Energy, Trophic Structure, and Ecosystem Productivity

Fill-in-the-blank flashcards covering energy flow, trophic structure, food chains/webs, and ecosystem productivity concepts.

In an system, energy flows in and out of Earth, whereas nutrients cycle within a system.

open ; closed

The primary energy source for nearly all life on Earth is _.

sunlight

The Law of Thermodynamics states that _ cannot be created or destroyed, only transformed.

energy

During photosynthesis, light energy is converted to chemical energy in the form of _.

glucose

Only about ___ % of incoming solar radiation is captured by photosynthetic organisms.

1

The balanced chemical equation for photosynthesis is 6CO₂ + 6H₂O → _ + O₂ (in the presence of light).

C₆H₁₂O₆

Organisms that produce their own food are called _ ("self-feeders").

autotrophs

Non-producers that obtain energy by consuming other organisms are called _.

heterotrophs

The trophic level made up of herbivores that eat plants is the _ consumer level.

primary

Carnivores or omnivores that consume herbivores occupy the _ consumer level.

secondary

Apex predators often function as _ consumers in a food chain.

tertiary

Detritivores feed on _ (dead organic matter).

detritus

_ (e.g., bacteria and fungi) break large organic molecules into smaller molecules that can be re-absorbed.

Decomposers

A diagram that shows energy transfer between trophic levels is called an energy _.

pyramid

On average, only about ___ % of the energy at one trophic level is transferred to the next level.

10

The total rate at which producers capture solar energy is called _ Primary Productivity (GPP).

Gross

After subtracting energy used in respiration, the remaining energy stored as biomass is _ Primary Productivity (NPP).

Net

Roughly _ % of the 1 % solar energy captured by plants is used in respiration.

60

NPP therefore represents about ___ % of the original solar energy reaching producers.

0.4

Ecosystem productivity is highest in beds & reefs and lowest in extreme & ice biomes.

algal ; desert

In terrestrial biomass pyramids, most biomass is found at the _ level.

producer

In many aquatic systems, the biomass pyramid appears _ (producers may have less biomass than consumers).

inverted

A sequence that shows "who eats whom" in an ecosystem is a food _.

chain

Because organisms often feed at multiple levels, a more realistic representation is a food _.

web

The efficiency of energy transfer from plants (P) to primary consumers (C₁) in Silver Springs, FL, was calculated to be about _ %.

16

Energy transfer from C₁ to secondary consumers (C₂) in Silver Springs was about _ %.

11

Energy transfer from C₂ to tertiary consumers (C₃) in Silver Springs was about _ %.

5

The term _ efficiency describes the proportion of energy passed from one trophic level to the next.

ecological

Marine ecosystems perform the majority of global _ because of abundant phytoplankton.

photosynthesis

Water and nutrient cycles are considered systems, whereas energy flow is .

closed ; open

The Greek root "troph" literally translates to _.

food

A biomass pyramid measures current living mass, often called the _ crop.

standing