1. What percentage of Earth's surface is covered by oceans?
(A) 50%
(B) 60%
(C) 70%
(D) 80%
2. Which ocean is the largest by area?
(A) Atlantic Ocean
(B) Indian Ocean
(C) Arctic Ocean
(D) Pacific Ocean
3. What is the study of the physical and biological aspects of the ocean called?
(A) Geology
(B) Oceanography
(C) Meteorology
(D) Astronomy
4. Which marine zone is closest to the shore and is affected by tides?
(A) Pelagic zone
(B) Abyssal zone
(C) Intertidal zone
(D) Hadal zone
5. What type of organism forms the base of most ocean food chains?
(A) Phytoplankton
(B) Zooplankton
(C) Fish
(D) Coral
6. What is the name of the largest coral reef system in the world?
(A) Red Sea Reef
(B) Great Barrier Reef
(C) Mesoamerican Reef
(D) Belize Barrier Reef
7. Which oceanic feature is a deep valley on the ocean floor?
(A) Continental shelf
(B) Abyssal plain
(C) Seamount
(D) Ocean trench
8. What is the primary cause of ocean tides?
(A) Wind
(B) Earth’s rotation
(C) Gravitational pull of the moon
(D) Underwater earthquakes
9. What is the term for the warm, nutrient-poor surface layer of the ocean?
(A) Thermocline
(B) Mixed layer
(C) Euphotic zone
(D) Epipelagic zone
10. Which gas is most abundant in seawater?
(A) Oxygen
(B) Nitrogen
(C) Carbon dioxide
(D) Hydrogen
11. What marine animals build calcium carbonate shells?
(A) Mollusks
(B) Jellyfish
(C) Sea stars
(D) Sharks
12. What process do marine plants use to convert sunlight into energy?
(A) Photosynthesis
(B) Respiration
(C) Fermentation
(D) Chemosynthesis
13. Which ocean zone is known as the “midnight zone” where no sunlight penetrates?
(A) Mesopelagic
(B) Bathypelagic
(C) Abyssopelagic
(D) Hadalpelagic
14. Hydrothermal vents are primarily found at which oceanic feature?
(A) Ocean trenches
(B) Mid-ocean ridges
(C) Continental shelves
(D) Abyssal plains
15. Which is the largest marine mammal?
(A) Orca
(B) Blue whale
(C) Humpback whale
(D) Sperm whale
16. What is the function of bioluminescence in marine animals?
(A) Photosynthesis
(B) Respiration
(C) Attract prey or mates
(D) Defense against bacteria
17. What type of plankton are small drifting animals in the ocean?
(A) Phytoplankton
(B) Zooplankton
(C) Bacterioplankton
(D) Viruses
18. Which of the following is a key nutrient for marine plant growth?
(A) Oxygen
(B) Helium
(C) Calcium
(D) Phosphorus
19. The process where seawater becomes denser due to cooling or increased salinity is called:
(A) Evaporation
(B) Upwelling
(C) Thermohaline circulation
(D) Diffusion
20. Which part of a sea turtle’s body helps it to swim efficiently?
(A) Flippers
(B) Claws
(C) Tail
(D) Shell
21. What is the name of the floating community of organisms at the ocean’s surface?
(A) Benthic community
(B) Pelagic community
(C) Neuston
(D) Nekton
22. Which ocean layer contains the highest pressure?
(A) Surface layer
(B) Thermocline
(C) Abyssal zone
(D) Epipelagic zone
23. What is the term for animals that live on or in the seabed?
(A) Pelagic
(B) Nekton
(C) Benthic
(D) Planktonic
24. What is the main cause of ocean currents?
(A) Tides and moon gravity
(B) Wind and Earth’s rotation
(C) Salinity only
(D) Pressure from marine animals
25. Which of these is a filter-feeding marine animal?
(A) Clam
(B) Shark
(C) Dolphin
(D) Octopus
26. Which marine plant is known as "sea grass"?
(A) Kelp
(B) Mangrove
(C) Phytoplankton
(D) Seagrass
27. What is the main component of coral reefs?
(A) Silica
(B) Calcium carbonate
(C) Salt
(D) Sand
28. The deepest part of the ocean is known as the:
(A) Continental slope
(B) Abyssal plain
(C) Ocean trench
(D) Seamount
29. Which gas dissolves in seawater to create carbonic acid?
(A) Oxygen
(B) Carbon dioxide
(C) Nitrogen
(D) Methane
30. What is a major threat to coral reefs worldwide?
(A) Overfishing
(B) Coral bleaching
(C) Plastic pollution
(D) All of the above
31. Which fish is known for its ability to generate electric shocks?
(A) Electric eel
(B) Barracuda
(C) Clownfish
(D) Anglerfish
32. Which type of symmetry do most adult echinoderms exhibit?
(A) Bilateral
(B) Radial
(C) Asymmetrical
(D) Spherical
33. Mangrove forests are important because they:
(A) Prevent coastal erosion
(B) Provide nursery habitats
(C) Act as carbon sinks
(D) All of the above
34. What causes ocean acidification?
(A) Increased salt content
(B) Increased dissolved CO2
(C) Increased temperature
(D) Decreased oxygen
35. What kind of feeders are baleen whales?
(A) Carnivores
(B) Filter feeders
(C) Herbivores
(D) Omnivores
36. Which of the following is a pelagic fish?
(A) Flounder
(B) Tuna
(C) Crab
(D) Lobster
37. The process by which nutrients from deep water rise to the surface is called:
(A) Upwelling
(B) Downwelling
(C) Thermohaline circulation
(D) Tidal flow
38. Which ocean zone supports the greatest biodiversity?
(A) Abyssal zone
(B) Bathypelagic zone
(C) Hadal zone
(D) Intertidal zone
39. What kind of organism is a krill?
(A) Fish
(B) Crustacean
(C) Mollusk
(D) Algae
40. What is a characteristic of plankton?
(A) They actively swim against currents
(B) They live only on the seabed
(C) They are free-floating organisms
(D) They are all animals
41. Which part of the ocean floor is relatively flat and extends from the shore?
(A) Continental shelf
(B) Seamount
(C) Trench
(D) Abyssal plain
42. What type of reproduction is common in marine corals?
(A) Sexual and asexual
(B) Only sexual
(C) Only asexual
(D) Budding only
43. What is the main source of energy for hydrothermal vent communities?
(A) Sunlight
(B) Photosynthesis
(C) Chemosynthesis
(D) Heat from the sun
44. Which marine animal has tentacles with stinging cells called nematocysts?
(A) Starfish
(B) Jellyfish
(C) Clam
(D) Crab
45. What is the salinity of average seawater?
(A) 15 ppt
(B) 30 ppt
(C) 35 ppt
(D) 50 ppt
46. What is the name for the large circular current systems in the oceans?
(A) Tides
(B) Gyres
(C) Waves
(D) Upwellings
47. Which of these animals is a nekton?
(A) Plankton
(B) Shark
(C) Coral
(D) Seaweed
48. The ocean's biological pump helps in:
(A) Carbon sequestration
(B) Heat circulation
(C) Salt regulation
(D) Nutrient depletion
49. Which layer of the ocean has the steepest temperature gradient?
(A) Surface mixed layer
(B) Thermocline
(C) Deep ocean
(D) Abyssal zone
50. What is the main purpose of mangrove roots?
(A) Absorb salt
(B) Stabilize shorelines
(C) Provide habitat
(D) All of the above