a)
5. (c)

Question 4.
Answer in One Word/Sentence:

1. Mention the two name of biotic components of ecosystem.
2. Who proposed the term ecosystem?
3. Which ecosystem is more stable?
4. Name the relatively loss stable ecosystem.
5. Name the ecosystem showing maximum stratification.
6. Give two examples of artificial ecosystem.
7. Give the name of any two food chains.
8. Write the name of basic unit of ecology.
9. Name the organisms found on the surface of water bodies.
10. Name the transitional zone of two adjacent communities.
11. Name the process of establishment of organisms is any new area.
12. From where xerosere started?
13. Who has proposed the term succession?
14. Name the succession started from naked rock. ‘

Answer:

1. Biotic, Aboitic
2. Tansley
3. Ocean
4. Desert
5. Aquatic
6. Aquarium, crop¬land
7. Grazing, Detritus
8. Producer
9. Benthos
10. Ecotone
11. Succession
12. Rocks
13. Hult(1885)
14. Lithosere.

Ecosystem Very Short Answer Type Questions

Question 1.
Name the process of soil formation.
Answer:
Pedogenesis.

Question 2.
What is the orientation of pyramid of energy?
Answer:
Upright.

Question 3.
Which ecosystem is most established?
Answer:
Complex ecosystem.

Question 4.
When many food chain operate simultaneously and interlock such pattern is formed.
Answer:
Food web.

Question 5.
Name the ecosystem which shows 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:

1. Phosphorus cycle
2. 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:

1. Grazing food chain,
2. 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 biosphere e.g., Helium, Neyon and Crypton are found in less quantity.

Question 4.
Differentiate between detritivore and decomposer.
Answer:
Detritivore are organisms which feed on detritus and break them into smaller particles, e.g., earth worm. And decomposer are organisms which by secreting enzyme’s break down complex organic matter into in organic substance e.g. some bacteria and fungi.

Question 5.
Explain consumers of ecosystems.
Answer:

1. Producers: All the green plants.
2. Consumers: Depends on others for food.
   (i) Primary consumer: Depends on plants called herbivores.
   (ii) Secondary consumers: Depends on herbivores for food.
   (iii) Tertiary consumers: Depends on secondary consumers.
3. Decomposers: They decomposed dead organic matter.

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 energy of grass land in ecosystem.
Answer:

Question 8.
Explain nitrogen cycle in nature.
Answer:

Question 9.
Explain sulphur cycle by 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 preparation of food for the whole living world. Light effects biological activities of plants by its intensity, period and duration. Plants are classified into following two categories on the basis of 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 as 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 as trophic level or energy level. In other, words each level of food in food-chain is called its trophic level. The first trophic level (T,) in an ecosystem is occupied by producers. Herbivores (primary consumers) form second trophic level (T2), secondary consumers form third trophic level (T3), tertiary consumers form fourth trophic level (T4) and decomposers form 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 :

1. Pyramid of Biomass
2. Pyramid of number
3. 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 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 which shows the number of individual organisms at each trophic level. It represents numerical relationship between different trophic level of a food-chain. In this pyramid more abundant species from the first trophic level and from the base of 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 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 energy of each types 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 area occupying ecosystems in nature are called biomes. If biomes are on land than 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 are:

(a) Abiotic component: All organic, inorganic substances and climatic factors together form abiotic component.

(b) Biotic component :

• Producers: Grasses, herb, shrubs.
• Primary consumers: Herbivore like cow, buffalo, goats, sheep, deer, rabbit, rat insect.
• Secondary consumers: Carnivore animals which eat primary consumers-like snake, birds, foxes, jackal etc.
• Tertiary consumers: These organism which eat secondary consumers because no other one eats them like Hawk, Peacock, etc.
• Decomposers: Micro-Fungus, Bacteria, actinomycetes are decomposer of grassland biomes and recycle the material back to 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 earth and are required by organisms for their body building and metabolism, they are known as Biogeochemicals 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 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 component of some amino acids. It is found in nature as element and also as sulphates in soil, water and rocks. After the death of plants and animals, they are decomposed by microbes like Asperigillus, 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. Molluscs and corals deposit a large quantity of calcium in their shells and skeletons making it unavailable for quick cycling.

MP Board Class 12th Biology Solutions