AP Environmental Science - Unit 1: Ecosystems, Biomes, and Biogeochemical Cycles

Comprehensive practice flashcards covering ecosystem organization, species interactions, biome distribution, aquatic zones, and biogeochemical cycles from Unit 1 AP Environmental Science notes.

Based on the levels of ecological organization, which level includes both all biotic (living) and abiotic (nonliving) factors in a given area?

Ecosystem

What are the four primary species interactions and their net effects on the involved organisms?

Mutualism ($+ / +$), Competition ($- / -$), Predation ($+ / -$), and Commensalism ($+ / 0$).

How do parasitoids differ from true parasites?

Parasitoids lay eggs inside a host organism where the hatching larvae eat and kill the host, whereas true parasites live on or inside a host for energy without usually killing it.

What are the three main types of resource partitioning shown in ecosystems to reduce competition?

Temporal partitioning (using resources at different times), spatial partitioning (using different areas of a shared habitat), and morphological partitioning (using different resources based on evolved anatomical features).

Which two climate factors primarily determine the distribution and characteristics of terrestrial biomes?

Average annual temperature and average annual precipitation.

According to the annual temperature and precipitation graph, which biome is found in regions with temperatures above $20,^\text{o}\text{C}$ and annual precipitation exceeding $250,cm$?

Tropical Rainforest

Why is the soil in tropical rainforests nutrient-poor despite supporting dense vegetation?

High temperatures and heavy rainfall lead to extremely rapid decomposition of organic matter and significant nutrient leaching from the soil.

In a freshwater lake diagram, which zone corresponds to shallow water where rooted emergent plants grow?

The littoral zone

What key difference separates the limnetic zone from the profundal zone in a lake?

The limnetic zone receives enough sunlight for photosynthesis by phytoplankton, whereas the profundal zone is too deep for light to penetrate, preventing photosynthesis.

What are three major ecological and economic benefits provided by freshwater wetlands?

Storing excess floodwater to lessen property damage, recharging groundwater supplies, and filtering pollutants from runoff water.

According to the diagram, what mutualistic relationship enables coral reefs to thrive in warm shallow ocean waters?

Coral polyps provide shelter and $\text{CO}_2$ to algae, while the photosynthetic algae supply nutrients and glucose to the coral.

How does the seaweed species Spiral wrack adapt to survive exposed low tides in intertidal zones?

It curls up and secretes mucus to retain water and prevent desiccation (drying out).

In open ocean zonation, what distinguishes the photic zone from the aphotic zone?

The photic zone receives sunlight sufficient for photosynthesis (down to $200,m$), whereas the aphotic zone is completely dark, forcing organisms to rely on sinking detritus or chemosynthetic microbes.

What is the functional difference between a carbon sink and a carbon source?

A carbon sink absorbs and holds more carbon than it releases (e.g., ocean sediments, forests), while a carbon source releases more carbon into the atmosphere than it absorbs (e.g., fossil fuel burning, deforestation).

How do photosynthesis and cellular respiration balance carbon movement between the atmosphere and biosphere?

Photosynthesis removes $\text{CO}_2$ from the atmosphere to convert solar energy into glucose, while cellular respiration breaks down glucose using $\text{O}_2$ to release energy, returning $\text{CO}_2$ to the atmosphere.

How does ocean sedimentation lead to long-term carbon storage on the ocean floor?

Marine organisms use dissolved $\text{CO}_2$ to form calcium carbonate exoskeletons, which precipitate to the ocean floor and are compressed over millions of years into sedimentary rocks like limestone.

What is the primary reservoir of nitrogen on Earth, and what form does it take?

The atmosphere, where nitrogen exists as $\text{N}_2$ gas, a form that cannot be directly taken up or used by plants or animals.

What is nitrogen fixation, and which symbiotic bacteria perform this process in plant roots?

Nitrogen fixation is the conversion of atmospheric $\text{N}_2$ gas into biologically available forms like ammonia ($\text{NH}_3$); it is performed by Rhizobacteria living in the root nodules of legumes.

In the nitrogen cycle, what occurs during nitrification and denitrification?

Nitrification converts ammonium ($\text{NH}_4^+$) into nitrite ($\text{NO}_2^-$) and nitrate ($\text{NO}_3^-$) by soil bacteria, while denitrification converts soil nitrate ($\text{NO}_3^-$) back into nitrous oxide ($\text{N}_2\text{O}$) and $\text{N}_2$ gas.

How does agricultural fertilizer runoff trigger aquatic eutrophication?

Nitrates ($\text{NO}_3^-$) leach into waterways, causing excessive algal blooms that block light, leading to algae death and bacterial decomposition that depletes dissolved oxygen and causes fish kills.