University:
Bradley University
Course:
BIO 300 | Population, Resources and Environment
Academic year:

2022
Views:

169

Pages:

3
Author:

Cale Mejia

Chapter 5: Populations Section 5-1: How Populations Grow Characteristics of Populations 1. Geographic distribution (range) 2. Density  Population Density: the number of individuals per unit area 3. Growth rate Three factors that affect population size:  Number of births  Number of deaths  Number of individuals that enter or leave the population  Immigration: movement of individuals into an area  Emigration: movement of individuals out of an area Exponential growth  Individuals in a population reproduce at a constant rate  Under ideal conditions with unlimited resources  J-shaped curve Logistic growth  A population’s growth slows or stops following a period of exponential growth  As resources become less available  S-shaped curve Carrying capacity: the largest number of individuals that a given environment can support Section 5-2: Limits to Growth Limiting Factor  Factor that causes population growth to decrease  Density-Dependent Limiting Factors o A limiting factor that depends on population size o Become limiting only when the population density reaches a certain level o Operate most strongly when a population is large and dense o Competition  The more individuals living in an area, the sooner they use up the available resources o Predation  o Predator—prey relationship  population control Parasitism and Disease  Parasites take nourishment at the expense of their hosts, usually causing disease or death  Density-Independent Limiting Factors o Affect all populations, regardless of the population size o Crash in population size o Examples  Unusual weather  Natural disasters  Seasonal cycles  Human activities (damming rivers, clearcutting forests) Section 5-3: Human Population Growth Historical Overview  The size of the human population tends to increase with time  For most of human existence, population grew slowly  About 500 years ago began growing more rapidly o Agriculture & industry made life easier & safer o More reliable food supply o Goods could be shipped around the world o Improved sanitation, medicine, & health care reduced death rate & increased longevity Patterns of Population Growth  Demography: the scientific study of human populations  Birthrates, death rates, & the age structure of a population help predict why some countries have high growth rates while other countries grow more slowly  The Demographic Transition o Population growth in the U.S., Japan & much of Europe has slowed dramatically o These countries have completed the demographic transition (a dramatic change in birth & death rates) o Advances in nutrition, sanitation & medicine, more children survive to adulthood & more adults live to old age o This lowers the death rate & begins the demographic transition o As societies modernize, increase levels of education, & raise their standard of living, families have fewer children o Birthrate falls & population growth slows Future Population Growth  Current predictions estimate that by 2050 the world population may be more than 9 billion  Growth rate projected to be 0.43 percent  Could lead to serious damage to the environment as well as the global economy

Chapter 5 Populations Answer Key

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