Biology Chapter 5
Terms in this set (63)
How do ecologists study population?
They study the populations' geographic range, density and distribution, growth rate, and age structure
the area inhabited by a population
the number of individuals per unit area
how individuals in a population are spaced out across the range of the population
what are different examples of distribution?
randomly, uniformly, or clumped
what does a population's growth rate determine?
whether the size of the population increases, decreases, or stays the same
the number of males and females of each age a population contains
why do ecologists study age structure?
because most plants and animals can not reproduce until they reach a certain age
what factors affect population growth?
birthrate, death rate, and rate by which individuals enter or leave the population
how can a population grow in terms of birthrate?
it can grow if there are more births than deaths
movement of individuals into an area occupied by an existing population
movement of individuals out of an area
what happens during exponential growth?
a population will grow exponentially under ideal conditions with unlimited resources
growth pattern in which the individuals in a population reproduce at a constant rate
what is exponential growth nicknamed?
when does logistic growth occur?
when a population's growth slows and then stops after a period of exponential growth
what is logistic growth nicknamed?
what are the phases of growth?
exponential growth, growth slows down, growth stops
what happens when the growth rate of a population stops?
it stays the same or decreases
what's more popular: exponential growth or logistic growth?
largest number of individuals of a particular species that a particular environment can support
what happens once a population reaches the carrying capacity of its environment?
a variety of factors act to stabilize it at that size
what factors determine carrying capacity?
a factor that controls the growth of the population
examples of limiting factors
competition, predation, parasitism, disease, unusual weather, natural disaster
who recognized the importance of limiting factors shaping the history of life on earth?
density- dependent limiting factors
limiting factors that depend on population density
what are examples of density dependent limiting factors
competition, predation, herbivory, parasitism, disease, and stress from overcrowding
what doesn't density dependent limiting factors usually affect?
small, scattered populations
density-independent limiting factors
limiting factors that affect all populations in similar ways regardless of population density
exampels of density- independent limiting factors
hurricanes, floods, droughts, natural disasters
what comes after exponential or logistic growth?
a population crash
when do density dependent limiting factors occur?
when a population is too large
who moves: predators or prey?
What are populations characterized by?
Density and distribution
The area inhabited by individuals
Density and Distribution
How individuals are spaced out
Can be measured
Number of males and females and ages
numbers of individuals in an area
What factors may affect population size?
Food, land, mates, disease, immigration and emigration, death rate, competition
Moving of individuals into a region occupied by an existing population
Moving of individuals out of a region
What are the two ways in which a population grows?
Exponential growth and logistic growth
Under ideal conditions, a populations grows extremely fast at a constant rate
"J" curve- from nothing to a steep increase
Not a god thing, can lead to infestation, negative impact on environment
Examples: fruit flies, rabbits, bacteria
Healthy way that most populations grow
Growth pattern in which a population's growth rate slows or stops following a period of exponential growth
Three phases of logistic growth
Growth pattern levels off and reaches carrying capacity
Occurs when the population in an area decreases or drops dramatically, could be from a group of hunters or predators coming in and killing the population, disease, competition, etc.
What are the two types of limiting factors?
Density-dependent and density-independent
Occurs when populations get too large
Limiting factor that depends on population size
Affects ALL types of populations in similar ways, regardless of population size
1. Weather, climate, natural disasters
2. Humans, such as pollution or construction
What happens to the predators when the prey die?
They emigrate, or migrate
What is the relationship between population size and competition?
As the size of a population increases, competition also increases for limited resources such as food, space, land, water, and mates
If an entire lynx population disappears, what is likely to happen to a hare population on which it preys?
The hare population will experience exponential growth of a great increase or growth in size
largest number of individuals of a population that a given environment can support
Mechanism of population control in which a population is regulated by predation
Factor that causes the growth of a population to decrease
What is any factor that causes population growth to decrease?
The scientific study of human population
In a logistic growth graph, what is the factor that keeps population growth from staying around the carrying capacity?
In a logistic growth graph, what is the ability for a population to experience exponential growth called?
If the number of organisms in a population is under the environment's carrying capacity, what happens to the births and deaths?
The births will be less than deaths and the population shrinks
If the number of organisms rises above the carrying capacity of the environment, what happens to the births and deaths?
Births will be greater than deaths and the population grows
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