Ecology basics
59 flashcards covering Ecology basics for the ACT Science section.
Ecology is the study of how living organisms interact with each other and their surroundings, including aspects like food chains, habitats, and the flow of energy in ecosystems. It explores topics such as population dynamics, biodiversity, and environmental factors that influence life on Earth. This foundational knowledge helps explain real-world issues like climate change and resource management, making it essential for understanding the interconnectedness of nature.
On the ACT Science section, ecology questions often appear in data interpretation passages, where you'll analyze graphs, charts, or experimental results related to ecosystems and species interactions. Common traps include mistaking correlation for causation or overlooking subtle variables, so focus on identifying patterns, evaluating evidence, and applying basic concepts like symbiosis or energy transfer. This skill is key for answering multiple-choice questions accurately under time pressure.
Practice sketching simple food webs to visualize relationships.
Terms (59)
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Ecology
Ecology is the scientific study of interactions among organisms and between organisms and their environment, including how these relationships affect the distribution and abundance of living things.
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Ecosystem
An ecosystem is a community of living organisms interacting with nonliving components of their environment, such as soil, water, and climate, forming a complex web of energy and nutrient exchanges.
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Biome
A biome is a large geographic area characterized by specific climate conditions and the plant and animal communities adapted to them, such as deserts or tundras.
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Habitat
A habitat is the natural environment where an organism lives and obtains the resources it needs to survive, including food, shelter, and breeding sites.
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Niche
A niche refers to the role and position a species has in its environment, including how it obtains food and interacts with other species, encompassing both its habitat and its way of life.
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Population
A population is a group of individuals of the same species living in the same area at the same time, where they can interbreed and interact.
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Community
A community in ecology is all the populations of different species living and interacting in a particular area.
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Biotic factors
Biotic factors are the living components of an ecosystem, such as plants, animals, and microorganisms, that influence the survival and behavior of other organisms.
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Abiotic factors
Abiotic factors are the nonliving physical and chemical elements of an ecosystem, like temperature, sunlight, soil, and water, that affect living organisms.
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Producer
A producer is an organism, typically a plant, that makes its own food through photosynthesis, converting sunlight into energy and forming the base of the food chain.
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Consumer
A consumer is an organism that obtains energy by eating other organisms, categorized into herbivores, carnivores, or omnivores depending on their diet.
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Decomposer
A decomposer is an organism, such as bacteria or fungi, that breaks down dead organic matter, recycling nutrients back into the ecosystem.
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Food chain
A food chain is a linear sequence showing how energy and nutrients pass from one organism to another, starting with producers and moving to consumers and decomposers.
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Food web
A food web is a complex network of interconnected food chains within an ecosystem, illustrating multiple feeding relationships among organisms.
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Trophic levels
Trophic levels are the hierarchical positions in a food chain or web, such as producers at level one, primary consumers at level two, and so on, each representing a transfer of energy.
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Energy pyramid
An energy pyramid is a graphical model showing the decrease in available energy at each trophic level, with producers at the base having the most energy and top predators the least.
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Biomass pyramid
A biomass pyramid illustrates the total mass of living organisms at each trophic level, typically decreasing upward due to energy loss.
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Primary succession
Primary succession is the gradual process of ecosystem development on barren, lifeless areas like bare rock, starting with pioneer species and leading to a stable community.
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Secondary succession
Secondary succession is the recovery process of an ecosystem after a disturbance, such as a fire, where soil and some organisms already exist, allowing faster regrowth.
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Climax community
A climax community is the stable, mature stage of ecological succession where the ecosystem is balanced and dominated by species well-adapted to the environment.
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Carrying capacity
Carrying capacity is the maximum population size of a species that an environment can sustain indefinitely, based on available resources like food and space.
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Limiting factors
Limiting factors are environmental conditions, such as food scarcity or predation, that restrict the growth, abundance, or distribution of a population.
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Exponential growth
Exponential growth is a pattern of population increase where the number of individuals rises rapidly over time, often modeled by the equation dN/dt = rN, assuming unlimited resources.
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Logistic growth
Logistic growth is a population growth model that starts exponentially but slows as it approaches the carrying capacity, following the equation dN/dt = rN(1 - N/K), where K is the carrying capacity.
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Biodiversity
Biodiversity is the variety of life in an ecosystem, including the number of species, their genetic differences, and the complexity of their interactions, which supports ecosystem stability.
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Species richness
Species richness is a measure of biodiversity that counts the number of different species in a given area, without considering their abundance.
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Species evenness
Species evenness is a component of biodiversity that describes how equally abundant the different species are in an ecosystem, affecting overall stability.
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Mutualism
Mutualism is a symbiotic relationship where both species benefit from the interaction, such as bees pollinating flowers while obtaining nectar.
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Commensalism
Commensalism is a symbiotic relationship in which one species benefits and the other is neither helped nor harmed, like birds nesting in trees without affecting the tree.
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Parasitism
Parasitism is a relationship where one organism benefits at the expense of another, harming the host without necessarily killing it, such as a tick feeding on a deer.
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Predation
Predation is an interaction where one organism, the predator, kills and eats another, the prey, which helps control population sizes and drive evolution.
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Competition
Competition occurs when organisms vie for the same limited resources, such as food or space, potentially leading to reduced growth or survival for one or both species.
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Symbiosis
Symbiosis is any long-term interaction between two different species, which can be mutualistic, commensal, or parasitic, affecting their survival and evolution.
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Water cycle
The water cycle is the continuous movement of water on, above, and below Earth's surface, involving processes like evaporation, condensation, precipitation, and runoff.
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Carbon cycle
The carbon cycle is the process by which carbon moves through the atmosphere, oceans, soil, and living organisms via photosynthesis, respiration, and decomposition.
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Nitrogen cycle
The nitrogen cycle is the biogeochemical process that converts nitrogen gas into forms usable by plants and animals, involving fixation, nitrification, and denitrification.
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Phosphorus cycle
The phosphorus cycle is the movement of phosphorus through rocks, soil, water, and organisms, primarily as phosphates, without a significant gaseous phase.
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Deforestation
Deforestation is the large-scale removal of forests, often for agriculture or urban development, which disrupts ecosystems, reduces biodiversity, and contributes to climate change.
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Pollution
Pollution is the introduction of harmful substances or energy into the environment, such as chemicals or waste, which can damage ecosystems and human health.
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Greenhouse effect
The greenhouse effect is the natural process where gases in the atmosphere trap heat from the sun, but human activities have intensified it, leading to global warming.
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Acid rain
Acid rain is precipitation made acidic by pollutants like sulfur dioxide and nitrogen oxides, which harms aquatic ecosystems, soils, and vegetation.
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Invasive species
Invasive species are non-native organisms that spread rapidly and cause harm to the environment, economy, or human health by outcompeting native species.
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Endangered species
Endangered species are plants or animals at risk of extinction due to factors like habitat loss or overhunting, requiring conservation efforts to prevent their disappearance.
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Conservation biology
Conservation biology is the scientific study and practice of protecting biodiversity and ecosystems, focusing on sustainable management of natural resources.
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Sustainable development
Sustainable development is a approach to growth that meets current needs without compromising the ability of future generations to meet theirs, balancing environmental and economic factors.
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Ecological footprint
An ecological footprint measures the amount of land and resources required to support a person's or population's lifestyle, indicating environmental impact.
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Biomagnification
Biomagnification is the process where concentrations of toxins increase at higher trophic levels in a food chain, such as mercury in fish eaten by humans.
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Eutrophication
Eutrophication is the excessive enrichment of water bodies with nutrients, leading to algal blooms that deplete oxygen and harm aquatic life.
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Keystone species
A keystone species is an organism that has a disproportionately large effect on its ecosystem, such as a predator that maintains balance by controlling prey populations.
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Indicator species
An indicator species is an organism whose presence or absence reflects the overall health of an ecosystem, like certain frogs indicating clean water.
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Photosynthesis
Photosynthesis is the process by which green plants convert sunlight, carbon dioxide, and water into glucose and oxygen, serving as the primary energy source in ecosystems.
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Respiration
Respiration is the process where organisms break down glucose to release energy, producing carbon dioxide and water, which cycles nutrients in ecosystems.
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Nutrient availability
Nutrient availability refers to the amount of essential elements like nitrogen and phosphorus that are accessible to organisms in an ecosystem, influencing growth and productivity.
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Adaptations
Adaptations are traits or behaviors that organisms develop to survive in their specific environments, such as camouflage in animals to avoid predators.
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Migration
Migration is the seasonal movement of animals from one region to another, often in response to changes in food availability or climate.
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Hibernation
Hibernation is a state of inactivity and reduced metabolism that some animals enter to conserve energy during cold periods when food is scarce.
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Common trap: Confusing habitat and niche
A common error is thinking habitat and niche are the same; habitat is the physical location, while niche includes the organism's specific role and interactions within that location.
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Strategy for interpreting food webs
When analyzing food webs, trace energy flow from producers upward and identify key interactions, as this helps understand ecosystem stability and predict impacts of species loss.
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Worked example: Energy transfer in food chain
In a food chain, if producers have 10,000 units of energy, only about 10% transfers to primary consumers, so they get roughly 1,000 units, demonstrating energy loss at each level.