Ecology Worksheet

Chapters 5 and 6

1) Name the 3 important characteristics of a population:

• Geographic distribution• Density• Growth rate

2)__________of the # of individuals per unit area.

• Population density

3) What can affect population density?

• Species• ecosystem

4) What factors can affect population size?

• Number of births• Number of deaths• Number of individuals that enter or leave a

population

5) Compare immigration and emigration.

• Immigration is the movement of individuals into an area and emigration is movement OUT OF an area. Immigration can cause a population to grow while emigration can cause a population to decrease .Searching for mates ,changes in resources and food can affect both.

6) What is exponential growth?

• Occurs when the individuals in a population reproduce @ a constant rate….@ first they increase slowly , but eventually they increase approaching an indefinitely large size—This is in the absence of predation and presence of unlimited resources

7)When will a population grow exponentially?

• Under ideal conditions with unlimited resources

8)What is logistic growth and how does that differ from exponential growth?

• As resources become less available,the growth slows or stops….This generally is an s-shaped curve….and occurs following a time of exponential growth---Exponential growth occurs @ ideal conditions only.

9) Define carrying capacity.

• The largest number of individuals that a given environment can support

10) What factors may cause carrying capacity to change?

• Natural disasters,resources limited..

11)Do analyzing data on p. 123fruitfly pop growth

0100200300400

1 2 3 4 5 6 7 8

days

# fr

uit f

lies

# fruit flies

# rabbits

0

5000

10000

15000

1 2 3 4 5 6 7 8

# rabbits

2) Logistic growth in fruit fly population and exponential growth in rabbits .Limiting factors must have affected fruit fly population, but not rabbits.

3)The graph of fruit flies seems to have reached carrying capacity @ 35 days,where 320 individuals are supported.

4)w/ predators added,the rabbits would show logistic growth,and population would slow or decrease

12. What are limiting factors and give examples.

• Can cause a population growth to decrease----eg.-human disturbances,drought and other climate extremes,parasitism and disease,predation,competition

13)List 3 density dependent factors and 3 density-independent factors.

• Density dependent:competition,predation parasitism and disease(are dependent on population)

• Density independent :unusual weather,natural disasters,seasonal cycles,human activities

14) How do competition and population size relate?

• When populations become larger and more crowded,organisms must compete w/one another for food,water,space,sunlight,and other essential resources.

15) If an entire fox population disappears ,what is likely to happen to the rabbit population?

• Explosive growth

16)—Do 4 and 5 from 127

4—prolonged drought-could cause death from crop loss and emigration

5--- natural disasters could decrease human and other organisms’ populations

17-Do 1 and 3 on p.132:Do 1-5 on p.149• 1-over tens of thousands of years,the human

population grew very slowly.Then , about 5oo years ago it began to grow exponentially and still increases.

• 3-Demography = scientific study of human populations

• P.149:• 1-renewable resource is able to regenerate and is

replaceable—example: water/nonrenewable cannot be replenished by regular processes—fossil fuels, forests under the right context

• 2-example—mining affecting land and air• 3-no one took responsibility for the resources,

although it is used world wide• 4-air is breathed/wetlands filter pollutants from water• 5-example-selective cutting of trees

1-5 on p.156

• 1-one of earth’s greatest natural resourcesw/foods and medicines• 2-altering habitats, extinction and introducing

foreign species can alter biodiversity• 3-protecting entire ecosystems and single

species• 4-smaller the habitat size, the fewer the species

living there• 5-each habitat is unique; once destroyed or

altered a habitat may be gone forever