AP Environmental Science Unit 1

What is competition?

Interaction between organisms or species that compete for the same resources (food, space, mates) in an ecosystem.

What is predation?

An interaction where one organism (the predator) kills and eats another (the prey).

What type of vegetation is found in deserts?

Sparse vegetation like cacti, shrubs, and drought-resistant plants.

What type of vegetation is found in the savanna biome?

Grasses with scattered trees and shrubs.

What type of vegetation is found in the boreal forest biome?

Coniferous trees such as pine, spruce, and fir.

What is the largest nitrogen reservoir on Earth?

The atmosphere (about 78% nitrogen gas, N₂).

How does nitrogen move through the nitrogen cycle?

Through nitrogen fixation, nitrification, assimilation, ammonification, and denitrification.

What causes N₂ to be converted into nitrogen compounds in the soil?

Nitrogen-fixing bacteria or lightning.

What are herbivores in a food web?

Primary consumers that eat plants.

What are omnivores in a food web?

Consumers that eat both plants and animals.

What are carnivores in a food web?

Secondary or tertiary consumers that eat other animals.

How do you calculate biomass using the 10% rule?

Each trophic level has about 10% of the biomass of the level below it.

What determines the amount of NPP (Net Primary Productivity) in a biome?

Amount of sunlight, temperature, and availability of water and nutrients.

What are abiotic factors in an environment?

Nonliving components such as temperature, light, water, and soil.

What are biotic factors in an environment?

Living components like plants, animals, bacteria, and fungi.

What is the role of decomposers in an ecosystem?

Break down dead organisms and recycle nutrients back into the environment.

Define nitrification.

Conversion of ammonia (NH₃) to nitrate (NO₃⁻) by bacteria.

Define denitrification.

Conversion of nitrates (NO₃⁻) back into nitrogen gas (N₂) by bacteria.

Define assimilation.

Process where plants absorb nitrates or ammonia to make organic nitrogen compounds.

Define ammonification.

Decomposition of organic nitrogen into ammonia by decomposers.

Define nitrogen fixation.

Conversion of atmospheric nitrogen (N₂) into ammonia (NH₃) by bacteria or lightning.

What is the equation for NPP?

NPP = GPP - Respiration.

What is the 10% rule between trophic levels?

Only about 10% of energy is passed to the next trophic level; 90% is lost as heat.

Describe the movement of energy in an ecosystem.

Energy flows in one direction — from the sun → producers → consumers → decomposers.

What is leaching?

The process of water carrying dissolved nutrients downward through soil layers.

Describe the savanna biome.

Warm year-round, distinct wet and dry seasons, dominated by grasses and scattered trees.

Describe the boreal forest biome.

Cold, long winters; short summers; dominated by coniferous trees.

Describe the tropical forest biome.

Warm, wet, high biodiversity, dense canopy, nutrient-poor soil.

Describe the desert biome.

Hot or cold, very dry, sparse vegetation, adapted plants and animals.

Which part of the ocean has the greatest biodiversity?

Coral reefs (shallow, warm waters).

What is sediment in the ocean mostly made of?

Silicon, calcium, and other mineral elements from rocks and shells.

Which cycle does not have an atmospheric reservoir?

The phosphorus cycle.

What are the processes of the carbon cycle?

Photosynthesis, respiration, decomposition, combustion, and diffusion.

What are the main parts of the carbon cycle?

Atmosphere, plants, animals, oceans, fossil fuels, and soil.

What is mutualism?

A relationship where both species benefit.

What is predation?

One organism kills and eats another.

What is competition?

Organisms compete for limited resources.

What is commensalism?

One species benefits while the other is unaffected.

What is parasitism?

One organism benefits while the other is harmed.

What is interspecific competition?

Competition between different species.

What is intraspecific competition?

Competition within the same species.

What is resource partitioning?

When species divide a niche to avoid competition.

What percentage of Earth's water is salt water?

About 97%.

What percentage of Earth's water is fresh water?

About 3%.

What are the steps of the nitrogen cycle in order?

Nitrogen fixation → Nitrification → Assimilation → Ammonification → Denitrification.

What element makes up most ocean sediment?

Silicon and calcium from shells and plankton.