Chapter 4- Ecologies And Ecosystems- Populations

Question 1

How does Natality affect population size?

Answer 1

Increases population size through reproduction

Question 2

How does immigration affect population size?

Answer 2

Increases population size from external population

Question 3

How does molarity affect population size?

Answer 3

Decreases population size as a result of death

Question 4

How does emigration affect population size?

Answer 4

Decreases population size as a result of loss of external population

Question 5

draw and label a graph showing the sigmoid population growth

Answer 5

Do it

Question 6

Sigmoid population growth curve- why initially is population growth slow?

Answer 6

Shortage or reproducing individuals

Question 7

Sigmoid population growth curve- as numbers increase what is the exponential growth phase?

Answer 7

Rapid increases in population size/growth as natality rate exceeds the morality rate

Question 8

Sigmoid population growth curve- exponential growth phase- why does rapid growth why does it happen?

Answer 8

Because there is an abundance of resources (eg good shelter and water) and limited to environmental problems (disease and predation uncommon)

Question 9

Sigmoid population growth curve- what is transitional phase?

Answer 9

Population continues to grow, eventually competition increases as availability of sources reduce

Question 10

Sigmoid population growth curve- transitional phase- competition increases, why?

Answer 10

Natality starts to fail and morality starts to rise, leading to q slower rate of population growth

Question 11

Sigmoid population growth curve- what is the plateau phase?

Answer 11

Eventually the increasing morality rates equals the Natality and population size becomes constant

Question 12

Sigmoid population growth curve- plateau phase- why does population size become constant?

Answer 12

Population has reached the carrying capacity (K) of the environment
Limited resources, predation and disease all contribute to keeping population size balanced

Question 13

Every species has environment limits- what are the factors affected by pop density?

Answer 13

Predation and parasite
Availability of shelter/water
Nutrient supply
Disease
Accumulation of water

Question 14

Every species has environment limits- what are factors unrelated to population density?

Answer 14

Climate and weather conditions
Availability of light, O2, CO2
Natural disasters

Question 15

What is the formula for a population size over a given period ?

Answer 15

Population size = (Natality + immigration) - ( morality + emigration)