| A | B |
|---|
| Define "limiting factor". | It's a factor that causes the growth of a population to decrease. |
| What types of factors limit population growth? | competition, predation, parasitism and disease, drought & other climate extremes, human disturbances |
| Define "density-dependent limiting factor. | It's a limiting factor that usuall affects denser populations: competition, predation, parasitism, disease. |
| How does competition limit population? | Organisms are competing for the same resources. If too many are competing for those same resources, the resources are used up more quickly. |
| Give examples of density-independent limiting factors in a population. | Natural disasters can cause a sudden decline in population, as can human activities (damming a river; over-cutting a forest); unusual weather; seasonal cycles. |
| Give examples of density-dependent limiting factors. | competition; parasites; predation |
| Explain the difference between a density-dependent limiting factor and a density-independent factor. | Density-independent limiting factors affect populations no matter what their size is; density-dependent ones affect the population only when the number of organisms reach a certain level. |
| How can competition between members of different species lead to changes in the species? | When they are competing for the same resources, both are under pressure to change in ways that will decrease the competition; over time, the species may evolve to occupy separate niches. (125) |
| What is a predator-prey relationship? | It's a mechanism of population control in which a population is regulated by predation (where one organism captures & feeds on another). |
| Know the predator-prey example of the moose and wolves on Isle Royale in Lake Superior. | See page 126. |
| What do parasites do to their hosts? | Parasites take nourishment at the expense of their hosts, often weakening them and causing disease or death. |
| Give examples of weather conditions that affect a population's size. | see pg. 127: heavy rainstorms; extremes of cold or hot weather; severe winter frosts; periodic droughts |
