Which factor primarily determines the vertical distribution of temperature in the oceans and affects marine life?
A Salinity
B Depth
C Currents
D Waves
Temperature decreases with depth due to reduced sunlight penetration, influencing density, stratification, and the habitats of marine organisms.
Why do upwelling zones along coasts like Peru and California have high fish productivity?
A Cold water only
B Nutrient-rich deep waters rise to surface
C Warm water only
D Low salinity
Upwelling brings nutrients from the deep ocean to surface layers, boosting phytoplankton growth and supporting abundant fish populations.
Which type of oceanic current transports warm water from equatorial regions toward polar regions?
A Cold currents
B Warm currents
C Surface tides
D Deep currents
Warm surface currents redistribute heat from equatorial to higher latitudes, moderating climates and influencing weather patterns along coastlines.
Why are coral reefs referred to as “rainforests of the sea”?
A High rainfall
B Extremely high biodiversity and productivity
C Shallow waters only
D Low oxygen
Coral reefs host thousands of marine species and complex interactions, providing food, shelter, and breeding grounds like terrestrial rainforests.
Which process explains the formation of tides and their effect on coastal ecosystems?
A Wave erosion
B Gravitational pull of moon and sun
C Ocean salinity
D Wind action
Tides result from lunar and solar gravitational forces, causing periodic high and low water levels that shape coastal habitats and influence species.
Why is ocean salinity lower near the mouths of major rivers?
A Evaporation
B Freshwater inflow dilutes seawater
C Tidal action
D High temperature
Large rivers discharge freshwater into oceans, decreasing local salinity and affecting water density, circulation, and marine ecosystems.
Which feature of coral reefs helps in protecting human settlements from storm surges?
A Coral height only
B Dissipates wave energy
C Salinity absorption
D Temperature regulation
Coral structures break and absorb wave energy, reducing coastal erosion, flood risk, and damage to human settlements during storms.
Why do mangroves act as carbon sinks in coastal regions?
A Increase oxygen
B Accumulate carbon in biomass and sediments
C Reduce tides
D Change salinity
Mangroves store carbon in roots, stems, and soils, preventing its release into the atmosphere and mitigating climate change impacts.
Which oceanic zone is most productive for photosynthesis due to sunlight penetration?
A Abyssal
B Photic
C Bathyal
D Hadal
The photic zone receives sufficient sunlight for photosynthesis, supporting primary producers like phytoplankton, which form the base of the marine food web.
Which human activity is most responsible for the degradation of coral reef ecosystems?
A Boating
B Overfishing, pollution, and climate change
C Swimming
D Sailing
Excessive fishing, pollutants, and rising sea temperatures disrupt reef health, decrease biodiversity, and threaten ecosystem services.
Why are estuaries considered highly productive ecosystems despite variable salinity?
A Constant salinity
B Nutrient-rich sediments support diverse species
C Low temperature
D Shallow water only
Mixing of freshwater and seawater creates nutrient-rich environments that promote high primary productivity and sustain a variety of flora and fauna.
Which oceanic current is responsible for the warm climate of Western Europe?
A Labrador Current
B North Atlantic Drift
C California Current
D Benguela Current
Warm waters of the North Atlantic Drift flow northeast, raising winter temperatures in Europe, moderating climate, and supporting agriculture.
Why are wetlands important for maintaining water quality in coastal regions?
A Increase salinity
B Filter pollutants and sediments
C Reduce tides
D Block sunlight
Wetlands trap sediments, absorb excess nutrients and pollutants, purifying water before it enters rivers, estuaries, and oceans.
Which ecological process ensures the recycling of nutrients from dead organic matter?
A Photosynthesis
B Decomposition
C Evaporation
D Sedimentation
Decomposers break down dead organisms, returning nutrients to soil or water, sustaining ecosystem productivity and nutrient cycles.
Why are food webs more stable than simple food chains in ecosystems?
A Single predator
B Multiple interconnections provide alternative energy paths
C Only plants
D Only animals
Food webs integrate multiple feeding relationships, allowing energy flow through several pathways, increasing ecosystem resilience and stability.
Which factor mainly affects the formation and health of coral reefs?
A Deep water
B Warm, shallow, and clear water
C Low salinity
D Ice cover
Coral reefs require sunlight for symbiotic algae photosynthesis, stable warm temperatures, and clear waters for optimal growth and biodiversity.
Why are upwelling areas considered hotspots for fisheries?
A Warm water
B Nutrient supply from deep ocean promotes plankton growth
C Shallow reefs
D Low salinity
Upwelling brings nutrients to surface waters, enhancing phytoplankton productivity and supporting rich fish populations critical for commercial fisheries.
Which factor explains the seasonal variation of salinity in some coastal regions?
A Salinity constant
B Rainfall and freshwater inflow
C Wind only
D Temperature only
Heavy rainfall or river discharge decreases salinity, while dry seasons increase it through evaporation, affecting marine species adapted to specific salinity ranges.
Why is mangrove deforestation a threat to coastal fisheries?
A Reduces waves
B Removes nursery grounds and shelter
C Reduces rainfall
D Lowers salinity
Mangroves provide critical habitat for juvenile fish and crustaceans; their loss reduces fish survival, affecting local fisheries and biodiversity.
Which oceanic phenomenon directly impacts rainfall and drought patterns in Asia and Australia?
A Tides
B El Niño and La Niña
C Upwelling only
D Salinity
Pacific Ocean temperature anomalies influence monsoon and precipitation patterns, causing floods, droughts, and agricultural impacts across Asia and Australia.
Which human activity is considered the largest contributor to coral bleaching?
A Sailing
B Global warming
C Fishing lightly
D Swimming
Rising sea temperatures stress corals and their symbiotic algae, causing bleaching and reducing reef resilience and biodiversity.
Why do phytoplankton form the base of marine food webs?
A They float
B Photosynthesis converts solar energy into biomass
C Provide shelter
D Absorb salinity
Phytoplankton produce organic matter via photosynthesis, supplying energy to herbivores and higher trophic levels in the marine ecosystem.
Which oceanic zone is least affected by seasonal temperature changes but supports unique deep-sea species?
A Photic
B Abyssal
C Littoral
D Neritic
Abyssal zones are deep, cold, and dark, experiencing stable temperatures year-round, supporting specially adapted organisms with unique survival mechanisms.
Why are coastal mangroves considered natural defense mechanisms against tsunamis?
A Increase rainfall
B Roots and vegetation dissipate wave energy
C Reduce tides
D Alter salinity
Dense mangrove roots slow down and absorb tsunami waves, reducing their impact on inland areas and protecting human settlements.
Which factor primarily controls oceanic thermohaline circulation?
A Wind only
B Temperature and salinity differences
C Wave height
D Tides
Variations in water density due to temperature and salinity drive deep ocean currents, distributing heat and regulating global climate.
Why is biodiversity higher in coral reef ecosystems than in polar oceans?
A Low temperature
B Warm, stable environment with high sunlight and productivity
C Ice cover
D Low oxygen
Tropical coral reefs have optimal light, temperature, and nutrient availability, supporting diverse species, unlike cold, ice-covered polar regions.
Which ecosystem service is provided by wetlands besides habitat provision?
A Salinity increase
B Flood control and water purification
C Increase waves
D Prevent rainfall
Wetlands act as natural sponges, storing floodwater, filtering pollutants, and maintaining water quality, crucial for environmental and human health.
Which factor makes upwelling regions important for global fisheries?
A Low temperature
B Nutrient enrichment promotes high primary productivity
C Shallow depth only
D Low salinity
Upwelling brings nutrients to the surface, enhancing phytoplankton growth and supporting abundant fish populations essential for global fisheries.
Why is the conservation of marine biodiversity critical for human food security?
A Reduces rainfall
B Provides sustainable fish and seafood resources
C Controls tides
D Regulates temperature
Healthy marine ecosystems sustain fish stocks, ensuring protein sources for millions and maintaining livelihoods dependent on fisheries.
Which factor mainly determines the geographic distribution of coral reefs globally?
A Ocean depth and temperature
B Salinity only
C Ice cover
D Wave height
Corals require shallow, warm, and sunlit waters for photosynthetic algae, restricting reefs to tropical and subtropical regions.
Which process ensures transfer of energy from primary producers to carnivores in marine ecosystems?
A Photosynthesis
B Consumption
C Evaporation
D Decomposition
Energy is transferred as herbivores eat producers and carnivores eat herbivores, forming marine food chains and webs.
Why are mangrove forests often referred to as “coastal guardians”?
A Increase rainfall
B Prevent erosion and protect biodiversity
C Increase tides
D Reduce currents
Mangroves stabilize shorelines, absorb wave energy, and provide habitats for numerous species, safeguarding coastal ecosystems and human communities.
Which ocean current flows along the west coast of Africa and cools the region?
A Labrador Current
B Benguela Current
C Gulf Stream
D Kuroshio Current
The cold Benguela Current flows northward along Africa’s west coast, lowering coastal temperatures and supporting productive fisheries through upwelling.
Why are estuaries considered critical for migratory bird populations?
A Low salinity
B Provide abundant food and shelter during migration
C Reduce tides
D Increase waves
Estuaries’ nutrient-rich waters support abundant fish and invertebrates, offering feeding and resting sites for migratory birds.
Which factor explains higher biodiversity in tropical coral reefs compared to temperate reefs?
A Ice cover
B Warm, nutrient-rich, stable environment
C Low salinity
D Low oxygen
Stable warm waters, high sunlight, and nutrient availability promote complex interactions and greater species richness in tropical coral reefs.
Why is monitoring phytoplankton populations important for ocean health?
A Aesthetic purposes
B Indicator of water quality and primary productivity
C Reduce waves
D Control tides
Phytoplankton abundance reflects nutrient availability and ecosystem productivity, forming the base of marine food webs and indicating ocean health.
Which human intervention threatens wetlands the most?
A Birdwatching
B Drainage for agriculture and urbanization
C Fishing lightly
D Sailing
Wetland reclamation destroys habitats, reduces biodiversity, increases flood risks, and disrupts natural water filtration processes.
Why do cold ocean currents support less diverse but highly productive fisheries in some regions?
A Warm water
B Upwelling of nutrients supports plankton but limits species diversity
C Low salinity only
D Ice cover only
Cold currents bring nutrient-rich waters enhancing plankton growth, supporting high fish abundance, but lower temperatures limit species diversity.
Which human activity accelerates ocean acidification, affecting coral reefs?
A Fishing
B CO₂ emissions from fossil fuels
C Sailing
D Tourism
Excess atmospheric CO₂ dissolves in oceans, lowering pH, weakening coral skeletons, and threatening reef ecosystems.
Why are mangroves vital for maintaining coastal water quality?
A Reduce waves
B Filter sediments and pollutants
C Increase tides
D Increase salinity
Mangrove roots trap sediments, absorb nutrients, and filter contaminants, preventing pollution from reaching sensitive marine ecosystems.
Which factor explains seasonal changes in ocean surface temperature in temperate regions?
A Ocean depth
B Variation in solar radiation and currents
C Salinity only
D Tides only
Seasonal sunlight changes and movement of currents alter ocean surface temperatures, affecting marine life distribution and productivity.
Which oceanic current contributes to the cooling of western South America?
A Gulf Stream
B Peru (Humboldt) Current
C North Atlantic Drift
D Kuroshio Current
The cold Peru Current flows along the coast, lowering sea temperatures, enhancing upwelling, and supporting fisheries while cooling the region.
Why are coral reefs highly sensitive to even slight increases in sea temperature?
A Adapt quickly
B Symbiotic algae are temperature-sensitive
C Resistant to temperature
D Grow in deep water
Coral health depends on algae for nutrition; small temperature rises disrupt symbiosis, causing bleaching and reducing reef resilience.
Which ecological role is performed by decomposers in marine ecosystems?
A Photosynthesis
B Nutrient recycling
C Energy transfer only
D Oxygen production
Decomposers break down organic matter, returning nutrients to water or sediments, sustaining primary producers and overall ecosystem productivity.
Why are upwelling regions along the west coast of continents particularly rich in fish?
A Warm water
B Nutrient influx boosts phytoplankton and food availability
C Shallow water
D Low salinity
Rising nutrient-rich waters enhance primary productivity, supporting abundant fish populations crucial for fisheries.
Which factor determines the distribution of coral reefs along coastlines globally?
A Depth, sunlight, and temperature
B Salinity only
C Ice cover
D Wave height only
Corals require shallow, warm, sunlit waters; optimal conditions for symbiotic algae photosynthesis and reef biodiversity restrict reefs to tropical regions.
Why are wetlands referred to as “biological supermarkets”?
A Produce food
B Support high diversity of plants, fish, and birds
C Reduce tides
D Increase salinity
Wetlands provide abundant resources and habitats, supporting a wide array of species and sustaining ecological food webs.
Which oceanic phenomenon can disrupt fisheries and lead to droughts in affected regions?
A Tides
B El Niño
C Upwelling
D Waves
Warmer Pacific waters reduce upwelling, decreasing nutrient supply for fish and altering rainfall patterns, causing droughts and agricultural impacts.
Why is the study of ocean salinity crucial for understanding thermohaline circulation?
A Reduces rainfall
B Salinity affects water density, driving deep currents
C Controls waves only
D Aesthetic mapping
Differences in salinity and temperature influence water density, propelling deep ocean currents that regulate global climate and nutrient distribution.
Which factor explains the global significance of coral reefs for human societies?
A Low biodiversity
B Coastal protection, fisheries, and tourism
C Increase salinity
D Reduce rainfall
Coral reefs provide shoreline protection, support livelihoods through fisheries and tourism, and maintain ecological balance, making them globally significant.