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Ecology Test Study Guide (BIO)

Ecology Test Study Guide Notes

Levels of Organization

  • The levels of organization in order from smallest to largest are:
    • Organism → Population → Community → Ecosystem → Biosphere

Energy Transfer in Food Chains/Webs

  • Only 10% of energy transfers from one step to another in a food chain or food web.

Limiting Factors

  • A limiting factor is an environmental factor that slows the growth of a population.
  • Examples:
    • Temperature
    • Water
    • Food

Density-Dependent vs. Density-Independent Factors

  • Density-independent factors: Reduce the population by the same proportion regardless of population size.
    • Example: Fires
  • Density-dependent factors: Their effects are triggered by increasing population density.
    • Example: Resources

Exponential Growth Curve

  • Positive population growth.
  • Carrying capacity has not been reached because this model assumes no limits to resources.

Logistic Growth Model

  • Carrying capacity has been reached.
  • The rate of growth stops, and the population size remains the same because of limited resources in the environment.

Species Interactions

  • Predation (+/-): When a predator eats prey.
    • Example: Cheetah (+) eats an impala (-).
  • Competition (-/-): When organisms compete for the same environmental resource.
    • Example: Cheetahs (-) and lions (-).
  • Commensalism (+/0): One organism benefits, and the other is unaffected.
    • Example: Barnacles (+) hitch a ride on whales (0).
  • Parasitism (+/-): One organism benefits (parasite), while the other is harmed (host).
    • Example: Parasitic wasp (+) and caterpillar (-).
  • Mutualism (+/+): Both organisms benefit from the interaction.
    • Example: Clownfish (+) and sea anemones (+).

Abiotic vs. Biotic Factors

  • Abiotic factors: Non-living components.
    • Example: Temperature.
  • Biotic factors: Living components.
    • Examples: Frog, plants.

Food Web Example

  • Based on the provided food web (Deer, Eagle, Snake, Trees, Frog, Mouse, Grass, Grasshopper).

Food Chain Example

  • Grass → Grasshopper → Frog → Eagle
    • (Producer) → (Primary Consumer) → (Secondary Consumer) → (Tertiary Consumer)

Energy Available in Food Chain

  • Initial energy in producers (grass): 23,405 kcal
  • Energy transfer:
    • Grasshopper: 2340.5 kcal
    • Frog: 234.05 kcal
    • Eagle: 23.405 kcal

Impact of Decreasing Frog Population

  • Grasshopper population would increase.
  • Snake and mouse populations might decrease because the eagle is left with fewer food options.

Water Cycle

  • Evaporation: Process of turning from liquid into vapor.
  • Condensation: Process where water vapor becomes liquid.
  • Precipitation: Any liquid or frozen water that falls from the atmosphere to Earth's surface.
  • Transpiration: Process where plants release water vapor into the atmosphere.
  • Infiltration: Process by which water on the ground surface enters the soil.
  • Runoff: The unconfined flow of water over the ground surface.

Carbon Cycle

  • Ways carbon gets into the atmosphere:
    • Natural processes: Respiration, decomposition, volcanic eruptions.
    • Human activities: Burning of fossil fuels (increases atmospheric carbon levels).

Water, Carbon, and Nitrogen Cycles

  • All are biogeochemical cycles that move and transform elements through the Earth's atmosphere, land, and water.
  • Ensure continuous recycling of essential elements.

Specialist vs. Generalist

  • Specialist: Has a limited diet and habitat.
  • Generalist: Has a wide range of foods and habitats.

Burning of Fossil Fuels

  • The burning of fossil fuels has greatly increased the levels of carbon dioxide in the atmosphere.
  • If this continues, atmospheric temperatures will increase.

Environmental Issues

  • Deforestation: The clearing or cutting down of trees in forests.
  • Wildfires: Large, uncontrolled fires that spread quickly.
  • Plastic Pollution: When plastic waste piles up in the environment.
  • Overpopulation: When there are too many people in an area for the available resources.
  • Eutrophication: When water gets too many nutrients, causing excessive algae growth.
  • Sea levels rising: When the ocean's water level increases, mainly due to melting ice.
  • Climate Change: The long-term change in Earth's weather patterns.
  • Biodiversity Loss: Decline in the variety of plant and animal species in an area.
  • Ocean Acidification: When the ocean becomes more acidic due to the absorption of excess carbon dioxide (CO_2).
  • Overfishing: When fish are caught faster than they can reproduce.

Biomes

  • Temperate Woodland and Shrubland: Warm, dry summers; cool, moist winters; shrubland areas known as chaparral.
  • Tundra: Characterized by permafrost, strong winds, low precipitation, short summers, long, cold, dark winters.
  • Northwestern Coniferous Forest: Mild, moist air and abundant rainfall nurture many tall conifers; mild temperatures; lush, dense, plant growth.
  • Temperate Forest: Cold winters and warm summers; year-round precipitation; deciduous trees shed their leaves in autumn.
  • Temperate Grasslands: Plains and prairies with fertile soils; land used for farms; heavy grazing by herbivores; plant communities dominated by grasses.
  • Tropical Rain Forest: Most species diversity; warm and wet year-round; tall trees form a canopy; shorter trees and vines form the understory.
  • Desert: Receives less than 25 cm of precipitation annually; undergo extreme daily temperature changes; many cacti; many animals get water from their food.
  • Boreal Forest: Also known as taiga; winters are bitterly cold, but summers are mild and long enough to allow the ground to thaw.

Population Growth Graph

  • Letter A represents a population reaching its carrying capacity.

Age Structure Diagrams

  • Different diagrams represent:
    • Rapid Growth
    • Slow Growth
    • Zero Growth
    • Negative Growth

Population Density Calculation

  • Population density: 123 squirrels per square kilometer
  • Area: 18 km x 555 km = 9990 km^2
  • Total Population: 123 \frac{squirrels}{km^2} \times 9990 km^2 = 1,228,770 squirrels

Population Size Change

  • Initial population: 894 deer
  • Changes: +37 (immigrate) - 29 (emigrate) - 16 (die) + 65 (born)
  • Final population size: 894 + 37 - 29 - 16 + 65 = 951 deer

Rate of Change in Bird Population

  • Population in 2008: 15,527 birds
  • Population in 2024: 9,750 birds
  • Rate of change: \frac{9750 - 15527}{2024 - 2008} = \frac{-5777}{16} = -361 birds per year

Dispersion Patterns

  • Clumped dispersion: Jaguars in a tropical rainforest found in clusters near riverbanks.
  • Random dispersion: Cacti scattered throughout a desert landscape without any particular pattern.
  • Uniform dispersion: Mountain goats in a mountain range establishing well-defined home ranges.

Survivorship Curves

  • Type I: Tortoise species with high survival rate until old age.
  • Type III: Salmon species with low survival rate in early life stages.
  • Type II: Frog species with a steady mortality rate across all life stages.

Primary vs. Secondary Succession

  • Primary Succession
    • Starts on bare rock
    • No previously existing life
    • Natural processes of ecosystem development
    • Results in a climax community
    • Starts as the result of a volcano or a receding glacier
    • Pioneer species: lichens, mosses
    • Happens relatively slowly
    • Starts without soil
  • Both
    • Involve pioneer species
  • Secondary Succession
    • Starts with soil already present
    • The natural processes of ecosystem development
    • Happens relatively fast
    • Comes after a natural disaster
    • Starts as a result of a forest fire or flood
    • Previously existing life
    • Pioneer species: grasses, weeds