Question

What is the pattern of food relationships in an ecosystem called?

• A. Ecological pyramid
• B. Food web
• C. Trophic organization
• D. Standing crop

Answer 1

Answer:

C. Trophic organization

Understanding Trophic Organization in Ecosystems

• Trophic organization refers to the hierarchical structure of feeding relationships within an ecosystem, categorizing organisms by their position in the food chain based on their primary source of energy.
• This organization dictates the flow of energy and nutrients through an ecosystem.

Key Components of Trophic Organization:

• 1. Trophic Levels:

  • A trophic level is the position an organism occupies in a food chain. It represents how an organism obtains energy.
  • Organisms at the same trophic level obtain energy from similar sources.

• 2. Producers (Autotrophs):

  • These are organisms, primarily plants and algae, that produce their own food using sunlight (photosynthesis) or chemical energy (chemosynthesis).
  • They form the first trophic level and are the base of almost all ecosystems.
  • Example: Grass, trees, phytoplankton.

• 3. Consumers (Heterotrophs):

  • These organisms obtain energy by consuming other organisms. They are categorized based on what they eat:
  • Primary Consumers (Herbivores): Organisms that feed directly on producers. They occupy the second trophic level.
  • Example: Deer, rabbits, caterpillars, zooplankton.
  • Secondary Consumers (Carnivores/Omnivores): Organisms that feed on primary consumers. They occupy the third trophic level.
  • Example: Snakes, small fish, birds that eat insects.
  • Tertiary Consumers (Top Carnivores/Omnivores): Organisms that feed on secondary consumers. They occupy the fourth trophic level.
  • Example: Eagles, sharks, lions, humans.

• 4. Decomposers (Detritivores):

  • These organisms, primarily bacteria and fungi, break down dead organic matter (dead plants, animals, and waste products).
  • They play a crucial role in nutrient cycling, returning essential nutrients back to the ecosystem for producers to reuse.
  • While not typically assigned a specific trophic level in the main chain, they operate at all levels by consuming dead matter from every trophic level.

Related Concepts for Competitive Exams:

• Food Chain: A simple, linear pathway showing the flow of energy from one organism to another (e.g., Grass → Deer → Lion).
• Food Web: A more complex and realistic representation of feeding relationships in an ecosystem, consisting of multiple interconnected food chains. It shows that most organisms eat, and are eaten by, more than one type of organism.
• Ecological Pyramids: Graphical representations of the trophic structure of an ecosystem. They can be:
• Pyramid of Energy: Always upright, showing the decreasing amount of energy available at successive trophic levels.
• Pyramid of Biomass: Represents the total mass of living organisms at each trophic level. Can be inverted in some aquatic ecosystems (e.g., phytoplankton biomass < zooplankton biomass).
• Pyramid of Numbers: Represents the number of individuals at each trophic level. Can be inverted (e.g., a single large tree supporting many insects).
• Ten Percent Law (Lindeman's Law): Proposed by Raymond Lindeman, this ecological rule states that only about 10% of the energy from one trophic level is transferred to the next trophic level. The remaining 90% is lost, primarily as heat during metabolic processes. This limits the number of trophic levels in most ecosystems to typically 4-5.
• Biomagnification/Bioaccumulation: The increase in concentration of persistent pollutants (like DDT or mercury) in organisms at higher trophic levels due to their consumption of contaminated prey. This is a critical environmental concern related to trophic organization.