Energy Flow & Biogeochemical Cycles – Lecture Review

Fill-in-the-blank flashcards covering ecosystems, food chains & webs, trophic levels, energy pyramids, and major biogeochemical cycles (carbon, oxygen, nitrogen).

An ecosystem is the system formed by the interaction between and abiotic factors.

biotic

Living components of an ecosystem are called factors.

biotic

Non-living components such as water, soil and air are called factors.

abiotic

The definite sequence in which energy is transferred from producer to various consumers is known as a .

food chain

A network of many inter-linked food chains is called a .

food web

In a food web, the presence of multiple predators increases the and competitiveness of organisms.

adaptability

Plants that manufacture their own food are termed .

producers

Herbivores that feed directly on producers occupy the consumer level.

primary

Carnivores that feed on herbivores are called consumers.

secondary

Top predators that have no natural enemies are known as consumers.

apex (or top)

Organisms that break down dead matter and recycle nutrients are called .

decomposers

The graphical representation showing decrease of energy at successive trophic levels is the of energy.

pyramid

Only about % of energy is transferred from one trophic level to the next higher level.

10

Energy flow in an ecosystem is (one-way/cyclic).

one-way

The continuous cyclic movement of nutrients between biotic and abiotic components is termed a cycle.

biogeochemical

Cycles that primarily involve gaseous elements like CO₂, O₂, or N₂ are classified as cycles.

gaseous

Carbon enters the biotic pool chiefly through the process of .

photosynthesis

Carbon returns to the atmosphere mainly by in plants and animals.

respiration

Burning of fossil fuels adds to the atmosphere.

carbon dioxide (CO₂)

About 21 % of Earth’s atmosphere consists of .

oxygen

Oxygen released during photosynthesis is consumed in processes such as in organisms.

respiration

Approximately 78 % of the atmosphere is composed of .

nitrogen

Conversion of atmospheric nitrogen into ammonia or nitrate is called nitrogen .

fixation

The step that converts ammonia to nitrites and then nitrates is called .

nitrification

Transformation of nitrates back to free nitrogen gas is termed .

denitrification