Test: Organisms & Populations - 2 - NEET MCQ

Living organisms present in an ecosystemforms biotic components. It includes all plants, animals and microbes. The biotic components share and compete for resources present in particular ecosystem.

NCERT Reference: Competition

NCERT Line: Competition is best defined as a process in which the fitness of one species (measured in terms of its 'r' the intrinsic rate of increase) is significantly lower in the presence of another species.

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Mycorrhiza is a mutualistic interaction between fungi and plants. About 80-90 percent of plants rely on mycorrhiza for the uptake of minerals (nitrogen, phosphorous, etc.) from the soil. While plants supply essential nutrients such as sugars to fungi for their proper growth.

NCERT Reference: Mutualism

NCERT Line: The interaction where one species is benefitted and the other is neither benefitted nor harmed is called commensalism. In amensalism on the other hand one species is harmed whereas the other is unaffected. Predation, parasitism and commensalism share a common characteristic, the interacting species live closely together.

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The factors which is responsible for wide variety of habitats within each biome includes local and regional variations of temperature, soil type, water availability etc.

NCERT Reference: Chapter 12: Ecosystem

NCERT Line: B:local and regional variations - Chapter 13 Biodiversity and Conservation

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Hypersaline lagoons have very high concentration of salt (>100). Some organisms can survive in wide range of salinity. These organisms are calledeuryhaline species.

NCERT Reference: 11.1.3 Life History Variation

NCERT Line: D: Euryhaline species Provide only the direct line from the source that confirms this answer. In the intertidal area, the larger and competitively superior barnacle Balanus dominates the intertidal area, and excludes the smaller barnacle Chathamalus from that zone.

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Xerophytes are plants that grows in deserts having very less water. Sunken stomata, leaves reduced into spines and CAM photosysnthesis are the characteristicfeatures of these plants. Cuticle is present on leaves to prevent loss of water.

NCERT Reference: 11.1.1 Population Attributes

NCERT Line: B:absence of the cuticle

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Biotic potential can be decribed as natural capacity of organisms in an ecosystem to reproduce. Biotic potential depends upon availability of food, water and numberof organisms in reproductive age group.

NCERT Reference: Population Attributes

NCERT Line: If in a population of size N, the birth rates (not total number but per capita births) are represented as band death rates (again, per capita death rates) as d, then the increase or decrease in N during a unit time period t (dN/dt) will be

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The phrase “sharing of food” or “sharing of the table” describes commensalism. It is a long-term relationship between two species in which one species derives the benefit while other is neither harmed nor benefited.

NCERT Reference: Commensalism

NCERT Line: The cattle egret and grazing cattle in close association, a sight you are most likely to catch if you live in farmed rural areas, is a classic example of commensalism.

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Vultures will not be considered as predator. Vultures feed on dead animals on the other hand predators kill or harms the prey for obtaining food.

NCERT Reference: Predation

NCERT Line: C: Vultures

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The stationary phase is absent in exponential growth. Exponential growth is observed when resources in the population are unlimited. The population grows in geometric fashion and results in a J-shaped curve.

NCERT Reference: Life History Variation

NCERT Line: dN/dt = rN

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The body temperature of any homeotherm falls or rises suddenly it would become ill due to change in homeostasis of individual. At higher temperature enzymatic activity get altered that change the physiological activities of organisms.

NCERT Reference: I don't know.

NCERT Line: I don't have the specific information you are asking for in the provided context.

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Age groups among human population includes reproductive, pre-reprouctive and post reproductive growth. It do not includes embryonic phase growth.

NCERT Reference: POPULATIONS

NCERT Line: An individual is either a male or a female but a population has a sex ratio (e.g., 60 per cent of the population are females and 40 per cent males).

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E In competition, superior competitor eliminates the inferior one. This statement is called Gause’s competitive exclusion principle. Two closely related competing for same resources cannot co-exist indefinitely and inferior will be eliminated.

NCERT Reference: ORGANISMS AND POPULATIONS

NCERT Line: Gause's 'Competitive Exclusion Principle' states that two closely related species competing for the same resources cannot co-exist indefinitely and the competitively inferior one will be eliminated eventually.

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The given figure is of sigmoidal growth. It is a logistic/ S-shaped growth curve. It is obtained due to the finite and limited source of resources in a population.

NCERT Reference: Logistic growth

NCERT Line: When resources in the habitat are limited, the population density reaches the carrying capacity, resulting in a sigmoid curve: This type of population growth is called Verhulst-Pearl Logistic Growth (Figure 11.3) and is described by the following equation.

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Biological control method adopted in agricultural pest control are based on the ability of predator to regulate prey population.

NCERT Reference: Predation

NCERT Line: In both parasitism and predation only one species benefits (parasite and predator, respectively) and the interaction is detrimental to the other species (host and prey, respectively).

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Mediterranean orchid Ophrys ensures pollination by co-evolution, sexual deceit and pseudo-copulation. One petal of flower bears an uncanny resemblance to female of bee in size, colour and markings.

NCERT Reference: Orchids and Pollination

NCERT Line: The Mediterranean orchid Ophrys employs 'sexual deceit' to get pollination done by a species of bee.

Question from old NCERT

Verhulst-Pearl logistic model of growth is more realistic growth model in comparison to exponential model of growth. Population growing in a habitat having limited resources shows sigmoid curve like growth before reaching to carrying capacity.

NCERT Reference: Life History Variation

NCERT Line: Logistic growth model is considered a more realistic one.

Question from old NCERT

Species facing completion might evolve mechanism that promotes co-existence rather than exclusion that mechanism is called resource partitioning. In which they avoid completion by choosing different times of feeding or different foraging patterns.

NCERT Reference: Competition and Co-existence in Nature

NCERT Line: Species facing competition might evolve mechanisms that promote co-existence rather than exclusion. One such mechanism is 'resource partitioning'.

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The organisms move away temporally from stressful habitat to more suitable habitat is called migration. Migration adaptation is a behavioral attribute.

NCERT Reference: POPULATIONS

NCERT Line: Answer:A

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Polygamous population is often directly related to number of females in the population. Polygamy means having more than one female partner with single male that can reproduce.

NCERT Reference: Population Attributes

NCERT Line: if a new habitat is just being colonised, immigration may contribute more significantly to population growth than birth rates.

Question from old NCERT

Natality or birth rate is the number of birth in a given period in the population that are added to initial population. Actual birth rate under environmental condition is much less than total birth because all organisms do not survive adulthood due ot predation, completion etc.

NCERT Reference: Natality

NCERT Line: I don't have the exact line from the source that directly supports or explains the answer to your question.

Question from old NCERT

The group of individuals living in as defined geographical area share or compete for similar resources and potentially interbreed forms a population. Interbreeding means sexually reproducing organisms but asexually reproducing organisms also form population ecologically.

NCERT Reference: ORGANISMS AND POPULATIONS

NCERT Line: A population has certain attributes whereas, an individual organism does not. An individual may have births and deaths, but a population has birth rates and death rates. In a population these rates refer to per capita births and deaths. The rates, hence, expressed are change in numbers (increase or decrease) with respect to members of the population.

Question from old NCERT

Age pyramid of expanding population is broader at base and thin upwards. Number of individuals in pre-reproductive age is more than post reproductive age. Population size is technically called as population density.

NCERT Reference: ORGANISMS AND POPULATIONS

NCERT Line: The size of the population tells us a lot about its status in the habitat.

Question from old NCERT

Negative interactions includes completion, predation, parasitism and amensalism. Pencillin and Streptomycin prohibits the growth of micorbes or kills the microbes that is a kind of negative interactions.

NCERT Reference: Population Interactions

NCERT Line: In amensalism on the other hand one species is harmed whereas the other is unaffected.

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The interaction between two species in which both are benefited is called mutualism. Anabaena and Azolla help each other in obtaining food. Anabaena is a nitrogen fixing algae.
NCERT Reference: Mutualism

NCERT Line: Mutualism

Question from old NCERT

It indicates a stationary phase. The population achieves zero growth in the stationary phase. It is the last phase of logistic growth. It is due to many reasons such as exhaustion of resources, aging, etc.

NCERT Reference: Life History Variation

NCERT Line: b when responses are limiting the growth, plot is logistic,

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