Plus Two Botany Chapter Wise Questions and Answers Chapter 7 Ecosystem

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Kerala Plus Two Botany Chapter Wise Questions and Answers Chapter 7 Ecosystem

Plus Two Botany Ecosystem One Mark Questions and Answers

Question 1.
The 10% law is associated with an important function of an ecosystem is
(a) Productivity
(b) Nutrient cycling
(c) Decreases the calorific value in successive trophic levels
(d) Increases the calorific value in successive trophic levels.
Answer:
(c) Decreases the calorific value in successive trophic levels

Question 2.
In the second step of trophic level, the energy storage is primarily associated with
(a) gross primary productivity
(b) net primary productivity
(c) secondary productivity
(d) none of the above
Answer:
(c) secondary productivity

Question 3.
If the energy storage at second trophic level is 4000 KJ what is the energy level of primary and secondary carnivore?
Answer:
In primary carnivore level the energy storage is 400 KJ while in second carnivore level it is 40 KJ.

Question 4.
Give an example for gaseous and sedimentary cycle
Answer:

• Gaseous cycle -Nitrogen cycle
• Sedimentary cycle – Phosphorus cycle

Question 5.
Which is the community next to lichen that occur in xerarch succession.
Answer:
Moss stage

Question 6.
In food chain transfer of energy takes place from one tropic level to the next is
(a) 5%
(b) 10%
(c) 15%
(d) 20%
Answer:
(b) 10%

Question 7.
The second trophic level in a lake is………….
(a) Phytoplankton
(b) Zooplankton
(c) Benthos
(d) Fishes
Answer:
(b) Zooplankton

Question 8.
Food chain in which microorganisms breakdown the food formed by primary producers
(a) Parasitic food chain
(b) Detritus food chain
(c) Consumerfoodcahin
(d) Predator food cahin
Answer:
(b) Detritus food chain

Question 9.
What is true of ecosystem?
(a) Primary consumers are least dependent upon producers
(b) Primary consumers out number producers
(c) Producers are more than primary consumers
(d) Secondary consumers are the largest and most powerfull
Answer:
(c) Producers are more than primary consumers

Question 10.
Which of these statements is correct?
(a) The base of the energy pyramid contains the largest trophic level.
(b) About 10% of energy available in food is actually incorporated into any trophic level.
(c) Humans are at the top of energy pyramids.
(d) All of these
Answer:
(d) All of these

Question 11.
The energy pyramid is always upright because the energy content
(a) decreases in successive trophic levels
(b) increases in successive trophic levels
(c) increases from the base to the top
(d) decreases from primary consumer to secondary consumer only
Answer:
(a) decreases in successive trophic levels

Question 12.
Which one of the following is not coming under decomposition
(a) catabolism
(b) anabolism
(c) mineralization
(d) the surface area of detritus increases
Answer:
(b) anabolism

Question 13.
Most useful step of decomposition for plants is
(a) mineralization
(b) catabolism
(c) humification
(d) fragmentation of detritus
Answer:
(a) mineralization

Question 14.
Food chains are not always linear, it is branched in some steps. Name the network of food chains.
Answer:
The network of the food chain is called food web.

Question 15.
The biotic community along with physical environment forms an interacting system called………..
Answer:
Ecosystem

Question 16.
If the energy storage at second trophic level is 4000 KJ what is the energy level of primary and secondary carnivore?
Answer:
In primary carnivore level the energy storage is 400 KJ while in second carnivore level it is 40 KJ.

Question 17.
Cite an example of an inverted ecological pyramid.
Answer:
Pyramid of number in tree ecosystem & pyramid of biomass in sea ecosystem is inverted.

Question 18.
Which among the following equation is related with net primary productivity?
(a) GPP + R = NPP
(b) NPP + GPP = R
(c) GPP – R = NPP
(d) R + R = GPP
Answer:
(c) GPP-R = NPP

Question 19.
Find out the stage given below which is not included in hydrarch succession.
(a) Forest
(b) Phytoplanktons
(c) Lichens
(d) Marsh-Meadow
Answer:
(c) Lichens

Question 20.
Which among the following decomposers.
(a) Autotrophs
(b) Saprotrophs
(c) Heterotrophs
(d) Herbivores
Answer:
(b) Saprotrophs

Question 21.
Which one of the following is a primary consumer in an aquatic ecosystem.
(a) Phytoplanktons
(b) Aquatic birds
(c) Zooplanktons
(d) Large Fishes
Answer:
(d) Zooplanktons

Plus Two Botany Ecosystem Two Mark Questions and Answers

Question 1.
GPP-R= NPP is an equation indicating productivity. Illustrate the terms denoted in the equation.
Answer:
GPP is the gross primary productivity which is the rate of production of organic matter during photosynthesis. R- is the respiration loses which is the amount of GPP utilized by plants in respiration. NPP is the available biomass for the consumption to hetrotrophs. (Herbivores and Decomposers).

Question 2.
Decomposition is the breakdown of complex organic matter into inorganic substances like C0₂, Water, etc.

1. Identify the gas which is most essential for decomposition.
2. Find out any two conditions which inhibit decomposition.

Answer:

1. Oxygen
2. Low temperature Anaerobiosis

Question 3.
Vast area of vegetation is destroyed mostly by fires and it results in clearing of lush vegetation. How long it takes to re-form climax community. Name the process is related in the above case.
Answer:
Time taken is about 50-100 years in case of a grassland and about 100-200 years for a forest. Secondary succession.

Question 4.
Healthy ecosystems are the base for a wide range of goods and services. Find out any four ecosystem services provided by a healthy forest ecosystem.
Answer:

1. Purify air and water
2. Mitigate drought and floods
3. Cycling of nutrients
4. Generate fertile soils

Question 5.
Differentiate between Standing state and Standing Crop.
Answer:
1. Standing crop
The amount of living material present in each trophic level.

2. Standing state
The amount of nutrients like carbon, nitrogen, phosphorus, calcium, etc present in the soil at a given time.

Question 6.
Distinguish between Grazing food chain and Detritus food chain.
Answer:
1. Grazing food chain
It starts with producers. In aquatic ecosystem major fraction of energy flow take place through GFCthan DFC.

2. Detritus food chain
It starts with detritus. In terrestrial ecosystem major fraction of energy flow take place through DFC than GFC.

Question 7.
Xerarch succession is mainly occurs in desert conditions

1. Name the pioneefspecies on a bare rock.
2. How do pioneer species help in establishing the next type of vegetation.

Answer:

1. Lichens
2. They secrete carbonic acid and dissolve rocks. This process forms soil to help growth of mosses.

Question 8.
Energy flow is always unidirectional, never return back. Do you agree. Give the justification of your answer.
Answer:
Yes. The flow of energy is based on thermodynamic laws.lt starts from producers and flows through successive trophiclevels, The efficiency of energy transfer from one trophic level to the next is 10%.

Question 9.
A Volcano erupted in Hawaii, and lava covered land that had been framed for centuries. Eventually, new lichens, and then plants, grew on the lava.

1. Is this an example of primary or secondary successions?
2. Give the reason also.

Answer:

1. This is an example of primary succession
2. Because it begins from a state of little or no life.

Question 10.
Decomposition is the process in which complex dead matters are broken down into simpler inorganic substances,

1. Name the step of decomposition in which biological activity not found?
2. Chemical composition of detritus influence decomposition why?

Answer:

1. Humification
2. If the detritus rich in Lignin and c.hitinthe rate of decomposition is very slow but it is rich in nitrogenous compounds and Sugars the rate of decomposition is very high.

Question 11.
Decaying Biomass is formed through the process of decomposition, from which different types of mineral ions are released based on the mineralisers act on it.

1. Name the microorganisms that helps to release phosphate and nitrate into the soil
2. Give an example for nutrient cycling that helps in the photosynthesis of land plants.

Answer:

1. Phosphate solubilizing bacteria and nitrifying bacteria
2. Carbon cycle

Question 12.
In Barren lands succession continuous and forms climax vegetation after many years

1. Name the Pioneer community formed.
2. Which is the community comes next to Pioneer community?

Answer:

1. lichen
2. bryophytes

Question 13.
Productivity is one of the key function of an ecosystem, it varies in different ecosystems.

1. Distinguish between primary productivity and secondary productivity.
2. Some Terrestrial ecosystem shows abundant and least productivity. Name it.

Answer:

1. The primary productivity is associated with producers while secondary productivity is associated with consumers.
2. Abundant productivity is found in tropical rainforest Least productivity is found in desert.

Question 14.
How can you differentiate primary productivity from secondary productivity?
Answer:

1. Primary productivity-productivity at producer level
2. Secondary productivity – productivity at consumer level

Question 15.
Mention the functions of ecosystem.
Answer:

• Productivity
• Decomposition
• Energy flow
• Nutrient cycling

Question 16.
Connect the terms in the column A with suitable definition given below and fill up column B.

(a) Rate of biomass production.
(b) Rate of storage of organic matter by producers in excess of their metabolic consumption.
(c) Rate of production of organic matter by plants during photosynthesis.
(d) Rate of formation of new organic matter by consumers.
Answer:

1. b
2. c
3. a
4. d

Question 17.
Measurement of biomass in terms of dry weight is more accurate than fresh weight. Why?
Answer:
Fresh Weight contains weight of water present inside the cells as cell sap. Where as dry weight is the actual weight of the materials making up the body of the organism.

Question 18.
Leaching, detritus, catabolism, humification, fragmentation, mineralization, detritivores, humus. Given above are the terms involved in the process of decomposition. Arrange them in correct sequence.
Answer:
Detritus ? detritivore ? fragmentation ? leaching ? catabolism ? humification ? humus ? Mineralization.

Question 19.
The given table shows the dry weight of different trophic levels of forest ecosystem.

Trophic level	Dry wt. (Kgm-2)
PP	809 kgm-2
PC	37 kgm-2
SC	11 kgm-2
TC	1.5 kgm-2

1. From the given data construct a pyramid of biomas.

2. if you select Lake ecosystem to construct pyramid of biomas, it contain producers (Phytoplanktons), Herbivores (Short lived fishes) and Carnivores (Long lived fishes) with dry weight 2mgm-3, 7mgm-3 and 9mgm-3 respectively. From the data construct a pyramid of biomas.
Answer:
1.

2.

Question 20.
Energy is an important key functional component of ecosystem and pyramid of energy is always upright.

1. Do you agree with this statement.
2. Give reason.

Answer:

1. Yes
2. Energy transfer in a pyramid follows the ll nd law of thermodynamics . It also obeys the 10 % law (only 10 % of energy is transferred to each tropic level from the lower tropic level).

Question 21.
In nature there is no independent food chain.

1. Do you agree with the statement? Justify?
2. Decomposers have important role in nutrient cycling. Substantiate.

Answer:
1. Yes. The members of one food chain depends the members of other food chains and forms interconnections.

2. Detritus or dead remains are broken down by detritivores catabolism results in breaking down of complex molecules by decomposers. This results in the formation of mineral nutrients into the soil, thereby recycling of nutrients are achieved.

Question 22.
While visiting a forest, Ranjan’s grandfather told that long back it was a pond.

1. Name the phenomenon takes place here.
2. Write down the different stages of that process.

Answer:

1. Hydrach
2. Phytoplankton stage – Submerged plant-stage – Submerged free floaloting plant stage – Reed swamp stage – Marsh meadow stage — Scrub stage – Forest stage.

Question 23.
Human activities have a significant role in carbon cycle.

1. Do you agree with the statement?
2. Mention the environmental hazard caused by excess release of CO₂?

Answer:
1. Yes.

2. Deforestation activities and massive burning of fossil fuels increase the amount of CO₂ in the atmosphere that causes reradiation of reflected solar radiations. This leads to heating of the troposphere called green house effect.

Question 24.
Ecological succession and species evolution would have been a parallel process. Justify.
Answer:
As succession gives to the replacement of one community by another and establishment of dominant species it can be considering as parallel steps to evolution.

Question 25.
Sedimentary cycle that occure in lithosphere

1. Give an example for sedimentary cycle.
2. Give a flow chart representing the above cycle.

Answer:
1. Phosphorous cycle.

2. The cycle consists of following steps.

Question 26.
The atmosphere contains only about 1% of total global carbon. But carbon cycle is an gaseous cycle since the reservoir is atmospheric CO₂. Justify.
Answer:
71% of carbon is found dissolved in oceans which regulates the amount of CO₂ in the atmosphere. Fossil fuels also represents a reservoir of carbon. Carbon cycle is considered as gaseous cycle since the cycling occurs through atmosphere, ocean and through living and dead organisms.

The CO₂ is released to the atmosphere by burning of fuels, processing of waste materials in land and ocean and hence it act as a reservoir of CO₂ in an ecosystem.

Question 27.
Why is the length of a food chain in an ecosystem generally limited to 3-4 trophic levels?
Answer:
Energy requirement for maintenance of body rises successively with higher level. As 90% energy is lost when it moves from one trophic level to the next, the residual energy decreases drastically within 2-3 trophic levels, as a result an ecosystem can support only limited number of trophic levels.

Question 28.
Name the type of food chain responsible for the flow of larger fraction of energy in aquatic and a terrestrial ecosystem respectively. Mention one difference between two food chains.
Answer:
In an aquatic ecosystem GFC is the major conduits for energy flow where as in terrestrial ecosystem a much larger fraction of energy flow through the detritus food chain than through the GFC. Detritus food chain may be connected with the grazing food chain at some levels.

Difference between two food chains:
Detritus food chain always start with dead organic matter where as GFC starts with plants.

Question 29.
A volcano erupted in Hawaii, and lava covered land that had been framed for centuries. Eventually new lichens and then plants grew on the lava.

1. Is this an example of primary or secondary successions ?
2. Give the reason.

Answer:

1. Yes
2. This is an example of primary succession because this begins from a state of little or no life.

Question 30.
Distinguish between grazing and detritus food chain. Name the type of food chain helps in the flow of major fraction of energy through aquatic ecosystem.
Answer:

• The food chain start with producers are called grazing food chain.
• It start with dead organic matters is called detritus food chain.
• In an aquatic ecosystem, majorfraction of energy flow occurs through GFC.

Question 31.
In lake ecosystem .biomass of trophic levels are different

1. Do you agree the pyramid of biomass is inverted.
2. Give reason.

Answer:

1. Yes
2. In lake ecosystem producers are phyto-planktons. The short lived and long lived fishes are arranged above the lelvel of producers.Here biomass is increased from base to the top of pyramid.

Question 32.
How much PAR is used by producers for gross primary productivity?
Answer:
Of the incident solar radiation less than 50 percent of it is photosynthetically active radiation(PAR. Plants capture only 2-10 per cent of the PAR for gross primary productivity.

Question 33.
Differentiate between a detrivore and a decomposer giving an example of each.
Answer:
Detrivores are the primary consumers of a detritus food chain which feed upon the detritus and include protozoan, bacteria, and fungi, while decompers form the last trophic level of both detritus and grazing food chains and break down complex organic compounds of dead plants and animals and include bacteria and fungi.

Question 34.
Why is the length of a food chain in an ecosystem generally limited to 3-4 trophic levels?
Answer:
Energy requirement for maintenance of body rises successively with higher level. As 90% energy is lost when it moves from one trophic level to the next, the residual energy decreases drastically within 2 – 3 trophic levels. As a result an ecosystem can support only a limited number of trophic levels.

Question 35.
Due to uncontrolled excessive hunting the population of tigers in a forest becomes zero. What are the long term effects of this situation on the population of deer in that forest.
Answer:
The reduction in predator population may result in the increase of prey population (deer), since they are not preyed upon. Increase in the number of deer will lead to overgrazing, hence, shortage of herbs and eventually reduction in the number of deer.

Question 36.
A Volcano erupted in Hawaii, and lava covered land that had been framed for centuries. Eventually, new lichens, and then plants, grew on the lava. Is this an example of primary or secondary successions? Give the reason also.
Answer:
This is an example of primary succession Because this begins from a .state of little or no life.

Question 37.
How can you differentiate primary productivity from secondary productivity?
Answer:

1. Primary productivity-productivity at producer level
2. Secondary productivity – productivity at consumer level

Question 38.
Observe the flow chart on functional components of ecosystem given below.

1. Identify the components given as A and B
2. What is stratification?

Answer:
1. components given as A and B:
A = Energy flow
B = Nutrient cycling

OR

A = Nutrient cycling
B = energy flow

2. Vertical distribution of different species occupying different levels.

Question 39.
Observe the food chain given below. Grass? Goat? Man

1. Identify the type of food chain,
2. How does it differ from detritus food chain?

Answer:

1. Grazing Food Chain
2. Grazing food chain starts with producers while detritus food chain starts with dead organic matter.

Question 40.
Given below is the flow chart of ecological succession occur in water bodies.

1. Identify the stages A, B, C, D, E and F
2. What is this succession called?

Answer:
1. The stages A, B, C, D, E, and F:

• A = Submerged plant stage
• B = Submerged free floating plant stage
• C = Reed-swamp stage
• D = Marsh-meadow stage
• E = Scrub stage
• F = Forest stage

2. Hydrarch succession

Question 41.
Given below is a simplified model of a nutrient cycling in a terrestrial ecosystem.

1. Identify the cycle?
2. How does it differ from a gaseous cycle?

Answer:

1. Phosphorus cycle
2. This cycle starts from earth’s crust(lithosphere) but gaseous cycle exists in atmosphere.

Question 42.
Decomposition of detritus is a complex process. Decomposition has various steps. Identify the steps given below and fill the blanks.

Answer:

1. Fragmentation
2. Leaching
3. Catabolism
4. Humification

Question 43.
Decomposition is the breakdown of complex organic matter into inorganic substances like CO₂, Water, etc.

1. Identify the gas which is most essential for decomposition.
2. Find out any two conditions which inhibit decomposition.

Answer:

1. Oxygen
2. Low temperature, Anaerobiosis.

Question 44.
In most ecosystems, all the pyramids of number, biomass, and energy are upright. Suggest on occasion each where the pyramid of number and pyramid of biomass are inverted.
Answer:
When a big tree is considered as an ecosystem- pyramid of number is inverted. Pyramid of biomass in sea is also inverted.

Question 45.
Ecological pyramids express the food or energy relationship between organisms, Write any three limitations of ecological pyramids.
Answer:

1. In some cases same species may belong to two or more trophic levels
2. It does not represent food web
3. Saprophytes are not given any place

Question 46.
Analyze the table given below and fill in the blanks suitably.

Answer:

1. Standing crop
2. The amount of nutrients presents in the soil or eosystem at any given time

Question 47.
Match the items of column A with column B
VAnswer:
(a) – (v)
(b) – (iii)
(c) – (ii)
(d) – (i)

Question 48.
Human activities have significantly influenced the carbon cycle by increasing the amount of C02- production. Justify this statement with minimum two points.
Answer:

1. It lead to rapid deforestation.
2. Massive burning of fossil fuel for energy and transport.

Question 49.
Given below is simplified mode of a biogeochemical cycle.
Fill up the blanks a), b), c) and d)

Answer:

1. Rock minerals
2. Producers
3. Consumers
4. Detritus

Question 50.
Construct a pyramid of biomass using the data given below.
PC 37Kgm^-2 TC 1.5Kgm^-2
PP 809Kgm^-2 SC 11Kgm^-2
Answer:

Question 51.
Carbon cycle and phosphorus cycle are two common biogeochemical cycles. Write any three differences between these two cylces.
Answer:

Carbon cycle	Phosphorous cycle
1. Gaseous cycle 2. Respiratory release into atmosphere 3. Atmospheric input through rainfall very high	a)  Sedimentary cycle b)  No respiratory release c)  Atmospheric input through rainfall is very low

Plus Two Botany Ecosystem Three Mark Questions and Answers

Question 1.
Primary succession is a long term process, while secondary succession is a short term process.

1. Do you agree?
2. Give reasons.
3. Name the pioneer species in hydrarch succession

Answer:
1. Yes.

2. In primary succession development of forest climax on a barren land may take about 1,000 years but in secondary succession it takes 50 – 100 years in case of a grassland and about 100 – 200 years for a forest.

3. Phtoplanktons.

Question 2.
Succession on different habitat are different in nature

1. Name the pioneer species on a bare rock.
2. How do they help in establishing the next type of vegetation?
3. Mention the type of climax community that will ultimately get established.

Answer:

1. Lichens are the pioneer species:
2. They absorb water due to their spongy structure and secrete carbonic acid which loosens rock particles and help in weathering of rocks and soil formation; thus, they pave way to some small plants like bryophytes.
3. The climax community will be a forest.

Question 3.
Most of the existing communities are evolved through a series of intermediate stage.

1. Name three plant communites that appear during ecological succession.
2. Elucidate the dynamic changes that happens in a water body.

Answer:
1. three plant communites that appear during ecological succession:

• Pioneer community
• Serai community (transitional community)
• Climax community

2. Phytoplankton stage? Submerged plant stage? Submerged free floating plant stage? Reed swamp stage? Marsh meadow stage? Scrub stage? Forest stage.

Question 4.
If decomposition not occur in nature huge amount of detritus of plants and animals may fill our ecosystems, it is seriously harm to living organisms of our environment

1. Define decomposition
2. Give the steps
3. Decomposers are known as scavengers of earth”. Justify.

Answer:
1. Breaking down of complex organic matter into simple inorganic substance like C02, H20 and Nutrients is called decomposition.

2. Decomposition steps are

• Fragmentation – It is the breaking down of detritus into smaller particle by the detrivores like earthworm.
• Leaching – Precipitation of water soluble or inorganic nutrient into soil horizon.
• Catabolism – It is the degradation of detritus into simple inorganic substances by the action of micro organism.
• Humification – It is the accumulation of dark coloured amorphous substance called humus. Humus serve as the reservoir of nutrients.
• Mineralization – The degradation of humus & release of nutrients from it by microbes is called mineralization.

3. Decomposers split the complex detritus into simple inorganic compounds while doing so they also bring about nutrient cycling. The degradation of detritus into simple organic substances by micro organism involves catabolic process. Without micro organism the earth would have been filled with dead organisms.

Question 5.
In an ecosystem there is unidirectional flow of energy and cyclic flow of matter.

1. Do you agree with the statement.
2. Give reason?
3. Mention the significance of standing crop and standing state in this contest.

Answer:
1. Yes.

2. Energy in an ecosystem flows unidirectionally from producers to different consumers through different tropic level. The constant supply of matter (nutrients like C, N„, P, Ca, etc.) are never lost from the ecosystem. Their constant supply is maintained by nutrient cycling.

3. The mass of living material in a tropic level at a particular time is a standing crop. The amount of nutrients present in a soil at a given time is called standing state.

Question 6.
Robert Constanza and his colleagues put price tags on nature’s life-support services. Price tag of US $ 33 trillion a year

1. What is meant by, ecosystem services? Give example.
2. Which is the most price lagged ecosystem service in nature?

Answer:
1. The product ecosystem process

• Generate fertile soil
• Pollinate crops

2. Soil creation is the most prize tagged ecosystem service.

Question 7.
Decomposition is largely an oxygen requiring process. Rate of decomposition depend upon many factors.

1. What are the factors influence the rate of decomposition
2. Explain it.

Answer:
1. The factors influencing the rate of decomposition are:

• Chemical nature of detritus
• Climatic condition (temperature and soil moistures)

2. Detritus which is rich in N₂ and water soluble substances like sugar decompose quickly than detritus containing lignin and chitin.

Warm and moist environment favour decomposition whereas low temperature and anaerobic condition inhibit decomposition.

Question 8.
The number of individuals in grass land ecosystem is given below.
Grass – 5842,000
Grasshopper – 7,08,000
Frogs – 3,54,000
Snakes – 3

1. Draw a pyramid representing the relationship of the given organisms in terms of number.
2. Give justification for the shape of pyramid.

Answer:
1.

2. The pyramid is an upright one the largest number being producers (grasses) forms the base of the pyramid. The Herbivores or primary consumer at the next level (grass hopper) are second to producers in number.

The third layer is occupied by secondary consumers (Frogs) which are smaller in number compared to the primary consumer. The tertiary consumer (snakes) are the least in number and occupies the top most level. Thus an upright pyramid is obtained.

Question 9.
Food chain ensures unidirectional flow of energy from producerto different levels of consumers. Construct a food chain? Is the flow of energy obey the law of thermodynamics?
Answer:

Yes, the first law of thermodynamics states that energy can neither be created nor destroyed; it can be converted from one form to another. In an ecosystem the plants capture 2-10% of PAR (Photosynthetically active radiation) from the sun.

The solar energy captured by plants flows through different organisms of an ecosystem in the form of food energy. This unidirectional flow of solar energy in accordance with 10% law.

Question 10.
Most of the existing communities are evolved through a series of intermediate stage.

1. Substantiate the above statement with the process involved in the above phenomenon.
2. Elucidate the dynamic changes that happens in a water body.

Answer:
1. Plant succession:
The gradual & predictable change in species composition or communities of a given area is called ecological successions. It occurs due to the change of communities in response to environmental changes. Important features of ecological successions are

• Invasion of a bare area by pioneer community
• sequence of communities that successfully change or modify the particular area called seres
• change in the diversity of species and organism in the successive serai communities
• formation of climax community.

2. Phytoplankton stage → Submerged plant stage → Submerged free floating plant stage → Reed swamp stage → Marsh meadow stage → Scrub stage → Forest stage.

Question 11.
In an ecosystem flow of energy through successive trophic levels decreases, this is very common in aquatic and terrestrial habitat.

1. Write down the first and second thermodynamic laws supports energy flow
2. What do you meant by 10% law

Answer:
1. In first law of thermodynamics energy can be transferred from one state to other while in second law of thermodynamics energy losses in the form of heat.

Question 12.
The average price tag of US is 22 trillion US dollars a year.

1. What does this data indicate?
2. How is it related to GNP?'(Gross National Production)
3. Which is the most price lagged ecosystem service in nature?

Answer:
1. Ecosystem are the base of wide range of economic, environmental and aesthetic goods and services. The products of ecosystem process are named as ecosystem services.

These services are usually taken for granted because they are free. Researches have tried to put prize tags on nature’s life support services in order to understand the values of services provided by nature.

2. Gross national production is the value of human resources and services of a particular country. It is only half the value of ecosystem services.

3. Soil creation is the most prize tagged ecosystem service.

Question 13.
Primary productivity varies in different types of ecosystems.

1. What is meant by primary productivity.
2. Give reason with suitable examples.

Answer:
1. Primary productivity is the amount of biomass or organic matter produced during photosynthesis. The gross primary productivity is the rate of production of organic matter during photosynthesis.

A considerable amount of GPP is utilized by plant in respiration. The gross primary productivity – Respiration losses is the net primary productivity.

2. In some ecosystems producers number and nutrient content are not stable.

Question 14.
In most ecosystems, all the pyramids are upright. But there are exceptions to this generalisation.

1. Give any of the cases where pyramid of number and biomass becomes inverted.
2. What is detritus food chain?

Answer:
1. The pyramid of number in a tree ecosystem is inverted. The primary producer tree is a single unit. The consumers like insects, small birds & large birds are the primary consumers secondary consumers &territory consumers respectively.

Thus the no. of consumer in tree ecosystem is more than that of the producer. The pyramid of biomass in sea is inverted because the biomass of fishes (Consumers) exceeds that of phytoplankton (producer).

2. Food chain starts with detritus called as detritus food chain.

Plus Two Botany Ecosystem NCERT Questions and Answers

Question 1.

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 eco systems, the limiting factor for the productivity is_______
4. Common ditritivores in our eco system are______
5. The major reservoir of carbon on earth is______

Answer:

1. Producers
2. Upright
3. Availability of sunlight.
4. Earthworm
5. Ocean

Question 2.
Which one of the following has the largest population in a food chain______
(a) Producers
(b) Primary consumers
(c) Secondary consumers
(d) Decomposers
Answer:
The decomposers can have the maximum population but they are excluded from food chain, hence the correct answer is – (a) Producers

Question 3.
The second trophic level in a lake is______
(a) Phytoplankton
(b) Zooplankton
(c) Benthos
(d) Fishes
Answer:
(b) Zooplankton

Question 4.
What is the percentage of photosyntheticaliy active radiation (PAR) , if incident solar radiation is considered 100%?
(a) 100%
(b) 50%
(c) 1-5%
(d) 2-10%
Answer:
(b) 50%

Question 5.
Give an account for flow of energy in an ecosystem.
Answer:
1. Flow of energy in an ecosystem is unidirectional from producers to consumers.

2. The flow of energy obeys the laws of the thermodynamics 2-10% of radiant energy (50% of which reaches the earth) is photosyntheticaliy active radiation. It travels through different tropic levels from producers in the form of food energy.

The producers convert radiant energy into chemical energy which is stored as biomass. When energy flows from one tropic level to another only 10% of the total energy is transferred, as certain amount of energy is utilized by the organism belonging to a particulartropic level.

Plus Two Botany Ecosystem Multiple Choice Questions and Answers

Question 1.
Which one of the following is not used for construction of ecological pyramids?
(a) Dry weight
(b) Number of individuals
(c) Rate of energy flow
(d) Fresh weight
Answer:
(d) Fresh weight

Question 2.
Which of the following is expected to have the highest value (gm/m2/yr) in a Grassland ecosystem?
(a) Secondary production
(b) Tertiary production
(c) Gross production
(d) Net production
Answer:
(c) Gross production

Question 3.
Which of the following ecosystem types has the highest annual net primary Productivity?
(a) Tropical rain forest
(b) Tropical deciduous forest
(c) Temperate evergreen forest
(d) Temperate deciduous forest
Answer:
(a) Tropical rain forest

Question 4.
An ecosystem, which can be easily damaged but can recover after some time if damaging effect stops, will be having
(a) low stability and high resilience
(b) high stability and low resilience
(c) low stability and low resilience
(d) high stability and high resilience
Answer:
(a) low stability and high resilience

Question 5.
The minimum number of components required for an ecosystem to survive
(a) Producer and primary consumer
(b) Producer and decomposer
(c) primary Consumer and decomposer
(d) primary and secondary Consumer
Answer:
(b) Producer and decomposer

Question 6.
In plant succession, when climax is reached, the net productivity
(a) continues to increase
(b) becomes halved
(c) becomes stable
(d) becomes zero
Answer:
(c) becomes stable

Question 7.
Detrivores are
(a) detritus eating vertebrates
(b) detritus eating fungus
(c) detritus decomposing bacteria
(d) detritus eating invertebrates
Answer:
(d) detritus eating invertebrates

Question 8.
How fig tree is benefited to its pollinator wasp?
(a) Pollens are edible
(b) Wasp lays eggs in fig fruits
(c) Floral petal resembles female to pseudo coupulate
(d) All of these
Answer:
(b) Wasp lays eggs in fig fruits

Question 9.
Which of the following contribute to the carbon cycle?
(a) Photosynthesis
(b) Respiration
(c) Fossil fuel combustion
(d) All of these
Answer:
(d) All of these

Question 10.
Weathering of rocks makes phosphorous available to
(a) Decomposers
(b) Consumers
(c) Producers
(d) All of the above
Answer:
(c) Producers

Question 11.
The 10% law associated with an important function of an ecosystem is
(a) productivity
(b) nutrient cycling
(c) decreases the calorific value in successive trophic levels
(d) increases the calorific value in successive trophic levels.
Answer:
(c) decreases the calorific value in successive trophic levels

Question 12.
In the reductive process, the conversion of nitrogen into ammonia occurs by
(a) nitrosomonas
(b) rhizobium
(c) nitrococcus
(d) pseudomonas
Answer:
(b) rhizobium

Question 13.
The primary productivity is least in
(a) coral reef
(b) grassland
(c) coniferous forest
(d) desert
Answer:
(d) desert

Question 14.
Choose the correct arrangement of plant communities
(a) marsh meadow stage, free floating stage, scrub stage and forest stage
(b) free floating stage, marsh meadow stage, scrub stage and forest stage
(c) marsh meadow stage, free floating stage, scrub stage and forest stage
(d) marsh meadow stage, woodland stage, scrub stage and forest stage
Answer:
(b) free floating stage, marsh meadow stage, scrub stage and forest stage

Question 15.
In the second step of trophic level, the energy storage is primarily associated with
(a) gross primary productivity
(b) net primary productivity
(c) secondary productivity
(d) none of the above
Answer:
(c) secondary productivity

Question 16.
Detritus is the
(a) dead remains of plants only
(b) dead remains of plants and animals
(c) excretory products of animals
(d) both b and c
Answer:
(d) both b and c

Question 17.
The plants efficiency of N₂ absorption is promoted when the nitrogen source available in the form of
(a) NO^3-
(b) NO^2-
(c) NH⁴⁺
(d) none of the above
Answer:
(a) NO^3-

Question 18.
Which one of the following process is associated with oxidation
(a) ammonification
(b) nitrification
(c) denitrification
(d) none of the above
Answer:
(b) nitrification

Question 19.
PAR belongs to the wavelength of
(a) 300-400 A0
(b) 400-700A0
(c) 600-800A0
(d) 700-1000A0
Answer:
(b) 400-700A0