- a. increases
- b. decreases
- c. remains constant
- d. none of the above
Ocean temperature generally decreases with depth because sunlight warms only the surface layers; deeper layers are colder.
b
- a. due to rotation of earth
- b. due to variation in temperature
- c. due to earth's movement
- d. all the above
Ocean currents are produced by a combination of factors: wind, Earth's rotation (Coriolis effect), differences in temperature and salinity (thermohaline), and tidal/other motions — hence 'all the above.'
d
- a. 1 and 2 are correct.
- b. 1 and 3 are correct.
- c. 2,3 and 4 are correct.
- d. 1,2 and 3 are correct
Statements 1 and 3 are correct: wide continental shelves provide shallow, nutrient-rich waters, and mixing of warm and cold currents increases nutrients. Statement 2 is generally false (upwelling/temperate zones are richer), statement 4 is true but not paired in given correct option.
b
- a. convergence of tectonic plates
- b. divergence of tectonic plates
- c. lateral movements of plates
- d. stearing of plates.
Mid-ocean (oceanic) ridges form at divergent plate boundaries where upwelling magma creates new oceanic crust.
b
- a. Continental shelf-Continental slope-Sea plain-Sea trench.
- b. Continental slope-Continental shelf-Sea plain-Sea trench.
- c. Sea plain-Continental slope-Continental shelf-Sea trench.
- d. Continental slope-Sea plain-Continental shelf-Sea trench.
Correct order from shore to deep ocean: continental shelf → continental slope → abyssal (sea) plain → ocean trench.
a
- a. Gulf Stream - Pacific Ocean
- b. Labrador current - North Atlantic Ocean
- c. Canary current - Mediterranean Sea
- d. Mozambique current - Indian Ocean
Gulf Stream flows in the North Atlantic Ocean (not the Pacific), so option (a) is incorrectly matched.
a
Concise definition: Hydrosphere comprises all Earth's water in liquid, solid and gaseous forms — oceans, seas, rivers, lakes, groundwater, glaciers and atmospheric moisture.
The hydrosphere is the global water envelope of Earth, including all water on the surface (oceans, lakes, rivers), underground, and in the atmosphere as vapor and ice.
Brief: Water evaporates from oceans and surfaces, forms clouds by condensation, returns as precipitation, then moves as surface runoff and groundwater back to oceans, completing the cycle.
The hydrological (water) cycle is the continuous movement of water between the oceans, atmosphere and land by processes of evaporation, condensation, precipitation, infiltration, runoff and subsurface flow.
List with short notes: Continental shelf (shallow), slope (steep), rise (sediment accumulation), abyssal plains (flat deep areas), mid-ocean ridges (undersea mountains), trenches (deepest), seamounts/guyots and canyons.
Major ocean floor features: continental shelf, continental slope, continental rise, abyssal plains, mid-ocean ridges (oceanic ridges), seamounts and guyots, submarine canyons, trenches (deeps), and oceanic islands.
Concise: Wind-driven forces for surface currents; thermohaline (density) differences drive deep currents; Coriolis effect deflects flows; tides and coast/sea-floor shapes also influence currents.
Main factors: wind action (surface currents), Earth's rotation (Coriolis effect), differences in water temperature and salinity (thermohaline circulation), tidal forces, and coastal configuration/seafloor topography.
Short note: Waves are energy transfer on water, generated chiefly by wind; their size depends on wind speed, duration and fetch. In deep water particles move in circular orbits; near shore waves break due to shallow depth.
Sea waves are oscillatory motions of the sea surface caused mainly by wind transferring energy to water; they have crest, trough, wavelength and amplitude, and break near shore forming surf.
Guyots are flat-topped seamounts formed from volcanic islands that were eroded and subsided. Thus both statements are true and the volcanic origin explains the existence of guyots.
A and R are true; R is the correct explanation of A.
Submarine canyons are steep-sided valleys cutting into the continental shelf, slope and rise. Their location on these features explains why they are deep gorges on the ocean floor.
A and R are true; R is the correct explanation of A.
Correct matches after correcting OCR mix-ups: 1) Mariana → Deepest point in the Pacific (Mariana Trench); 2) Great Barrier Reef → Australia; 3) Spring tides → On full and new moon days; 4) Heavy rains → Decreases salinity in the oceans; 5) Kuroshio → Along the coast of Japan; 6) Continental slope → Second order landform (part of submarine relief).
1-3, 2-4, 3-6, 4-1, 5-2, 6-5
Explanation: Distribution of continents shows most landmasses (Eurasia, North America, parts of Africa) lie in the Northern Hemisphere, whereas large oceans (Southern Ocean, southern parts of Pacific and Atlantic) dominate the Southern Hemisphere.
Because the Northern Hemisphere contains a larger proportion of Earth's land area (major continents), while the Southern Hemisphere contains more ocean area, it is called the Water Hemisphere.
Reasoned points: shallow depth (light for photosynthesis), nutrient supply from rivers and upwelling, and stable habitats make continental shelves ideal for fisheries.
Continental shelves are shallow, receive abundant sunlight and nutrients (from land runoff and upwelling), and have favorable temperatures — all of which promote high primary productivity and rich fish populations.
1. Food: Oceans supply fish and other seafood that are major protein sources for millions.
2. Livelihoods: Fisheries, aquaculture, processing, and related services employ large numbers of people.
3. Trade & transport: Seas provide economical routes for international trade and support ports and shipping industries.
4. Raw materials: Marine areas yield salt, sand, aggregates, minerals and hydrocarbons (offshore oil and gas).
5. Energy: Renewable marine energy (tidal, wave, offshore wind) contributes to power generation.
6. Tourism & recreation: Coastal and marine environments support tourism, boosting local economies.
7. Medicine & research: Marine organisms are sources of pharmaceutical compounds and scientific knowledge.
8. Environmental services: Oceans regulate climate, sequester carbon, and sustain biodiversity essential for ecological balance.
Marine resources influence mankind by providing food (fish and seafood), livelihoods (fishing, processing, allied industries), trade and transport (shipping routes and ports), raw materials (salt, minerals, oil and gas), energy (tidal, wave, offshore wind), recreation and tourism, sources of medicinal compounds, and by regulating climate and supporting biodiversity.
Distinction: Spring tides = larger tidal amplitudes (alignment of gravitational forces). Neap tides = smaller tidal amplitudes (partial cancellation of forces).
Spring tide: Highest tidal range occurring at new and full moon when Sun, Earth and Moon align. Neap tide: Lowest tidal range occurring at first and third quarters when Sun and Moon are at right angles.
Distinguish: Abyssal plains = flat, sediment-covered deep-sea floors; Ocean deeps/trenches = very deep, narrow troughs formed by subduction, much steeper and deeper than abyssal plains.
Abyssal plains are broad, flat areas of the deep ocean floor typically between 3,000–6,000 m depth, formed by fine sediment deposition. Ocean deeps (trenches) are the deepest, narrow, steep-sided depressions in the ocean floor, often found at convergent plate boundaries.
Paragraph: Continental shelves are nearshore, shallow zones with gradual slopes that extend from the shoreline and support rich marine life and fisheries. At the shelf edge the seabed drops more steeply at the continental slope, which connects the shelf to the deeper ocean basins and often contains submarine canyons and sediment deposits that form the continental rise.
The continental shelf is the gently sloping submerged extension of a continent, relatively shallow (usually up to 200 m deep), receiving sediments and sunlight, making it biologically productive. The continental slope marks the steeper descent from the shelf to the deep ocean floor; it is characterized by a sharper gradient, submarine canyons and sediment transport to the continental rise and abyssal plains.
Paragraph: Define currents and list types briefly: (1) Surface/wind-driven currents — horizontal flows in upper layers influenced by Coriolis effect (e.g., Gulf Stream); (2) Thermohaline/deep currents — density-driven vertical and horizontal flows forming global circulation; (3) Warm vs cold currents — differing temperature effects on climate and marine life; (4) Tidal and local coastal currents influenced by tides, bathymetry and geometry.
Ocean currents are continuous, directed movements of seawater produced by wind, Earth's rotation, differences in water density (temperature and salinity), tides and coastal features. Types include surface (wind-driven) currents, which affect the upper ocean and form gyres; deep (thermohaline) currents driven by density differences and forming global conveyor belts; warm currents (carry warm water poleward) and cold currents (carry cold water equatorward); and tidal currents associated with tidal flow.
Concise paragraph summarizing key influences: marine resources supply food and livelihoods, enable transport and trade, provide raw materials and energy, support tourism and scientific advances, and deliver essential environmental services like climate regulation and biodiversity support.
Marine resources profoundly affect human life: they provide a primary source of food through fisheries and aquaculture, sustain millions of livelihoods in fishing, processing and shipping, and support global trade via sea routes and ports. Oceans supply raw materials such as salt, minerals and offshore hydrocarbons, offer renewable energy potential (tidal, wave, wind), and drive coastal tourism and recreation that boost local economies. Additionally, marine organisms are valuable for medicine and research, while the oceans play a crucial role in climate regulation, carbon sequestration and maintaining biodiversity that underpins human well‑being.