Questions: The diagram below shows a marine food chain with the amount of energy available to each trophic level in parentheses. Why does the amount of energy decrease as you move up the chain? Decomposers are using up the energy between each trophic level. Individual organisms at the upper trophic levels require less energy to survive than those at the lower ones. Producers use most of the energy before it can reach the upper levels. Some energy is lost as heat or not consumed by organisms at the next trophic level.

The diagram below shows a marine food chain with the amount of energy available to each trophic level in parentheses. Why does the amount of energy decrease as you move up the chain?
Decomposers are using up the energy between each trophic level.
Individual organisms at the upper trophic levels require less energy to survive than those at the lower ones.
Producers use most of the energy before it can reach the upper levels.
Some energy is lost as heat or not consumed by organisms at the next trophic level.

Transcript text: The diagram below shows a marine food chain with the amount of energy available to each trophic level in parentheses. Why does the amount of energy decrease as you move up the chain? Decomposers are using up the energy between each trophic level. Individual organisms at the upper trophic levels require less energy to survive than those at the lower ones. Producers use most of the energy before it can reach the upper levels. Some energy is lost as heat or not consumed by organisms at the next trophic level.

Solution

Solution Steps

Step 1: Analyze the trophic pyramid

The diagram shows a trophic pyramid, representing a marine food chain. The numbers in parentheses represent the amount of energy available at each trophic level. The energy decreases as you move up the pyramid, from phytoplankton (2500) to zooplankton (500), herring (50), mackerel (5), and finally tuna (0.5).

Step 2: Evaluate the given options

Option 1: Decomposers play a crucial role in breaking down organic matter and recycling nutrients, but they do not directly consume energy between trophic levels in the way a predator consumes its prey. While they get energy from dead organisms at all trophic levels, their presence doesn't explain the progressive decrease of available energy _between_ each trophic level.
Option 2: Organisms at higher trophic levels generally require _more_ energy overall than those at lower levels due to their larger size and greater metabolic demands.
Option 3: While producers (phytoplankton) use energy for their own metabolic processes, they are the base of the food chain, producing energy that is available to higher trophic levels. They do not actively prevent energy from reaching higher trophic levels.
Option 4: According to the 10% rule in ecology, only about 10% of the energy available at one trophic level is transferred to the next. This is because organisms use energy for life processes like respiration, movement, and reproduction. Some energy is also lost as heat. Additionally, not all organisms at one level are consumed by those at the next level; some die and decompose before being eaten.