Ecosystems – structure and function MCQs With Answer

Ecosystems – structure and function MCQs With Answer

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Ecosystems – structure and function MCQs With Answer

This question set is designed for M.Pharm students studying Hazards and Safety Management who need a focused review of ecosystem structure and function. The quiz connects core ecological principles—energy flow, trophic organization, nutrient cycles, resilience, and ecosystem services—with pharmaceutical and environmental safety concerns such as pollutant fate, bioaccumulation, and antibiotic resistance. Each multiple-choice question probes conceptual understanding and applied implications for drug safety, waste management, and environmental risk assessment. Use these items to test comprehension, prepare for exams, and stimulate thinking about how pharmaceutical practices interact with ecosystem processes and public and environmental health.

Q1. What best defines an ecosystem?

  • A spatial distribution of abiotic factors without living organisms
  • A community of organisms interacting with each other and their abiotic environment
  • A single species population within a habitat
  • An artificial laboratory model of food chains

Correct Answer: A community of organisms interacting with each other and their abiotic environment

Q2. Which pair correctly categorizes ecosystem components?

  • Primary and secondary components
  • Biotic (living) and abiotic (non-living) components
  • Structural and nutritional components
  • Producers and decomposers only

Correct Answer: Biotic (living) and abiotic (non-living) components

Q3. Which trophic level forms the base of most terrestrial and aquatic food chains?

  • Primary consumers (herbivores)
  • Secondary consumers (omnivores and carnivores)
  • Primary producers (autotrophs)
  • Decomposers (detritivores)

Correct Answer: Primary producers (autotrophs)

Q4. How does energy typically move through an ecosystem?

  • Energy cycles repeatedly through trophic levels without loss
  • Energy flows unidirectionally from producers to consumers and is lost as heat
  • Energy is created at each trophic transfer
  • Energy moves only between consumers, not producers

Correct Answer: Energy flows unidirectionally from producers to consumers and is lost as heat

Q5. Net primary productivity (NPP) is defined as which of the following?

  • Total sunlight captured by an ecosystem
  • GPP minus autotrophic respiration
  • Biomass consumed by herbivores per year
  • Gross production plus decomposition losses

Correct Answer: GPP minus autotrophic respiration

Q6. What distinguishes a food web from a food chain?

  • A food web represents a linear sequence of energy flow
  • A food web shows multiple interconnected feeding relationships among species
  • A food web includes only predator–prey pairs while a food chain includes detritus
  • There is no difference; terms are interchangeable

Correct Answer: A food web shows multiple interconnected feeding relationships among species

Q7. Which statement correctly contrasts bioaccumulation and biomagnification?

  • Bioaccumulation refers to increasing concentrations up a food chain; biomagnification is accumulation within a single organism
  • Bioaccumulation occurs at the population level; biomagnification occurs at molecular level
  • Bioaccumulation is the buildup of a pollutant within an individual organism over time; biomagnification is the increase in pollutant concentration at higher trophic levels
  • Both terms mean the same and are interchangeable

Correct Answer: Bioaccumulation is the buildup of a pollutant within an individual organism over time; biomagnification is the increase in pollutant concentration at higher trophic levels

Q8. What does carrying capacity refer to in ecology?

  • The maximum number of species an ecosystem can host
  • The maximum sustainable population size of a species in a given environment
  • The rate at which resources are consumed
  • The minimum viable population needed for reproduction

Correct Answer: The maximum sustainable population size of a species in a given environment

Q9. How is an ecological niche different from a habitat?

  • A niche is the physical location; habitat is the functional role of a species
  • A niche is a species’ functional role and interactions in an ecosystem; habitat is the physical place it lives
  • They are synonyms and interchangeable
  • A niche only applies to microorganisms while habitat applies to larger organisms

Correct Answer: A niche is a species’ functional role and interactions in an ecosystem; habitat is the physical place it lives

Q10. What characterizes primary succession compared to secondary succession?

  • Primary succession occurs after a forest fire; secondary occurs on bare rock
  • Primary succession begins on newly formed substrate with no soil; secondary occurs where soil remains after disturbance
  • Primary succession is faster than secondary succession
  • Secondary succession never leads to a climax community

Correct Answer: Primary succession begins on newly formed substrate with no soil; secondary occurs where soil remains after disturbance

Q11. Which of the following lists the common categories of ecosystem services?

  • Structural, numerical, biological, chemical
  • Provisioning, regulating, supporting, cultural
  • Primary, secondary, tertiary, quaternary
  • Abiotic, biotic, trophic, genetic

Correct Answer: Provisioning, regulating, supporting, cultural

Q12. In ecological terms, what best describes resilience?

  • The ability of an ecosystem to resist change under disturbance
  • The rate at which an ecosystem produces biomass
  • The speed and extent to which an ecosystem recovers to pre-disturbance state after a disturbance
  • The diversity of species present at a single trophic level

Correct Answer: The speed and extent to which an ecosystem recovers to pre-disturbance state after a disturbance

Q13. Which statement about the phosphorus cycle is correct?

  • Phosphorus cycles mainly through the atmosphere as gaseous phosphates
  • Phosphorus has a large atmospheric reservoir similar to nitrogen
  • The phosphorus cycle lacks a significant gaseous phase and is primarily lithospheric and aquatic
  • Phosphorus is readily lost to the atmosphere through volatilization

Correct Answer: The phosphorus cycle lacks a significant gaseous phase and is primarily lithospheric and aquatic

Q14. What is a major ecological risk of releasing antibiotics into aquatic environments?

  • Immediate large-scale mortality of all fish species
  • Promotion and selection of antibiotic-resistant microbial communities
  • Rapid mineralization of antibiotics without biological effect
  • Permanent elimination of primary producers only

Correct Answer: Promotion and selection of antibiotic-resistant microbial communities

Q15. Which wastewater treatment technology is particularly effective at degrading diverse pharmaceutical residues?

  • Primary sedimentation alone
  • Conventional chlorination without secondary treatment
  • Advanced oxidation processes (AOPs) such as UV/H2O2 or ozonation
  • Simple bar screening

Correct Answer: Advanced oxidation processes (AOPs) such as UV/H2O2 or ozonation

Q16. What are the standard steps of ecological risk assessment?

  • Exposure assessment, hazard identification, dose-response assessment, risk characterization
  • Sampling, reporting, litigation, remediation
  • Hazard elimination, economic evaluation, marketing, distribution
  • Observation only, with no quantitative analysis

Correct Answer: Exposure assessment, hazard identification, dose-response assessment, risk characterization

Q17. Which organism group is commonly used as an indicator of air pollution, especially sulfur dioxide and heavy metals?

  • Macroalgae in oceans
  • Lichens
  • Birds of prey only
  • Large mammals

Correct Answer: Lichens

Q18. What is a primary ecological consequence of habitat fragmentation?

  • Increase in total contiguous habitat area
  • Enhanced genetic exchange among isolated populations
  • Creation of edge effects and reduced habitat connectivity leading to loss of biodiversity
  • Immediate increase in ecosystem services across fragments

Correct Answer: Creation of edge effects and reduced habitat connectivity leading to loss of biodiversity

Q19. What is a trophic cascade?

  • A phenomenon where changes at one trophic level cause reciprocal changes across other levels, often triggered by predator removal or addition
  • A linear increase in biomass from producers to top predators without feedbacks
  • A method of measuring primary productivity using cascaded ponds
  • A nutrient enrichment process affecting only decomposers

Correct Answer: A phenomenon where changes at one trophic level cause reciprocal changes across other levels, often triggered by predator removal or addition

Q20. Why do lipophilic pharmaceuticals often persist and bioaccumulate in organisms?

  • They are rapidly metabolized and excreted unchanged
  • They preferentially partition into fatty tissues and resist aqueous degradation
  • They are highly volatile and leave the organism quickly
  • They only bind to external surfaces and do not enter tissues

Correct Answer: They preferentially partition into fatty tissues and resist aqueous degradation

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