Q110. Which of the following belongs to the shellfish group?
[RRB Group D, 11 December 2025]
(A) Silver carp
(B) Bombay duck
(C) Tuna
(D) Molluscs
Answer: (D) Molluscs
Explanation: Molluscs such as oysters, clams and mussels are classified as shellfish in fisheries. Fishery resources include finfish and shellfish, including many crustaceans. Shellfish are commercially important but can accumulate contaminants from polluted coastal waters.
Q109. Which is NOT a factor controlling the formation and movement of ocean currents?
[RRB NTPC Undergraduate CBT-I, 14 August 2025]
(A) Soil type
(B) Temperature differences
(C) Earth’s rotation
(D) Wind
Answer: (A) Soil type
Explanation: Ocean currents respond to winds, density differences and Earth’s rotation. The type of soil on land has no direct, general role in forming these flows. Currents transport heat and nutrients, thereby affecting marine ecosystems and regional climate.
Q108. Which among the Alaska Current, North Atlantic Drift and West Wind Drift is a cold ocean current?
[UPSC NDA-I General Ability, 13 April 2025]
(A) Alaska Current only
(B) Alaska Current and North Atlantic Drift
(C) North Atlantic Drift and West Wind Drift
(D) West Wind Drift only
Answer: (D) West Wind Drift only
Explanation: The West Wind Drift, also called the Antarctic Circumpolar Current, carries cold water around Antarctica. The Alaska Current and North Atlantic Drift are warm-current systems. These contrasting flows influence sea temperatures, weather and marine productivity.
Q107. Which is NOT a primary factor determining the formation and direction of ocean currents?
[DSSSB Assistant Section Officer, 20 August 2025]
(A) Salinity gradients
(B) Prevailing winds
(C) Temperature gradients
(D) Lunar phases
Answer: (D) Lunar phases
Explanation: Winds and seawater-density gradients influence circulation directly, while lunar gravitational effects mainly generate tides. Ocean currents and tides are distinct movements, even though they can interact in shallow coastal settings and estuaries.
Q106. The Sundarbans mangrove forest in India is primarily located in which state?
[SCL Assistant, 13 July 2025]
(A) Odisha
(B) West Bengal
(C) Assam
(D) Kerala
Answer: (B) West Bengal
Explanation: India’s Sundarbans occupy the southern part of West Bengal within the Bengal delta. Tidal channels and saline conditions favour mangrove species. Their roots trap sediment and provide shelter for juvenile fish, crustaceans and numerous other organisms.
Q105. Mangrove vegetation is usually found in which landform?
[RPF Constable, 18 March 2025]
(A) Cold deserts
(B) Hot deserts
(C) River deltas
(D) High plateaus
Answer: (C) River deltas
Explanation: Mangroves commonly occupy tropical deltaic shorelines, estuaries and sheltered coastal wetlands. Sediment deposition and regular tidal flooding create suitable conditions. Their ecological services include shoreline protection, nutrient cycling and nursery grounds for fish and prawns.
Q104. In which state are the Sundarbans mangroves located?
[RPF Constable, 5 March 2025]
(A) Kerala
(B) West Bengal
(C) Gujarat
(D) Odisha
Answer: (B) West Bengal
Explanation: The Indian Sundarbans extend across the lower Ganga delta of West Bengal. Saline and freshwater mixing produces a complicated network of creeks and islands. This environment supports mangroves, estuarine fisheries and globally important coastal wildlife.
Q103. Which vegetation type dominates the Sundarbans?
[RPF Constable, 18 March 2025]
(A) Tropical thorn forest
(B) Tropical deciduous forest
(C) Tropical evergreen upland forest
(D) Mangrove forest
Answer: (D) Mangrove forest
Explanation: The Sundarbans are named for their mangrove environment, where species have adaptations such as breathing roots and salt tolerance. Tides periodically inundate the sediment. These forests offer natural protection from storms and sustain aquatic biodiversity.
Q102. Which country was selected for the vice-presidency of the International Organization for Marine Aids to Navigation?
[RRB NTPC Undergraduate CBT-I, 29 August 2025]
(A) France
(B) Japan
(C) Australia
(D) India
Answer: (B) Japan
Explanation: Japan’s selection concerned the leadership of an international body responsible for improving maritime navigation safety. Clear navigation systems support shipping and port commerce while helping vessels avoid accidents that could damage marine and coastal habitats.
Q101. Which statement about El Niño and La Niña is INCORRECT?
[RPSC RAS Preliminary Examination, 2 February 2025]
(A) Both are types of tropical cyclones
(B) El Niño can reduce marine phytoplankton off Peru
(C) La Niña commonly strengthens Pacific trade winds
(D) Both are Pacific climate patterns
Answer: (A) Both are types of tropical cyclones
Explanation: El Niño and La Niña are opposing phases of the El Niño–Southern Oscillation, not tropical cyclones. Changes in equatorial Pacific winds and upwelling affect sea temperatures, nutrients and fish catches, particularly along the South American coast.
