Chapter 4- Ecologies And Ecosystems- Populations Flashcards Preview

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Flashcards in Chapter 4- Ecologies And Ecosystems- Populations Deck (15)
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1
Q

How does Natality affect population size?

A

Increases population size through reproduction

2
Q

How does immigration affect population size?

A

Increases population size from external population

3
Q

How does molarity affect population size?

A

Decreases population size as a result of death

4
Q

How does emigration affect population size?

A

Decreases population size as a result of loss of external population

5
Q

draw and label a graph showing the sigmoid population growth

A

Do it

6
Q

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

A

Shortage or reproducing individuals

7
Q

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

A

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

8
Q

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

A

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

9
Q

Sigmoid population growth curve- what is transitional phase?

A

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

10
Q

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

A

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

11
Q

Sigmoid population growth curve- what is the plateau phase?

A

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

12
Q

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

A

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

13
Q

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

A
Predation and parasite
Availability of shelter/water
Nutrient supply
Disease
Accumulation of water
14
Q

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

A

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

15
Q

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

A

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

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