Q.58 Given below are two statements:
Statement-I: Oxygen produced by algal photosynthesis allows the growth of aerobic bacteria.
Statement-II: Commensal relationships are associations in which both the interacting organisms benefit from each other.
In the light of the above statements, choose the most appropriate answer
from the options given below:
(A) Both Statement-I and Statement-II are correct
(B) Both Statement-I and Statement-II are incorrect
(C) Statement-I is correct but Statement-II is incorrect
(D) Statement-I is incorrect but Statement-II is incorrect
Statement-I is correct, but Statement-II is incorrect, making (C) the right choice.
Key Facts
Algal photosynthesis produces O₂, enabling aerobic bacteria growth in low-oxygen environments like wastewater or aquatic systems, as seen in algal-bacterial granules. Statement-I holds true. Commensalism involves one organism benefiting while the other is unaffected—not both benefiting, which defines mutualism. Statement-II is false.
Options Explained
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(A) Both correct: Wrong; II confuses commensalism with mutualism.
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(B) Both incorrect: Wrong; I is a validated ecological process.
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(C) I correct, II incorrect: Correct; matches definitions and examples.
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(D) I incorrect, II correct: Wrong; I is factual, II misdefines symbiosis.
Introduction: Oxygen from Algal Photosynthesis and Commensal Relationships
Oxygen produced by algal photosynthesis allows aerobic bacteria to thrive, powering nutrient cycles in ecosystems. Commensal relationships feature one-sided benefits, unlike mutualism where both gain. These concepts are key for NEET ecology MCQs testing Statement-I and II accuracy.
Algal Photosynthesis and Aerobic Bacteria
Algae generate O₂ via photosynthesis, benefiting aerobes:
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In algal-bacterial consortia, photosynthetic O₂ enables ammonia oxidation and P uptake at low DO (<0.5 mg/L).
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Supports bacterial respiration without mechanical aeration, aiding wastewater treatment.
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Ancient cyanobacteria O₂ paved way for aerobic life.
Defining Commensal Relationships
Standard definition: One benefits (+), other neutral (0)—not both benefit.
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Examples: Barnacles on whales (shelter, no whale harm); clownfish-anemone (protection, anemone unaffected).
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Differs from mutualism (++/ e.g., bees-flowers) and parasitism (+/-).
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Rare true cases; some shift based on conditions.
MCQ Analysis: Statement-I and Statement-II
Question: I: Oxygen by algal photosynthesis allows aerobic bacteria growth. II: Commensals benefit both organisms.
| Option | Why Correct/Incorrect |
|---|---|
| (A) Both correct | Incorrect; II describes mutualism |
| (B) Both incorrect | Incorrect; I is ecological fact |
| (C) I correct, II incorrect | Correct; precise per sources |
| (D) I incorrect, II correct | Incorrect; reverses truths |
Answer: (C)
Ecological Relevance
These interactions sustain biodiversity: algal O₂ fuels bacteria for nutrient removal; commensalism allows coexistence without harm. Vital for exams and conservation.
