EcologyLesson 1 of 2 in the course Ecosystems

Ecosystem Energy Flow, Productivity, and Trophic Patterns

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

Energy powers the processes that keep organisms alive, from building large molecules to carrying out metabolism. In this lesson, we trace how energy first enters an ecosystem and how it becomes available to organisms at different trophic levels.

Organisms need a continuing energy supply to build macromolecules such as proteins, lipids, nucleic acids, and complex carbohydrates. Cells often use adenosine triphosphate (ATP) to power these reactions.

All flashcards

What is trophic level transfer efficiency (TLTE)?
The percentage of production at one trophic level represented as production at the next level.
What is net production efficiency (NPE)?
The percentage of assimilated energy that consumers convert into new biomass.
Why can an aquatic biomass pyramid be inverted?
Rapidly reproducing producers can have low standing biomass while supporting consumers with greater biomass.
What is biomagnification?
An increase in the concentration of a persistent toxic substance in organisms at higher trophic levels.
How do gross and net primary productivity differ?
GPP is the rate at which producers capture energy into organic compounds; NPP is the energy remaining after producer respiration.

Quiz questions

  1. Why does less energy generally remain available at each successive trophic level?Answer: Organisms use energy for life processes, release heat, and do not consume or assimilate all available food.
  2. Consumers at one trophic level produce 1,103 kcal/m2/yr1{,}103\ \text{kcal}/\text{m}^2/\text{yr} from 7,618 kcal/m2/yr7{,}618\ \text{kcal}/\text{m}^2/\text{yr} of production at the previous level. What is the approximate TLTE?Answer: 14.5%14.5\%
  3. Why do ectotherms generally have higher net production efficiency than endotherms?Answer: They usually expend less assimilated energy maintaining body temperature.
  4. Why can an aquatic ecosystem have an inverted biomass pyramid?Answer: Phytoplankton reproduce and are consumed rapidly, so their standing biomass can remain low.
  5. Why is an energy pyramid always upright?Answer: Less energy is available at each successive trophic level after energy use and losses.

Based on Biology 2e by Mary Ann Clark, Matthew Douglas, Jung Choi (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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