Microtheme: Marine Ecosystem —
14 questions asked in Prelims in the past.

1. [2026] Which of the following best explain(s) the rationale for protecting mangrove ecosystems in the context of climate resilience?
   1. Mangroves reduce tidal energy and store freshwater, making them ideal sites for paddy cultivation in saline estuarine belts.
   2. Their salt-sensitive roots filter seawater, making mangroves key to converting coastal land into freshwater aquaculture zones.
   3. By withstanding tidal surges and offering biomass resources, mangroves function both as natural bio-shields and livelihood bases for rural communities.
   • (a) 1 only
   • (b) 1 and 2
   • (c) 2 and 3
   • (d) 3 only
   Correct Answer: (D) 3 only
2. [2021] Consider the following kinds of organisms:
   1. Copepods
   2. Cyanobacteria
   3. Diatoms
   4. Foraminifera
   Which of the above are primary producers in the food chains of oceans?
   • (a) 1 and 2
   • (b) 2 and 3
   • (c) 3 and 4
   • (d) 1 and 4
   Correct Answer: (B) 2 and 3
3. [2021] What is blue carbon?
   • (a) Carbon captured by oceans and coastal ecosystems
   • (b) Carton sequestered in forest biomass and agricultural soils
   • (c) Carbon contained in petroleum and natural gas
   • (d) Carbon present in atmosphere
   Correct Answer: (A) Carbon captured by oceans and coastal ecosystems
4. [2021] Which one of the following is a filter feeder?
   • (a) Catfish
   • (b) Octopus
   • (c) Oyster
   • (d) Pelican
   Correct Answer: (C) Oyster
5. [2018] Consider the following statements :
   1.Most of the world’s coral reefs are in tropical waters.
   2.More than one-third of the world’s coral reefs are located in the territories of Australia, Indonesia and Philippines.
   3.Coral reefs host far more number of animal phyla than those hosted by tropical rainforests.
   Which of the statements given above is/are correct ?
   • (a) 1 and 2 only
   • (b) 3 only
   • (c) 1 and 3 only
   • (d) 1, 2 and 3
   Correct Answer: (D) 1, 2 and 3
6. [2015] With reference to ‘dugong’ a mammal found in India, which of the following statements is/are correct?
   (1) It is a herbivorous marine animal.
   (2) It is found along the entire coast of India.
   (3) It is given legal protection under Schedule I of the Wildlife (Protection) Act 1972.
   Select the correct answer using the code given below.
   • (a) 1 and 2
   • (b) 2 only
   • (c) 1 and 3
   • (d) 3 only
   Correct Answer: (C) 1 and 3
7. [2014] Which of the following have coral reefs?
   1. Andaman and Nicobar Islands
   2. Gulf of Kachchh
   3. Gulf of Mannar
   4. Sunderbans
   Select the correct answer using the code given below:
   • (a) 1, 2 and 3 only
   • (b) 2 and 4 only
   • (c) 1 and 3 only
   • (d) 1, 2, 3 and 4 only
   Correct Answer: (A) 1, 2 and 3 only
8. [2013] Consider the following animals:
   (1). Sea cow
   (2). Sea horse
   (3). Sea lion
   Which of the above is/are mammal/mammals?
   • (a) 1 only
   • (b) 1 and 3 only
   • (c) 2 and 3 only
   • (d) 1, 2, and 3
   Correct Answer: (B) 1 and 3 only
9. [2012] What would happen if phytoplankton of an ocean is completely destroyed for some reason?
   1. The ocean as a carbon sink would be adversely affected.
   2. The food chains in the ocean would be adversely affected.
   3. The density of ocean water would drastically decrease.
   Select the correct answer using the code given below:
   • (a) 1 and 2 only
   • (b) 2 only
   • (c) 3 only
   • (d) 1, 2 and 3
   Correct Answer: (A) 1 and 2 only
10. [2012] The acidification of oceans is increasing. Why is this phenomenon a cause of concern?
    1. The growth and survival of calcareous phytoplankton will be adversely affected.
    2. The growth and survival of coral reefs will be adversely affected.
    3. The survival of some animals that have phytoplanktonic larvae will be adversely affected.
    4. The cloud seeding and formation of clouds will be adversely affected. Which among the statements given above is/are correct?
    • (a) 1, 2 and 3 only
    • (b) 2 only
    • (c) 1 and 3 only
    • (d) 1, 2, 3 and 4
    Correct Answer: (A) 1, 2 and 3 only
11. [2011] In the context of ecosystem productivity, marine upwelling zones are important as they increase marine productivity by bringing the:
    • (a) Decomposer microorganisms to the surface
    • (b) Nutrients to the surface
    • (c) Bottom-dwelling organisms to the surface
    • (d) None of the above
    Correct Answer: (B) Nutrients to the surface
12. [2011] The 2004 Tsunami made people realize that mangroves can serve as a reliable safety hedge against coastal calamities. How do mangroves function as a safety hedge?
    • (a) The mangrove swamps separate the human settlements from the sea by a wide zone in which people neither live nor venture out.
    • (b) The mangroves provide both food and medicines which people are in need of after any natural disaster.
    • (c) The mangrove trees are tall with dense canopies and serve as an excellent shelter during a cyclone or Tsunami.
    • (d) The mangrove trees do not get uprooted by storms and tides because of their extensive roots.
    Correct Answer: (D) The mangrove trees do not get uprooted by storms and tides because of their extensive roots.
13. [2009] The marine animal called dugong which is vulnerable to extinction is a/an:
    • (a) Amphibian
    • (b) Bony Fish
    • (c) Shark
    • (d) Mammal
    Correct Answer: (D) Mammal
14. [2007] The largest coral reef in the world is found near the coast of which one of the following countries?
    • (a) Australia
    • (b) Cuba
    • (c) Philippines
    • (d) Maldives
    Correct Answer: (A) Australia