Population Ecology

Question 1

Definition of a population

Answer 1

Organisms of the same species that live in the same geographic area at the same time, with the capability of interbreeding

Question 2

Definition of a community

Answer 2

An interacting group of various species at a common location

Question 3

Definition of an ecosystem

Answer 3

Community of organisms + physical environment (biotic + abiotic)

Question 4

Definition of population ecology

Answer 4

The study of changes in the sizes of populations of species over time

Question 5

The alternations between measles and whooping cough is likely caused by ____ ____, where…

Answer 5

Ecological interference; Diseases directly compete for pool of non-immune human hosts
- As susceptible individuals die or become immune from one pathogen, competitor can establish

Question 6

Herd Immunity refers to…

Answer 6

The protection offered to unimmunized individuals in a population/herd by a high percentage of immunized individuals

Question 7

Disease elimination generally requires population vaccination rates of…

Answer 7

75% to 95%

Question 8

Who are the most protected by herd immunity?

Answer 8

Infants too young for vaccination, individuals for whom vaccines are ineffective, and who are immune-compromised

Question 9

4 Types of Traditional Vaccines

Answer 9

1. Live-atenuated
2. Inactivated
3. Toxoid
4. Recombinant protein

Question 10

2 Types of Newer Vaccines

Answer 10

1. mRNA
2. Adenovirus

Question 11

Live-attenuated vaccine

Answer 11

Uses a weakened virus (MMR vaccine)

Question 12

Inactivated vaccine

Answer 12

Uses a dead virus (Annual flu vaccines)

Question 13

Toxoid vaccine

Answer 13

Uses inert toxin (tetanus shot)

Question 14

Recombinant protein vaccine

Answer 14

Uses a small part of the virus (HPV vaccine)

Question 15

mRNA vaccine

Answer 15

Uses mRNAto get cells to produce the viral antigens (Pfizer and Moderna COVID-19 vaccines)

Question 16

Adenovirus vaccines

Answer 16

Uses a carrier virus to deliver DNA (AstraZeneca and Johnson&Johnson COVID-19 vaccines)

Question 17

Why are mRNA vaccines so fast to make?

Answer 17

• We can easily synthesize bits of mRNA
• We can easily sequence pathogen DNA or RNA
• We just need to change the mRNAbit to create the next vaccine.

Question 18

What are some troubles with mRNA vaccines and how do we address them?

Answer 18

1. mRNA is fragile and easily destroyed
   - Disguise it and make it more like mRNA in the body
2. mRNA is a large molecule
   - Package it in layered lipids and get the cells to “eat” it

Question 19

Exponential growth model

Answer 19

delta N / delta t = rN, where r = per capita rate of increase, and N = population size

Question 20

Logistic growth

Answer 20

delta N / delta t = rN[(K-N)/N], where K = carrying capacity

Question 21

In a logistic growth model, as K increases, (____) will approach zero, and ____ ____ will also be approaching zero.

Answer 21

[(K-N)/N); population growth

Question 22

Lotka-Volterra equations
*V = #prey, P = #predators
*b = prey birth rate
*a = predator attack rate
*r = predator birth rate
*m = predator death rate

Answer 22

• delta V / delta t = bV -aPV
• delta P / delta t = rVP - mP

Question 23

SI model

Answer 23

Population of hosts assumed to be:
1. Susceptible to infection, or
2. Infected
and there is no immunity against the disease
Population: N = S+I

Question 24

In a SI model, the rate of change for susceptible individuals depends on

Answer 24

• loss of susceptibles to infected population
• return of infecteds to susceptible population

Question 25

In a SI model, the rate of change for infected individuals depends on

Answer 25

• Gain and loss of infecteds to susceptible population

Question 26

SIR Model

Answer 26

Population of hosts assumed to be:
1. Susceptible to infection
2. Infected currently, or
3. Recovered from infection (and immune for lifetime)
And eventually there will be an immune decay that returns the R group to the S group

Question 27

What is R0?

Answer 27

The mean number of secondary infections that a single infection will cause

Question 28

When R0 > 1, the infection will ____;
When R0 < 1, the infection will ____ ____

Answer 28

spread; die out