Aquatic ecosystems – oceans MCQs With Answer are essential for B. Pharm students to understand marine biodiversity, environmental chemistry, and pharmacological potential of marine organisms. This concise, informative set covers ocean zones, salinity, primary productivity, marine toxins, bioaccumulation, algal blooms, and marine-derived drugs and extraction techniques. Emphasis is placed on how ocean health, pollutants, and microbial communities influence drug discovery, safety, and pharmacology. Ideal for pharmacognosy and environmental pharmacology review, these MCQs reinforce applied knowledge needed for research and clinical relevance in marine pharmacology. Now let’s test your knowledge with 50 MCQs on this topic.
Q1. Which ocean zone receives enough sunlight for photosynthesis and hosts most phytoplankton?
- Bathypelagic zone
- Epipelagic (euphotic) zone
- Abyssopelagic zone
- Hadopelagic zone
Correct Answer: Epipelagic (euphotic) zone
Q2. Which marine primary producers are most important for global carbon fixation and a key source of marine natural products?
- Marine fungi
- Phytoplankton
- Benthic macroalgae only
- Cnidarians
Correct Answer: Phytoplankton
Q3. What term describes the increase in nutrient levels leading to excessive algal growth and oxygen depletion?
- Thermal stratification
- Eutrophication
- Osmoregulation
- Bioremediation
Correct Answer: Eutrophication
Q4. Which algal toxin is responsible for amnesic shellfish poisoning and is a concern in marine pharmacology?
- Saxitoxin
- Domoic acid
- Tetrodotoxin
- Brevetoxin
Correct Answer: Domoic acid
Q5. Bioaccumulation differs from biomagnification in that bioaccumulation refers to:
- Progressive concentration increase at higher trophic levels
- Accumulation of a substance in one organism over time
- Immediate excretion of pollutants
- Dilution of toxins in the food web
Correct Answer: Accumulation of a substance in one organism over time
Q6. Which heavy metal is well-known for methylation in marine sediments leading to neurotoxic forms that affect pharmaceuticals and public health?
- Lead
- Mercury
- Cadmium
- Arsenic
Correct Answer: Mercury
Q7. Conotoxins, studied for analgesic drug development, are derived from which marine organisms?
- Sponges
- Cone snails (Conus species)
- Corals
- Seaweeds
Correct Answer: Cone snails (Conus species)
Q8. Ziconotide, a peptide analgesic used clinically, was originally isolated from:
- Marine sponge
- Marine bacterium
- Cone snail venom
- Brown algae
Correct Answer: Cone snail venom
Q9. Which process is primarily responsible for ocean acidification affecting carbonate chemistry and potentially drug stability studies?
- Decreased salinity
- Increased atmospheric CO2 absorption
- Enhanced photosynthesis globally
- Thermal desalination
Correct Answer: Increased atmospheric CO2 absorption
Q10. In marine bioprospecting, bioassay-guided fractionation typically uses which analytical techniques for compound isolation?
- Gram staining only
- HPLC, LC-MS, and bioassays
- Simple filtration alone
- Visual microscopy only
Correct Answer: HPLC, LC-MS, and bioassays
Q11. Which group of microorganisms dominate marine microbial production and are crucial for nutrient cycling relevant to drug biodegradation?
- Dinoflagellates only
- Heterotrophic bacteria and phytoplankton
- Marine viruses only
- Macroalgae
Correct Answer: Heterotrophic bacteria and phytoplankton
Q12. Paralytic shellfish poisoning is primarily caused by which class of marine toxins?
- Saxitoxins
- Domoic acids
- Brevetoxins
- Aflatoxins
Correct Answer: Saxitoxins
Q13. Which oceanic zone is characterized by high pressure, low temperature, and absence of light, where unique drug leads from extremophiles may be found?
- Intertidal zone
- Mesopelagic zone
- Abyssal zone
- Epipelagic zone
Correct Answer: Abyssal zone
Q14. Marine sponges are prolific sources of pharmacologically active compounds because they:
- Are photosynthetic
- Host diverse symbiotic microbes producing secondary metabolites
- Only produce structural proteins
- Have no associated microbes
Correct Answer: Host diverse symbiotic microbes producing secondary metabolites
Q15. Which parameter is most directly measured to assess water’s ability to support aerobic life, crucial for marine sampling in pharmacology studies?
- Electrical conductivity
- Dissolved oxygen (DO)
- Total suspended solids
- Chloride concentration
Correct Answer: Dissolved oxygen (DO)
Q16. What is the principal effect of salinity on drug solubility and partitioning in marine matrices?
- Salinity has no effect on solubility
- Salting-out can decrease solubility of many organic drugs
- Salinity always increases drug solubility
- Salinity converts drugs to gases
Correct Answer: Salting-out can decrease solubility of many organic drugs
Q17. Which marine-derived anticancer drug was originally isolated from the sea squirt Ecteinascidia?
- Penicillin
- Trabectedin (ET-743)
- Ziconotide
- Artemisinin
Correct Answer: Trabectedin (ET-743)
Q18. Which sampling method is most appropriate for collecting a single-point surface seawater sample for pollutant analysis?
- Composite sampling from multiple depths only
- Grab sampling
- Remote sensing imaging alone
- Sediment coring
Correct Answer: Grab sampling
Q19. Which metabolic adaptation allows many marine organisms to survive in high-salinity environments and is relevant for biochemical studies?
- Osmoregulation and compatible solute accumulation
- Complete desiccation
- Photosynthetic inversion
- Loss of membrane proteins
Correct Answer: Osmoregulation and compatible solute accumulation
Q20. Harmful algal blooms (HABs) are often promoted by elevated levels of which nutrients?
- Calcium and magnesium
- Nitrogen and phosphorus
- Silicon and iron exclusively
- Oxygen and ozone
Correct Answer: Nitrogen and phosphorus
Q21. Microplastics in the ocean can influence pharmaceuticals by:
- Neutralizing drug potency
- Sorbing and transporting hydrophobic drug residues
- Converting drugs into amino acids
- Eliminating microbial degraders
Correct Answer: Sorbing and transporting hydrophobic drug residues
Q22. Which analytical technique is commonly used to confirm molecular mass and structures of marine natural products?
- Thin-layer chromatography only
- Mass spectrometry (MS) and NMR
- Gram staining
- pH titration
Correct Answer: Mass spectrometry (MS) and NMR
Q23. Marine-derived antiviral and anticancer leads often originate from which class of secondary metabolites?
- Polyketides and alkaloids
- Simple sugars only
- Inorganic salts
- Cellulose polymers
Correct Answer: Polyketides and alkaloids
Q24. Which marine habitat acts as a nursery for many species, traps pollutants, and is crucial for pharmacological ecological studies?
- Open ocean gyres
- Mangrove forests and estuaries
- Deep-sea trenches only
- Polar ice caps exclusively
Correct Answer: Mangrove forests and estuaries
Q25. Which toxin blocks voltage-gated sodium channels and is studied for both toxicity and therapeutic potential?
- Domoic acid
- Tetrodotoxin
- Saxitoxin only
- Chlorophyll
Correct Answer: Tetrodotoxin
Q26. Which factor most directly reduces oxygen solubility in seawater?
- Lower temperature
- Higher temperature
- Lower salinity
- Increased pressure
Correct Answer: Higher temperature
Q27. Marine bacteria producing novel enzymes adapted to cold and pressure are called:
- Thermophiles
- Psychrophiles and piezophiles
- Halophiles only
- Photoautotrophs
Correct Answer: Psychrophiles and piezophiles
Q28. Which term describes organisms living on or in the seabed and are important for benthic drug discovery?
- Pelagic organisms
- Benthic organisms
- Nekton only
- Plancton exclusively
Correct Answer: Benthic organisms
Q29. The primary method to remove salts and produce freshwater for pharmaceutical uses from seawater is:
- Distillation only
- Reverse osmosis desalination
- Simple filtration through sand
- Ion exchange without membranes
Correct Answer: Reverse osmosis desalination
Q30. Which marine zone is most influenced by tidal changes and is critical for studying pollutant exchange with land?
- Bathyal zone
- Intertidal (littoral) zone
- Abyssal plain
- Hadal trench
Correct Answer: Intertidal (littoral) zone
Q31. Marine-derived anticoagulant lead compounds can be isolated from which organism group?
- Cephalopods
- Sea cucumbers and leeches (marine annelids/cucumbers)
- Phytoplankton only
- Non-living sediments
Correct Answer: Sea cucumbers and leeches (marine annelids/cucumbers)
Q32. Which water quality indicator estimates the amount of organic matter that can be biologically decomposed and is critical in coastal pharmaceutical waste assessment?
- Biochemical oxygen demand (BOD)
- Total dissolved solids (TDS)
- Specific conductivity
- Alkalinity only
Correct Answer: Biochemical oxygen demand (BOD)
Q33. Marine sediments often act as sinks for hydrophobic organic pollutants due to:
- Low organic carbon content
- High organic matter and particle adsorption
- High oxygen saturation
- Rapid biodegradation only
Correct Answer: High organic matter and particle adsorption
Q34. Which group of marine organisms is most commonly associated with producing brevetoxins?
- Diatoms
- Karenia brevis (dinoflagellates)
- Sponges
- Marine fungi
Correct Answer: Karenia brevis (dinoflagellates)
Q35. The phenomenon where dissolved oxygen decreases sharply with depth due to decomposition and limited mixing is called:
- Oxygen supersaturation
- Oxygen minimum zone (OMZ)
- Photosynthetic peak
- Halocline inversion
Correct Answer: Oxygen minimum zone (OMZ)
Q36. Which marine-derived compound class is known for complex macrolide structures with anticancer activity?
- Simple fatty acids
- Macrolides and polyketides
- Monosaccharides
- Inorganic oxides
Correct Answer: Macrolides and polyketides
Q37. Which preservation method is commonly used to stabilize seawater samples for nutrient analysis in the lab?
- Immediate freezing or refrigeration
- Leaving samples at room temperature overnight
- Adding large amounts of sugar
- Exposing to direct sunlight
Correct Answer: Immediate freezing or refrigeration
Q38. Which process in hydrothermal vent communities supports primary production independent of sunlight?
- Photosynthesis
- Chemoautotrophy (chemosynthesis)
- Fermentation only
- Evaporation-driven synthesis
Correct Answer: Chemoautotrophy (chemosynthesis)
Q39. In marine ecotoxicology, LC50 refers to:
- Lowest concentration causing bioaccumulation
- Lethal concentration for 50% of test organisms
- Legal concentration limit for pharmaceuticals
- Lowest caloric value of plankton
Correct Answer: Lethal concentration for 50% of test organisms
Q40. Which environmental factor most influences the speciation and toxicity of metals in seawater?
- pH and redox conditions
- Light intensity only
- Wave height exclusively
- Presence of plankton only
Correct Answer: pH and redox conditions
Q41. Which marine natural product class has given rise to clinically used anticancer agents like eribulin analogue inspiration?
- Sterols only
- Halogenated marine macrolides and polyketides
- Simple amino acids exclusively
- Cellulose derivatives
Correct Answer: Halogenated marine macrolides and polyketides
Q42. Which indicator organism is often monitored to assess fecal contamination in coastal waters affecting pharmaceutical safety?
- Vibrio cholerae only
- Escherichia coli and enterococci
- Synechococcus
- Salinity-tolerant algae
Correct Answer: Escherichia coli and enterococci
Q43. Halophilic enzymes from marine microbes are valuable in pharmaceutical biocatalysis because they:
- Require no salt to function
- Remain active in high-salt and often extreme conditions
- Are completely denatured by salts
- Only act on inorganic substrates
Correct Answer: Remain active in high-salt and often extreme conditions
Q44. Which class of compounds from marine algae has shown anticoagulant and antiviral properties and is often sulfated polysaccharides?
- Proteases
- Sulfated polysaccharides (e.g., carrageenans, fucoidans)
- Chlorophyll derivatives only
- Algal lipids exclusively
Correct Answer: Sulfated polysaccharides (e.g., carrageenans, fucoidans)
Q45. The term “marine pharmacognosy” primarily refers to:
- Study of seawater desalination
- Study of marine-derived natural products for therapeutic use
- Marine weather prediction
- Commercial fishing regulations
Correct Answer: Study of marine-derived natural products for therapeutic use
Q46. Which measurement provides a rapid estimate of phytoplankton biomass in seawater relevant for toxin monitoring?
- Chlorophyll-a concentration
- Magnesium content
- Total dissolved solids (TDS)
- pH only
Correct Answer: Chlorophyll-a concentration
Q47. Marine-derived peptides often require which formulation consideration due to seawater-derived salt influence?
- Ignore ionic strength effects
- Adjust for ionic strength and stability during extraction/formulation
- Always make them more hydrophobic
- Convert peptides to polysaccharides
Correct Answer: Adjust for ionic strength and stability during extraction/formulation
Q48. Which marine ecosystem provides significant carbon sequestration and is relevant for climate-related pharmaceutical impact studies?
- Open sandy beaches only
- Blue carbon habitats (mangroves, seagrasses, salt marshes)
- Deep-sea sediments exclusively
- Pelagic dead zones only
Correct Answer: Blue carbon habitats (mangroves, seagrasses, salt marshes)
Q49. How can antibiotic residues in coastal waters influence marine microbiomes and future drug resistance?
- They have no effect on microbes
- Select for resistant strains and alter microbial ecology
- Completely sterilize seawater
- Only affect fish physiology, not microbes
Correct Answer: Select for resistant strains and alter microbial ecology
Q50. Which approach integrates chemical analysis, bioassays, and genomic tools to discover marine drug leads effectively?
- Single-molecule isolation without screening
- Multi-omics and bioassay-guided fractionation
- Visual inspection of organisms only
- Random sampling without analysis
Correct Answer: Multi-omics and bioassay-guided fractionation
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