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Q80 (IAS/2014) Environment & Ecology › Ecology & Ecosystem Basics › Food chains Official Key

Which one of the following is the correct sequence of a food chain?

Result
Your answer: —  Âˇ  Correct: A
Explanation

The correct answer is option A: Diatoms-Crustaceans-Herrings.

In a food chain, energy flows from producers to consumers. Diatoms are autotrophs, prepare their own food.[1] Algae and diatoms are the most important species of phytoplankton communities.[2] As primary producers, diatoms form the base of the marine food chain.

Crustaceans are consumers / heterotrophs.[3] They feed on phytoplankton like diatoms. Finally, Herrings are carnivorous animals which feed on Crustaceans.[1] This establishes the correct sequence: Diatoms (producers) → Crustaceans (primary consumers) → Herrings (secondary consumers).

The other options are incorrect because they violate the basic principle of energy flow in food chains, where producers must come first, followed by herbivores, and then carnivores.

Sources
  1. [2] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 3: MAJOR BIOMES > Classifcation of marine ecosystems > p. 31
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Don’t just practise – reverse-engineer the question. This panel shows where this PYQ came from (books / web), how the examiner broke it into hidden statements, and which nearby micro-concepts you were supposed to learn from it. Treat it like an autopsy of the question: what might have triggered it, which exact lines in the book matter, and what linked ideas you should carry forward to future questions.
Q. Which one of the following is the correct sequence of a food chain? [A] Diatoms-Crustaceans-Herrings [B] Crustaceans-Diatoms-Herrings …
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Origin: Books + Current Affairs Fairness: Low / Borderline fairness Books / CA: 2.5/10 ¡ 7.5/10
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This is a classic 'Concept Application' question. You are not expected to memorize every specific food chain, but you must master the functional roles: Diatoms = Producers (Phytoplankton), Crustaceans = Consumers (Zooplankton), Herrings = Carnivores (Nekton). If you know the hierarchy, this is a free mark.

How this question is built

This question can be broken into the following sub-statements. Tap a statement sentence to jump into its detailed analysis.

Statement 1
Is the sequence Diatoms → Crustaceans → Herrings a correct food chain among diatoms, crustaceans and herrings?
Origin: Direct from books Fairness: Straightforward Book-answerable
From standard books
Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 3: MAJOR BIOMES > Classifcation of marine ecosystems > p. 31
Presence: 5/5
“Tese are found in all oceanic depths. At diferent landforms of the seashore, there develop numerous types of fauna and fora. Crabs, crustaceans are important in the seashore, who make holes in the sea-sand. A large number of birds feed on their prey by probing into the sand or mud on the seashore. Several species of fsh and grasses are also found in the coastal ecosystems. Te numerous fauna and fora species are confned and concentrated along the photic zone. Te communities include planktons, phytoplanktons and diatoms. Algae and diatoms are the most important species of phytoplankton communities. Numerous types of bacteria are also found in the pelagic biome. (ii) Benthic Biome: It is the zone of the ocean bottom.”
Why this source?
  • Identifies diatoms as important members of phytoplankton communities in marine ecosystems.
  • Places diatoms at the base of planktonic communities, consistent with a producer role in a food chain.
Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 4: Aquatic Ecosystem > iii) Planktoni > p. 33
Presence: 5/5
“• This group includes both microscopic plants like algae (phytoplankton) and animals like crustaceans and protozoans (zooplankton) found in all aquatic ecosystems, except certain swift moving waters. • The locomotory power of the planktons is limited so that their distribution is controlled, largely, by currents in the aquatic ecosystems.”
Why this source?
  • Defines plankton group as including microscopic plants (phytoplankton) and animals like crustaceans (zooplankton).
  • Explicitly identifies crustaceans as planktonic animals (zooplankton) that feed within aquatic ecosystems.
Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 3: MAJOR BIOMES > Food Chains in Marine Biomes > p. 33
Presence: 4/5
“Tese zooplanktons come upward during the night time to graze phytoplanktons. Most of the nekton fshes and many benthos animals like carnivorous crustaceans also come upward during nights to catch their preys. Tese carnivorous nekton and benthos animals again return to their respective places during daytime. Te above description reveal that the maritime food chain is very complex. Man's activities in the marine ecosystem have been confned largely to the uppermost trophic level. Exploitation of marine life by man, has been almost solely concerned with animals large enough in size and numbers to make them worth catching. Because of the complexity of the marine ecosystem, the visible afects of pollution are often only seen at a late stage, when it has already afected all trophic levels.”
Why this source?
  • States zooplanktons graze phytoplanktons and that nekton fishes come up to catch their prey at night.
  • Links zooplankton (which include crustaceans) as prey for nekton fishes, implying the next trophic step to fish such as herrings.
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Statement analysis

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