Biology Chapter 5 Flashcards
What is geographic distribution?
Geographic distribution, or range, describes an inhabited area of a population
What are the three main characteristics of a population?
Geographic Distribution, Density, and Growth Rate
What is density?
The amount of something in a given unit of area.
What three factors can affect population size?
Births, deaths, and imm/emigration
What is the difference between immigration and emigration?
Immigration means moving in, emigration means moving out.
Why might an organism change location?
Looking for a mate or food.
What is exponential growth?
It is when individuals constantly reproduce
What shape does a line on a graph of exponential growth make?
J-shape
What happens when exponential growth stops?
The carrying capacity is reached.
True or false: The time it takes an organism to reproduce affects exponential growth.
False
What is logistic growth and when does it occur?
It is when population growth slows after exponential growth.
What shape does a line on a logistic growth graph make?
S-shape
What is it called when a population reaches the maximum population it can possibly hold?
Carrying capacity.
What is a limiting factor?
A factor that causes population to decrease.
What is an example of a limiting factor?
A limiting nutrient.
What is a density-dependent limiting factor?
Factors that prevail or fail depending on the density of a given population.
When does a density-dependent factor become limiting?
When the population shrinks to a certain amount.
What are examples of a density-dependent limiting factor?
Competition, predation, parasitism, and disease.
How are parasites like predators?
Both benefit at the demise of another organism.
What is a density-independent limiting factor?
A factor that affects a population regardless of its size.
What are examples of density-independent limiting factors?
Unusual weather, natural disasters, seasonal cycles (i.e. droughts), and some human activity
What usually happens to a population affected by a density-independent limiting factor?
It recovers but after it drops.
What is the current trend of the human population?
Exponential growth
Why was population growth not significant 2000 years ago?
Life expectancy was not a large number.
Will the human population grow forever? Why?
No because Earth has limited resources.
What is demography?
The scientific study of populations.
What factors can be used to predict human population change?
Birth rates, death rates, and age structure.
Why has population slowed in some parts of the world?
Demographic transition.
What factors have helped lower death rates?
Better nutrition, sanitation, and medicine.
True or false: As countries finish the demographic transition, human population growth will slow down.
True
What will probably happen if human population growth does not slow down?
Serious damage to the environment and economy.
What is the estimated human population in 2050?
9 billion
