AP Environmental Science Flashcards
What are ecosystems?
A biological community of organisms that interact with each other and their physical environment
What is the difference between biotic and abiotic components?
Biotic components are anything that is living (plants, animals, bacteria, etc.)
Abiotic components are anything that is not living (rocks, soil, air, etc.)
What is the biosphere?
The sum of all ecosystems on earth
What is a biome?
A large, natural community of biotic (living) organisms interacting within a major habitat
(tundra, grassland, desert, etc.)
What is the difference between an ecosystem and a biome?
An ecosystem includes all biotic and abiotic factors in an environment
A biome is a collection of different ecosystems that share a similar climate
What is a predator-prey relationship?
A relationship where a predator is some organism eats another organism (prey)
(a wolf eating a deer)
What is symbiosis?
A close and long-term interaction between two species in an ecosystem
(mutualism, commensalism, and paratism)
Types of Symbiosis:
- Mutualism: A relationship where both organisms benefit (e.g., bees pollinating flowers)
- Commensalism: A relationship where only one organism benefits (e.g., a bird building a nest in a tree)
- Parasitism: A relationship where one organism benefits and the other is harmed (e.g., diseases)
What is biological competition?
When two species share limited resources and must compete for those resources
What is resource partitioning?
Using the available resources in different ways to reduce competition
(giraffes eat higher-up leaves while gazelles eat lower-down leaves)
What are keystone species?
Species that are fundamental to an ecosystem
Removing keystone species will greatly disrupt an ecosystem
What are ecosystem engineers?
A type of keystone species that modify their ecosystem in a way that maintains the habitat for other organisms
(elephants leave big paths which help stop wildfires)
What are terrestrial biomes?
All biomes that exist on land
Desert
A dry biome that receives very little rainfall and has low primary productivity
Plants in deserts must adapt to having little water
Savanna
A dry grassland spotted with low-lying shrubs and scattered trees; between a desert and a forest
Has distinct dry/wet seasons, but not too much rainfall
Tropical Rainforest
A hot, moist biome that receives rainfall all year and is incredibly biodiverse
Found close to the equator; typically low soil quality due to fast nutrient uptake
Temperate Grassland
An open and flat biome filled with grass; medium rainfall and soil productivity
Shrubland
A biome made up of shrubs that thrive on steep rocky slopes; not enough rain to support trees and low productivity
Frequent fires due to lightning in the hot summers
Temperate Seasonal/Deciduous Forest
A biome with hot summers and cold winters (seasons); tall trees and high primary productivity
Leaves change colors, fall off, and grow back to adapt to the temperature
Temperate Rainforest
A coastal biome with mild summers and winters and heavy rainfall
In temperate (more Northern or Southern) regions as opposed to the Tropical Rainforest
Taiga
A forest in a cold, subarctic region with temperatures often below freezing
Low nutrient levels because soils don't decompose easily in the low temperature
Tundra
A treeless, frigid biome in the arctic and on the tops of mountains, with a cold climate and very little rainfall
Nutrient-poor soils and low primary productivity; only a couple of plants can survive
Layer of permafrost covering the ground
Rainfall is generally heaviest near the equator and lightest near the poles
(e.g., heavy in Subsaharan Africa, Brazil, Southeast Asia; light in Northern Canada)
What are aquatic biomes?
Biomes that exist in water or have water as a key component
What is salinity?
The concentration of dissolved salt in water
(higher salinity = saltier = more dense)
What is turbidity?
How cloudy water is; influenced by soil runoff
(high turbidity = very cloudy)
Wetlands
Biomes whose soil is either permanently or periodically saturated with water
Different from lakes, as wetlands are shallow and may dry out
(marshes, swamps, bogs, mudflats, salt marshes)
Why are wetlands important?
- Store excess water from floods
- Remove excess nutrients from runoff
- Provide a unique, lush habitat that is filled with biodiversity
What is emergent vegetation?
Wetland plants that have roots underwater in the soil but extend out of the water
(grown in wetlands because wetlands are shallow)
Types of Wetlands:
- Marshes: low-lying, treeless areas
- Swamps: low-lying wetlands dominated by trees
- Bogs: wetlands with floating mats of plant matter
Lakes and Ponds
BIomes naturally filled with standing freshwater
(ponds = smaller; lakes = bigger)
What is the difference between oligotrophic lakes and eutrophic lakes?
Oligotrophic lakes have low productivity (low nitrogen and phosphorus)
Eutrophic lakes have high productivity (also higher turbidity from nutrients)
(mesotrophic lakes are in between)
Four Zones of Lakes:
- Littoral zone: Shallow area of water near the shore where photosynthesis can occur
- Limnetic zone: Sunlit, surface area away from the shore; can only support algae, but photosynthesis does occur
- Profundal zone: Deep open water where sunlight can't reach; lower oxygen levels
- Benthic zone: Muddy bottom of the lake with decomposing matter
Streams and Rivers
An aquatic biome with flowing freshwater
Freshwater fish exist here
Parts of a River:
- Source: The start of the river; low nutrients, high oxygen
- Transition zone: A wider, deeper, and warmer part of the river
- Mouth: Where the river enters the ocean
Mangrove Swamps
Coastal wetlands in tropical/subtropical regions with trees whose roots are constantly submerged in water
Important for having high biodiversity and preventing erosion by breaking waves
The Open Ocean
Water in the ocean beyond what is near the shore; contains deep water that the sun cannot penetrate
Vertical Zones of the Open Ocean:
- Euphotic Zone: Brightly lit upper zone with numerous drifting photoplankton
- Bathyal Zone: Dimly lit middle zone; no photosynthesis
- Abyssal Zone: Deepest zone at the bottom of the ocean; decaying organisms provide nutrients
Intertidal Zones
Narrow bands along the coast that experience a range of environmental conditions due to the rising/receding tide
(including daily changes in sunlight, temperature, and water; barnacles, sea stars, crustaceans, etc.)
Coral Reefs
Vast ecosystems built on the exoskeletons of coral polyps; contain many biodiverse plants and animals
Found in warm, shallow, sunlit waters
What are polyps?
Tiny animals that form massive colonies and build coral reefs by secreting a protective limestone exoskeleton
The exoskeleton remains after polyps die, providing a platform for other organisms in the reef
How do polyps and algae interact?
Algae provide the polyps with food and oxygen via photosynthesis
Polyps provide the algae with carbon dioxide via cellular respiration
Why are coral reefs important?
- Remove CO2 from the atmosphere to moderate temperatures
- Act as natural barriers against erosion
- Provide habitats for many species
What is coral bleaching?
When increased stress causes algae in coral reefs to die off, leaving only a "bleached" skeleton remaining
(increased temperature, acidity, etc.)
Estuary
An area where a freshwater river/stream meets the ocean
Water is brackish (slightly salty)
Types of Estuaries:
- Inlet: A long, narrow indentation of the shoreline
- Bay: A recessed, coastal body of water that connects to a larger body of water
- Sound: An inlet that is substantially larger than a bay
- Salt Marsh: Coastal wetlands that are flooded and drained by oceanic saltwater
- Mangrove Forest: Many tangled roots and dense vegetation; maintain water quality by filtering out pollutants, excess nutrients, and sediments
What are biogeochemical cycles?
Pathways for chemical substances to cycle through the biotic and abiotic parts of the earth
(carbon cycle, nitrogen cycle, phosphorus cycle, hydrologic cycle)
What are carbon sinks?
Anything that absorbs more carbon from the atmosphere than it releases
(plants, the ocean, soil, etc.)
What are carbon sources?
Anything that releases more carbon than it absorbs
(burning of fossil fuels, volcanic eruptions, etc.)
What is the carbon cycle?
The movement of carbon between sources and sinks on Earth
What are the two stages of the carbon cycle?
Fast carbon cycle: the movement of carbon between living organisms and the atmosphere (animals release their carbon when they die)
Slow carbon cycle: the movement of carbon between the lithosphere (rocks), soil, ocean, and atmosphere (takes millions of years)
How does photosynthesis affect the carbon cycle?
Plants uptake carbon from the atmosphere and store it within their tissues
(eventually the plant will die, and decomposers will release the stored carbon back into the soil)
What is the ocean-atmosphere carbon exchange?
The process of the ocean absorbing some CO2 from the atmosphere and releasing roughly the same amount
(the ocean is a huge carbon sink)
What is sedimentation?
The process of CO2 combining with calcium ions in the ocean to form calcium carbonate, which accumulates as sediment
Photosynthesis absorbs carbon; cellular respiration releases carbon
What causes annual fluctuations in carbon dioxide concentration?
Green plants do more photosynthesis in the summer and less in the winter
(i.e., levels of photosynthetic activity is seasonal)
How can humans disrupt the carbon cycle?
Using fossil fuels extracts carbon from the ground faster than sedimentation deposits it back in
Deforestation reduces the number of plants to absorb carbon (forests are huge carbon sinks)
What is the nitrogen cycle?
The cycle of processes that move nitrogen through both biotic and abiotic elements of the earth
What is nitrogen fixation?
The process that turns nitrogen gas ( Loading KaTeX... Loading KaTeX...
(see how it occurs)
What are the two ways nitrogen fixation can occur?
Biotically: nitrogen-fixing bacteria convert Loading KaTeX...
Abiotically: Loading KaTeX...
What is nitrification?
The process that converts ammonia and other compounds into nitrite ( Loading KaTeX... Loading KaTeX...
What is nitrogen assimilation?
The process that plants use to form organic nitrogen compounds from inorganic nitrogen compounds
(plants cannot use inorganic nitrogen compounds directly, so they rely on assimilation)
What is ammonification?
The process of decomposers breaking down organic into inorganic ammonium
What is denitrification?
The process of bacteria reducing nitrite and nitrate to gaseous forms of nitrogen so that it can return back to the atmosphere
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Importance of Steps in the Nitrogen Cycle:
- Fixation: Turns nitrogen gas into nitrate so that plants can use it
- Nitrification: converts ammonium into nitrite, then nitrate
- Assimilation: converts inorganic nitrogen into organic nitrogen so that it can be used by plants
- Ammonification: breaks down organic nitrogen after organisms die
- Denitrification: returns nitrogen back into the atmosphere
How do humans disrupt the nitrogen cycle?
By inserting excess nitrogen into ecosystems, for example, by overuse of nitrogen-based fertilizers
(can lead to algal blooms and other disruptions)
What is the phosphorus cycle?
The biogeochemical cycle that describes the movement of phosphorus through biotic and abiotic components of earth
How does weathering affect the phosphorus cycle?
Most phosphorus is found in rocks; weathering these rocks releases phosphorus
How is phosphorus absorbed by living organisms in the phosphorus cycle?
Plants absorb phosphorus dissolved in soil water and animals eat plants containing phosphorus
Why is the phosphorus cycle so slow?
Phosphorus is released from rocks, which can take thousands of years to break down due to weathering
There is no gaseous phase
How does phosphorus in organisms return to the ecosystem?
Decomposers break down dead organisms, converting the phosphorus back to an inorganic form
What happens after phosphorus enters the ocean?
It is deposited into sediments at the bottom of the ocean and is eventually returned to mountains through geological uplift
What is the hydrologic cycle?
(the water cycle)
The biogeochemical cycle that describes how water moves through earth
What is evaporation?
The process of liquid water turning to gas and entering the atmosphere
What is transpiration?
Water exiting a leaf's stomata and entering the atmosphere
What is condensation?
The process of water vapor in the air turning to liquid (clouds)
What is precipitation?
The fall of rain/snow that brings liquid water from clouds back to the ground
What is infiltration? (water)
Water entering the soil through the earth's surface
What is groundwater flow?
The flow of water within the earth's soil
(occurs after infiltration)
What is runoff?
Water pulled across the surface by gravity; leads towards lakes, rivers, and eventually the ocean
(occurs when there is excess precipitation, and the ground cannot absorb any more water)
Where is most of the earth's water stored?
The oceans are the biggest source, with ice caps and groundwater as smaller sources
What is primary productivity?
The rate at which sunlight is converted into organic compounds via photosynthesis over time
(measures how productive an ecosystem is)
What is gross primary productivity?
The total rate of energy storage via photosynthesis in a given area over time
What is net primary productivity?
The gross primary productivity minus the energy lost to respiration
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How is productivity measured?
Units of energy per unit area per unit time
e.g., Loading KaTeX...
If the net primary productivity of an ecosystem is Loading KaTeX... Loading KaTeX...
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What are autotrophs/producers?
Organisms that can create their own food using photosynthesis
(first trophic level)
What are consumers/heterotrophs?
Organisms that can't produce their own food and must eat others to survive
What are primary consumers?
Consumers that eat producers
(second trophic level; e.g., cows)
What are secondary consumers?
Organisms that eat primary consumers
(third trophic level)
What are tertiary consumers?
Consumers that eat secondary consumers
(fourth trophic level)
What are the five trophic levels?
- Producers
- Primary Consumers
- Secondary Consumers
- Tertiary Consumers
- Apex Predators
What are decomposers?
Organisms that obtain nutrients by decomposing organic material
(many bacteria and fungi are decomposers)
What are detrivores?
A type of decomposer that eats dead organisms and waste to decompose it
(normal decomposers don't necessarily eat waste)
What are trophic levels?
A hierarchical level in an ecosystem that contains organisms that share the same function in the food chain
(see the five levels)
How does energy move in an ecosystem?
It begins as solar energy and is transformed into chemical energy as it moves upwards through trophic levels
What is the First Law of Thermodynamics?
In a closed system, energy can be neither created nor destroyed
(it can be transferred)
What is the Second Law of Thermodynamics?
Every time energy changes form, entropy increases
(entropy = disorder)
What is biomass?
The total mass of all living matter in a specific area
What is the 10% Rule?
Only 10% of energy in one trophic level is passed to the next
(if producers have 1,000 J of energy from photosynthesis, primary consumers will only get 100 J)
What are food chains?
A series of organisms, each dependent on the next as a source of food
(grass -> grasshopper -> mouse -> snake -> hawk)
What are food webs?
What are negative feedback loops?
A feedback loop where a system responds to a change by trying to return to its original state or by slowing the rate at which the change is occurring
(if there's a drought, a lake will shrink due to evaporation, leading to less surface area, which causes less evaporation)
What are positive feedback loops?
A feedback loop where some change continues to increase in intensity
(increased global temperatures lead to ice caps melting, leading to more sunlight absorption (darker), causing more melting)
What is a trophic cascade?
The changes that occur to an entire ecosystem when top predators are impacted
(if wolves die off, deer will flourish and overeat plants, severely damaging the ecosystem)
What is ecosystem resistance?
How well an ecosystem can withstand a disturbance
What is ecosystem resilience?
How well an ecosystem can recover after a disturbance
What is the intermediate disturbance hypothesis?
The idea that species biodiversity is highest when ecological disturbance is neither too frequent nor too rare
What is biodiversity?
The variety of of life within a habitat or ecosystem
What is genetic diversity?
The variation of genes within individual species
What is species diversity?
The number of different species in an ecosystem and the relative abundance of those species
(species richness and species evenness)
What is habitat diversity? (ecosystem diversity)
The variability of habitats within a given geographic area
What is species richness?
The total number of species in an area
What is species evenness?
How evenly distributed the species in a given area are
What is genetic drift?
The change of a population's genetic composition over time as a result of random mating
What are mutations?
Random changes in genetic code that occur due to errors in the copying process
What is gene flow?
The process of individuals moving from one population to another and altering the genetic composition of both populations as a result
What is the bottleneck effect?
A reduction in a population's genetic diversity caused by a reduction of its size
(occurs when only a few individuals survive a catastrophe)
What is the founder effect?
When only a few individuals from an old population colonize a new, isolated habitat
(the new habitat has much lower genetic diversity)
What are ecosystem services?
Various benefits to humans that healthy natural ecosystems provide
What are supporting ecosystem services?
Providing living spaces for plants or animals and maintaining biodiversity
(ocean fish reproduce in estuaries, decaying leaves help form soil, etc.)
What are provisioning ecosystem services?
Material benefits from ecosystems
(timber, medicine, honey, sand, etc.)
What are regulating ecosystem services?
The benefit that ecosystems provide to moderate natural phenomena
(carbon storage, pollination, flood control, air purification, etc.)
What are cultural ecosystem services?
Non-material benefits from ecosystems, including aesthetic inspiration, cultural identity, and sense of home
(scenic parks, religious importance, etc.)
What is island biogeography?
The study of factors that affect species richness and composition on islands
What determines the richness (number) of species found on an island?
The rate at which new species immigrate to the island
The rate at which existing species go extinct
What is the Equilibrium Theory of island biogeography?
Describes the relationship between the rate of immigration and extinction of a species on an island
- Islands closer to the mainland have higher rates of immigration
- Large islands can support more species and have lower rates of extinction
What is the equilibrium number (of species on an island)?
The balance between the immigration of new species and the extinction of existing species
(as more species come to the island, the probability of extinction increases)
What is an ecological niche?
The specific environmental conditions that match a species
(giraffes have the niche of eating high-up leaves)
What are specialist species?
Species of animals that require very special conditions to survive
(pandas, koalas, etc.; opposite of generalist species)
What are generalist species?
Species that can live in many different places and don't have any specific requirements
(flies, cockroaches, raccoons, etc.; opposite of specialist species)
What are endemic species?
Species found in a specific area and found nowhere else in the world
(usually a type of specialist species)
What are invasive species?
Species that have few natural predators and are able to fill a broad niche
(usually generalists; often damages endemic species)
What is ecological tolerance?
The range of conditions (temperature, salinity, flow rate, sunlight) that an organism can endure before becoming injured or dying
Ecological tolerance applies to both individuals and species
(e.g., salmon have a tolerance range of 6°C-22°C, but some populations have a higher tolerance due to genetic diversity)
What are the zones of ecological tolerance?
- Optimal range: organisms survive, grow, and reproduce
- Zone of physiological stress: organisms survive, but experience stress (e.g., infertility, lack of growth)
- Zone of intolerance: organisms will die
- Optimal range: organisms survive, grow, and reproduce
- Zone of physiological stress: organisms survive, but experience stress (e.g., infertility, lack of growth)
- Zone of intolerance: organisms will die
How can increased temperatures from global warming relate to ecological tolerance?
Increased temperatures from global warming can shift temperatures outside a species' range of tolerance, damaging the species' ability to reproduce
(warm water holds less oxygen leading to suffocation)
What are natural disruptions?
Natural events that disrupt the structure and/or function of an ecosystem
(tornados, hurricanes, fires, etc.)
What are anthropogenic changes?
Changes that occur as a result of humans
(anthropogenic climate change vs. natural climate change)
Frequency of Natural Disruptions
- Periodic: occurs with regular frequency (e.g., dry-wet seasons)
- Episodic: occasional events with irregular frequency (e.g., hurricanes, droughts, fires)
- Random: no regular frequency (e.g., volcanoes, earthquakes, asteroids)
How do natural disruptions cause migration?
Animals may move to a new habitat as a result of a natural disruption
(birds fly south in the winter to stay at similar temperatures)
What is the difference between resistance and resilience in ecosystems?
Resistance is how well an ecosystem can withstand a disturbance
Resilience is how well an ecosystem can recover after a disturbance
What does the intermediate disturbance hypothesis claim?
Species diversity is highest when an ecosystem experiences neither too few nor too many ecological disturbances
What are traits?
A specific characteristic of an individual
(eye color, height, amount of fur/feathers)
What is adaptation?
A new trait that increases an organism's ability to survive and reproduce (fitness)
How do new traits occur?
Random mutations when DNA is being copied
Crossing over parents' chromosomes for new combinations
What is natural selection?
Organisms that are better adapted to their environment are more likely to reproduce and pass down their genes
(beneficial adaptations become more numerous this way)
What is a selective pressure/force?
An environmental condition that forces organisms to adapt in order to survive
(a predator can be a selective pressure that forces prey to evolve)
The more rapidly an environment changes, the less likely a species will be able to adapt to those changes
Higher genetic diversity allows a species to adapt more easily
What is reproductive isolation?
When two populations are no longer able to reproduce with each other
(due to allopatric or sympatric speciation)
What is allopatric speciation?
A species evolving into separate species due to a physical/geographic barrier
(e.g., existing on an island)
What is sympatric speciation?
A species evolving into separate species without a physical/geographic barrier
(e.g., due to different mating seasons)
What is the difference between sympatric and allopatric speciation?
- Sympatric: speciation without a physical barrier (mnemonic: same space)
- Allopatric: speciation with a physical barrier (mnemonic: all over the place)
What is ecological succession?
The progressive change in an ecological community's species structure over time
What is primary succession?
Ecological succession that occurs when a new patch of land is created/exposed for the first time
(e.g., volcanic eruptions creating new land)
What is secondary succession?
Ecological succession that occurs in an area that previously had wildlife but was disturbed (e.g., due to a forest fire)
What are pioneer species?
Species that are the first to colonize barren environments in ecological succession
(mosses and lichens pave the way for larger plants)
What happens as an ecosystem progresses through ecological succession?
Larger and more complex plants begin to grow, increasing total biomass, species richness, and net productivity
(mosses/lichens -> grasses -> shrubs -> small trees -> large trees)
What are keystone species?
Species whose activities have a particularly significant role in determining the structure of an ecological community
What are indicator species?
Species that demonstrate that some distinctive aspect of an ecosystem is present
(presence of amphibians means healthy water; decrease in amphibians may signal pollution)
What are generalist species?
Species that can live in many different places and don't have any specific requirements
(flies, cockroaches, raccoons, etc.; opposite of specialist species)
What are specialist species?
Species of animals that require very special conditions to survive
(pandas, koalas, etc.; opposite of generalist species)
Are specialist or generalist species more likely to survive natural disruptions?
Generalist species because they do not require as specific conditions and are therefore more adaptable
Are invasive species more likely to be generalists or specialists?
Generalists because generalists have less specific requirements, meaning that they can thrive in foreign habitats more effectively
(it's hard to imagine pandas (specialists) as being invasive)
Specialist species tend to be advantaged in habitats that remain constant, while generalist species tend to be advantaged in habitats that are changing
What are reproductive strategies?
How animals mate and raise offspring
(K-selected vs. r-selected)
What are the characteristics of K-selected species?
Have few offspring, but put a lot of parental care into those offspring
Typically larger
(e.g., elephants, humans, bison)
What are the characteristics of r-selected species?
Have a lot off of offspring, but invest little parental care into each offspring
Typically small
(e.g., rodents, insects, weeds)
What is biotic potential?
The maximum reproductive rate of a population in ideal conditions
(assuming infinite resources with no limiting factors)
Are all species only r-selected or K-selected?
No, species can be in between r and K-selected
(it's a spectrum, not either/or options)
K-selected species are typically more adversely affected by invasive species than r-selected species
Most invasive species are r-selected species
What are survivorship curves?
Lines that display the relative survival rates of groups of individuals of the same age in a population
(three main types)
What are the three survivorship curves?
- Type I: Most of the population dies off near old age (typically K-selected due to extensive parental care)
- Type II: Constant death rate regardless of age
- Type III: Lots of early deaths with few living to old age (typically r-selected due to lack of parental care)
Three Survivorship Curves
- Type I: Most of the population dies off near old age (typically K-selected due to extensive parental care)
- Type II: Constant death rate regardless of age
- Type III: Lots of early deaths with few living to old age (typically r-selected due to lack of parental care)
What is carrying capacity (K)?
The maximum size of a population given the resources available in an environment
What is overshoot?
(in populations)
When a population exceeds its carrying capacity
(this can cause resource depletion)
What happens as a result of overshoot?
Severe or catastrophic dieback of the population
(there are no more resources left, so the population rapidly decreases)
What is population growth?
The rate at which a population can grow, given environmental limitations such as the available resources and space
What is exponential growth?
When populations grow at a constant rate (r), making the population grow faster and faster as it gets larger
(bacteria in a petri dish)
Does exponential growth occur in nature?
Yes, but only in the short-term
Resource availability will make the growth logistic in the long-term
What is logistic growth?
When a population's growth rate (r) decreases as it approaches carrying capacity
What is growth rate (r)?
The percent change in a population over time
(10% growth rate -> the population increases exponentially by 10% each year)
When the resources needed by a population for growth are abundant, population growth usually accelerates
Resource depletion leads to unequal distribution, which causes mortality and decreased fecundity, resulting in population decline to or below carrying capacity
What are age structure diagrams (population pyramids)?
Models that show the distribution of age and sex in a population
Age structure diagram cohorts:
- Pre-reproductive age: 0-14
- Reproductive age: 15-44
- Post-reproductive age: 45+
Why are age structure diagrams useful?
They can be used to interpret a population's growth rate and stage in the demographic transition model
A rapidly growing population will have a higher proportion of younger people compared to stable or declining populations
What is total fertility rate?
The average number of children born to a woman over her lifetime
What influences total fertility rate?
- The age at which women have their first child
- Educational opportunities for women
- Access to family planning
- Government acts and policies
What is replacement rate?
The total fertility rate required for a population not to shrink
(~2.1; if TFR is below replacement rate, a population will shrink)
What is infant mortality rate?
The number of infant deaths per 1,000 live births
(high IMR = lots of deaths)
What influences infant mortality rate?
Whether or not mothers have access to good healthcare and nutrition
What are crude birth rate and crude death rate?
- Crude birth rate: the number of births per 1000 people
- Crude death rate: the number of deaths per 1000 people
What factors influence whether a population is growing or declining?
- Crude birth and death rate
- IMR
- TFR
- Access to education
- Postponement of marriage
What is Malthusian theory?
Population growth is exponential, but food/resource growth is linear, so population will eventually exceed resources leading to decline
(criticized for being mostly incorrect and often having racist implications)
What are density-independent factors?
Factors that affect population growth regardless of the population size, such as natural disasters