Shankar IAS MCQs: Marine Organisms | Environment for UPSC CSE PDF Download

Q1: Statement 1: Sea grasses are unique as they are the only group of higher plants adapted to life in saltwater.
Statement 2: Major sea grass meadows in India are found primarily along the west coast of Maharashtra.
(a) Both statements are true
(b) Statement 1 is true, Statement 2 is false
(c) Statement 1 is false, Statement 2 is true
(d) Both statements are false
Ans: (b)
Statement 1 is correct as sea grasses are indeed unique for being the only higher plants adapted to saltwater. Statement 2 is false as major sea grass meadows in India are found along the south-east coast of Tamil Nadu and in the Lakshadweep Islands, not primarily along the west coast of Maharashtra.

Q2: Match the following sea grass functions with their correct descriptions:
(a) 1 - B, 2 - D, 3 - C, 4 -A
(b) 1 - A, 2 - B, 3 - C, 4 -D
(c) 1 - D, 2 - C, 3 - B, 4 -A
(d) 1 - C, 2 - A, 3 - B, 4 -D
Ans: (a)
Reducing wave and current energy and stabilizing bottom sediments both contribute to controlling erosion. Enhancing fish populations is achieved by offering food and shelter, particularly in lagoon areas. Acting as nutrient sinks helps in buffering nutrient and chemical inputs to the marine environment.

Q3: Assertion (a): Seaweeds are important for human consumption, animal feed, and as plant fertilizers.
Reason (R): Seaweeds are macroscopic algae known as thalloid plants and lack true tissues.
(a) Both A and R are true, and R is the correct explanation of A
(b) Both A and R are true, but R is not the correct explanation of A
(c) A is true, but R is false
(d) A is false, but R is true
Ans: (b)
The assertion about the importance of seaweeds is true. The reason is also true in describing the biological nature of seaweeds. However, the lack of true tissues in seaweeds is not directly related to their importance as human food, animal feed, or fertilizers.

Q4: Statement 1: Seaweeds are classified into different classes based on the color of their pigmentation.
Statement 2: The main classes of seaweeds are blue-green, green, yellow, and red.
(a) Both statements are true
(b) Statement 1 is true, Statement 2 is false
(c) Statement 1 is false, Statement 2 is true
(d) Both statements are false
Ans: (b)
Statement 1 is correct as seaweeds are classified based on pigmentation color. However, Statement 2 is incorrect; the main classes are blue-green, green, brown, and red, not yellow.

Q5: Assertion (a): Rotting seaweed is a source of hydrogen sulfide, a toxic gas.
Reason (R): Seaweeds are used as potential indicators of pollution in coastal ecosystems.
(a) Both A and R are true, and R is the correct explanation of A
(b) Both A and R are true, but R is not the correct explanation of A
(c) A is true, but R is false
(d) A is false, but R is true
Ans: (b)
Both statements are true, but the reason (seaweeds as pollution indicators) is not a direct explanation for the assertion (rotting seaweed producing hydrogen sulfide).

Q6: Dugong, a mammal dependent on sea grass for food, is not considered at risk of extinction.
(a) True
(b) False
Ans: (b) False
The statement is false. Dugong, a mammal that relies on sea grass, is indeed on the verge of extinction.

Q7: Arrange the following species of turtles nesting on the Indian coast in the order of their mention in the provided information:
1. Olive Ridley
2. Green turtle
3. Leatherback sea turtle
4. Hawksbill
5. Loggerhead turtle
(a) 3, 2, 1, 4, 5
(b) 1, 2, 3, 4, 5
(c) 2, 3, 4, 1, 5
(d) 5, 4, 3, 2, 1
Ans: (a) 3, 2, 1, 4, 5
The correct order as mentioned in the provided information is Leatherback sea turtle, Green turtle, Olive Ridley, Hawksbill, and Loggerhead turtle.

Q8: Which of the following is a unique characteristic of sea grasses?
(a) They are microscopic organisms.
(b) They are the only group of higher plants adapted to life in saltwater.
(c) They thrive in deep oceanic waters.
(d) They lack root systems.
Ans: (b)
Sea grasses are marine flowering plants adapted to life in saltwater, distinguishing them as the only group of higher plants with this adaptation.

Q9: Seaweeds play a role in the biodegradation process, producing gases like methane.
(a) True
(b) False
Ans: (a) True
The statement is true. Seaweeds contribute to the biodegradation process, which can lead to the production of gases like methane.

Q10: Statement 1: Seaweeds are commonly distributed from inter-tidal to sub-tidal regions down to a depth of 15m.
Statement 2: IUCN prioritizes the conservation of sea grass.
(a) Both statements are true
(b) Statement 1 is true, Statement 2 is false
(c) Statement 1 is false, Statement 2 is true
(d) Both statements are false
Ans: (c) Statement 1 is false, Statement 2 is true
Statement 1 is false because seaweeds are commonly

Q11: Seagrass beds enhance fish and migratory bird populations by offering food and shelter.
(a) True
(b) False
Ans: (a)
True, as seagrass beds provide a habitat for various marine invertebrates and fishes, enhancing fish and migratory bird populations by offering food and shelter.

Q12: Match the following seaweed pigmentation classes with their colors:

(a) 1 - B, 2 - C, 3 - A, 4 - D
(b) 1 - A, 2 - B, 3 - C, 4 -D
(c) 1 - D, 2 - C, 3 - B, 4 -A
(d) 1 - C, 2 - D, 3 - A, 4 -B
Ans: (a)
Chlorophyta is green, Phaeophyceae is brown, Rhodophyta is red, and Cyanophyceae is blue-green.

Q13: Assertion (a): Eutrophication leads to algal blooms, which can harm seagrass beds.
Reason (R): Algal blooms reduce sunlight penetration, essential for the growth of seagrass.
(a) Both A and R are true, and R is the correct explanation of A
(b) Both A and R are true, but R is not the correct explanation of A
(c) A is true, but R is false
(d) A is false, but R is true
Ans: (a)
Eutrophication leads to excessive algal growth, which can block sunlight, vital for the growth of seagrass. Therefore, R is a correct explanation of A.

Q14: Statement 1: Seaweeds are used as a drug for goiter treatment and intestinal disorders.
Statement 2: Seaweeds are a significant source of freshwater.
(a) Only Statement 1 is true
(b) Only Statement 2 is true
(c) Both statements are true
(d) Both statements are false
Ans: (a)
Seaweeds are indeed used for medicinal purposes like goiter treatment and intestinal disorders. However, Statement 2 is false, as seaweeds do not provide a source of freshwater.

Q15: Trawling and overexploitation for commerce are major threats to both seagrass beds and seaweeds.
(a) True
(b) False
Ans: (a)
True, as both trawling and overexploitation directly threaten the health and sustainability of seagrass beds and seaweed ecosystems.

Q16: Seaweeds are broadly classified into different classes based on the color of their pigmentation, such as blue-green, green, brown, and ______.
(a) Yellow
(b) Orange
(c) Red
(d) Purple
Ans: (c) Red
Seaweeds are classified as blue-green, green, brown, and red based on their pigmentation.

Q17: Assertion (a): Seaweeds serve as important indicators of pollution in coastal ecosystems.
Reason (R): They have a high capacity to bind and accumulate heavy metals.
(a) Both A and R are true, and R is the correct explanation of A
(b) Both A and R are true, but R is not the correct explanation of A
(c) A is true, but R is false
(d) A is false, but R is true
Ans: (a)
Seaweeds are indeed used as indicators of pollution because of their ability to bind and accumulate heavy metals, making R a correct explanation for A.

Q18: Statement 1: Seagrass beds filter suspended sediments from the water.
Statement 2: Seagrass beds are predominantly found in deep oceanic waters.
(a) Only Statement 1 is true
(b) Only Statement 2 is true
(c) Both statements are true
(d) Both statements are false
Ans: (a) Only Statement 1 is true
Seagrass beds do filter suspended sediments from the water, but they are not found in deep oceanic waters; they thrive in shallow coastal waters.

Q19: Seagrass beds are major contributors to oxygen production in marine ecosystems.
(a) True
(b) False
Ans: (a) True
True, as seagrass beds, like other photosynthetic organisms, contribute to oxygen production in marine ecosystems.

Q20: What functions do sea grass beds perform in marine ecosystems?
I. Reduce wave and current energy.
II. Act as nutrient sinks on reef flats.
III. Provide habitat for terrestrial mammals.
(a) I only
(b) I and II only
(c) II and III only
(d) I, II, and III
Ans: (b)
Sea grass beds contribute to reducing wave energy and act as nutrient sinks, but they do not provide habitat for terrestrial mammals.