Chapter 5 Populations

Question 1

What is population density?

Answer 1

refers to the number of individuals per unit area

Question 2

What is an age structure?

Answer 2

the number of males and females of each age a population contains

Question 3

Immigration vs Emigration

Answer 3

Immigration- individuals move into range of population from somewhere else (increases size)Emigration- individuals move out of the population’s range (decreases size)

Question 4

What is exponential growth?

Answer 4

a function that has a number risen to a certain power, in this case a positive number. The larger the population gets, the faster it grows. (J-shaped curve)

Question 5

What is logistic growth?

Answer 5

occurs when a population’s growth slows and then stops, following a period of exponential growth. (S-shaped curve)

Question 6

What is carrying capacity?

Answer 6

the maximum number of individuals of a particular species that a particular environment can support

Question 7

How do population ecologists study populations?

Answer 7

researchers study populations’ geographic range, density and distribution, growth rate, and age structure

Question 8

What factors affect population growth?

Answer 8

birthrate, death rate, and the rate at which individuals enter or leave the population

Question 9

What happens during exponential growth?

Answer 9

Under ideal conditions (unlimited resources and no danger to population) a population will grow exponentially

Question 10

What is logistic growth?

Answer 10

occurs when a population’s growth slows and then stops, following a period of exponential growth

Question 11

What is a limiting factor?

Answer 11

a factor that controls the growth of a population

Question 12

Describe density-dependent limiting factor. What are a few examples?

Answer 12

operate strongly only when population density (number of organisms per unit area) reach a certain level.Examples include: competition, predation, herbivory, parasitism, disease, and stress from overcrowding

Question 13

Describe density-independent limiting factors. What are a few examples?

Answer 13

Affect all populations in similar ways, regardless of population size and density.Examples- unusual weather events like hurricanes, droughts, floods, natural disasters such as wildfires, tsunamis, earthquakes, and supervolcanic eruptions can act as density independent limiting factors.

Question 14

What factors determine carrying capacity?

Answer 14

Acting separately or together, limiting factors determine the carrying capacity of an environment for a species

Question 15

What limiting factors depend on a population?

Answer 15

(density-dependent) limiting factors include competition, predation, herbivory, parasitism, disease, and stress from overcrowding

Question 16

What limiting factors do not typically depend on population density?

Answer 16

(density-independent) limiting factors

Question 17

What is demography?

Answer 17

scientific study of human populations

Question 18

How has human population size changed over time?

Answer 18

the human population, like populations of other organisms, tends to increase. The rate of that increase has changed dramatically over time.

Question 19

Why do population growth rates differ among countries?

Answer 19

birthrates, death rates, and the age structure of a population help predict why some countries have high growth rates while other countries grow more slowly

Question 20

What is demographic transition?

Answer 20

a dramatic change from high birthrates and death rates to low birthrates and death rates. To date, United States, Japan, and Europe have completed the demographic transition. Parts of South America, Africa, and Asia are passing through stage II. A large part of ongoing human population growth is happening in only ten countries, with India and China in the lead. Globally, human population is still growing rapidly, but the rate of growth is slowing down. (transition from J-shape to S shape logistic growth)