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$$$NPP = GPP - RL$$
  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.