APES Unit 1 Study Guide Notes

Ecosystems

• Ecosystems: Interaction of living (biotic) & nonliving (abiotic) things in a specific area.
• Habitat: Specific environmental conditions that a given species needs to survive.
• Environment: The broader natural world, including ecosystems.

Symbiosis

• Symbiosis: General term for close interactions between different species, which can be beneficial or harmful.
• Mutualism: A specific type of symbiosis that benefits both species involved (e.g., bees and flowering plants).

Terrestrial Biomes

• Biome: An area sharing average yearly temperature and precipitation patterns.
• Examples of biomes with lower temperature and precipitation compared to tropical rainforests:
  • Temperate forest
  • Boreal forest
  • Woodland/shrubland
  • Temperate grassland
• Desert Species: Cacti are adapted to their environment with thick, waxy cuticles to conserve water and prevent loss from heat.
• Impact of Global Climate Change: Warming may expand tropical rainforests' range to subtropical regions.

Aquatic Biomes

• Mangrove Tree Adaptations:
  • Thicker membranes/leaf pores that prevent salt from entering, or pump salt out.
  • Stilt-like roots that provide stability and support against water.
• Characteristics of Estuaries:
  • Locations where rivers meet oceans, resulting in mixing of fresh and saltwater.
  • High productivity due to sediment deposition from rivers.
• Biodiversity in Estuaries: Nutrient-rich sediments support diverse animal species.

Carbon Cycle

• Atmosphere as a Carbon Reservoir: Plays a critical role in regulating Earth’s temperature; increased carbon leads to increased temperatures.
• Carbon Sources vs. Sinks:
  • Sources: Fossil fuel combustion, decomposition, respiration, volcanic activity, forest fires.
  • Sinks: Sedimentary rocks, old-growth forests (e.g., redwoods/sequoias), soil.
• Differential Effects of Carbon Release:
  • Carbon from fossil fuels has been out of circulation for millions of years, while cellular respiration carbon is part of a current cycle.

Biogeochemical Cycle Terminology

• Reservoir: Temporary storage areas for matter.
• Source: Processes that move matter between reservoirs.
• Sink: Reservoirs that store more matter than they release.

Nitrogen Cycle

• Differences between Nitrogen and Carbon Cycles:
  • Nitrogen cycles faster and is biologically unavailable in its atmospheric form (N₂).
• Nitrogen Fixation: Conversion of atmospheric N₂ into biologically available forms like ammonia (NH₃) or nitrate (NO₃).
• Forms of Nitrogen Fixation:
  • Biotic: Soil bacteria (e.g., Rhizobacteria).
  • Abiotic: Lightning strikes, fossil fuel combustion.
• Process Descriptions:
  • Assimilation: Uptake of nitrogen by plants and animals.
  • Ammonification: Conversion of organic nitrogen into ammonium (NH₄) by microbes.
  • Nitrification: Conversion of ammonium (NH₄) into nitrate (NO₃) by bacteria.
  • Denitrification: Conversion of nitrates (NO₃/NO₂) back into N₂ gas by denitrifying bacteria.

Phosphorus Cycle

• Differences in Phosphorus Cycle:
  • Phosphorus has no gaseous phase; it does not enter the atmosphere.
  • Major reservoir is in rocks and sediments, leading to slower cycling.
• Weathering vs. Erosion:
  • Weathering: Breakdown of rocks into smaller sediment pieces containing phosphates.
  • Erosion: Movement of these sediments into ecosystems via water or wind.
• Limiting Nutrient: Phosphorus is limited due to its slow cycling from rocks and sediments.

Trophic Levels & 10% Rule

• Energy Transfer: In a trophic pyramid, only 10% of energy is transferred to the next trophic level (90% lost as heat).
• Trophic Pyramid Example (starting with 10,000 kcal):
  • Producers: 10,000 kcal
  • Primary Consumers: 1,000 kcal
  • Secondary Consumers: 100 kcal
  • Tertiary Consumers: 10 kcal
• Large Land Requirement for Tertiary Consumers: Due to the 10% rule, much more biomass of lower levels is needed to support them.

Hydrologic Cycle

• Driving Energy Source: Sunlight heats water allowing evaporation to occur.
• Steps:
  • Evaporation: Sunlight converts water from liquid to vapor.
  • Precipitation: Condensed vapor returns as rain or snow.
• Vegetative Influence: Dense vegetation increases water infiltration and transpiration rates.
• Largest Freshwater Reservoir: Ice caps and glaciers.

Primary Productivity

• Definition: Rate at which plants convert sunlight into organic matter (glucose).
• Units: Kilocalories/m²/year.
• Respiration Loss: Energy used by plants during their own cellular respiration.
• NPP Calculation Formula: NPP = GPP - RL
  where GPP is Gross Primary Productivity and RL is Respiration Loss.
• NPP Examples:
  1. Fremont High School:
  • GPP: 1221 g C/m²/yr, RL: 450 g C/m²/yr → NPP = 771 g C/m²/yr.
  1. Golf Course:
  • NPP: 1,100 g C/m²/yr, RL: 350 g C/m²/yr → GPP = 1450 g C/m²/yr.
  1. Alfalfa Patch:
  • NPP: 304 kcal/m²/yr, GPP: 421 kcal/m²/yr → RL = 117 kcal/m²/yr.

Food Webs

• Arrows in Food Webs: Indicate the direction of energy and matter transfer.
• Population Dynamics: Decreasing secondary consumer populations can lead to increased primary consumer populations, impacting primary producers negatively.
• Organisms in Food Web: Tertiary & quaternary consumer example: Leopard seal; only secondary consumer example: Squid, Blue whale, Fish.