6. Populations Cannot Grow Indefinitely

Question 1

What is the formula for population growth?

Answer 1

BIDE processes

(births + immigration) - (deaths + emigration)

Question 2

What are the 2 ideal population growth models?

Answer 2

exponential growth (J-shaped curve)

logistic growth (S-shaped curve)

Question 3

What are characteristics of the exponential growth model?

Answer 3

constant rate of increase
(like compounded interest)

can happen when there are unlimited resources

Question 4

When is the exponential growth model mostly seen?

Answer 4

when a population is initially colonizing a new environment (like bacteria on a petri dish)

a population recovering from a crash (overhunting, habitat loss, etc.)

Question 5

is indefinite exponential growth possible?

Answer 5

Malthus says no

there is a carrying capacity
(the environment can only support so many, you can’t have unlimited resources forever)

there’s a struggle for existence the more individuals there are / less space there is

Question 6

What slows population growth?

Answer 6

intra-specific competition

disease

predation

Question 7

How does competition slow population growth?

Answer 7

mortality rate increases

female fertility decreases

individual growth rate decreases

Question 8

What letter represents carrying capacity in ecological graphs usually?

Answer 8

K

Question 9

What are characteristics of the logistic growth model?

Answer 9

S-shaped curve

carrying capacity (K)
(populations will stay around the carrying capacity once they reach it, determined by resources and space)

initially looks exponential

Question 10

What growth model are humans following right now?

Answer 10

currently exponential growth, is expected to turn logistic

Question 11

Human’s life expectancy and development have been what? Why?

Answer 11

increasing globally

advances in agriculture → lots of protein

decrease in infant mortality → modern medicine

Question 12

Human’s birth rates have been what?

Answer 12

decreasing, some countries are even below replacement

Question 13

Are the birth rates above or below the death rates in Canada?

Answer 13

below

Question 14

Is the world population still growing?

Answer 14

yes, but it is slowing down

Question 15

What is demographic transition?

Answer 15

a phenomenon and theory which refers to the historical shift from high birth rates and high death rates to low birth rates and low death rates

Question 16

How do you achieve demographic transition?

Answer 16

increase in wealth → need fewer children to work

gender equality → access to education, jobs, and contraception (women have more options and delay reproduction)

education and equality drive wealth

Question 17

Is there an environmental cost to development?

Answer 17

yes, increase in ecological footprint because of economic growth

if we focused more on gender equality (no extra emissions) there would be less ecological repercussions

Question 18

What has breaching the carrying capacity of the earth resulted in?

Answer 18

climate change, ocean acidification, hole in the ozone, ocean dead zones, biodiversity loss

Question 19

What is more important for the future of the earth: overconsumption or overpopulation?

Answer 19

lots of confusion on this issue

overconsumption is the more pressing issue, but it doesn’t mean overpopulation isn’t one

Question 20

What is I=PAT?

Answer 20

environmental Impact of humans on the biosphere = Population size x Affluence x Technology

Question 21

Who produces more C02 by capita?

Answer 21

wealthy countries produce more C02 per capita, but decreasing and increasing in poorer countries

Question 22

What is the more current version of I=PAT?

Answer 22

I = N x ecological footprint/person (WATCH SLIDES FOR EXPLANATION)