Examkin

Question

Difficulty: MediumBasic Ecological Concepts and Ecosystem Structure

In a balanced terrestrial ecosystem, dead organic matter and excreted wastes accumulate on the forest floor and are acted upon by microorganisms such as fungi and bacteria. Which of the following statements correctly describes the ecological role and nutritional mechanism of these decomposers within the ecosystem structure?

  1. They perform extracellular saprophytic digestion to break down complex organic compounds, recycling inorganic nutrients back to the abiotic environment.Answer
  2. B
    They ingest solid organic waste holozoically and store primary energy, forming an inverted pyramid of energy at the apex of the ecosystem.
  3. C
    They absorb soil minerals and synthesize complex organic food internally through autotrophic light-independent reactions.
  4. D
    They convert soil nitrates directly into free atmospheric nitrogen gas to remove nutrients from the trophic structure.

Answer

Decomposers perform extracellular saprophytic digestion to break down complex organic matter, recycling inorganic nutrients back to the abiotic environment.
Decomposers (fungi and bacteria) are essential biotic components of ecosystem structure. They release digestive enzymes externally onto dead plant and animal matter to break down complex molecules into simple soluble compounds that are absorbed, releasing inorganic mineral nutrients back to the soil and abiotic environment.

Step-by-Step Solution

1
Identify the primary function of decomposers in an ecosystem structure.
Decomposers act as biotic recyclers that break down organic detritus into inorganic components.
Ecosystem nutrient cycles depend on decomposers to release minerals tied up in biomass back into abiotic pools.
2
Analyze the mode of nutrition utilized by fungi and decomposer bacteria.
They employ saprophytic nutrition involving extracellular digestion.
Enzymes are secreted onto dead substrates to break down complex polymers externally before absorption.
3
Evaluate the option choices against ecological principles.
The statement emphasizing extracellular saprophytic digestion and inorganic nutrient recycling accurately captures their function.
Energy pyramids cannot be inverted, saprophytes are heterotrophic rather than autotrophic, and ammonification differs from denitrification.

Key Concept

Role of Decomposers and Saprophytic Nutrition in Ecosystem Structure
Estimated Time:1m 15s
Rate this question

Topics

Basic Ecological Concepts and Ecosystem Structure

More questions from this topic