ORGANISMS AND POPULATION MCQs for NEET UG BIOLOGY — Medium

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You never see any cattle or goat browsing on Calotropis due to

View answer and explanation

Correct option: C

Formation of cardiac glycosides

Option C (Formation of cardiac glycosides) is correct because Calotropis produces cardiac glycosides, which are toxic and make the plant unpalatable to most herbivores.

Solution approach

Correct Answer + Core Reason: Formation of cardiac glycosides. These compounds are toxic to herbivores.

Step-by-Step Solution:

Step 1: Identify Calotropis' Defense Mechanism: Calotropis produces cardiac glycosides, which are toxic chemicals.

Step 2: Understand the Effect: These glycosides are harmful to herbivores, deterring them from feeding on the plant.

Step 3: Conclusion: Cattle and goats avoid Calotropis due to the formation of cardiac glycosides.

Why other options are wrong:
- Option A (Its appearance): While appearance can play a role, it's not the primary reason cattle and goats avoid Calotropis.
- Option B (Production of foul odour): While some plants use odor as a defense, cardiac glycosides are the main deterrent in Calotropis.
- Option D (Distastefulness of its leaves): The distastefulness is due to the presence of cardiac glycosides, making option C more specific and accurate.

Key Concepts:
- Plant Defense Mechanisms
- Cardiac Glycosides
- Herbivory

Memory Aids:
- Cardiac glycosides = Heart (think of their effect on the heart, making them toxic)

Quick Tips:
- Remember that chemical defenses are common in plants to deter herbivores.

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A species inhabiting different geographical area is known as

View answer and explanation

Correct option: A

Allopatric

Option A (Allopatric) is correct because allopatric speciation occurs when populations are geographically isolated, leading to the evolution of distinct species.

Solution approach

Correct Answer + Core Reason: Allopatric. Allopatric speciation involves geographic isolation.

Step-by-Step Solution:

Step 1: Define the terms.

Step 2: Allopatric speciation occurs when biological populations of the same species become isolated from each other to an extent that prevents or interferes with genetic interchange.

Step 3: Sympatric speciation occurs when new species evolve from a single ancestral species while inhabiting the same geographic region.

Step 4: Biospecies refers to a group of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups.

Step 5: Sibling species are species that are morphologically similar but reproductively isolated.

Step 6: Since the question specifies different geographical areas, allopatric is the correct answer.

Why other options are wrong:
- Option B: Sympatric speciation occurs in the same geographic area, not different ones.
- Option C: Biospecies is a general term for a species defined by reproductive compatibility, not geographic location.
- Option D: Sibling species are morphologically similar but not necessarily geographically separated.

Key Concepts:
- Allopatric Speciation
- Sympatric Speciation
- Speciation

Memory Aids:
- Allo = different, Patric = place (different place)

Quick Tips:
- Understand the different types of speciation.

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In aquatic environment the types of benthic animals are determined by

View answer and explanation

Correct option: B

Type of sediment characteristics

Option B (Type of sediment characteristics) is correct because the sediment type directly influences the availability of food and suitable habitats for benthic animals.

Solution approach

Correct Answer + Core Reason: Type of sediment characteristics. Sediment type determines the habitat and food availability for benthic animals.

Step-by-Step Solution:

Step 1: Define benthic animals.

Step 2: Benthic animals live on or in the bottom sediments of aquatic environments.

Step 3: Sediment characteristics, such as grain size, organic matter content, and chemical composition, influence the types of benthic animals that can survive.

Step 4: Different sediment types provide different habitats and food sources.

Why other options are wrong:
- Option A: While the type of water is important, sediment characteristics are more directly related to benthic animal distribution.
- Option C: Light availability primarily affects photosynthetic organisms, not benthic animals directly.
- Option D: Nutrient availability is important, but sediment characteristics determine how those nutrients are utilized by benthic organisms.

Key Concepts:
- Benthic zone
- Sediment characteristics
- Aquatic ecosystems
- Habitat selection

Memory Aids:
- Benthic = Bottom; Sediment = Substrate.

Quick Tips:
- Consider the direct relationship between sediment and the organisms living within it.

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In an area there are 200 Parthenium and is single banyan tree. Which of the conculsion (s) is/are correct?
I. Population density of banyan is low
II. Population cover area of banyan is high
III. In above cases the percentage of cover of biomass is more meaningful than population size

View answer and explanation

Correct option: D

All of these

Option D (All of these) is correct because all three conclusions are valid when comparing a large number of small plants to a single large tree.

Solution approach

Correct Answer + Core Reason: All of these. All three conclusions are valid when comparing a large number of small plants to a single large tree.

Step-by-Step Solution:

Step 1: Analyze each conclusion:
- I. Population density of banyan is low: Correct, as there is only one banyan tree.
- II. Population cover area of banyan is high: Correct, as a single banyan tree can cover a large area.
- III. In above cases the percentage of cover of biomass is more meaningful than population size: Correct, as the banyan tree's large size makes population size less informative.

Step 2: Determine the correct option: All three conclusions are valid.

Step 3: Final Answer: All of these

Why other options are wrong:
- Option A: Conclusions II and III are also correct.
- Option B: Conclusion III is also correct.
- Option C: Conclusion I is also correct.

Key Concepts:
- Population density
- Biomass
- Population ecology

Memory Aids:
- Population density: Number of individuals per unit area.
- Biomass: Total mass of organisms in a given area or volume.

Quick Tips:
- Consider both the number of individuals and their size when assessing population characteristics.

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Find out the correct ones
I. Mammals of colder climate generally have shorter ears and limbs to minimize heat loss
II. All organisms have behavioural adaptations that allow them to respond quickly to a stressful situation
III. Some organisms possess behavioural adaptations which allow them migrating temporarily to a less stressful situation
IV. Invertebrates and fishes live at great depths in the ocean have biochemical adaptation to cope with high pressure

View answer and explanation

Correct option: C

I, III and IV

Option C (I, III and IV) is correct because these statements accurately describe adaptations to environmental conditions.

Solution approach

Correct Answer + Core Reason: I, III and IV. These statements correctly describe adaptations to different environmental conditions.

Step-by-Step Solution:

Step 1: Evaluate Statement I: Mammals in colder climates have shorter appendages to minimize heat loss (Allen's Rule). This is correct.

Step 2: Evaluate Statement II: Not all organisms have behavioral adaptations to respond quickly to stressful situations. Some may rely on physiological or morphological adaptations. This is incorrect.

Step 3: Evaluate Statement III: Some organisms migrate to less stressful environments. This is a valid behavioral adaptation. This is correct.

Step 4: Evaluate Statement IV: Invertebrates and fishes at great depths have biochemical adaptations to cope with high pressure. This is correct.

Step 5: Conclusion: Statements I, III, and IV are correct.

Why other options are wrong:
- Option A (I and II): Statement II is incorrect.
- Option B (II and III): Statement II is incorrect.
- Option D (I, II and IV): Statement II is incorrect.

Key Concepts:
- Allen's Rule
- Behavioral Adaptations
- Biochemical Adaptations
- Environmental Stress

Memory Aids:
- Remember Allen's rule for statement I.

Quick Tips:
- Carefully evaluate each statement for accuracy.

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Sea plants are an example of

View answer and explanation

Correct option: C

hydrophyte

Option C (hydrophyte) is correct because hydrophytes are plants adapted to aquatic environments, like sea plants.

Solution approach

Correct Answer + Core Reason: Sea plants are hydrophytes.

Step-by-Step Solution:

Step 1: Define Xerophyte: Xerophytes are plants adapted to arid or dry environments.

Step 2: Define Mesophyte: Mesophytes are plants adapted to moderately moist environments.

Step 3: Define Hydrophyte: Hydrophytes are plants adapted to aquatic environments.

Step 4: Define Submerged plant: Submerged plant is a type of hydrophyte, but hydrophyte is the broader category.

Step 5: Relate sea plants to the definitions: Sea plants live in aquatic environments, so they are hydrophytes.

Why other options are wrong:
- Option A: Xerophytes are adapted to dry environments, not aquatic ones.
- Option B: Mesophytes are adapted to moderately moist environments, not aquatic ones.
- Option D: While sea plants are submerged, \"hydrophyte\" is the more general and accurate term.

Key Concepts:
- Xerophyte
- Mesophyte
- Hydrophyte
- Plant adaptations

Memory Aids:
- Hydro = water

Quick Tips:
- Consider the environment when classifying plants.

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Schimper’s second low related to

View answer and explanation

Correct option: A

Local distribution of plants

Option A (Local distribution of plants) is correct because Schimper's second law relates to the local distribution of plants based on environmental factors.

Solution approach

Correct Answer + Core Reason: Local distribution of plants. Schimper's second law focuses on local plant distribution.

Step-by-Step Solution:

Step 1: Understand Schimper's Laws: Schimper's laws relate to plant geography and distribution.

Step 2: Identify the Second Law: Schimper's second law specifically addresses the local distribution of plants, influenced by factors like competition, microclimate, and soil conditions.

Step 3: Conclusion: Schimper's second law is related to the local distribution of plants.

Why other options are wrong:
- Option B (Geographical distribution of plants): While Schimper's work broadly covers plant geography, his second law is more specific to local distribution.
- Option C (Geographical distribution of animals): Schimper's work primarily focused on plants, not animals.
- Option D (Geographical distribution of animals and plants): Schimper's work primarily focused on plants, not animals, and his second law is specifically about local distribution.

Key Concepts:
- Schimper's Laws
- Plant Geography
- Local Distribution

Memory Aids:
- Think of "local" as a specific area for Schimper's second law.

Quick Tips:
- Remember Schimper's laws deal with plant distribution, and the second law is about local factors.

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If 4 individuals in a laboratory population of 40 fruitflies died during a specified time interval (i.e., a week), the death rate in the population during that period is:

View answer and explanation

Correct option: B

0.1

Option B (0.1) is correct because the death rate is calculated by dividing the number of deaths by the total population.

Solution approach

Correct Answer + Core Reason: 0.1. The death rate is calculated by dividing the number of deaths by the total population.

Step-by-Step Solution:

Step 1: Identify the given information: Number of deaths = 4, Total population = 40.

Step 2: Calculate the death rate: Death rate = (Number of deaths) / (Total population).

Step 3: Substitute the values: Death rate = 4 / 40.

Step 4: Simplify: Death rate = 0.1.

Step 5: Final Answer: 0.1

Why other options are wrong:
- Option A (1): This is incorrect because it's calculated by dividing the total population by the number of deaths, which is the inverse of the death rate.
- Option C (0.01): This is incorrect because it's likely a miscalculation or confusion with percentage.
- Option D (0.4): This is incorrect because it's likely a miscalculation or confusion with percentage.

Key Concepts:
- Population dynamics
- Death rate calculation

Memory Aids:
- Death rate = (Number of deaths) / (Total population)

Quick Tips:
- Always ensure you are dividing the number of deaths by the total population to get the death rate.

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Life on earth originated in

View answer and explanation

Correct option: B

Water

Option B (Water) is correct because scientific evidence suggests that life originated in aquatic environments due to the presence of necessary elements and conditions.

Solution approach

Correct Answer + Core Reason: Water. Life is believed to have originated in water.

Step-by-Step Solution:

Step 1: Consider the conditions for early life: Early Earth's atmosphere was different, and water provided a stable environment for the formation of complex molecules.

Step 2: Evaluate the options: Water is the most likely environment for the origin of life.

Step 3: Conclusion: Life on Earth originated in water.

Why other options are wrong:
- Option A: Air lacks the necessary stable environment and dissolved nutrients for the origin of life.
- Option C: Soil, while important for terrestrial life, is not considered the primary origin point of life.
- Option D: While all are important, water is considered the place where life originated.

Key Concepts:
- Origin of Life
- Abiogenesis
- Early Earth Conditions

Memory Aids:
- Remember the primordial soup theory, which suggests life began in a nutrient-rich aquatic environment.

Quick Tips:
- Consider the conditions necessary for the formation of complex organic molecules when answering questions about the origin of life.

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The soil with poorest water holding capacity is

View answer and explanation

Correct option: C

Sandy

Option C (Sandy) is correct because sandy soil has the largest particles and therefore the poorest water holding capacity.

Solution approach

Correct Answer + Core Reason: Sandy. The soil with poorest water holding capacity is Sandy.

Step-by-Step Solution:

Step 1: Describe soil types.\nDifferent soil types have different particle sizes and structures, which affect their water-holding capacity.

Step 2: Explain water-holding capacity.\nWater-holding capacity refers to the ability of a soil to retain water.

Step 3: Compare soil types.\nSandy soil has large particles and large pore spaces, leading to poor water retention. Clay soil has small particles and small pore spaces, leading to high water retention. Loam is a mixture of sand, silt, and clay, providing moderate water retention.

Why other options are wrong:
- Option A: Clay has the highest water-holding capacity due to its small particle size and small pore spaces.
- Option B: Loam has moderate water-holding capacity, better than sandy soil but less than clay soil.
- Option D: None of these is incorrect because sandy soil has the poorest water-holding capacity.

Key Concepts:
- Soil types
- Water-holding capacity
- Sandy soil
- Clay soil
- Loam

Memory Aids:
- Think of sand as having large gaps between particles, allowing water to drain quickly.

Quick Tips:
- Remember the relationship between particle size and water-holding capacity: smaller particles = higher water-holding capacity.

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Pedology refers to study of

View answer and explanation

Correct option: A

Soil

Option A (Soil) is correct because pedology is the scientific study of soil, including its formation, classification, and mapping.

Solution approach

Correct Answer + Core Reason: Soil. Pedology is the study of soil.

Step-by-Step Solution:

Step 1: Define Pedology: Pedology is a branch of soil science that focuses on the formation, morphology, classification, and mapping of soils.

Step 2: Relate to the options: The question asks what pedology refers to. The correct answer is soil.

Step 3: Conclusion: Therefore, pedology is the study of soil.

Why other options are wrong:
- Option B: Water is studied in hydrology or oceanography, not pedology.
- Option C: Population is studied in demography or population biology, not pedology.
- Option D: Fossils are studied in paleontology, not pedology.

Key Concepts:
- Pedology
- Soil Science

Memory Aids:
- Think of \"ped\" as in \"pedestal,\" which supports the soil.

Quick Tips:
- Remember that \"ology\" usually refers to the study of something.

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Among four basic processes, which contribute more significantly to population growth if a habitat is colonised newly?

View answer and explanation

Correct option: D

Immigration

Option D (Immigration) is correct because immigration, the influx of new individuals, directly adds to the population size in a newly colonized habitat.

Solution approach

Correct Answer + Core Reason: Immigration. Immigration adds individuals to a population, directly increasing its size.

Step-by-Step Solution:
Step 1: Define the terms: Natality (births), Mortality (deaths), Emigration (individuals leaving), Immigration (individuals entering).
Step 2: Consider a newly colonized habitat. The initial population is likely small.
Step 3: To grow the population, new individuals must arrive (immigration) or be born (natality).
Step 4: In a new habitat, immigration is often the more significant initial contributor to population growth because natality depends on the existing population size.

Why other options are wrong:
- Option A: Natality contributes to population growth, but it's limited by the initial population size in a newly colonized habitat.
- Option B: Mortality decreases population size, so it doesn't contribute to growth.
- Option C: Emigration decreases population size, so it doesn't contribute to growth.

Key Concepts:
- Population dynamics
- Immigration, emigration, natality, mortality

Memory Aids:
- I (Immigration) = In, E (Emigration) = Exit

Quick Tips:
- Focus on the initial conditions of a newly colonized habitat when considering population growth.

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Statement I: The number of fish caught per trap is good enough measure of its population density in the lake.
Statement II: For certain ecological investigations, there is no need to know the absolute population densities: relative densities serve the purpose equally well.

View answer and explanation

Correct option: C

Both statements I and II are correct

Option C (Both statements I and II are correct) is correct because both relative and absolute densities can be useful in ecological studies.

Solution approach

Correct Answer + Core Reason: Both statements I and II are correct. Both relative and absolute densities can be useful in ecological studies.

Step-by-Step Solution:

Step 1: Analyze Statement I: The number of fish caught per trap is a good measure of its population density in the lake. This is a measure of relative density, which can be useful.

Step 2: Analyze Statement II: For certain ecological investigations, there is no need to know the absolute population densities; relative densities serve the purpose equally well. This is also correct, as relative densities can be sufficient for some studies.

Step 3: Determine the correct option: Both statements are correct.

Step 4: Final Answer: Both statements I and II are correct

Why other options are wrong:
- Option A: Statement II is also correct.
- Option B: Statement I is also correct.
- Option D: Both statements are correct.

Key Concepts:
- Population density
- Relative density
- Absolute density
- Ecological investigations

Memory Aids:
- Relative density: A measure of population size relative to another area or time.
- Absolute density: The actual number of individuals per unit area.

Quick Tips:
- Understand the difference between relative and absolute density and when each is useful.

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To a large extent the vegetation in any area is determined by

View answer and explanation

Correct option: C

pH, mineral composition and topography.

The correct answer is C (pH, mineral composition and topography) because these factors significantly influence plant distribution and vegetation type.

Solution approach

Correct Answer + Core Reason: pH, mineral composition and topography. These factors directly influence plant growth and distribution.

Step-by-Step Solution:

Step 1: Consider factors affecting vegetation: Several factors influence plant growth.

Step 2: Analyze pH: Soil pH affects nutrient availability to plants.

Step 3: Analyze mineral composition: Essential minerals are required for plant growth.

Step 4: Analyze topography: Slope, aspect, and elevation influence water availability and sunlight exposure.

Step 5: Analyze temperature and light: While important, pH, mineral composition, and topography are more direct determinants of vegetation type in many areas.

Why other options are wrong:
- Option A: Temperature is important but pH is a more direct determinant of vegetation type.
- Option B: Light is important but topography is also a key factor.
- Option D: Mineral types are important, but pH and topography are also crucial.

Key Concepts:
- Factors affecting vegetation
- Soil pH
- Mineral nutrients
- Topography

Memory Aids:
- Remember that soil properties and landscape features determine vegetation.

Quick Tips:
- Consider the direct impact of each factor on plant growth.

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Monarch butterflies are highly distasteful to predator due to

View answer and explanation

Correct option: B

A special chemical present in its body

Option B (A special chemical present in its body) is correct because monarch butterflies sequester chemicals from milkweed plants, making them distasteful to predators.

Solution approach

Correct Answer + Core Reason: Monarch butterflies are distasteful due to a chemical in their body.

Step-by-Step Solution:

Step 1: Describe Monarch Butterfly Diet: Monarch caterpillars feed on milkweed plants.

Step 2: Explain Chemical Sequestration: Milkweed contains cardiac glycosides, which are toxic chemicals.

Step 3: Explain the effect on predators: Monarchs sequester these chemicals, making them distasteful and toxic to predators.

Why other options are wrong:
- Option A: While appearance can play a role, the primary defense is the chemical.
- Option C: The chemical is the main reason, not just the \"ugly look.\"
- Option D: Monarchs don't secrete poison from special glands; they sequester chemicals from their diet.

Key Concepts:
- Chemical defense
- Monarch butterfly
- Milkweed
- Cardiac glycosides

Memory Aids:
- Think of Monarchs eating Milkweed and becoming toxic.

Quick Tips:
- Remember that some animals acquire defenses from their diet.

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Assertion: Photosynthesis is an essential life process of plants.

Reason: Small plants growing in forest are adapted to other process than photosynthesis because they are over-shadowed by tall canopied trees

View answer and explanation

Correct option: B

If both the assertion and reason are true but the reason is not a correct explanation of the assertion

The correct answer is B (If both the assertion and reason are true but the reason is not a correct explanation of the assertion) because photosynthesis is essential, and small plants may have adaptations to other processes, but the latter isn't *because* of being overshadowed.

Solution approach

Correct Answer + Core Reason: If both the assertion and reason are true but the reason is not a correct explanation of the assertion. Both statements are correct, but the reason doesn't fully explain the assertion.

Step-by-Step Solution:

Step 1: Analyze the assertion: Photosynthesis is essential for plants.

Step 2: Analyze the reason: Small plants in forests are adapted to other processes because they are overshadowed.

Step 3: Determine if both are true: Both statements are generally true.

Step 4: Determine if the reason explains the assertion: While small plants may have adaptations to other processes, it's not *solely* because they are overshadowed. They still rely on photosynthesis, even if they have other adaptations.

Why other options are wrong:
- Option A: The reason is not the *correct* explanation, though it is related.
- Option C: Both the assertion and reason are true.
- Option D: Both the assertion and reason are true.

Key Concepts:
- Photosynthesis
- Plant adaptations
- Forest ecology

Memory Aids:
- Remember that plants need light for photosynthesis, but can have other adaptations as well.

Quick Tips:
- Consider whether the reason fully explains the assertion.

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When two related populations occupy geographically or spatially separate areas, they are called

View answer and explanation

Correct option: A

Allopatric population

Option A (Allopatric population) is correct because allopatric populations are defined as populations of the same species that are geographically isolated from each other.

Solution approach

Correct Answer + Core Reason: Allopatric population. This refers to populations that are geographically separated.

Step-by-Step Solution:

Step 1: Define Allopatric: Allopatric populations are geographically separated, preventing gene flow.

Step 2: Define Quantum population: Quantum evolution is a rapid form of speciation.

Step 3: Define Saltational population: Saltational speciation involves large, sudden mutations leading to new species.

Step 4: Define Parapatric population: Parapatric populations are adjacent but do not overlap significantly, and gene flow is limited.

Step 5: Match the definition: The question describes geographically separate populations, which is allopatric.

Why other options are wrong:
- Option B: Quantum population refers to a mode of speciation, not spatial separation.
- Option C: Saltational population refers to a mode of speciation, not spatial separation.
- Option D: Parapatric population refers to adjacent populations, not geographically separate ones.

Key Concepts:
- Speciation
- Allopatric, Sympatric, Parapatric speciation
- Population genetics

Memory Aids:
- Allo = Apart (Allopatric = populations are apart)

Quick Tips:
- Understand the different modes of speciation based on geographic isolation.

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Which of the following does not make a nest of its own?

View answer and explanation

Correct option: C

Cuckoo

Option C (Cuckoo) is correct because cuckoos are brood parasites, meaning they lay their eggs in the nests of other birds.

Solution approach

Correct Answer + Core Reason: Cuckoo. Cuckoos are brood parasites and lay their eggs in other birds' nests.

Step-by-Step Solution:

Step 1: Analyze Crow: Crows build their own nests.

Step 2: Analyze Parrot: Parrots typically nest in tree hollows or build their own nests.

Step 3: Analyze Cuckoo: Cuckoos are brood parasites and lay their eggs in the nests of other birds. They do not build their own nests.

Step 4: Analyze Sparrow: Sparrows build their own nests.

Step 5: Conclusion: The cuckoo does not make a nest of its own.

Why other options are wrong:
- Option A: Crows build their own nests.
- Option B: Parrots build their own nests or nest in tree hollows.
- Option D: Sparrows build their own nests.

Key Concepts:
- Brood parasitism
- Nest building behavior in birds

Memory Aids:
- Cuckoo = Cheater (doesn't build its own nest)

Quick Tips:
- Be familiar with examples of brood parasites in the animal kingdom.

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Biological control methods adopted in agricultural pest control are mainly based on:-

View answer and explanation

Correct option: A

Predation

Option A (Predation) is correct because biological control relies on predators to control pest populations.

Solution approach

Correct Answer + Core Reason: Predation. Biological control uses natural predators to manage pest populations.

Step-by-Step Solution:

Step 1: Define biological control. Biological control is a method of controlling pests using other living organisms.

Step 2: Consider the options. Predation involves one organism (the predator) consuming another (the prey, in this case, the pest). Competition involves two organisms vying for the same resources. Mutualism is a relationship where both organisms benefit. Commensalism is a relationship where one organism benefits and the other is neither harmed nor helped.

Step 3: Determine the most relevant relationship. In agricultural pest control, the goal is to reduce the pest population. This is achieved when a predator consumes the pest.

Step 4: Conclusion. Predation is the most direct and effective biological control method.

Why other options are wrong:
- Option B: Competition might occur, but it's not the primary mechanism of biological control. Introducing a competitor doesn't guarantee pest reduction.
- Option C: Mutualism is unlikely to be a direct pest control method, as it involves both organisms benefiting.
- Option D: Commensalism is also unlikely, as it doesn't directly reduce the pest population.

Key Concepts:
- Biological control
- Predation
- Competition
- Mutualism
- Commensalism

Memory Aids:
- Think of a ladybug eating aphids as a classic example of predation in biological control.

Quick Tips:
- When considering biological control, focus on relationships where one organism directly benefits by reducing the pest population.

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If in a pond there are 80 lotus plants last year and through reproduction 8 new plants are added, taking the current population to 88. The value of birth rate will be

View answer and explanation

Correct option: B

0.1

Option B (

0.1

) is correct because the birth rate is calculated by dividing the number of new plants by the initial population.

Solution approach

Correct Answer + Core Reason: $0.1$ . The birth rate is calculated by dividing the number of new plants by the initial population.

Step-by-Step Solution:

Step 1: Identify the given information: Number of new plants = 8, Initial population = 80.

Step 2: Calculate the birth rate: Birth rate = (Number of new plants) / (Initial population).

Step 3: Substitute the values: Birth rate = 8 / 80.

Step 4: Simplify: Birth rate = 0.1.

Step 5: Final Answer: $0.1$

Why other options are wrong:
- Option A (11): This is incorrect because it's calculated by adding the new plants to the initial population and dividing by a smaller number, which is not the correct formula for birth rate.
- **Option C ( $0.9$ ): This is incorrect because it's likely a miscalculation or confusion with other population parameters.
- Option D ( $1.1$ ): This is incorrect because it's likely a miscalculation or confusion with other population parameters.

Key Concepts:
- Population dynamics
- Birth rate calculation

Memory Aids:
- Birth rate = (Number of new individuals) / (Initial population)

Quick Tips:**
- Always ensure you are dividing the number of new individuals by the initial population to get the birth rate.

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Photosynthetically Active Radiation(PAR) have the electromagnetic region of

View answer and explanation

Correct option: B

400-700 nm

Option B (400-700 nm) is correct because Photosynthetically Active Radiation (PAR) falls within the visible light spectrum, ranging from 400 to 700 nm.

Solution approach

Correct Answer + Core Reason: PAR is in the 400-700 nm range.

Step-by-Step Solution:

Step 1: Define PAR: Photosynthetically Active Radiation (PAR) is the portion of the electromagnetic spectrum that plants use for photosynthesis.

Step 2: Recall the range of PAR: PAR falls within the visible light spectrum.

Step 3: Identify the correct range: The visible light spectrum ranges from approximately 400 to 700 nm.

Why other options are wrong:
- Option A: 300-700 nm includes some UV radiation, which is not part of PAR.
- Option C: 200-700 nm includes UV radiation, which is not part of PAR.
- Option D: 300-600 nm excludes a significant portion of the visible light spectrum used in photosynthesis.

Key Concepts:
- Photosynthetically Active Radiation (PAR)
- Electromagnetic spectrum
- Photosynthesis

Memory Aids:
- Remember that PAR is within the visible light range.

Quick Tips:
- Know the approximate wavelengths of different parts of the electromagnetic spectrum.

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Plant grows best in the
I. acidic soil
II. basic soil
III. neutral soil
IV. slightly acidic soil
Choose the correct combination

View answer and explanation

Correct option: C

III and IV

Option C (III and IV) is correct because most plants thrive in neutral to slightly acidic soil conditions.

Solution approach

Correct Answer + Core Reason: III and IV. Plants generally grow best in neutral to slightly acidic soil.

Step-by-Step Solution:

Step 1: Recall the optimal soil pH for plant growth.

Step 2: Most plants prefer a soil pH that is slightly acidic to neutral (around 6.0 to 7.0).

Step 3: Acidic soil has a pH less than 7, basic soil has a pH greater than 7, and neutral soil has a pH of 7.

Step 4: Slightly acidic soil provides the best nutrient availability for most plants.

Why other options are wrong:
- Option A: Acidic and basic soils are generally not optimal for most plants, as they can hinder nutrient uptake.
- Option B: Basic soil is not optimal for most plants.
- Option D: While some plants tolerate acidic soil, neutral to slightly acidic is generally better.

Key Concepts:
- Soil pH
- Nutrient availability
- Plant physiology

Memory Aids:
- Remember that slightly acidic soil is generally best for plant growth.

Quick Tips:
- Consider the impact of pH on nutrient solubility and availability.

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Model is

View answer and explanation

Correct option: B

Object to which mimic resemble

Option B (Object to which mimic resemble) is correct because the model is the organism or object that the mimic imitates.

Solution approach

Correct Answer + Core Reason: Object to which mimic resemble. The model is what the mimic copies.

Step-by-Step Solution:

Step 1: Define mimicry: Mimicry is when one species (the mimic) evolves to resemble another species (the model) or an object.

Step 2: Identify the model: The model is the organism or object that the mimic resembles.

Step 3: Evaluate the options:
- The species which mimic: This is the *mimic*, not the model.
- Object to which mimic resemble: This is the *model*.
- Both (1) and (2): Incorrect because only the object being resembled is the model.
- Neither (1) nor (2): Incorrect because the object being resembled *is* the model.

Why other options are wrong:
- Option A (The species which mimic): This describes the mimic, not the model.
- Option C (Both (1) and (2)): Only the object being resembled is the model.
- Option D (Neither (1) nor (2)): The object being resembled *is* the model.

Key Concepts:
- Mimicry
- Model
- Mimic

Memory Aids:
- Model: The original that is being copied.

Quick Tips:
- Remember the difference between the mimic (the one doing the copying) and the model (the one being copied).

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Nosema notabilis is an example for

View answer and explanation

Correct option: D

Hyperparasitism

Option D (Hyperparasitism) is correct because Nosema notabilis is a parasite that parasitizes another parasite, making it an example of hyperparasitism.

Solution approach

Correct Answer + Core Reason: Hyperparasitism. Nosema notabilis is a parasite of a parasite.

Step-by-Step Solution:

Step 1: Define Parasitism. Parasitism is a relationship where one organism (the parasite) benefits at the expense of another organism (the host).

Step 2: Define Hyperparasitism. Hyperparasitism is a form of parasitism where a parasite parasitizes another parasite.

Step 3: Analyze the options:
- A. Commensalism: One organism benefits, and the other is neither harmed nor helped.
- B. Symbiosis: A close and long-term interaction between different biological species.
- C. Ectoparasitism: A parasite lives on the outer surface of its host.
- D. Hyperparasitism: A parasite lives on or in another parasite.

Why other options are wrong:
- Option A: Commensalism doesn't involve harm to either organism, unlike parasitism.
- Option B: Symbiosis involves mutual benefit, not harm to a host.
- Option C: Ectoparasitism describes where the parasite lives, not its host type.

Key Concepts:
- Parasitism: A relationship where one organism benefits at the expense of another.
- Hyperparasitism: A parasite of a parasite.

Memory Aids:
- "Hyper-" means above or beyond, so hyperparasitism is parasitism on top of parasitism.

Quick Tips:
- Understand the different types of symbiotic relationships and their definitions.

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Life history traits of organisms have evolved in relation to the constraints imposed by which components of habitat

View answer and explanation

Correct option: D

Both (2) and (3)

Option D (Both (2) and (3)) is correct because life history traits are shaped by both abiotic (non-living) and biotic (living) components of the habitat.

Solution approach

Correct Answer + Core Reason: Both (2) and (3). Life history traits are influenced by both abiotic and biotic factors in the habitat.

Step-by-Step Solution:

Step 1: Define life history traits: These are characteristics of an organism's life cycle, such as reproduction rate, lifespan, etc.

Step 2: Consider abiotic components: These include non-living factors like temperature, water availability, and sunlight.

Step 3: Consider biotic components: These include living factors like competition, predation, and disease.

Step 4: Recognize that both abiotic and biotic factors impose constraints on life history traits. For example, limited water (abiotic) can affect reproduction, and high predation (biotic) can affect lifespan.

Step 5: Conclude that both abiotic and biotic components are correct.

Why other options are wrong:
- Option A (Organic components): Organic components are part of biotic components.
- Option B (Abiotic components): This is incomplete as it omits biotic components.
- Option C (Biotic components): This is incomplete as it omits abiotic components.

Key Concepts:
- Life history traits
- Abiotic factors
- Biotic factors
- Habitat constraints

Memory Aids:
- Remember that an organism's life is shaped by both its environment (abiotic) and its interactions with other organisms (biotic).

Quick Tips:
- Consider both the physical environment and the biological interactions when analyzing life history traits.

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A secondary compound are the part of the plants

View answer and explanation

Correct option: B

Secondary metabolism

Option B (Secondary metabolism) is correct because secondary compounds are products of secondary metabolic pathways in plants.

Solution approach

Correct Answer + Core Reason: Secondary metabolism. Secondary compounds are products of secondary metabolic pathways in plants.

Step-by-Step Solution:

Step 1: Define Secondary Compounds: Secondary compounds are organic compounds produced by plants that are not directly involved in growth, development, or reproduction.

Step 2: Relate to Metabolism: These compounds are products of secondary metabolic pathways.

Step 3: Conclusion: Secondary compounds are part of the plants' secondary metabolism.

Why other options are wrong:
- Option A: Normal metabolism is incorrect because normal metabolism refers to primary metabolic processes essential for basic survival and growth.
- Option C: Evolution is incorrect because while secondary compounds can play a role in plant evolution, they are directly products of secondary metabolism.
- Option D: Genetic difference is incorrect because while genetic differences can influence the production of secondary compounds, they are directly products of secondary metabolism.

Key Concepts:
- Secondary Compounds
- Secondary Metabolism
- Plant Physiology

Memory Aids:
- Think of "secondary" as "extra" - these compounds aren't essential for basic survival but provide other benefits.

Quick Tips:
- Differentiate between primary and secondary metabolism in plants.

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Ecologist say that niche is like a species …A…, while habitat is like a …B… there A and B indicate

View answer and explanation

Correct option: C

A-occupation; B-address

Option C (A-occupation; B-address) is correct because an ecological niche is often described as a species' "occupation" or role in the ecosystem, while a habitat is its "address" or physical location.

Solution approach

Correct Answer + Core Reason: A-occupation; B-address. Niche is like a species' occupation, habitat is its address.

Step-by-Step Solution:

Step 1: Define Niche. An ecological niche is the role and position a species has in its environment; how it meets its needs for food and shelter, how it survives, and how it reproduces.

Step 2: Define Habitat. A habitat is the natural environment where an organism lives.

Step 3: Analyze the options:
- A. A-education; B-occupation: This doesn't accurately describe the relationship between niche and habitat.
- B. A-appearance; B-physiology: These are characteristics of the organism itself, not its role or location.
- C. A-occupation; B-address: This is the most accurate analogy. Niche is the species' role (occupation), and habitat is its location (address).
- D. A-physiology; B-anatomy: These are characteristics of the organism itself, not its role or location.

Why other options are wrong:
- Option A: Education and occupation don't directly relate to niche and habitat.
- Option B: Appearance and physiology are characteristics of the organism, not its role or location.
- Option D: Physiology and anatomy are characteristics of the organism, not its role or location.

Key Concepts:
- Niche: The role and position a species has in its environment.
- Habitat: The natural environment where an organism lives.

Memory Aids:
- Niche is what a species *does* (occupation), habitat is where it *lives* (address).

Quick Tips:
- Use the analogy of occupation and address to understand the difference between niche and habitat.

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Individual alive at the beginning of 1 year to 2 year age interval is 800. During this interval 200 individual die. Then find out the death rate

View answer and explanation

Correct option: D

0.25

Option D (0.25) is correct because the death rate is calculated by dividing the number of deaths during the interval by the number of individuals alive at the beginning of the interval (200/800 = 0.25).

Solution approach

Correct Answer + Core Reason: 0.25. Death rate is calculated by dividing the number of deaths by the initial population.

Step-by-Step Solution:
Step 1: Identify the number of deaths: 200 individuals.
Step 2: Identify the initial population: 800 individuals.
Step 3: Calculate the death rate: $Death\ Rate = \frac{{Number\ of\ Deaths}}{{Initial\ Population}}$
Step 4: Substitute the values: $Death\ Rate = \frac{{200}}{{800}}$
Step 5: Calculate the death rate: $Death\ Rate = 0.25$

Why other options are wrong:
- Option A: 200 is the number of deaths, not the death rate.
- Option B: 800 is the initial population, not the death rate.
- Option C: 0.4 is incorrect. It's not a logical calculation based on the given data.

Key Concepts:
- Death rate
- Population dynamics

Memory Aids:
- Death Rate = Deaths / Population

Quick Tips:
- Ensure you are dividing the number of deaths by the correct initial population size.

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“Complete competitiors cannot coexist” is true for

View answer and explanation

Correct option: B

Competitive exclusion

Option B (Competitive exclusion) is correct because the competitive exclusion principle states that two species competing for the same limited resources cannot coexist indefinitely; one will eventually outcompete the other.

Solution approach

Correct Answer + Core Reason: Competitive exclusion. This principle states that two species competing for the same resources cannot coexist.

Step-by-Step Solution:
Step 1: Define the terms: Character displacement (evolution of different traits to reduce competition), Competitive exclusion (one species eliminates another due to competition), Primary succession (ecological succession starting in a lifeless area), Secondary succession (ecological succession starting in an area with existing soil).
Step 2: Consider the scenario of \"complete competitors,\" meaning species with identical resource needs.
Step 3: The competitive exclusion principle directly addresses this scenario, stating that coexistence is impossible.

Why other options are wrong:
- Option A: Character displacement is a result of competition, not the impossibility of coexistence itself. It's an evolutionary response to reduce competition.
- Option C: Primary succession describes ecological changes over time, not the direct interaction between competing species.
- Option D: Secondary succession describes ecological changes over time, not the direct interaction between competing species.

Key Concepts:
- Competitive exclusion principle
- Ecological competition

Memory Aids:
- Competitive EXclusion = EXistence is impossible

Quick Tips:
- Remember the core idea of the competitive exclusion principle: \"one wins, the other loses.\"

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When a population grows in a habitat with limited resources, the population growth after phase of acceleration and deceleration finally achieves asymptote

View answer and explanation

Correct option: A

If the population density reaches the carrying capacity

Option C (Both (i) and (iii)) is correct because natality (birth rate) and immigration (arrival of individuals from other areas) increase the population density.

Solution approach

Correct Answer + Core Reason: Both (i) and (iii). Natality and immigration increase population density.

Step-by-Step Solution:

Step 1: Define natality. The birth rate of a population.

Step 2: Define mortality. The death rate of a population.

Step 3: Define immigration. The movement of individuals into a population from another area.

Step 4: Define emigration. The movement of individuals out of a population to another area.

Step 5: Natality and immigration increase population density, while mortality and emigration decrease it.

Why other options are wrong:
- Option A: Mortality decreases population density, not increases it.
- Option B: Mortality decreases population density, not increases it.
- Option D: Both mortality and emigration decrease population density.

Key Concepts:
- Natality
- Mortality
- Immigration
- Emigration
- Population Density

Memory Aids:
- Immigration: \"in\" to the population.
- Emigration: \"exit\" from the population.

Quick Tips:
- Remember the definitions of natality, mortality, immigration, and emigration.

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