AP Environmental Science: Unit 1 Energy Dynamics

Primary Productivity

The rate at which solar energy is converted into organic compounds via photosynthesis over a unit of time.

Gross Primary Productivity (GPP)

The total rate of photosynthesis in a given area.

Net Primary Productivity (NPP)

The rate of energy storage by photosynthesizers in a given area, after subtracting the energy lost to respiration.

Respiration (R)

The energy plants use for their own cellular maintenance, growth, and reproduction.

NPP Formula

NPP = GPP - R, where NPP is Net Primary Productivity, GPP is Gross Primary Productivity, and R is Respiration.

Factors Affecting Productivity

Temperature, water availability, and nutrient availability are key factors that influence ecosystem productivity.

High Productivity Ecosystems

Ecosystems such as tropical rainforests and coral reefs that typically have high temperatures, high water availability, and consistent sunlight.

Medium Productivity Ecosystems

Ecosystems like temperate forests and grasslands with seasonal limitations that affect productivity.

Low Productivity Ecosystems

Ecosystems such as deserts and tundras, which suffer from a lack of water or nutrients.

Trophic Levels

The hierarchical levels in an ecosystem, consisting of producers, primary consumers, secondary consumers, and tertiary consumers.

Producers (Autotrophs)

Organisms that produce their own energy through photosynthesis or chemosynthesis.

Primary Consumers

Herbivores that feed on producers, such as crickets or cows.

Secondary Consumers

Carnivores or omnivores that eat primary consumers, like birds or frogs.

Tertiary Consumers

Apex predators at the top of the food chain, such as eagles or sharks.

Decomposers

Organisms like fungi and bacteria that break down organic matter into simpler nutrients.

Detritivores

Organisms like earthworms and vultures that physically break down dead tissues and waste.

First Law of Thermodynamics

Energy cannot be created or destroyed, only transformed.

Second Law of Thermodynamics

As energy is transferred, some is lost as heat; the quality of energy decreases.

10% Rule (Ecological Efficiency)

Only about 10% of the energy from one trophic level is transferred to the next level.

Food Chains

A linear sequence of organisms where nutrients and energy are transferred from one organism to another.

Food Webs

A complex network of interconnected food chains.

Trophic Cascade

When a predator at a high trophic level suppresses the abundance of prey, affecting lower trophic levels.

Keystone Species

A species that has a disproportionately large effect on its environment relative to its abundance.

Arrow Direction Mistake

Mistake of drawing arrows pointing to who eats whom; arrows should represent energy flow.

Biomass vs. Energy Mistake

Assuming the largest animal has the most energy; in reality, producers have the most energy.

GPP vs. NPP Mistake

Confusing NPP as just photosynthesis; NPP is what's actually available for growth and consumption.

Energy vs. Matter Mistake

Saying energy cycles; energy flows while matter cycles.