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Ch.22 Populations and Communities

Ch.22 Populations and Communities. Ecosystem- All the living and nonliving things that interact in an area. Why would this be an ecosystem? What are some other ecosystems?. Section 1: Living Things and the Environment. Section 1: Living Things and the Environment.

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Ch.22 Populations and Communities

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  1. Ch.22 Populations and Communities

  2. Ecosystem- All the living and nonliving things that interact in an area. Why would this be an ecosystem? What are some other ecosystems? Section 1: Living Things and the Environment

  3. Section 1: Living Things and the Environment • Habitat- a place where an organism lives and that provides the things that the organism needs. • A needs of an organism: food, water, shelter, and other things it needs to live, grow and reproduce from its surroundings.

  4. Abiotic vs. Biotic Factors • Biotic Factors- living parts of an ecosystem. • Grass, fungi, animals, etc. • Abiotic Factors- the nonliving parts of an ecosystem • Water, sunlight, oxygen, temperature, and soil.

  5. Abiotic Factors • Water- your body is about 65 percent water. Water is needed for chemical reactions, dissolving substances, keeping cell shape and size, keeping body temperature constant. Plants need water for photosynthesis. • Sunlight- energy needed from the sun for photosynthesis. • Oxygen- most living things require oxygen (respiration). • Atmosphere is 20 percent oxygen and 78 percent nitrogen. • Aquatic animals receive dissolved oxygen in water from plants.

  6. Abiotic Factors • Temperature- the temperature of an area determines the types of organisms that can live there. • Plants and animals have adaptations to help them survive in different temperatures • Soil- mixture of rock fragments, nutrients, air, water, and the decaying remains of living things.  The type of soil influences the type of plants.

  7. Populations • Population- all the members of one species in a particular area. • Oak trees, ladybugs, prairie dogs. • Why would trees in a forest not be a population?

  8. Communities • Community- all the different populations that live together in an area. • Levels of organization in an ecosystem (smallest to largest): • Organism • Population • Community • Ecosystem

  9. Ecology • Ecology- the study of how living things interact with one another and with their environment. • Ecologists- are scientists who study ecology, look at how the biotic and abiotic factors in an ecosystem are related.

  10. Section 2: Studying Populations • Population Density- the number of individuals in a specific area. • The equation for figuring out population density is: Population density= Number of individuals Unit area • Example: 50 butterflies 10 square meters  Equals five butterflies per square meter

  11. Determining Population Size • Direct observation- counting all the members. • Indirect observation- may be too small or too hard to find exact population number, so evidence is used (tracks, nests, or other signs) to estimate the population • Sampling- the population may be too large or spread out over a large area, so an estimate – or an approximation of a number, based on reasonable assumptions (count a small area and then multiply the number in a large area).

  12. Determining A Population Size • Mark-and-recapture- animals are first captured, marked, and released, then another group of animals is captured. The marked animals determine the population size.  Hunters: what are some signs that you look for to determine how many bucks are in an area?

  13. Changes in Population Size • Populations change in size when new members enter the population or when members leave the population. • Birth rate- the number of births in a certain amount of time • Death rate- the number of deaths in a certain amount of time. If birth rate > death rate, population size increases If death rate > birth rate, population size decreases

  14. Changes in Population Size • Immigration- moving in to a population • Emigration- moving out of a population. • Refer to page 698 graph.

  15. Limiting Factors • Limiting factor- an environmental factor that prevents a population from increasing. • Food, space, and weather conditions. • Through human activity, how are we a limiting factor? • Carrying capacity- the largest population that an environment can support. How does the predator/prey relationship affecting carrying capacity?

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