Population Growth
A population is….
A group of organisms, of the same species,
that live in the same location.
Ex: population of frogs in Lums Pond
Ex; population of bacteria in a mouth
Ex: human population of Delaware
Biotic Potential
The highest rate of reproduction under ideal
conditions
Ex: a fly’s biotic potential is 900.
Ex: a human’s biotic potential is over 68
children.
Population Density
The number of individuals in
a given area .
(Ex: 22 students/classroom
or 18 people/phone booth)
Calculating Population Density
Population Density
=
Number of Individuals
Unit Area
Example:
Suppose you counted 200 Oak trees in a 100 acre area. What is
the population density?
Answer : 200 oaks/100 acres
or 2 oaks/1 acre
Question
If both Wilmington and Milton are
considered the same size area, which would
have the higher Population Density?
Three basic patterns for a
population’s growth
Linear growth
Exponential growth
Logistic growth
Linear Growth
Growth that occurs at a constant rate would
be considered linear growth
Example: If my hair grows .25 inches every
week, then in one month my hair grows 1
inch, in two months it grow two inches, and
in three months it grows three inches
Linear growth
Exponential Growth
Bacteria can reproduce quickly
given the resources…
Exponential Growth
Describe what it means by looking at the graph.
Starts out slowly…takes a long time to build up and then it
has a rapid increase.
Current world populations is approximately is over 7.2
Billion since October 2013.
Logistic Growth: The S curve
Logistic Growth
What does it mean according the graph pattern?
The population grows exponentially until limiting
factors halt population growth and things
eventually start to die out.
No population can grow forever:
Growth stops when the population reaches
its CARRYING CAPACITY
The maximum number of individuals that
an environment can support!
Scientists estimate the world’s carrying
capacity for humans to be around 8.5-10
billion people.
Population Growth Depends on 2
Things
Birth Rate
Death Rate
Number of births in a
given amount of time
Ex: US birth rate is
14.16/1000 people
Number of deaths in a
given amount of time
Ex US death rate is
8.27/1000 people
Changes in Predator and Prey
populations
Predator and Prey relationship
As the population of prey increases ( ), the
predator population ( ) begins to follow it.
As prey populations begin to decrease ( ),
the predator populations begin to decrease
( ).
Whooping Cranes (Grus americana) are the tallest birds in North
America. They stand about 1.6 metres tall and have a wingspan of two
metres.
Beginning in the 1900s the Whooping Crane population began to decline
as wetland habitat was drained for farmland and as birds were shot. By
1941, only 16 birds survived and shortly after this a concerted
conservation efforts by Canada and the United States began. This effort
has succeeded in increasing the population to about 180 birds by 1999.
Distribution
1. Which type of graph
represents human population
growth?
A. Exponential
86%
B. Linear
C. Logistic (S curve)
D. parabola
5%
9%
0%
2. The most accurate way to determine
population size. This is where they count
every organism.
59%
A. Sampling
B. Indirect
observation
C. Mark and
recapture
D. Direct observation
27%
14%
0%
3. The largest population an area
can support.
A. Biodiversity
91%
B. Biotic potential
C. Carrying capacity
D. Limiting factors
5%
5%
0%
4. When an organism leaves a
population
A. Immigration
91%
B. Emigration
C. Death rate
D. Birth rate
9%
0%
0%
5. An environmental factor that
causes a population to
decrease.. Ex. Lack of water.
91%
A. Environmental
factor
B. Limiting factor
C. Carrying capacity
D. community
9%
0%
0%
6. The number of births in a
certain amount of time.
A. Birth rate
100%
B. Baby rate
C. Death rate
D. Marriage rate
0%
0%
0%
7. When you move into a
population
A. Emigration
100%
B. Immigration
C. Sampling
D. Mark and
recapture
0%
0%
0%
8. The highest rate of reproduction under
ideal conditions
67%
A. Carrying potential
B. Biotic potential
33%
C. Reproduction
potential
D. Baby making
potential
0%
0%
9. If the birth rate exceeds the
death rate the population will:
A. Increase
86%
B. Decrease
C. Stay the same
D. immigrate
14%
0%
0%
10. Counting signs of organisms (like their
home) then determining their population
size.
68%
A. Observation
B. Indirect
observation
C. Direct observation
D. sampling
32%
0%
0%
11. Scientist capture a group of organisms and
mark them without causing harm and release
them. Later they capture more and compare
the amount of marked vs. unmarked species to
100%
calculate a population.
A. Random sampling
B. Mark and
recapture
C. Reassigned
sampling
D. Direct observation
0%
0%
0%
12. What is the approximate
current population of the world?
A. 6.9 million
95%
B. 6.9 billion
C. 9.6 million
D. 9.6 billion
5%
0%
0%
13. On a population graph who
would have the higher
population?
A. Prey
67%
B. Predators
C. Smiles
D. Sunshine and
33%
rainbows
0%
0%
14. What is the population density of oak
trees in Mrs. C’s backyard. There are 10
oak trees in 20 square meters.
50%
A. 200 oak trees per
square meter
B. .5 oak trees per
square meter
C. 2 oak trees per
square meter
41%
9%
15. Ms. Webb counts the amount of
poison ivy in a 1 meter radius. She then
multiplies it by her yard of 20 square
meters. This is an example of:
A. Mark and
recapture
B. Direct observation
C. Indirect
observation
9%
0% 0%
D. sampling
91%
16. If there is 40 poison ivy plants
in a 1 meter radius, how many
poison ivy plants are there in her
77%
20 square meter yard?
A. 800 plants
B. 80 plants
C. 600 plants
23%
D. 60 plants
0%
0%
17. Limiting factors of population
size are:
A. Predators,
disease, birth
rate, death rate
B. Food, water,
space, weather
C. Food, carrying
capacity, disease,
immigration
91%
5%
5%
18. What historical event led to a
huge increase in the world
population?
82%
A. World War 1
B. Dust Bowl
C. War on Terrorism
D. Industrial
Revolution
9%
9%
0%
19. What happens when the
rabbit population increases
95%
A.
B.
C.
The
amount of
fox
increase.
The
amount of
fox
decrease
The
amount of
fox stays
the same.
5%
0%
20. Why is the population of
rabbits more than the population
of fox?
100%
A.
B.
C.
Because rabbits are
lower on the food chain
so there is more of them
in the energy pyramid.
It is because of where
they calculated this data
from had less fox.
As you move up the
food chain the easier it
is to obtain energy.
0%
0%