Ecosystem MCQ Quiz in मल्याळम - Objective Question with Answer for Ecosystem - സൗജന്യ PDF ഡൗൺലോഡ് ചെയ്യുക

The correct answer is inorganic nutrients from humus

Explanation:

• Mineralisation is a process carried out by microorganisms, including bacteria and fungi, which break down organic matter in the soil and release inorganic nutrients.
• Humus is the decomposed organic matter in the soil, rich in nutrients and essential for soil fertility.
• During the mineralisation process, microorganisms decompose the complex organic compounds in humus into simpler inorganic forms, such as nitrates, phosphates, and other essential mineral nutrients.
• These inorganic nutrients are then available for uptake by plants, facilitating their growth and development.

The Correct answer is Ecosystem.

Key Points

• An ecosystem comprises all the living organisms, such as plants, animals, and microorganisms, in a given area, interacting with each other and their non-living environments (weather, earth, sun, soil, climate, atmosphere).
• The concept of an ecosystem was first introduced by Arthur Tansley in 1935.
• Ecosystems can be of various sizes, and they can be marine, aquatic, or terrestrial.
• Examples of ecosystems include a forest, a desert, a coral reef, a pond, or a grassland.
• Ecosystems function through the flow of energy and the cycling of nutrients, supporting the survival and growth of organisms.

 Additional Information

• Food Web
  • A food web is a complex network of interconnected food chains in an ecosystem.
  • It depicts how energy and nutrients flow through different organisms via predation, parasitism, and other ecological interactions.
  • Food webs illustrate the feeding relationships and the transfer of energy within an ecosystem.
• Life Circle
  • The term life circle is not scientifically recognized; it might be a misinterpretation of the term life cycle.
  • A life cycle refers to the series of stages an organism goes through from birth to reproduction and eventually to death.
  • Examples include the life cycle of a butterfly (egg, larva, pupa, adult) and the life cycle of a plant (seed, seedling, mature plant).
• Species
  • A species is a group of organisms that can interbreed and produce fertile offspring.
  • Species are the basic unit of classification in biological taxonomy.
  • Examples of species include Homo sapiens (humans), Panthera leo (lions), and Quercus robur (oak trees).

The correct answer is Ocean

Explanation:

• The Earth's carbon cycle involves the movement of carbon among the atmosphere, oceans, soil, and living organisms.
• Carbon reservoirs are places where carbon is stored. The largest reservoirs include the ocean, forests, soil, and the atmosphere.
• The ocean is the largest carbon reservoir, holding a significant portion of the Earth's carbon, primarily in the form of dissolved carbon dioxide, bicarbonate, and carbonate ions.
• The Ocean is the largest existing ecosystem on our planet. 
• It covers over 71% of the Earth's surface.
• It is a source of livelihood for over 3 billion people.
• The ocean also works as the primary “lung” of our planet, releasing more oxygen into the atmosphere, notably through marine plants, than all the forests in the world, and absorbing 30% of the carbon dioxide produced by humans.
• The ocean contains about 70% of the total global carbon.
• It plays a crucial role in the global carbon cycle by absorbing carbon dioxide from the atmosphere and storing it in various forms.
• The deep ocean acts as a long-term carbon sink, storing carbon for thousands of years.

Other Options:

• Forest: Forests are important carbon sinks as they absorb carbon dioxide through the process of photosynthesis and store it in biomass (trees and vegetation) and soil. 
• Grassland: Grasslands also store carbon in soil and vegetation, but their capacity to store carbon is significantly less compared to forests and oceans.
• Agricultural ecosystem: Agricultural ecosystems can store carbon in crops and soil, but their carbon storage capacity is limited due to continuous cultivation and harvesting practices.

Concept:

• The transfer of food energy from producers (plants) through a series of organisms that consume and are consumed is termed the food chain.
• A food chain shows the linear movement of energy through a system by indicating the path of food from a producer to a final consumer.
• Food chains may have 3 to 5 trophic links with 15 to 20 species.
• The length of a particular food chain reflects the physical characteristics of a particular ecosystem.
• Within any ecosystem, there are 2 major food chains, such as the Grazing food chain and the Detritus food chain.
• The difference between these two food chains is the source of energy for the primary consumers.
• The grazing food chain starts with photosynthetic plants, while the detritus food chain starts with dead organic matter.
• Most of the natural ecosystems possess both grazing and detritus food chains.
• In terrestrial and shallow-water ecosystems grazing food chains dominate because a major proportion of the annual energy flow passes through this chain.
• In tidal marshes, almost 90% of the primary production is routed through the detritus food chains.

Explanation:

• Detritus food chains begin with dead organic matter and go from non-living organic matter to detrivores and their predators.
• Dead leaves → Woodlouse → Blackbird represents the detritus food chain.
• A large amount of organic matter is generated by the death of plants and their parts, animals, and their excretory products in all ecosystems.
• In these food chains, the flow of energy is not unidirectional. 
• The waste materials and dead organic matter in each of the trophic levels are recycled and returned as input to the dead organic matter at the base of the detritus food chains.

Additional Information

• Oaktree → Insects → Warbler and Grass → Rat → Snake → Eagle food chain represents the grazing food chain.
• Phytoplanktons → Zooplanktons → Small fish → Large fish food chain represents the aquatic grazing food chain.

Hence, the correct option is (3) Dead leaves → Woodlouse → Blackbird.

The correct answer is 50%

Explanation:

• Photosynthetically Active Radiation (PAR) is the range of solar radiation wavelengths from 400 to 700 nm that photosynthetic organisms can use for photosynthesis.
• PAR comprises a portion of the total incident solar radiation that reaches Earth.
• 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 and this small amount of energy sustains the entire living world.

The correct answer is 10x(kcal m^-2)yr^-1

Explanation:

• In an ecosystem, Gross Primary Productivity (GPP) at the first trophic level is the total amount of energy produced through photosynthesis. Net Primary Productivity (NPP) is the energy that is left after subtracting the energy used by primary producers for respiration.
• Net Primary Productivity (NPP): Energy available after respiration by producers [ NPP = GPP - Respiration ]
• Gross Primary Productivity (GPP): Total energy produced.

NPP at first trophic level would be the GPP for second trophic level. NPP at second trophic level would be GPP for third trophic level.

First trophic level (producers): NPP = 100x

• NPP at first trophic level would be the GPP for second trophic level.

Second trophic level (primary consumers/herbivores): GPP is 100x for second trophic level. 

• Energy available = 100x

Third trophic level (secondary consumers/carnivores): They receive about 10% of the energy from the second trophic level’s available energy.

• Energy available = ( 100x X 10% = 10x )

Concept:

• An ecological pyramid is a pictorial representation of the relationship between different organisms in an ecosystem.
• It is of three types: Pyramid of the number, Pyramid of biomass, and Pyramid of energy.
• The base of each pyramid represents the producers or the first trophic level while the apex represents the tertiary or top-level consumer.

Explanation:

The Limitations of an ecological pyramid are:

• It does not take into account the same species belonging to two or more trophic levels.
• It assumes a simple food chain, something that almost never exists in nature; it does not accommodate a food web.
• The saprophytes are not given any place in ecological pyramids even though they play a vital role in the ecosystem.
• Thereby, the correct option is ''all of them''

Important Points

• The pyramid of biomass in the sea or pond is generally inverted because the biomass of fishes far exceeds that of phytoplankton.  

• The pyramid of energy is always upright, can never be inverted, because when energy flows from a particular trophic level to the next trophic level, some energy is always lost as heat at each step.

Concept:

• An ecosystem refers to a geographic area where all organisms including plants and animals as well as abiotic factors such as climate and landscape work together.
• Thus an ecosystem comprises both biotic and abiotic factors.
• Ecosystems can range from very small to large-sized ecosystems encompassing the entire earth.
• In an ecosystem, the different species occupying particular habitat changes over time. This change is referred to as ecological succession.
• ​Ecological succession thus can be defined as the occurrence of a definite sequence of communities over a period of time in the same area.
• Ecological succession ultimately gives rise to a climax community.

Important Points

• Assertion - TRUE
  • A climax community is the final stage of ecological succession.
  • It represents a stable community.
  • It can be defined as an ecological community comprising all organisms - both plants and animals - that remain stable and exist in balance with their environment.
  • A climax community will not change as long as the climate and physiography remain the same.
  • Thus it can be said that a climax community is more or less stable with the climate.
• ​Reason - TRUE
  • A climax community is the final stage of ecological succession.
  • A climax community is characterized by dominant species. These species cannot be replaced by any other and remain fairly stable in the community.
  • A community begins with an invasion of a pioneer species. 
  • A pioneer species is one that first colonizes an area after disturbance.
  • These pioneer species are succeeded by other advanced complex species ultimately giving rise to the stable climax community.
  • In a climax community, species diversity remains the same because the species have successfully reproduced and do not allow invading species to thrive.
  • Thus these are the dominant species that provide stability to the climax community.

​

• Thus, both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).

So the correct answer is option 1.

Concept:

• Growth models help us understand if the growth of any population over time follows a particular pattern or not.
• This also helps us to understand several other attributes of the population.
• Growth models explain 2 types of growth curves:
  • Exponential - This takes place when the resources are unlimited and the population keeps growing.
  • Logistic - This is a growth model that takes the limitations of resources into account.

Important PointsLogistic Growth - 

• Resources are not available to any species population in unlimited amount.
• Thus, the species compete for the available resources to survive.
• This competition restricts the exponential or unlimited growth of any population.
• Any given habitat can only provide resources to support a maximum possible number, beyond which it further growth of population is not possible.
• This is known as the carrying capacity (K) for a particular species in a habitat.
• Such growth pattern is also known as the Verhulst-Pearl Logistic Growth.

Explanation:

It can be denoted by the equation:

where, N = Population Density,

K = Carrying Capacity,

 = Rate of change of population density.

• Here, 'r' represents the intrinsic rate of natural increase, which is the difference between the per capita birth and death (b-d).
• The environmental resistance is represented in the equation as .
• When the population density (N) is plotted against time (t), it produces a S-shaped curve (sigmoid curve).
• Logistic growth shows 3 different phases:
  • Lag phase - This represents the initial lag time that a population shows before it starts growing.
  • Log phase - This is the phase of accelerated growth, which is itself an exponential growth.
  • Asymptote - This is the stationary phase where the population density reaches the carrying capacity.