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Marine and Freshwater Biology MCQs

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1. : The study of freshwater ecosystems is called:





2. : The study of marine organisms and ecosystems is called:





3. : Which zone of a lake receives sufficient sunlight for photosynthesis?





4. : Organisms living at the bottom of oceans and lakes are called:





5. : Which of the following are microscopic drifting organisms in water?





6. : Phytoplankton are important in aquatic ecosystems because they:





7. : The salinity of seawater is approximately:





8. : Eutrophication in freshwater bodies is mainly caused by:





9. : Coral reefs are primarily built by:





10. : Which gas is essential for fish survival in aquatic ecosystems?





11. : The zone of the ocean that extends to a depth of about 200 meters and receives sunlight is called:





12. : Anadromous fishes are those that:





13. : Catadromous fishes, like eels, migrate from:





14. : The oxygen minimum zone (OMZ) in oceans is caused by:





15. : Estuaries are highly productive ecosystems because:





16. : Freshwater constitutes about what percentage of Earth’s total water?





17. : Hypoxia in aquatic systems refers to:





18. : Which adaptation helps deep-sea fishes survive in darkness?





19. : The process of mixing of surface and deep lake waters during autumn and spring is called:





20. : Mangrove forests are found in:





21. : Which freshwater biome has the highest flow velocity?





22. : The primary cause of coral bleaching is:





23. : Oligotrophic lakes are characterized by:





24. : Nekton refers to aquatic organisms that:





25. : The ultimate importance of marine phytoplankton is that they:





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