02/12/13 Interactions Among Living Things p. 3 Table of Contents

Quick Review Population Density- The size of a population that occupies an area of limited size The more individuals there are in a given amount of space, the more dense the population.

Limiting Factors What are the limiting factors in the classroom? The size of populations is always changing HOW? One way populations change is through limiting factors A limiting factor is any biotic or abiotic factor that restricts the number of individuals in a population Ex. Food, water, living space, mates, nesting sites and other resources Can indirectly affect other populations in the community What are the limiting factors in the classroom?

What is Carrying Capacity? Another characteristic of populations is carrying capacity Carrying capacity is the largest number of individuals an environment can support and maintain for a long period of time. Think of filling a shopping bag with food. It will only hold so much until it runs out of room.

How about biotic potential? Biotic Potential-The maximum rate at which a population increases when there is plenty of food, water, ideal weather, and no disease or enemies is its biotic potential Most populations never reach their biotic potential…eventually the carrying capacity of the environment is reached and the population stops increasing

a. biotic factors b. abiotic factors 1. Water, sunlight, temperature, soil, and air are ______. a. biotic factors b. abiotic factors 2. Organisms depend on other organisms for food, shelter, protection, and reproduction. These other organisms are ______. a. biotic factors b. abiotic factors 3. All the mallard ducks living on a lake at the same time make up a ______. a. population b. community 4. A population of squirrels and all the populations they interact with make up a ______. a. community b. biosphere

5. A coral reef is an example of an ______. a. abiotic factor b. ecosystem 6. Scientists call tropical rain forests and mountains ______. a. biomes b. ecosystems 7. Biomes, communities, and populations are part of the ______. a. biosphere b. ecosystem 8. The number of individual organisms that occupy a definite area is called population ______. a. size b. density 9. If the amount of food in an area can support only a certain number of deer in a population, the amount of food is called a ______. a. carrying capacity b. limiting factor

Populations and Communities Prentice Hall Science Explorer As you view the video, think about some of the differences between populations and communities and some examples of each.

Read the selection and answer the following questions on p. 3 1. What abiotic factors affected the recovery of the forest at Mt. St. Helens? What were the biotic factors? 2. What role could fungi have played in the mountain’s recovery? 3. Were the prairie lupines a population or a community? What role did they play in the forest’s recovery? 4. According to the selection, scientists are studying the lessons they learned at Mount St. Helens to “jump start”other areas that have been disturbed. How could these lessons help them do this?