1. Which of the following is NOT a characteristic of freshwater ecosystems? a) Low salinity
b) Presence of saltwater organisms
c) Found in lakes, rivers, and ponds
d) Occurrence of freshwater fish
Answer: b) Presence of saltwater organisms
2. What is the main difference between freshwater and marine ecosystems? a) Water temperature
b) Water salinity
c) Types of organisms
d) Water depth
Answer: b) Water salinity
3. Which of the following is a primary producer in freshwater ecosystems? a) Phytoplankton
b) Fish
c) Plankton
d) Decomposers
Answer: a) Phytoplankton
4. What is the most common organism in marine ecosystems? a) Fish
b) Phytoplankton
c) Sharks
d) Seals
Answer: b) Phytoplankton
5. In which of the following zones would you find the majority of marine life? a) Aphotic zone
b) Benthic zone
c) Intertidal zone
d) Littoral zone
Answer: c) Intertidal zone
6. Which of these freshwater ecosystems is characterized by standing water? a) Rivers
b) Ponds
c) Streams
d) Wetlands
Answer: b) Ponds
7. Which of the following organisms is an example of a benthic organism in a freshwater ecosystem? a) Algae
b) Snails
c) Plankton
d) Fish
Answer: b) Snails
8. What is the term for the area where a freshwater river meets the ocean? a) Estuary
b) Wetland
c) Coral reef
d) Bay
Answer: a) Estuary
9. Which of these ecosystems has the highest biodiversity? a) Freshwater lakes
b) Marine ecosystems
c) Rivers
d) Wetlands
Answer: b) Marine ecosystems
10. Which of the following organisms would you expect to find in both freshwater and marine ecosystems? a) Salmon
b) Clams
c) Tuna
d) Coral
Answer: a) Salmon
11. What type of organisms are primarily responsible for the production of oxygen in both freshwater and marine ecosystems? a) Fish
b) Phytoplankton
c) Mollusks
d) Crustaceans
Answer: b) Phytoplankton
12. Which of the following is a major source of salinity in marine ecosystems? a) Rainfall
b) Evaporation
c) River input
d) Wind
Answer: b) Evaporation
13. Which zone of the ocean is characterized by the absence of light? a) Photic zone
b) Aphotic zone
c) Benthic zone
d) Neritic zone
Answer: b) Aphotic zone
14. Which of the following is a type of freshwater ecosystem? a) Coral reef
b) Ocean trench
c) Pond
d) Mangrove swamp
Answer: c) Pond
15. What is the role of decomposers in both freshwater and marine ecosystems? a) To photosynthesize
b) To break down organic matter
c) To produce oxygen
d) To produce food for herbivores
Answer: b) To break down organic matter
16. Which of the following ecosystems is typically more nutrient-rich? a) Freshwater lakes
b) Marine ecosystems
c) Coral reefs
d) Open ocean
Answer: a) Freshwater lakes
17. Which of the following factors is most important in determining the type of species found in aquatic ecosystems? a) Temperature
b) Water salinity
c) Amount of sunlight
d) Depth of water
Answer: b) Water salinity
18. What term describes the uppermost layer of ocean water where sunlight penetrates? a) Aphotic zone
b) Benthic zone
c) Photic zone
d) Estuarine zone
Answer: c) Photic zone
19. Which of the following organisms is a keystone species in marine ecosystems? a) Blue whale
b) Great white shark
c) Phytoplankton
d) Sea otter
Answer: d) Sea otter
20. In marine ecosystems, what type of organisms are most affected by ocean acidification? a) Phytoplankton
b) Mollusks
c) Fish
d) Seals
Answer: b) Mollusks
21. Which of the following is a characteristic of estuaries? a) High salinity
b) Constant temperature
c) Low biodiversity
d) Mixture of freshwater and seawater
Answer: d) Mixture of freshwater and seawater
22. What is the term for the bottom of a freshwater ecosystem, including the sediment and water? a) Littoral zone
b) Profundal zone
c) Benthic zone
d) Neritic zone
Answer: b) Profundal zone
23. Which of the following is an example of an adaptation in marine organisms to high salinity? a) Large kidneys
b) Specialized gills
c) Heavy exoskeletons
d) Ability to store water
Answer: b) Specialized gills
24. What is the primary source of energy for aquatic ecosystems? a) Tidal movement
b) Organic matter
c) Sunlight
d) Chemical reactions
Answer: c) Sunlight
25. What type of relationship is most commonly observed between organisms in coral reef ecosystems? a) Predation
b) Parasitism
c) Symbiosis
d) Competition
Answer: c) Symbiosis
26. Which of the following is NOT a significant threat to marine ecosystems? a) Overfishing
b) Pollution
c) Habitat destruction
d) Freshwater inflow
Answer: d) Freshwater inflow
27. What role do wetlands play in freshwater ecosystems? a) They act as a buffer against flooding
b) They are a source of freshwater
c) They are only a habitat for birds
d) They support high marine biodiversity
Answer: a) They act as a buffer against flooding
28. Which of the following is NOT a common feature of freshwater ecosystems? a) Presence of plankton
b) Aquatic plants
c) Saltwater organisms
d) Low salinity
Answer: c) Saltwater organisms
29. Which of the following organisms is most likely to be found in the benthic zone of marine ecosystems? a) Sea turtles
b) Crabs
c) Dolphins
d) Coral
Answer: b) Crabs
30. What type of adaptation allows certain fish to live in both freshwater and marine environments? a) Ectothermic metabolism
b) Osmoregulation
c) Saltwater filtration
d) Migration
Answer: b) Osmoregulation
