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CBSE Questions for Class 12 Medical Biology Ecosystem Quiz 6 - MCQExams.com
CBSE
Class 12 Medical Biology
Ecosystem
Quiz 6
________ is required to maintain the balance in nature.
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Biotic factors
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Abiotic factors
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Biogeochemical cycle
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None of the above
Explanation
The path through which a nutrient travels as it moves from the air, water or soil into the bodies of living organisms and back to the air, water or soil is called a biogeochemical cycle. It is one of the requirements to maintain the balance in nature.
The energy pyramid is always _________-.
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Upright
0%
Inverse
0%
Horizontal
0%
Flat
Explanation
The flow of energy is always unidirectional. The energy passes from primary producers to primary consumers. From primary consumer the energy passed to secondary consumers and then to teritary consumers. Thus the energy pyramid is always upright.
Intermediate community between pioneer and climax communities is called as
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Seral community
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Biotic community
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Temporary community
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Ecosere
Explanation
A seral community (or sere) is an intermediate stage in ecological succession which proceeds towards the climax community. In many cases more than one seral stage evolves until climax conditions are attained. Thus, the correct answer is option A.
__________ is concerned with creating more value with less impact.
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Eco-efficiency
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Deforestation
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Bio-accumulation
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Global Warming
Explanation
$$\textbf {Correct Option (A):} $$
$$\textbf {Solution:} $$
$$\textbf {Option (A):} $$
$$\bullet$$ Eco-efficiency is the utilisation of resources very optimally to minimize waste and increase production with limited resources.
$$\textbf {Option (B):} $$
$$\bullet$$ Deforestation is basically cutting trees at a rate faster than they are grown and hence creating vacant land.
$$\textbf {Option (C):} $$
$$\bullet$$ Bio-accumulation is when organisms consume a lot of chemicals, inorganic substances and pesticides and cannot process them fast enough o eliminate that.
$$\textbf {Option (D):} $$
$$\bullet$$ Global warming is the phenomenon that means warming or heating of the earth's atmosphere.
Hence, the option(A) is the correct answer.
In biogeochemical cycle, the chemical cycle moves through
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Abiotic compartments
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Biotic compartments
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Both A and B
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None of the above
Explanation
A biogeochemical cycle is the cycle which involves the exchange minerals between biotic and abiotic materials. Biotic components include biosphere and abiotic components include lithosphere, atmosphere, and hydrosphere.
So, the correct answer is option C.
Pyramid of energy in ecosystems is
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Always upright
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Always inverted
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Mostly upright
0%
Mostly inverted
Explanation
Pyramid of energy is ecological pyramid that gives graphic representation of amount of energy trapped by different trophic levels per unit area. It is always upright because during transfer of energy from one trophic level to the next a lot of wastage occurs in metabolism at each trophic level and only 10% of energy is transferred to the next successive trophic level. Hence, the correct answer is option A.
In a terrestrial food chain which of the following organisms comprise the greatest mass of living substance (biomass)?
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Decomposers (e.g., bacteria)
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Producers (e.g., grasses)
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Primary consumers (e.g., mice)
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Secondary consumers (e.g., snakes)
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Tertiary consumers (e.g., hawks)
Explanation
Primary producers are organisms that fix atmospheric carbon into organic matter and thereby incorporate it into living biomass. Moving from primary producers to top consumers in a terrestrial food chain, a part of energy is lost in respiration. Therefore, primary producers comprise the greatest biomass in these food chains. Correct answer is B.
Which of the plain community have greatest biomass?
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Hawks
0%
Foxes
0%
Prairie dogs
0%
Grasses
0%
Beetles
______ is the final stage of succession, remaining relatively unchanged until destroyed by an event such as fire human interference.
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Final community
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Climax community
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Apex community
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Summit community
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Composite community
Explanation
A climax community is the final stage of succession, remaining relatively unchanged until destroyed by an event such as fire or human interference. It is an ecological community in which populations of plants or animals remain stable and exist in balance with each other and their environment.
Which ecosystem has the highest gross primary productivity?
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Desserts
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Coral reefs
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Mangroves
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Grasslands
Explanation
There are many ecosystems which have a very higher level of primary productivity. Coral reefs show the highest gross primary productivity in the aquatic ecosystem. There are the wide number of phytoplankton and aquatic phototrophs which contribute to the productivity of the ecosystem. Tropical rainforests have the highest primary productivity on the terrestrial ecosystem.
So, the correct answer is option B.
The amount of energy get reduce as it moves from producers to primary consumers because
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Saprophytic activity
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Biomass decreases
0%
Secondary consumers eat primary consumers
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Respiration and metabolic activity
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None of the above
In ecological succession,
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Pioneer species move into new communities first
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Climax communities have lower total biomass than preceding communities
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Species diversity is greatest in the early stages of succession
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Climax communities shift constantly
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All of the above
Explanation
Correct Option: A
Explanation:
Ecological succession is the process of gradual change in the species structure of an ecological community over time.
Pioneer species are the species that are first to colonize an area and begin a chain of ecological succession that ultimately leads to a more biodiverse steady-state ecosystem.
Plants that are first to invade the bare area are called pioneer species, e.g., lichens (succession on rocks).
Thus, the correct answer is the option 'Pioneer species move into new communities first'.
The vegetation of an area changes over time, resulting in a climax community is known as
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Succession
0%
Dispersion
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Fertilization
0%
Speciation
0%
Mutation
Explanation
The process of change in ecological community of an area over time which in turn results in formation of climax community is termed as succession. Option A is correct answer.
Option B is incorrect as dispersion refers to spread.
Option C is incorrect as fertilization is fusion of male and female gamete.
Option D is incorrect as splitting of existing species into daughter species or transformation of existing species into new one without formation of any lineage species is termed as speciation.
Option E is incorrect as sudden random changes in genome is mutation.
Therefore, the correct answer is option A.
A rocky community near a pond has no vegetation or animal life. After a period of approximately 50 years, the community boasts a wide variety of flora and fauna, including trees, animals and insects.
Mostly, lichens are the first organisms to colonize rocky areas. These are known as the
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Primary community
0%
Starter community
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Colony organisms
0%
Pioneer organisms
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Settler organisms
Explanation
Pioneer species are the first species which colonize an ecosystem which has already been disrupted.
Lichens in the given situation are called as pioneer species.
So, the correct answer is option D.
In an ecosystem undergoing succession, replacement of a plant community takes place due to
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Pollution
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Herbivory
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Parasitism
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Abiotic factors
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Intraspecific competition
Explanation
In an ecosystem undergoing succession, replacement of a plant community takes place due to abiotic factors.
Ecological succession is the observed as the process of gradual change in an ecological community over time.
Abiotic factors are the non-living things in an ecosystem like
water depth, pH, sunlight, turbidity (amount of water cloudiness), salinity (salt concentration), available nutrients (nitrogen, phosphorous, etc.), and dissolved oxygen (amount of oxygen dissolved in the water). Abiotic variables found in terrestrial ecosystems can include things like rain, wind, temperature, altitude, soil, pollution, nutrients, pH, types of soil, and sunlight.
So, the correct answer is option D.
The diagram above shows an ecological pyramid of net productivity that describes the multiplicative loss of energy in a food chain. Each trophic level in the food chain is represented by a bar in the pyramid, with primary producers forming the foundation of the pyramid. The size of each block represents the productivity at each trophic level per unit of time.
In the above example, approximately how much energy available in each trophic level is converted into new biomass in the
trophic level above it?
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$$1$$%
0%
$$5$$%
0%
$$10$$%
0%
$$50$$%
0%
$$100$$%
Explanation
The diagrams show ecological pyramid,
it is graphically represented to show the biomass or productivity of the biomass at each trophic level in an ecosystem.
According to ten percent
law
, during the transfer of energy from organic food from one trophic level to the next, only about ten
percent
of the energy is transferred from one trophic level to another. The remaining is lost during transfer, broken down in respiration, or lost to incomplete digestion by higher trophic levels. In the example given, as 10000J of energy is produced by producers, but only 1,000J is
transferred
to primary consumers and same way only 100J is
transferred
to secondary consumers. Hence, the correct answer is option C.
Select the correct statement about succession.
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All farm ponds will eventually fill in and dry up.
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Secondary succession involves the formation of dirt and soil.
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Climax communities are not subject to change.
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Random events play little, if any, part in succession.
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In temperate deciduous forests, oaks and hickories are replaced by pines and furs.
Explanation
All farm ponds will eventually fill in and dry up.
Ecological succession is the process of change in the species structure of an ecological community over time. The time scale can be decades (for example, after a wildfire), or even millions of years after a mass extinction.
Ecological succession, the process by which the structure of a biological community evolves over time. Two different types of succession—primary and secondary—have been distinguished. Primary succession occurs in essentially lifeless areas—regions in which the soil is incapable of sustaining life as a result of such factors as lava flows, newly formed sand dunes, or rocks left from a retreating glacier. Secondary succession occurs in areas where a community that previously existed has been removed; it is typified by smaller-scale disturbances that do not eliminate all life and nutrients from the environment.
The energy flow for the given energy pyramid can be best described by the statement
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Energy is passed up the pyramid with the least energy at the top.
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Energy is passed up the pyramid with the most energy at the top.
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Energy is passed down the pyramid with the most energy at the top.
0%
Energy is passed down the pyramid with the most energy at the bottom.
0%
Energy is constant in the pyramid.
Explanation
Energy is transferred up the pyramid because each organism is consumed by the one above it. The amount of energy available decreases at each trophic level because the transfers are not 100% efficient as only 10% energy is transferred from one trophic level to another. Some energy is used to run the life processes and some energy is converted into heat. Therefore least energy is available at the top. Hence, the correct answer is option A.
Which of the following differentiates gross primary production and net primary production?
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Respiration
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The difference in photosynthetic rates between morning and afternoon
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The amount of energy transferred between trophic levels
0%
Negligible in C$$_4$$ plants
0%
None of the above
Explanation
Gross primary production refers to the total organic matter produced by primary prodducers per unit area per unit time. Net primary prodction refers to net fixation of carbon by producers per unit area and is equals to the differnece between gross primary production and energy lost during respiration. Thus, the correct answer is option A.
Find the incorrect statement about the energy flow through an ecosystem?
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Energy is conserved and stays in an ecosystem, to be used by organisms repeatedly.
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Solar radiation is the original energy source for the vast majority of organisms on earth.
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Energy flow is one-way, from autotrophs to progressively higher trophic levels.
0%
Energy flow is inefficient; a lot is lost in each transfer from one organism to another.
0%
All solar radiation used in photosynthesis will eventually be lost as heat.
Explanation
Solar energy is the ultimate source of energy. The light energy is given by the sun is converted to chemical energy by plants. This energy is taken up by consumers further, in the form of food.
But during each trophic level, 90% of energy is lost as heat and only 10% is transferred to the next trophic level.
Thus, the statement in option A is incorrect.
Which of the following accounts for greatest mass in a pond community?
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Algae
0%
Insects
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Frogs
0%
Fish
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Fungi
The least amount of stored chemical energy is found in which of the following trophic level?
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Primary producers
0%
Decomposers
0%
Primary consumers
0%
Secondary consumers
0%
Tertiary consumers
Read the passage and answer the following question.
Vegetation follows established patterns of regrowth and change after disturbances by farming, timber harvesting, hurricanes, or fire. This process of patterned regrowth and change is called plant succession. The rate of succession and the species present at various stages depending on the type and degrees of disturbance, the environment of the particular sites, and the species available to occupy the site. In the Piedmont of North Carolina, land subjected to disturbances will grow back in a century or two to become mixed hardwood forest.
Based on this diagram, after 80 years, which will make up the majority of trees?
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Young pines
0%
Mature pines
0%
Oat trees
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Oat and hickory trees
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Pine, oak and hickory trees
Explanation
According to the given diagram, the 70th to 100th year will exhibit a transition from Pine to the hardwood community. The 80th year will have mix vegetation of Pine, Oak, and hickory forest and after 100 plus years, Pine will disappear leading to the formation of climax community i.e. Oak hickory forest. Thus, the correct answer is option D.
Due to the clearance of many forest areas in the Eastern United States, the cultivation got abondoned but eventually returned back to forests. Such a process of revival of an ecosystem is known as
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Primary succession
0%
Secondary succession
0%
Decomposition
0%
Interspecific competition
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Eutrophication
What change would take place in the given ecosystem with time?
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The herbivores will decline because there is not enough food to support them.
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The herbivores will increase and the secondary customers increase.
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The population of producers, herbivores and carnivores will remain the same.
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The secondary customers will decline and the producers will increase.
0%
The producers will increase to support the herbivores.
Explanation
In given ecological pyramid, the population of producers is less as compare to Herbivores. Once herbivores start consuming producers which includes plants, the population of producers will decrease and it will creates competition between herbivores which ultimately leads to decline in population of Herbivores as there is not enough food to support them. Hence, the correct answer is option A.
Which of the following processes is responsible for the existence of a stream free of pollutants within a few miles downstream of a point at which a small amount of sewage is dumped into it?
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Succession
0%
Biological magnification
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Evaporation
0%
Photosynthesis
0%
Decomposition
Explanation
The presence of decomposers (bacteria) in sewage leads to decomposition of complex organic compounds of sewage into simpler substances. These simpler substances are then consumed by the decomposers as a source of organic compounds. This led to the formation of pollution free stream out of a sewage dump. Thus, the correct answer is option E.
Choose the correct statement about ecological succession.
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It is a natural progression of plant types that cannot be reversed.
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It always occurs over a short period of time.
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The rate can be changed by factors such as fire, clear cutting, and lava flows.
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It only takes place on freshly cleared or new land such as islands.
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The rate is very slow and constant.
Explanation
Succession is a process of gradual changes that starts where no living organisms are there. The species that inhabit in a bare area are called as pioneer species. A pioneer community is a group of organisms, that starts the process of biological succession (the progression of an ecosystem over time). These organisms are typically plants,
animals
, and fungi.
However, the rate of ecological succession depends on various factors like natural disturbance (flood, forest fire and severe wind) and human based disturbance.
Read the passage and answer the following question.
A population study of plants was done in an abandoned field. Each year for $$3$$ years the vegetation was sampled. The chart indicates the results of the body.
Year
Number of Plants per Acre
Sandspur
Ragweed
Timothy Grass
Goldenrod
Wire Grass
$$1$$
$$3,800$$
$$4,900$$
$$600$$
$$0$$
$$412$$
$$2$$
$$1,500$$
$$2,209$$
$$1,185$$
$$75$$
$$796$$
$$3$$
$$752$$
$$180$$
$$2,234$$
$$790$$
$$1,643$$$
Given data describes that
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Fires cause the changes in the populations.
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Floods cause the changes in the populations.
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The plants in the population have similar life spans.
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Plant populations are replacing one another.
0%
The reproductive capacity of plants changes with time.
Explanation
The data of the population study shows Sandspur and Ragweed decreasing in their population while the Timothy Grass, Goldenrod and Wiregrass has increased. The data shows how plant populations are replacing one another slowly.
The main factor determining the distribution and abundance of eukaryotic extremophiles is
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Temperature
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Water availability
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Location
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Abundance of food
Explanation
Extremophiles are organisms living in habitat that have extreme environmental conditions, like trophical regions, the Arctic and the Aantarctica etc this is because these organisms are adapted to these extreme conditions and this is possible because probably the organism got adapted as the habitat had abundance of food and lesser competition.
So, the correct answer is 'Abundance of food'
All of the following statements are true of primary succession except
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primary succession occurs after a volcanic eruption.
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pioneer plants include lichens and mosses.
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primary succession occurs after a destructive forest fire.
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development of a community occurs in an area where no soil initially exists.
0%
primary succession occurs on coastal sand dunes.
Explanation
Primary succession occurs in an area which is barren or lifeless and not suitable for sustaining normal life forms as soil is absent and no humus while secondary succession is the series of community changes which takes place on a previously colonized, but disturbed or damaged habitat. Examples include areas which have been cleared of existing vegetation and destructive events such as fires. Therefore, destructive forest fire leads to secondary succession where there is still some organic matter to allow new plants to grow.
So, the correct answer is option C.
How does photosynthesis help to maintain the percentage of oxygen and carbon dioxide in the atmosphere?
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By giving off carbon dioxide and absorbing oxygen
0%
By giving off oxygen and absorbing carbon dioxide
0%
By releasing oxygen and carbon dioxide
0%
By absorbing oxygen and carbon dioxide.
Explanation
During photosynthesis, carbon dioxide is fixed to form carbohydrate by the dark reaction. The water molecules are broken down during the light reaction and release oxygen. Thus, the two process helps to maintain the balance of oxygen and carbon dioxide in the atmosphere.
So, the correct answer is option B.
In phosphorus, cycle phosphorus enters an ecosystem, during which of the following processes?
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Weathering
0%
Respiration
0%
Photosynthesis
0%
Nitrification
0%
Condensation
Explanation
A. Weathering is the breakdown of rocks into smaller particles by the action of various environmental factors like wind, water, sunlight etc.
B. Respiration is the process by which living organisms derive energy by the oxidation of various complex organic substances.
C. Photosynthesis is the process by which green plants capture solar energy and convert it into light energy.
D. Nitrification is the conversion of ammonia into nitrates and is performed in two steps, nitrite formation and nitrate formation.
E. Condensation is the process by which gas changes into liquid drops.
Since rocks are made up of phosphorus and contain phosphates, their weathering will cause dissolution of phosphates in the soil and thus, phosphorus enters the ecosystem.
So, the correct answer is 'Weathering'.
Which of the following gases is/are produced by decomposers during the decaying process?
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Only carbon dioxide gas
0%
Only carbon dioxide and nitrogen gases
0%
Only oxygen gas
0%
Only carbon dioxide and oxygen gases
Explanation
Decomposers feed on the dead or decaying organic matter(carbohydrate, proteins and lipids ) and produce nitrogen and carbon dioxide gases as an organic matter are mainly made up of carbon, oxygen, hydrogen and nitrogen. Thus, the correct answer is option B.
The amount of light energy converted to chemical energy by photosynthesis per unit time is called
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Trophic efficiency
0%
Biomass
0%
Secondary production
0%
Gross primary productivity
0%
Net primary productivity
Explanation
A. Trophic efficiency or ecological efficiency is the percentage of energy transferred from one trophic level to the next.
B. Biomass is the amount of living matter present in an ecosystem and is synthesised by the producers that convert light energy into chemical energy by the process of photosynthesis.
C. Secondary production or secondary productivity is the rate of energy storage at consumer's level i.e. herbivores, carnivores and decomposers.
D. Gross primary productivity is the total rate of photosynthesis including the organic matter used up in respiration during the measurement period.
E. Net primary productivity is the rate of storage of organic matter in plant tissues in excess of the respiratory utilisation by plants during the measurement period.
So, the correct answer is 'Biomass'.
The movement of energy and nutrients through living systems differs in what way?
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Energy recycles while nutrients flow in two directions.
0%
Nutrients recycle while energy flows in one direction.
0%
Nutrients are lost as heat while energy forms chemical compounds.
0%
Nutrients are constantly available while energy is limited.
0%
Nutrients are lost as heat while energy is limited.
Explanation
Energy is passed from one trophic level to the next trophic level. Hence, energy flows in one direction through successive trophic levels in a food chain.
Nutrients are produced from the matter. The matter may be organic or inorganic. The organic and inorganic matter is produced, exchanged, and moved within the ecosystem and this is called cycling. Hence, nutrients are recycled.
So, the correct answer is option B
.
The removal of 'Keystone' species will effect
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0%
The producers
0%
The consumers
0%
The ecosystem
0%
The decomposers
Explanation
Keystone species are relatively fewer species but exert a profound effect on structure and functioning of the ecosystem as they regulate the availability of food, water and other resources. Removal of these species makes the other species in the community more abundant, rarer or may even cause their extinction. The correct answer is option C.
In primary succession on rocks, the pioneer species are usually
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Algae
0%
Fungi
0%
Lichens
0%
Bryophytes
Explanation
Lichens are considered as pioneer species in primary succession on rocks because they can easily grow on rocks where other plants cannot grow. They produce oxalic acid which induced the weathering of rocks and thus soil is formed. When these lichens die they increase the soil fertility so other plants can grow and start the chain reaction.
Identify the incorrect statement from the following.
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Pyramid of energy is always upright.
0%
Pyramids of number and biomass is always upright.
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Pyramid of biomass in sea is generally inverted as the biomass of fish far exceeds that of phytoplanktons.
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Food chains are generally short with few trophic levels as only $$10$$% of the energy is transferred to each trophic level from the lower trophic level.
Explanation
The pyramid of numbers and biomass can either be upright or inverted. This depends on the type of food chain and the nature of the food chain. The pyramid of numbers in grassland is upright. The pyramid of numbers in a parasitic food chain is inverted. The pyramid of biomass in the grasslands and forests is upright. The pyramid of biomass in the pond ecosystem is inverted.
Thus, the correct answer is option B.
The rate of formation of new organic matter by deer in a forest ecosystem is called
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0%
Primary productivity
0%
Secondary productivity
0%
Standing crop
0%
Net primary productivity
Explanation
Primary productivity is the rate at which energy is converted by photosynthetic and chemosynthetic autotrophs to organic substances.
The rate at which the consumers convert the chemical energy of their food into their own biomass is called secondary productivity.
A standing crop is the total dried biomass of the living organisms present in a given environment.
Net primary production is the rate at which all the plants in an ecosystem produce net useful chemical energy.
Thus, the correct answer is option B.
African elephants push over or remove small acacia trees that sprout among the grasses in grasslands where they roam. The elephants' actions prevent the trees from getting too large and shading out the important grasses they consume Because the roots of the grasses run deep into the ground, they are able to continue to grow even when the shoots above the ground are eaten. This best describes the role of African elephants as
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0%
A keystone species
0%
A producer
0%
A decomposer
0%
A scavenger
0%
A secondary consumer
Explanation
A. A keystone species paly a crucial role in the functioning of an ecosystem and its absence can affect the functioning of an ecosystem drastically.
B. A producer is a green plant that captures the light energy and convert it into solar energy.
C. A decomposer is a saprophyte and reduces the organic matter.
D. A scavenger is an animal that feeds on the dead plant and animal material.
E. A secondary consumer or carnivore is an animal that feeds on the primary consumers (herbivores) and producers (plants).
Since African elephants are playing important role in maintaining the growth of grasses and acacia trees, they are keystone species of that ecosystem.
So, the correct answer is 'Keystone species'.
The pioneer species in Xerarch and Hydrarch succession are respectively
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Lichens and sedges
0%
Lichens and rooted hydrophytes
0%
Lichens and phytoplanktons
0%
Phytoplanktons and lichens
Explanation
$$\textbf{Correct option:}$$ $$\textbf{(C)}$$
$$\textbf{Solution:}$$
$$\bullet$$ Lichens and phytoplanktons, respectively, are the pioneer species in xerarch and hydrarch succession.
$$\bullet$$
A plant succession that begins on bare land or rock and ends in a mature climax forest is known as xerarch.
$$\bullet$$
The progressive deposit of soil is caused by pioneer species such as lichens and mosses.
$$\bullet$$
Hydrarch is a plant succession that begins in shallow water, such as ponds and lakes, and ends in a mature forest, such as phytoplankton, $$Hydrilla$$, and $$Vallisneria$$.
$$\textbf{Thus the Correct option is (C)}$$
Net primary productivity is equal to
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The amount of light energy converted to chemical energy by photosynthesis per unit time.
0%
The amount of energy used by primary producers for respiration.
0%
The amount of light energy converted to chemical energy by photosynthesis per unit time plus the amount of energy used by primary producers for respiration.
0%
The amount of energy used by primary producers for respiration minus the amount of light energy converted to chemical energy by the primary producers.
0%
The amount of light energy converted to chemical energy by photosynthesis per unit time minus the energy used by primary producers for respiration.
Explanation
NPP or net primary productivity is the rate of storage of organic matter in plant tissues in excess of respiratory utilization by plants during the measurement period. It is the weight of organic matter stored by producers in a unit area/volume per unit time. NPP is equal to the rate of organic matter created by photosynthesis minus the rate of respiration and other losses.
So, the correct answer is '
The amount of light energy converted to chemical energy by photosynthesis per unit time minus the energy used by primary producers for respiration'.
Which best describes the movement of energy and matter through living systems?
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Energy flows while matter is cycled.
0%
Matter flows in two directions while energy flows in one direction.
0%
Energy is cycled while some matter is lost as heat.
0%
Energy forms chemical compounds while matter flows.
0%
Matter is always available while energy is cycled.
Explanation
Energy is passed from one trophic level to the next trophic level. Hence energy flows through successive trophic levels in a food chain.
Matter may be organic or inorganic. The organic and inorganic matter is produced, exchanged and moved within the ecosystem and this is called cycling. Hence matter is cycled.
So, the correct answer is '
Energy flows while matter is cycled'.
Which of the following is expected to have the highest value $$\left(gm/{m}^{2}/yr\right)$$ in a grassland ecosystem?
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0%
Secondary Production (SP)
0%
Tertiary Production (TP)
0%
Gross Production (GP)
0%
Net Production (NP)
Explanation
Secondary production is the production of biomass of consumers such as herbivores and carnivores in an ecosystem. Tertiary production is the production of biomass of carnivores. Gross production is the total amount of biomass production in as ecosystem whereas net production is amount of energy or biomass left after respiration from the gross production (NP= GP - R). Thus, the correct answer is option C.
Oxygen forms about ............. of the air in the atmosphere.
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0%
20%
0%
30%
0%
40%
0%
45%
Living organisms require ............. to produce proteins and nucleic acids in their body.
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0%
Oxygen
0%
Nitrogen
0%
Carbon
0%
Water
In forest ecosystem, the pyramid of energy is
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0%
Always inverted
0%
Always upright
0%
first upright then inverted
0%
None of the above
Explanation
The pyramid of energy is upright for any ecosystem including the forests. The producers are at the first level and possess a high amount of energy.
As per the 10% law, there is a decrease in the amount of energy with the increase in the trophic level.
The primary consumer will have energy less than the producer and go on decreasing with the higher trophic levels.
There is a number of plants and trees as compared to carnivores.
Thus, the correct answer is option B.
Gross primary productivity is the rate of production of .......... during photosynthesis.
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0%
Organic matter
0%
Oxygen
0%
Carbon di-oxide
0%
Chlorophyll
Explanation
The rate of production of total organic matter during photosynthesis is called the gross primary productivity. It is also equal to the amount of carbon fixed during photosynthesis by all producers in that particular ecosystem. Thus the correct answer is option A.
Which of the following event does not lead into secondary succession?
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0%
All organisms that existed are lost
0%
Where no living organisms ever existed
0%
Abandoned crop field
0%
Land affected by flood
Explanation
The appearance of living organisms on disturbed or damaged habitat is referred to as secondary succession.
Primary succession occurs in a barren land where no life existed before.
So, flooded land abandoned croplands and the area where organisms existed before exhibit the secondary succession.
So, the correct answer is option B.
The simplest of all nutrient cycles operating in an ecosystem is .......... cycle.
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0%
Carbon
0%
Phosphorous
0%
Nitrogen
0%
Sulphur
Explanation
The simplest of all nutrient cycles is phosphorus cycle as it exists in only one form and that is phosphate. Phosphorus is present either as a part of an organism, dissolved in water or in the form of rock and never makes its way into the atmosphere. The rocks with phosphate on coming in contact with water containing little acid undergo weathering and thus phosphorus goes into solution. Plants take this phosphorus through their roots and utilize it in various ways.
Thus, the correct answer is option B.
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Practice Class 12 Medical Biology Quiz Questions and Answers
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