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Biology chapter 5 EA
Nabor chapter 5
| Question | Answer |
|---|---|
| geographic range | the area inhabited by a population |
| population density | refers to the number of individuals per unit of area |
| distribution | refers to how individuals in a population are spaced out across the range of the population |
| three type of distribution | random, uniform, and clumped |
| a population's growth rate determines whether the size of the population___? | increases, decreases, or constant |
| hydrilla | a plant that was from Asia and is very adaptable. |
| age structure | the number of males and female of each age a population contains. (refer to page 144 and 145 for diagram) |
| factors that affect a population size | birthrate, death rate, and rate at which individuals enter of leave the population |
| a population ___ when its birthrate is higher than its death rate | grows |
| if the birthrate ___ the death rate, the population remains the same | equals |
| immigration | when individuals move into its range from elsewhere |
| emigration | when individuals move out of the population's range |
| emigration does what to a population? | decreases |
| immigration does what to a population? | increases |
| exponential growth | the size of each generation of offspring will be larger than the generation before it. the larger a population gets, the faster it grows. |
| when can exponential growth occur? | under ideal conditions with unlimited resources. |
| the three phrases of growth | exponential growth, growth slows down, growth stops. |
| growth slows down | population does not decrease, just begins to slow down. the rate of growth slows down. |
| growth stops | the population growth drops to zero. begins to level off, will remain at or near this indefinitely. |
| logistic growth | in a graph, is represented by an s shaped curve. occurs when a population's growth slows and then stops, following a period of exponential growth |
| carrying capacity | maximum number of individuals of a particular species that a particular environment can support |
| limiting factor | a factor that controls the growth of a population. keep most natural populations somewhere between extinction and overrunning the planet |
| examples of limiting factors | competition, predation, parasitism, disease, natural disasters, and unusual weather |
| density-dependent limiting factors | limiting factors that operate strongly only when population density reaches a certain level |
| density-dependent limiting factors examples | competition, predation, herbivory, parasitism, disease, and stress from overcrowding |
| competition | a limiting factor that is caused by competing for food, water, space, sunlight, and other essentials |
| predation-prey relationships | wolves hunt moose. (refer to page 138-139) predators' populations rise and fall as a result of their prey |
| parasitism | organisms that feed at the expense of their hosts, weakening them and often causing disease or death. |
| stress from overcrowding | species will fight amongst themselves if the area becomes overcrowded. can lower birthrates, raise death rates, and also increase emigration |
| density-limiting factors | affects all populations in similar ways, regardless of population size and density |
| examples of density-independent liming factors | hurricanes, droughts, floods, and wildfires |
| example of density-independent limiting factor that is dependent | heavy snow covers the plants. the effects of the weather on the large dense population were greater than they would have been on a small population. there would have been less competition and more food available for a small population. |
| How has human population size changed over time? | The human population, like populations of other organisms, tends to increase. the rate of that increase has changed dramatically over time. |
| limiting factors on humans | war, famine, and disease |
| demography | the scientific study of human populations |
| birthrates, death rates, and age structures of a population help predict___ | why some countries have high growth rates while other countries grow more slowly |
| demographic transition | a dramatic change form birthrates and death rates to low birthrates and death rates (refer to page 144 for graph) |
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