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80 Cards in this Set
- Front
- Back
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what is socioeconomic status?
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-lowerclass
-middleclass -upperclass |
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What is PGR or population growth rate?
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-can be less than 0 or above 0
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How do you find the PGR?
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to find PGR, you find birthrate plus immigration rate minus deathrate plus immigration rate=PGR
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What is carrying capacity?
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the number of otganisms in an ecosystem that can be supported without killing off the whole ecosytem, rapid life organisms go above it.
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What is a J-curve?
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represents unlimited growth, its less realistic then an S-curve. As the population gets larger they increase at a faster rate.
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What is doubling size?
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when a country doubles in size
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what is age structure?
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graph that shows relationship/compares
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what is immigration?
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the movement of people into a country either legal or illegal
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what is demography?
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the study of populations
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what are density dependent factors?
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abiotic/biotic factors that affect a population depending on how many organisms are present
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what is competition?
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when organisms or species compete within the enviroment for certain resources, it increases as population increases
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what are density independent factors?
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factors such as tempertature, storms, floods, drought or habitat disruptions that effect all populations regardless of their density.
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What is an S-curve?
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it represents a community where there are limiting factors. it also shows the community's carrying capacity.
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what is population?
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a group of organisms, all of the same species, that live in the same area at the same time.
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what will a healthy population do?
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will grow/increase in numbers and die at a relatively steady rate unless it runs out of food, water, space, or is attacked by disease or predators.
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what resembles a J-curve?
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Growth of a population starts out small, then the growth quickly increases
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what creates a J-curve?
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The initial increase in the number of organisms is slow because the number of reproducing individuals is small. However, when the rate of the population growth increases, and the total number of individuals that are able to reproduce increases. This leads to a drastic increase in population numbers.
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what does a J-curve show?
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unlimited growth
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what is unlimited growth?
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This curve shows that as populations get larger, they also increase in number at a faster rate. This can lead to unchecked/uncontrolled growth.
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what is an S-curve?
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certain factors exist that limit the potential for unchecked growth. More realistically, the population curve will end up being an S-curve, in which population number stabilizes after a certain point.
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: the number of organisms of one species that the environment can support.
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carrying capacity
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what happens when birth rate exceeds death rate?
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there are more organisms living in the environment than it can support. In this case, organisms begin to die off until the population number becomes closer to the carrying capacity number again.
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what are reproduction patterns also called?
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life history patterns
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what also affects population size?
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life history patterns
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what do elephants exhibit?
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a slow life history pattern
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why do elephants have a slow life history pattern?
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They have a slow rate of reproduction and produce few offspring over their lifetime.
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why do mosquitos exhibit a rapid life history pattern?
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They have rapid reproduction and produce large amounts of offspring over their lifetime.
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what are the rapid life history patterns?
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Common among organisms from changing or unpredictable environments.
Organisms usually have a small body size, mature, rapidly, reproduce early, and have a short life span. (for example, insects) These traits affect the population growth. The population of rapid life history organisms usually increases rapidly, then declines when environmental factors such as temperature drastically changes and becomes unsuitable for sustaining life. The small population that does survive will reproduce exponentially when environmental conditions become favorable again, bringing the population size back up or near to the carrying capacity. |
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what are the slow life history patterns?
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Large species that live in more stable environments
For example, elephants, bear, humans, trees Reproduce and mature slowly, and live a long life Population size remains at or near the carrying capacity. Therefore, the population size of slow life history organisms is always more stable than that of rapid life history organisms. |
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what are limiting factors?
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biotic or abiotic factors that determine whether or not an organism can live in a particular environment.
Limited food supply, space, chemicals produced by plants themselves, extreme temperatures, and storms are examples. |
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what is dispersal?
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refers to how organisms are spread out in a community.
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what are the 3 types of dispersal?
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random, clumped, and uniform.
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what is random?
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no specific organization to how organisms are spread out in a community.
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what is clumped?
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organisms are concentrated in a certain area within the community
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what is uniform?
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organisms are spread out evenly in a community
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what is density?
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If a population is dense, it has a large number of individuals in it. For example, a city has a lot of humans living in close proximity to one another. It is a community that is densely population with humans
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what is a community that is not denslely populated with humans?
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In a country setting, humans live far apart (sometimes there are miles between neighbors!).
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what are two factors that are realted to dispersal?
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density-dependent and density-independent factors.
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what are density dependent factors?
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factors that have an increasing effect as the population increases. These factors include: diseases, competition, predators, parasites, food.
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what is an example of disease as a density dependent factor?
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disease has an increasingly harmful effect in populations where members live close to one another. This is because disease can then spread more rapidly from one organism to another.
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what are density independent factors?
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can affect populations regardless of their density. Most are abiotic factors such as volcanic eruptions, temperature, storms, floods, drought, chemical pesticides, etc.
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what are the most vulnerable to density independent factors?
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the most vulnerable appear to be small organisms with large populations, like insects.
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how does predation affect population size?
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When a predator consumes its prey on a large enough scale, it can have a drastic effect on the size of the prey population.
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what does competition within a population affect?
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population growth
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what happens when the population increases and the demand for resources exceed supply?
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population size will decrease
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what happens when population numbers are low?
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resources can build up and become plentiful
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what happens when resources are used up?
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the population increases in size and competition for resources such as food, water, and territory again increases.
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what are the symptoms of stress?
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aggression, decrease in parental care, decreased fertility, and decreased resistance to disease.
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what happens when populations of organisms become crowded?
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individuals may exhibit symptoms of stress
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what do the symptoms of stress do?
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All of these symptoms can have negative effects on a population. They become limiting factors for growth and keep populations below carrying capacity.
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how often is a census taken in the U.S?
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every 10 years
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what does a census provide?
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this information provides a picture of how many people there are in the U.S., their economic condition, and where they live
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what does a person's economic condition do?
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describes their financial resources
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what is a socioeconomic status?
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We use the words lower class, lower middle class, middle class, upper middle class, and upper class to refer to a person’s economic condition
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the study of human population size, density and distribution, movement, and birth and death rates.
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Demography
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what happened until the 1800's?
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human population growth remained fairly slow
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what happened since the 1930's?
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world population has grown rapidly, reaching 6 billion in 1999
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what happened in 2002?
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, human population was growing at a rate of 1.3 million people per year
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how is human population growth different from the population growth of other organisms ?
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because humans can consciously change their environment
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what are examples of humans changing the enviroment?
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we have had medical advances that have eradicated diseases such as smallpox. We have developed methods for producing more food. We have also had technological advances that have improved the delivery of clean water. When these factors are accounted for, people live longer and produce offspring that are healthier and live longer, and population increases.
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the number of live births per 1000 in a given year
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birthrate
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the number of deaths per 1000 in a given year
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deathrate
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movement of individuals into a population
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immigration
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movement of individuals out of a population
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emigration
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If birthrate, death rate, immigration, and emigration values are correct, the most accurrate method for acquiring population growth rate is?
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(birthrate + immigration rate)- (Death rate + emigration rate) = Population Growth Rate (PGR)
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what do we abbreviate population growth rate as ?
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PGR
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what happens if birthrate equals deathrate?
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then population growth is zero
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Immigration and Emigration rates are usually not accurrate. These values are difficult to correctly determine.for simplicity and convenience, we often use:
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Birthrate- Death rate = Population Growth Rate (PGR)
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the time needed for a population to double in size
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Doubling Time
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what is a country that has a slow doubling time?
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developed country
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describe a developed country?
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They have already reached a population size near their carrying capacity and are relatively stable
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A country with a rapid doubling time
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developing country, They have not yet come close to their carrying capacity
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Scientists can calculate doubling time for?
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countries, and also for smaller regions, like cities and small towns.
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what is age structure?
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Refers to the proportions of the population that are in different age levels
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what can an age structure graph can tell you?
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how many males and females there are in a population, and how many people there are at each age level.
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What are some things that populations need to grow and survive?
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Uncontaminated water for drinking and agriculture (farming)
Adaquete sewage facilities Ability to provide food for a growing population |
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why do rapidly growing (developing) countries have age structures with a wide base?
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because a large percentage of the population is made up of children and teenagers. If the percentage of people in each age category is fairly equal, the population is stable.
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How can a population be threatened?
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Sometimes, a population grows more rapidly than the available resources can handle (competition increases).
Resources needed for life, such as food and water, become scarce or contaminated. The amount of waste produced by the large population becomes difficult to dispose of. These conditions can lead to stress on current resources and contribute to the spread of disease that affect the stability of human populations. |
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the study of population characteristics such as growth rate, age structure, and movement of individuals (immigration and emigration).
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Demography
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How do populations differ?
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Birthrate, death rate, immigration, and emigration, as well as doubling time and age structures differ considerably among different countries. There are uneven population growth patterns throughout the world (some countries are developing, and some are already developed).
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