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HES: CHAPTER 8 Study Guide –
POPULATION DYNAMICS, CARRYING CAPACITY, AND CONSERVATION BIOLOGY
“We cannot command nature
except by obeying her.”
~Sir Francis Bacon
8-1 Population Dynamics and Carrying Capacity
1. What are population dynamics?
Biotic and abiotic factors that tend to increase or decrease the
population size and age and sex make-up of a species
2. What are four (4) ways populations change in response to stress or changes in environmental
conditions?
size, density, dispersion, age distribution
3. What four (4) variables govern changes in population size?
births, deaths, immigration, emigration
4. Write an equation showing how population change is related to births, deaths, immigration, and
emigration.
population change = (births+immigration) – (deaths+emigration)
5. What is the biotic potential of a population?
the capacity for growth
6. What are four (4) characteristics of a population with a high intrinsic rate of increase (r)?
reproduce early in life, have short generation times, can reproduce
many times, have many offspring each time they reproduce
7. What is environmental resistance?
all of the factors that limit the growth of a population
8. What is carrying capacity?
the number of individuals of a given species that can be sustained
indefinitely in a given space
9. How do biotic potential and environmental resistance interact to determine carrying capacity?
biotic potential allows growth and environmental resistance limits how
big a population can get – so these two factors together will
determine how many individuals an area can support
10. List four (4) factors that can alter an area’s carrying capacity.
light, water, space, nutrients, too many competitors or predators
11. Distinguish between exponential and logistic growth of a population. Give an example of each
type.
Exponential growth starts out slowly and then proceeds faster and
faster as the population increases. Makes a j-shaped curve.
Logistic growth involves exponential growth followed by a steady
decrease in population growth until carrying capacity is reached.
Makes a s-shaped curve.
12. How can a population overshoot its carrying capacity? What are the consequences of doing this?
There is a reproductive time lag – the time needed for the birth rate to
fall and the death rate to rise in response to resource
overconsumption.
13. Distinguish between density-dependent and density-independent factors that affect a
population’s size.
Density-independent controls affect a population’s size regardless of
its population density.
Density-dependent controls have a greater impact as the population
grows in density.
14. Determine if each of the following is density-dependent (DD) or density-independent (DI):
a.
b.
c.
d.
e.
f.
g.
h.
i.
j.
DI
DD
DD
DI
DI
DI
DD
DD
DI
DD
flood
bubonic plague
competition for resources
fire
pesticide spraying
clear cutting a forest
disease
predation
hurricane
parasitism
15. What are the four (4) types of population fluctuations?
stable, irruptive, irregular, cyclic
16. Indicate what type of population fluctuation is being described below:
a.
irregular
The population sizes of some species change irregularly for mostly
unknown reasons.
b.
stable
c.
cyclic
d.
irruptive
The population size of a species with a fairly unchanging population
fluctuates slightly above and below its carrying capacity.
The population undergoes sharp increases in size, followed by crashes
over fairly regular time intervals.
The populations of some species may occasionally explode to a high
peak and then crash to a more stable lower level.
8-2 Connections: The Role of Predation in Controlling Population Size
17. Differentiate between the top-down control hypothesis and the bottom-up control hypothesis.
Top-down: predators control prey populations
Bottom-up: prey populations control predator populations
8-3 Reproductive Patterns and Survival
18. What are the two types of reproduction that can pass genes on to offspring?
Asexual & sexual
19. Use the chart below to differentiate between the two types of reproduction.


Asexual Reproduction
All offspring are genetic copies of
parent
Common in single-celled species
Sexual Reproduction
Organisms produce offspring by
combining gametes
Offspring have combination of parents’
genes
 About 97% of known organisms
reproduce this way


20. What are three (3) risks/problems associated with sexual reproduction?
Females have to produce twice as many offspring to maintain the same number of young in
the next generation as an asexually reproducing organism
 Increased chance of genetic errors when splitting and recombination of chromosomes
 Courtship & mating use energy, can transmit disease, & can inflict injury on males competing
for mates
21. Why is sexual reproduction important? (give 2 reasons)



Provides greater genetic diversity to offspring
Males can gather food for young and females, and help protect and train offspring
22. What are the two (2) fundamental reproductive patterns?
r-relected and k-selected
23. List the characteristics of the two patterns.
r-Selected
Example: bacteria, rodents, annual plants
 Many small offspring
 Little of no parental care
 Early reproductive age
 High population growth rate
k-Selected
Example: elephants, whales, humans, birds of
prey, long-lived plants
 Fewer, larger offspring
 High parental care
 Later reproductive age
 Lower population growth rate
24. What does a survivorship curve show/represent?
The # of survivors of each age group for a particular species