UPSC Prelims 2014 Question:

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

Explanation:

• Organisms in food chains are grouped into categories called trophic levels. Roughly speaking, these levels are divided into producers (first trophic level), consumers (second, third, and fourth trophic levels), and decomposers.
  
  
• Producers, also known as autotrophs, make their own food. They make up the first level of every food chain.
  
  
• Diatoms are phytoplankton, they are the primary producers in the oceans while herrings are fish who eat crustaceans. Crustaceans live mostly in the ocean or other waters. Crustaceans have a hard, external shell that protects their body. The most commonly known crustaceans are the crab, lobster, and barnacle.
  
  

Therefore, option (1) is the correct answer.

Subject: Environment | Terrestrial and Aquatic Ecosystem