Table of Contents Living Things and the Environment Studying Populations Interactions Among Living Things Changes in Communities

Living Things and The Environment All living things must interact with their surroundings. Organism —a complete and whole living thing Habitat —a place where an organism lives. It provides food, water, shelter and a place to reproduce. Ex: a woodpecker’s habitat is the trees in a forest. Niche —the role of an organism in its community. How it makes a living. Ex: a woodpecker’s niche is catching and eating insects.

Biotic and Abiotic Factors Biotic Factors —all living parts of an organism’s habitat. Abiotic Factors —all nonliving parts of an organism’s habitat. (water, sunlight, oxygen, temperature, soil)

Levels of Organization The living things in an environment must be organized into larger and larger groups within their environment. Species —a group of organisms that are physically similar and can mate with each other and produce offspring that can also mate and reproduce. Populations —all the members of one species in a particular area. Community –- all the different populations that live together and interact with each other in a particular area.

Levels of Organization Ecosystem —the community of organisms that live in a particular area, along with their nonliving surroundings. Ex: pond, garden, forest Biosphere —the entire region of the world where living things are found. Ecology —the study of how living things interact with each other and with their environment

Levels of Organization Living Things and the Environment Levels of Organization The smallest level of organization is a single organism, which belongs to a population that includes other members of its species.

Levels of Organization Living Things and the Environment Levels of Organization The population belongs to a community of different species.

Levels of Organization Living Things and the Environment Levels of Organization The community and abiotic factors together form an ecosystem.

Four Characteristics of a Self-sustaining Ecosystem A self-sustaining ecosystem has four characteristics: 1. A constant source of energy (usually the sun) 2. Transfer of energy into organic compounds (usually through photosynthesis) 3. Interactions between biotic factors (predator/prey, mutualism, commensalism) 4. Cycling of materials (water cycle, nitrogen cycle, oxygen/carbon dioxide cycle, nutrient cycle)

Studying Population Size Four methods of determining population size: 1. Direct Observation —count all members of a population. 2. Indirect Observation —observe and count signs of a population. Ex: count nests or dens observed 3. Sampling —make an estimate of the population by counting the number of organisms in a small area (a sample), and then multiplying to find the number in a larger area. Estimate —an approximation of a number. 4. Mark-and-Recapture Studies —capture, mark, and release organisms several times to calculate their population number.

Changes in Population Size Populations can change in size when members either leave or join the population. Population size can change by births, deaths, immigration or emigration. Birth rate —number of births in a population in a certain amount of time. Death rate —number of deaths in a population in a certain amount of time. Birth rate > Death rate = population increase Death rate > Birth rate = population decrease Immigration —organisms move into a population Emigration —organisms move out of a population

Changes in Population Activity Studying Populations Changes in Population Activity Click the Active Art button to open a browser window and access Active Art about changes in population.

Population Density Population Density —the number of individuals in a specific area. Population Density = Number of individuals Unit area

Changes in Population Density Studying Populations Changes in Population Density In many situations, it is helpful to know the population density–the number of individuals in a specific area. Population density =

Limiting Factors Limiting Factor —an environmental factor that causes a population to decrease. They include: food, water, space, and weather conditions Limiting Factors help determine the carrying capacity of an environment. Carrying Capacity —the largest population that an area can support .

Inequalities Studying Populations The population statement is an example of an inequality. An inequality is a mathematical statement that compares two expressions. Two signs that represent inequalities are: < (is less than) > (is greater than) For example, an inequality comparing the fraction to the decimal 0.75 would be written < 0.75

Inequalities Practice Problems Studying Populations Inequalities Practice Problems Write an inequality comparing each pair of expressions below. 5 __ –6 5 > –6

Inequalities Practice Problems Studying Populations Inequalities Practice Problems Write an inequality comparing each pair of expressions below. 0.4 __ 0.4 <

Inequalities Practice Problems Studying Populations Inequalities Practice Problems Write an inequality comparing each pair of expressions below. –2 - (–8) __ 7 - 1.5 –2 - (–8) > 7 - 1.5

Changes in Population Size Studying Populations Changes in Population Size Populations can change in size when new members join the population or when members leave the population.

Asking Questions Studying Populations Before you read, preview the red headings. In a graphic organizer like the one below, ask a question for each heading. As you read, write the answers to your questions. Question Answer How do you determine population size? Some methods of determining population size are direct observation, indirect observation, sampling, and mark-and-recapture studies. What causes populations to change in size? Some factors include birth, death, immigration, and emigration. What are limiting factors? These are factors that can limit population growth if they are unfavorable for the organisms in the population. Food and water, space, and weather conditions can be limiting factors.

Adapting to the Environment Each organism in a community has unique characteristics that allow them to interact with each other and to survive. Adaptations —the behaviors and physical characteristics that allow organisms to live successfully in their environment. Natural Selection —individuals with the best adaptations will survive to pass on these traits to their offspring. These better characteristics will therefore become more common in the population.

Adapting to the Environment Interactions Among Living Things Adapting to the Environment Every organism has a variety of adaptations that are suited to its specific living conditions.

Interactions Among Living Things There are three major types of interactions among organisms: Competition, Predation, and Symbiosis 1. Competition —the struggle for organisms to survive as they attempt to use the same limited resources. Animals compete for food, water, shelter, territory and mates Plants compete for sunlight, water and growing space

-It helps weed out diseased or less-fit members 2. Predation —one organism kills another for food. Predator —does the killing Prey —is killed -It helps control overpopulation of non-predatory species. -It helps weed out diseased or less-fit members of a non-predatory species. -Populations of predators and their prey rise and fall in related cycles.

Predator - Prey Interactions Interactions Among Living Things Predator - Prey Interactions On Isle Royale, an island in Lake Superior, the populations of wolves (the predator) and moose (the prey) rise and fall in cycles. Use the graph to answer the questions.

Predator - Prey Interactions Interactions Among Living Things Predator - Prey Interactions Reading Graphs: What variable is plotted on the x-axis? What two variables are plotted on the y-axis? Year; numbers of wolves and moose

Predator - Prey Interactions Interactions Among Living Things Predator - Prey Interactions Interpreting Data: How did the moose population change between 1965 and 1972? What happened to the wolf population from 1973 through 1976? The moose population increased and then decreased; the wolf population increased.

Predator - Prey Interactions Interactions Among Living Things Predator - Prey Interactions Inferring: How might the change in the moose population have led to the change in the wolf population? As the moose population increased, more food was available to the wolf population and it increased.

Predator - Prey Interactions Interactions Among Living Things Predator - Prey Interactions Drawing Conclusions: What is one likely cause of the dip in the moose population between 1974 and 1981? The wolf population increased.

Predator - Prey Interactions Interactions Among Living Things Predator - Prey Interactions Predicting: How might a disease in the wolf population one year affect the moose population the next year? Disease would cause a decrease in the wolf population, so fewer moose would be eaten and the population could increase.

Predator/prey Activity http://www.mcgrawhill.ca/school/applets/bcscience7/predator/index.htm

Interactions Among Living Things 3. Symbiosis —a close relationship between two species that benefits at least one of the species. Three types: -Mutualism —both species benefit Example—lichens: a mutual relationship between algae and fungi: algae makes food for the fungi and the fungi makes living conditions better for the algae. Example—bees visit flowers: bees get nectar and flowers get pollinated.

-Commensalism —one species benefits and the other is neither helped nor harmed. Example: barnacles attached to gray whales: barnacles get a free ride to find food and the whale is unaffected. Gray whales can be identified by their barnacle patches. Some may carry as much as 400 lbs of barnacles and whale lice. Example: orchid growing on a tree: orchid gets a place to grow and the tree is unaffected

-Parasitism —one species benefits and the other is harmed. -Parasite —organism that benefits -Host —organism that the parasite lives in or on and is harmed. 1. Hookworm 2. Tapeworm 3. Tapeworm eggs 4. Roundworm 5. Pin worm

Using Prior Knowledge Interactions Among Living Things Before you read, look at the section headings and visuals to see what this section is about. Then write what you know about how living things interact in a graphic organizer like the one below. As you read, continue to write what you learn. What You Know Organisms interact in different ways. What You Learned Organisms are adapted to their environments. Organisms have niches, which are their roles in their habitats. Organisms compete for resources. Some organisms eat others, and this affects the size of populations. Some organisms live together in symbiotic relationships, of which there is mutualism (both benefit), commensalism (one benefits, the other is not helped or harmed), and parasitism (one benefits, the other is harmed).

More on Population Interactions Interactions Among Living Things More on Population Interactions Click the PHSchool.com button for an activity about population interactions.

Changes in Communities Communities change constantly---sometimes suddenly; sometimes slowly. Succession —the series of predictable changes that occur in a community over time. Two types: 1. Primary Succession —the series of changes that occur in an area where no soil or organisms exist. Example: Following a volcanic eruption. Pioneer species —first species to populate such an area. Examples: mosses and lichens

Primary Succession Changes in Communities Primary succession is the series of changes that occur in an area where no soil or organisms exist.

Changes in Communities 2. Secondary Succession —the series of changes that occur in an area where the ecosystem has been disturbed, but where soil and organisms still exist. Examples: following fires, hurricanes, tornados, farming, logging or mining.

Secondary Succession Changes in Communities Secondary succession is the series of changes that occur in an area where the ecosystem has been disturbed, but where soil and organisms still exist.

Comparing and Contrasting Changes in Communities Comparing and Contrasting As you read, compare and contrast carbohydrates, proteins, and lipids in a table like the one below. Factors in Succession Primary Succession Secondary Succession Volcanic eruption Fire Possible cause No soil or organisms exist. Soil and organisms exist. Type of area No Yes Existing ecosystem?

Click the SciLinks button for links on succession. Changes in Communities Links on Succession Click the SciLinks button for links on succession.

Mark-and-recapture studies Graphic Organizer Main Idea There are four main ways to determine the size of a population. Detail Detail Detail Detail Mark-and-recapture studies Direct observation Indirect observation Sampling