Concept of an ecosystem MCQs With Answer

Introduction: The Concept of an ecosystem MCQs With Answer collection is designed specifically for B. Pharm students to strengthen understanding of ecological principles linked to pharmaceutical sciences. This SEO-friendly guide covers ecosystem components, energy flow, nutrient cycles, biodiversity, bioaccumulation, and environmental impacts of drugs with clear, concise MCQs. Emphasis on environmental pharmacology, pollutant fate, biodegradation, and ecosystem services helps pharmacy students appreciate drug–environment interactions and regulatory implications. Each question reinforces key terms like ecosystem MCQs, biotic and abiotic factors, trophic levels, and ecological balance to prepare you for exams and practical applications. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. What defines an ecosystem?

• A group of organisms of the same species living in an area
• The physical environment only
• Interactions between living organisms and their physical environment
• Only the food chains within a forest

Correct Answer: Interactions between living organisms and their physical environment

Q2. Which of the following is a biotic component of an ecosystem?

• Temperature
• Soil pH
• Plants
• Sunlight intensity

Correct Answer: Plants

Q3. What term describes the non-living chemical and physical factors in an environment?

• Biotic factors
• Abiotic factors
• Producers
• Consumers

Correct Answer: Abiotic factors

Q4. In an ecological pyramid, which trophic level typically has the highest biomass?

• Top carnivores
• Herbivores
• Producers
• Secondary consumers

Correct Answer: Producers

Q5. Gross primary productivity (GPP) refers to:

• The energy lost by plants through respiration
• The total organic carbon fixed by photosynthesis
• The biomass consumed by herbivores
• The net biomass available to consumers

Correct Answer: The total organic carbon fixed by photosynthesis

Q6. Net primary productivity (NPP) equals:

• GPP minus respiration by plants
• Respiration by consumers only
• Total energy in an ecosystem
• GPP plus decomposition

Correct Answer: GPP minus respiration by plants

Q7. Which organisms are primary decomposers in most ecosystems?

• Herbivores
• Fungi and bacteria
• Predatory birds
• Autotrophic algae

Correct Answer: Fungi and bacteria

Q8. Biomagnification is best described as:

• Decrease of pollutant concentration at higher trophic levels
• Accumulation of pollutants in individual organisms only
• Increase in pollutant concentration as it moves up the food chain
• Breakdown of pollutants by microbes

Correct Answer: Increase in pollutant concentration as it moves up the food chain

Q9. Bioaccumulation differs from biomagnification because bioaccumulation:

• Refers to pollutant increase in a single organism over time
• Describes pollutant transfer between species
• Occurs only in aquatic predators
• Always leads to decomposition

Correct Answer: Refers to pollutant increase in a single organism over time

Q10. Which nutrient cycle is most directly linked to eutrophication in aquatic systems?

• Carbon cycle
• Nitrogen cycle
• Silicon cycle
• Hydrogen cycle

Correct Answer: Nitrogen cycle

Q11. What is a keystone species?

• A species with minor ecological impact
• A species whose removal drastically alters ecosystem structure
• A species always at the top of the food chain
• A species that only lives in freshwater

Correct Answer: A species whose removal drastically alters ecosystem structure

Q12. Which process converts atmospheric nitrogen into forms usable by plants?

• Nitrification
• Denitrification
• Nitrogen fixation
• Ammonification

Correct Answer: Nitrogen fixation

Q13. Which microbial process returns nitrogen to the atmosphere as N2?

• Ammonification
• Nitrification
• Denitrification
• Nitrogen fixation

Correct Answer: Denitrification

Q14. Primary succession initiates in areas:

• With existing soil and plant life
• That have been recently disturbed but still contain seed bank
• Never previously occupied by life, like new volcanic rock
• With mature forests

Correct Answer: Never previously occupied by life, like new volcanic rock

Q15. An ecological niche includes:

• Only the habitat of an organism
• All biotic interactions and resource use of an organism
• Only the feeding behavior of an organism
• Only the reproductive strategy

Correct Answer: All biotic interactions and resource use of an organism

Q16. Which term describes the maximum population size an environment can sustain?

• Carrying capacity
• Intrinsic rate
• Exponential growth
• Ecological footprint

Correct Answer: Carrying capacity

Q17. Which is an example of an ecosystem service relevant to pharmacy?

• Biological control of pests that affect medicinal plants
• Road construction
• Urban development
• Increased industrial emissions

Correct Answer: Biological control of pests that affect medicinal plants

Q18. Persistent pharmaceutical pollutants in waterways often result in:

• Immediate disappearance of all microbes
• Altered microbial communities and development of resistance
• Increased primary productivity always
• Complete sterilization of sediments

Correct Answer: Altered microbial communities and development of resistance

Q19. Which property of a drug increases its likelihood of bioaccumulation?

• High water solubility
• Low octanol-water partition coefficient
• High lipophilicity
• Rapid biodegradability

Correct Answer: High lipophilicity

Q20. Eutrophication is primarily caused by excess:

• Trace metals
• Nutrients like nitrogen and phosphorus
• Atmospheric oxygen
• Salinity

Correct Answer: Nutrients like nitrogen and phosphorus

Q21. Which term describes species introduced to a new habitat that cause harm?

• Endemic species
• Keystone species
• Invasive species
• Indicator species

Correct Answer: Invasive species

Q22. Indicator species are used to:

• Increase biodiversity
• Signal environmental changes or pollution
• Promote invasive species spread
• Fix atmospheric nitrogen

Correct Answer: Signal environmental changes or pollution

Q23. Which biome typically has the highest biodiversity?

• Tropical rainforest
• Tundra
• Desert
• Boreal forest

Correct Answer: Tropical rainforest

Q24. What role do wetlands play in ecosystems relevant to pharmaceuticals?

• They amplify pharmaceutical concentrations
• They act as natural filters reducing pollutant loads
• They prevent all microbial activity
• They convert all drugs into harmless gases

Correct Answer: They act as natural filters reducing pollutant loads

Q25. Which process breaks down complex organic compounds into simpler inorganic substances?

• Photosynthesis
• Decomposition
• Primary production
• Niche construction

Correct Answer: Decomposition

Q26. Antibiotic residues in the environment most directly promote:

• Increased photosynthesis in algae
• Selection for antibiotic-resistant bacteria
• Immediate removal of all pollutants
• Faster nutrient cycling

Correct Answer: Selection for antibiotic-resistant bacteria

Q27. Which factor most influences primary productivity in aquatic ecosystems?

• Light availability and nutrient concentration
• Altitudinal variation
• Number of predators only
• Wind direction alone

Correct Answer: Light availability and nutrient concentration

Q28. Which is an example of an abiotic stress affecting drug degradation in the environment?

• Microbial enzymatic activity
• Sunlight-induced photolysis
• Herbivory
• Plant competition

Correct Answer: Sunlight-induced photolysis

Q29. The concept of ecological resilience refers to:

• The speed at which an ecosystem loses species
• An ecosystem’s capacity to recover after disturbance
• The total species richness only
• Permanent shifts to new climates

Correct Answer: An ecosystem’s capacity to recover after disturbance

Q30. Which term describes the total area required to sustain a population’s resource needs?

• Carrying capacity
• Ecological footprint
• Biomagnification index
• Species richness

Correct Answer: Ecological footprint

Q31. Which cycle is most important for maintaining soil fertility and plant growth?

• Ozone cycle
• Phosphorus cycle
• Neon cycle
• Argon cycle

Correct Answer: Phosphorus cycle

Q32. Which of the following best explains why aquatic top predators often have high pollutant loads?

• They metabolize pollutants faster
• They feed on many contaminated prey leading to biomagnification
• They live shorter lives
• They excrete pollutants immediately

Correct Answer: They feed on many contaminated prey leading to biomagnification

Q33. Which practice helps reduce pharmaceutical contamination entering ecosystems?

• Flushing unused medications down the toilet
• Improved wastewater treatment and take-back programs
• Unregulated industrial discharge
• Increasing use of persistent drugs

Correct Answer: Improved wastewater treatment and take-back programs

Q34. Saprotrophs obtain energy by:

• Photosynthesis
• Feeding on living prey
• Decomposing dead organic matter externally
• Symbiosis with plants only

Correct Answer: Decomposing dead organic matter externally

Q35. Which process contributes to the removal of pharmaceuticals in activated sludge treatment?

• Photolysis only
• Biodegradation by microbes and sorption to sludge
• Purely dilution in effluent
• Fossilization

Correct Answer: Biodegradation by microbes and sorption to sludge

Q36. Habitat fragmentation typically leads to:

• Increased gene flow between populations
• Reduced biodiversity and isolated populations
• Uniform distribution of species
• Instant ecosystem recovery

Correct Answer: Reduced biodiversity and isolated populations

Q37. Which is true about food webs compared to simple food chains?

• Food webs show multiple interlinked feeding relationships
• Food webs include only two species
• Food webs exclude decomposers
• Food webs are always linear

Correct Answer: Food webs show multiple interlinked feeding relationships

Q38. Which term describes loss of species from an ecosystem?

• Succession
• Extinction
• Primary production
• Immigration

Correct Answer: Extinction

Q39. Which factor most directly influences species richness on islands according to island biogeography?

• Distance from the mainland and island size
• Altitude only
• Soil pH exclusively
• Presence of predators only

Correct Answer: Distance from the mainland and island size

Q40. Which pollutant class is most likely to persist and bioaccumulate in food chains?

• Highly water-soluble salts
• Volatile gases only
• Hydrophobic organic compounds and certain heavy metals
• Readily biodegradable carbohydrates

Correct Answer: Hydrophobic organic compounds and certain heavy metals

Q41. In ecosystem management, adaptive management emphasizes:

• Rigid rules regardless of outcomes
• Learning-by-doing and adjusting strategies based on monitoring
• Avoiding monitoring to save costs
• Permanent closure of all habitats

Correct Answer: Learning-by-doing and adjusting strategies based on monitoring

Q42. Which describes a food chain starting with phytoplankton?

• Phytoplankton → Zooplankton → Small fish → Large fish
• Large fish → Small fish → Zooplankton → Phytoplankton
• Zooplankton → Phytoplankton → Bacteria → Fish
• Tree → Herbivore → Carnivore → Decomposer

Correct Answer: Phytoplankton → Zooplankton → Small fish → Large fish

Q43. Which mechanism can lead to loss of pharmaceutical activity in soil?

• Sorption to soil particles and microbial degradation
• Instant conversion to oxygen
• Production of new pharmaceuticals by plants
• Increase in soil salinity only

Correct Answer: Sorption to soil particles and microbial degradation

Q44. Which describes competitive exclusion principle?

• Two species with identical niches cannot coexist indefinitely
• Predators always outcompete prey
• Species always share the same niche
• Competition never affects population sizes

Correct Answer: Two species with identical niches cannot coexist indefinitely

Q45. Riparian zones are important because they:

• Are unrelated to water quality
• Buffer streams, support biodiversity, and filter pollutants
• Always increase erosion
• Are only urban areas

Correct Answer: Buffer streams, support biodiversity, and filter pollutants

Q46. Which statement about invasive plants and pharmaceuticals is relevant?

• Invasive plants never affect drug-producing native species
• They can outcompete medicinal plants, reducing available resources and biodiversity
• They always improve biosynthesis of pharmaceuticals
• They reduce the need for conservation

Correct Answer: They can outcompete medicinal plants, reducing available resources and biodiversity

Q47. Which is an effect of climate change on ecosystems relevant to pharmacy?

• No impact on medicinal plant distribution
• Shifts in distribution of medicinal plants and possible loss of species
• Immediate sterilization of soils
• Unlimited increase in biodiversity

Correct Answer: Shifts in distribution of medicinal plants and possible loss of species

Q48. Which monitoring approach helps detect pharmaceutical contamination in water?

• Regular chemical analysis combined with bioindicator species assessment
• Only surveying terrestrial mammals
• Ignoring effluent discharges
• Relying solely on visual inspection of water

Correct Answer: Regular chemical analysis combined with bioindicator species assessment

Q49. Which action supports conservation of ecosystem services that supply medicinal resources?

• Uncontrolled harvesting of wild medicinal plants
• Habitat protection, sustainable harvesting, and community-based management
• Replacing natural habitats with monocultures
• Ignoring indigenous knowledge

Correct Answer: Habitat protection, sustainable harvesting, and community-based management

Q50. Which best summarizes why B. Pharm students should study ecosystem concepts?

• Ecosystems are unrelated to drug development or safety
• Understanding ecosystems helps assess environmental fate of drugs, mitigate impacts, and support sustainable sourcing
• Only ecologists need such knowledge
• It solely concerns agricultural practices

Correct Answer: Understanding ecosystems helps assess environmental fate of drugs, mitigate impacts, and support sustainable sourcing

G S Sachin

I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.

Mail- Sachin@pharmacyfreak.com