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IB ESS Topic 2 Flashcards
Comprehensive topic 2 knowts.
The biosphere is an ecological system where life exists. It consists of individuals, populations, communities, and ecosystems.
Species:
An individual organism belongs to a species.
A species can interbreed and produce fertile offspring.
Classification of Organisms:
Allows for efficient identification and prediction of traits.
First name is the genus, second is the species (e.g., Salmo salar).
Taxonomists use tools like dichotomous keys and DNA surveys to identify organisms.
Dichotomous Keys: Include two choices and can be branching or stepped.
Population: A group of same species living in the same area and capable of interbreeding.
Abiotic factors: Non-living physical factors (e.g., temperature, sunlight, pH, salinity).
Biotic factors: Living components of an ecosystem.
Niche:
Describes abiotic and biotic conditions an organism responds to.
Includes space, nutrition, interactions, reproductive habits, and ecosystem impact.
Species Interactions:
Competition: Individuals depend on the same resources (intraspecific = same species; interspecific = different species).
Herbivory: Primary consumers feed on plants.
Predation: Consumer eats and kills another consumer.
Parasitism: An organism lives on/in a host, gaining advantage at the host's expense.
Mutualism: Two organisms co-exist and benefit each other.
Carrying Capacity: Maximum population size due to limited resources like food, habitat, and predation.
Population Size Regulation:
Regulated by density-dependent factors and negative feedback.
Density-independent factors also influence size.
Population Growth:
Exponential growth (J-curve) occurs without limiting factors.
Limited growth (S-curve) is affected by carrying capacity.
J Curves: Show boom and bust patterns, often overshooting carrying capacity before collapsing (diebacks).
S-Curve Phases: Exponential, transitional, and plateau; see diagram in transcript
Human Carrying Capacity: Difficult to estimate due to varied resource use, substitution, lifestyles, technology, and importation of resources.
Quadrats: Used for estimating abundance of non-motile organisms.
Transects: Used to identify changes in organisms along an environmental gradient.
Lincoln Index (Mark and Recapture): Used to estimate animal population size: Population size = (n1 * n2) / n3 where n1 = total captured, n2 = total in second capture, and n_3 = marked animals in the second capture.
Community: A collection of interacting populations within an ecosystem.
Habitat: The location where a community, species, population or organism lives.
Ecosystem: A community and its physical environment, which are open systems where energy and matter can enter and exit.
Sustainability in Ecosystems: Relies on balanced inputs and outputs.
Ecosystem Tipping Points: Human activities can lead to ecosystem collapse and a new, unstable equilibrium.
Keystone Species: Have disproportionate impact on community structure.
Planetary Boundaries Model: Highlights that changes to biosphere integrity have passed a critical threshold.
Ecosystems: Sustained by supplies of energy and matter; they are open systems.
First Law of Thermodynamics: Energy can be transformed but not created or destroyed.
Photosynthesis: Conversion of light energy to chemical energy (glucose) by autotrophs.
Producers: Form the first trophic level.
Cellular Respiration: Releases energy from glucose, generating heat.
Second Law of Thermodynamics: Energy transformations are inefficient, with energy degraded into heat.
Consumers: Gain energy from other organisms.
Food Chains: Organic matter flows from producers to consumers.
Trophic Levels: Stages in a food chain.
Energy and Matter Losses: Occur as food is transferred along a food chain.
Productivity:
Gross Productivity (GP): Total gain in biomass.
Net Productivity (NP): Amount remaining after cellular respiration losses.
Limited Trophic Levels: Due to energy losses between levels.
Energy Transfer Efficiency: Typically only 10% or less is available to the next level.
Food Webs: Show complex trophic relationships.
Ecological Pyramids: Used to represent biomass and energy at different trophic levels.
Biomass Total mass of a living organism or organisms:
Pyramids of energy always decrease up the food chain
Bioaccumulation: Increasing concentration of pollutants in organisms over time.
Biomagnification: Increasing concentration of pollutants along a food chain.
Human impacts on flow of energy and matter: burning fossil fuels, deforestation etc
Biogeochemical Cycles: Ensure elements are available to living organisms.
Carbon Cycle Storages: Organic (organisms, fossil fuels) and inorganic (atmosphere, soils, oceans).
Carbon cycle:
-Photosynthesis: CO2 to glucose -Cellular Respiration: Glucose to CO2
Fossil Fuels: Stores of carbon with unlimited residence times.
Oceans: Acts as a carbon sink
-Agricultural Systems can act as carbon stores (cover crops), sources(drainage of wetland) and sinks (crop rotation)
Reducing Human Impact on Carbon Cycle:
Low-carbon technologies
Reduction in the use of fossil fuels
Carbon Capture through reforestation and artificial sequestration
Weather: Short-term atmospheric conditions.
Climate: Long-term atmospheric patterns.
Biomes: Large ecosystems with similar climatic conditions.
Insolation (light), precipitation and temperature are major influences on the distribution of terrestrial biomes.
Temperature decreases with both increased latitude and altitude.
Abiotic factors influence biome distribution.
P/E ratio= precipitation/ evaporation describes the precipitation to evaporation ratio
Distribution follows by Tricellular Model of Atmospheric Circulation
Tricellular Model consists of Hadley cell, Ferrel cell and Polar Cell
-Disturbance and Succession: An ecosystem's capacity to tolerate disturbances and maintain equilibrium, depends on its diversity and resilience.
The following increases ecosystem resilience: Increased biodiversity, Complex food webs
Zonation: Changes in community along an environmental gradient.
Succession: Replacement of one community by another over time.
Primary succession begins with no soil while secondary successions happens with previously developed soil.
Tricellular Model and Biome Distribution
The Tricellular Model explains how air circulates on Earth due to convection cells formed by temperature differences. These cells influence the distribution of biomes by creating distinct climate patterns:
Hadley Cell:
Located near the equator (0-30 degrees latitude).
Warm, moist air rises at the equator, cools, and releases precipitation, creating tropical rainforests.
Dry air descends at around 30 degrees latitude, leading to deserts.
Ferrel Cell:
Located in the mid-latitudes (30-60 degrees latitude).
Influenced by both the Hadley and Polar cells, creating temperate climates.
Supports biomes like temperate forests and grasslands.
Polar Cell:
Located near the poles (60-90 degrees latitude).
Cold, dry air descends, creating polar deserts and tundra biomes.
Biome Differences and Key Factors
Tropical Rainforest:
Key Factors: High temperature, high precipitation, high humidity.
Characteristics: High biodiversity, dense vegetation, nutrient-poor soils.
Desert:
Key Factors: Low precipitation, high temperature, high evaporation.
Characteristics: Sparse vegetation, drought-resistant plants, adaptations for water conservation.
Temperate Forest:
Key Factors: Moderate temperature, moderate precipitation, distinct seasons.
Characteristics: Deciduous trees, fertile soils, moderate biodiversity.
Grassland:
Key Factors: Moderate temperature, low to moderate precipitation, seasonal drought.
Characteristics: Dominated by grasses, grazing animals, frequent fires.
Tundra:
Key Factors: Low temperature, low precipitation, short growing season.
Characteristics: Permafrost, low-growing vegetation, cold-adapted animals.