Mapping of the ocean floor

Correct answer: B. Bathymetric map

Explanation: A bathymetric map shows the depth and features of the ocean floor. Exam tip: connect it with submarine relief maps.

Correct answer: A. Sound wave

Explanation: Sonar sends sound waves and uses their echo to find depth. Exam tip: remember sonar with sound.

Correct answer: C. Isobath

Explanation: An isobath joins points of equal depth in a sea or ocean, so option C is correct. An isobar joins places of equal atmospheric pressure, whereas an isotherm represents equal temperature. Exam tip: associate “bath” in isobath with water depth.

Correct answer: B. Shallow sea area near the coast

Explanation: A continental shelf is a shallow area near the coast. Exam tip: connect it with resource-rich zones.

Correct answer: A. Continental shelf

Explanation: The continental slope begins after the shelf and deepens quickly. Exam tip: remember the order of shelf and slope.

Correct answer: B. Abyssal plain

Explanation: Abyssal plains are wide flat parts of the deep ocean. Exam tip: treat them as deep ocean plains.

Correct answer: C. Oceanic trench

Explanation: Oceanic trenches are long narrow and very deep parts. Exam tip: connect trenches with the deepest areas.

Correct answer: A. Mid-oceanic ridge

Explanation: A mid-oceanic ridge is a long raised chain on the ocean floor. Exam tip: understand it as an underwater mountain chain.

Correct answer: B. Seamount

Explanation: A seamount rises from the sea floor but often remains below the surface. Exam tip: remember it as a submerged mountain.

Correct answer: C. Guyot

Explanation: A guyot is a seamount whose summit has been eroded flat, usually by wave action when it was near sea level. Therefore, guyot is the correct answer. A ridge is a long elevated feature on the ocean floor, while a continental shelf is the shallow submerged edge of a continent. Exam tip: a flat-topped seamount is called a guyot.

Correct answer: A. Submerged deep valley

Explanation: The direct answer is A, a submerged deep valley. A submarine canyon is a long, narrow, steep-sided depression cut into the sea floor. It resembles a valley on land, but it is underwater. Such canyons may continue from the edge of a continent down the continental slope and can carry sediment into deeper parts of the ocean. Option A is correct because “submerged deep valley” describes its shape and position exactly. Option B, a desert dune, is a wind-built mound of sand on land and has the opposite form. Option C, a Himalayan peak, is a high mountain summit, not a deep channel in the ocean floor. Option D, a plain field, is broad and nearly level, whereas a canyon is narrow and deeply incised. The key is to separate “submarine” meaning under the sea from “canyon” meaning a deep valley. Memory cue: submarine canyon = underwater valley.

Correct answer: B. Recording water depth and bottom information

Explanation: Hydrographic survey deals with depths and bottoms of water bodies. Exam tip: connect it with navigation charts.

Correct answer: A. Because it shows marine depth and obstacles

Explanation: Knowing depths and obstacles helps ships choose safe routes. Exam tip: link mapping with ship safety.

Correct answer: B. It can measure a wide sea-floor area at once

Explanation: Multibeam sonar maps a wide floor area using many sound beams. Exam tip: connect it with detailed surveys.

Correct answer: A. It gives clues from small sea-surface variations

Explanation: Small sea-surface variations can indicate large features below. Exam tip: treat satellites as a supporting technique.

Correct answer: B. Between slope and abyssal plain

Explanation: The continental rise forms below the slope from sediments and meets the deep plain. Exam tip: treat it as a transition zone.

Correct answer: A. Deposition of sediments

Explanation: Sediments deposited in the deep sea cover uneven parts. Exam tip: link sediments with flatness.

Correct answer: B. Steep slope

Explanation: Closely spaced lines show a rapid change in depth. Exam tip: remember it like the rule of contour lines.

Correct answer: B. Gentle slope

Explanation: Isobaths join points of equal depth. When they are widely spaced, depth changes only slightly over a horizontal distance, indicating a gentle slope of the sea floor. A steep slope produces a rapid change in depth, so its isobaths are close together. Exam tip: closer contour or isobath lines indicate a steeper slope.

Correct answer: B. Mid-oceanic ridge

Explanation: New ocean floor formation is linked with mid-oceanic ridges. Exam tip: remember ridge and spreading together.

Correct answer: B. Convergent boundary

Explanation: Trenches often form where one plate sinks beneath another. Exam tip: connect trenches with convergence.

Correct answer: A. By giving information about marine structure and depth

Explanation: Knowing marine structure helps identify possible resource areas. Exam tip: connect resource exploration with mapping.

Correct answer: A. Because route depth and slope must be known

Explanation: The bottom structure and risks must be known for a safe cable route. Exam tip: connect it with modern communication.

Correct answer: A. Ocean floor features and trenches

Explanation: Trenches and marine structures help understand seismic zones. Exam tip: remember the link between undersea earthquakes and tsunamis.

Correct answer: A. Identification of undersea mountains and trenches

Explanation: Mapping identifies the real features of the ocean floor. Exam tip: treat identification and measurement as key results.