Population growth follows either a linear or exponential pattern. Linear growth sees population increase by the same number each year, while exponential growth causes the population to increase at an accelerating rate over time. All populations are limited by their environment's carrying capacity, which is the maximum population size the available resources can sustain. As human population has exceeded Earth's carrying capacity, factors like disease, starvation, pollution and climate change are expected to cause human numbers to decline back towards that limit.

1. Population Growth and
Carrying Capacity

2. Objectives
• SWBAT explain population growth and
carrying capacity
• SWBAT discuss the potential decline of human
beings

3. Principles of Population Growth
• Population is a group of organisms, all of
the same species, that live in a specific area
at the same time.
• Population growth is defined as an increase
in size of a population over time…
• However, populations grow at different
rates.

4. Linear Growth
• If a population grew at a set amount each
year, say by 10 organisms per year, then the
population has LINEAR GROWTH
• However, populations normally do not have
linear growth. Linear growth looks like this
(Please draw in your notes)

5. Question
Your parents give you two options for allowance
1. 1,000 a month
2. A penny on the first day of the month that
doubles to two pennies on the second day
and so on until the last day
of the month
Which option do you choose?

7. .01 .02 .04 .08 .16 .32
.64 1.28 2.56 5.12 10.24 20.48 40.96
81.92 163.84 327.68 655.36 1310.72 2621.44 5242.88
10,485.76 209711.52 41943.04 83886.08 167772.16 335544.32 671088.64
1342177.28
2684354.56
5368709.12
10,737,418.24
Over 10 million!!
On 31 day months

8. Exponential Growth
• If you graph the allowance we just saw on the
graph it will look like this, its is called
EXPONENTIAL GROWTH:
• (Please draw in your notes)
0
2000
4000
6000
8000
10000
12000
14000
16000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

9. Exponential Growth
• A population that is growing without any limits,
would have exponential growth.
• Meaning that as the population gets bigger, it also
will grow faster
• But, populations cannot keep exponential growth
for very long, because the environment would
not be able to support it.

10. Exponential Growth

11. Carrying Capacity
• The environment has a CARRYING
CAPACITY for each population…
• Carrying capacity is the maximum number
of organisms in a population supported by
an ecosystem’s resources/limiting factors
– Effected by factors such as the amount of:
• Food, water, space, etc…
– Can change when these factors change
• EX: more food = higher carrying capacity!

12. Limiting Factors
• Definition?
Limiting factors are any biotic or abiotic factor
that causes population size to decrease and
influences what can live where

13. Question
• What are some examples of things that can
limit growth?

14. Question
• What are some examples of things that can
limit growth?
– Food, space, ability to reproduce, water,
predators…

15. What can limit growth?
• Limiting factors limit growth
• Different sizes of populations will also
have different factors affecting them.
• When growth has been limited its
graph will look like this:
(please draw in your notes)
0
200
400
600
800
1000
1200
1400
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

16. Claim, Evidence, and Reasoning
• Look at the next slide and make a claim about
human population.
• Then use evidence to support your claim
• Use reasoning to explain your claim.

18. Claim
• Human beings have exceeded their carry
capacity on Earth and they will eventually
return back to that capacity.

19. Evidence
• What part of the graph supports your claim?

20. Reasoning
• What will cause the human population to go
down?

21. Reasoning
• What will cause the human population to go
down?
– Disease
– Starvation
– Weather events (hurricanes, tornados, global
warming)
– War/Crime
– Lack of fresh water
– Pollution

24. QUESTION: Interpreting Graphs and Data
What happens
during the
“transitional
stage”?
a. Birth rates rise; death rates drop; population increases
b. Birth rates drop; death rates drop; population decreases
c. Death rates drop; birth rates are stable; population
increases
Figure 7.18

25. QUESTION: Interpreting Graphs and Data
What happens
during the
“transitional
stage”?
a. Birth rates rise; death rates drop; population increases
b. Birth rates drop; death rates drop; population decreases
c.Birth rates are stable; death rates drop; population
increases
Figure 7.18

26. Exit Ticket
• What is population growth?
• Describe the difference between linear and
exponential growth?
• What is a carrying capacity?
• Name 3 reasons that the human population
may decline?

27. Centers
• Bill Nye Center
• Population Growth Center
• BrainPOP