Chapter 18 Interactions of Living Things

1. Chapter 18Interactions of Living Things Mr. Perez

2. Important Vocabulary • Ecology • Abiotic factor • Biotic factor • Population • Community • Ecosystem • Biosphere • Population density • Limiting factor • Symbiosis • Niche • Habitat • Producer • Consumer • Decomposer • Food chain • Food Web

3. Ecology • The study of interactions among organisms and their environment. • Ecologists organize the environmental factors that influence organisms into two groups • Abiotic factors- non-living parts of the environment • Biotic factors- living or once-living organisms in the environment

4. Abiotic factors • Water • All organisms need water to survive • Organism bodies are 50%-95% water • Important in cytoplasm in cells • Respiration, photosynthesis, digestion and other important life processes can’t happen without water • More than 95% of the Earth’s surface water is found in the ocean

5. Abiotic factors • Light and temperature • Sunlight is important for plants and other photosynthetic organisms • Temperature can determine which plants/animals can live there • Air • Composed of gases including nitrogen, oxygen and carbon dioxide • Needed for respiration • Soil • Soil type is determined by the amounts of sand, silt and clay • Different kinds contain different nutrients, minerals and moisture

6. Biotic factors Levels of organization: Organism Population Community Ecosystem Biome Biosphere

7. Characteristics of Populations • Population size can be difficult to measure because individuals are too widespread or move around too much • Instead, we estimate the population size (sampling) • The size of a population is always changing • Births • Deaths • Migration • Immigration

8. Characteristics of Populations • Population density- the number of individuals in a population that occupy a definite area • Ex: If 100 mice live in an area of one square kilometer, the population density is 100 mice per square kilometer • Population spacing is how the organisms are arranged in a given area • Evenly- consistent distance between them • Randomly- each organism’s location is independent of the locations of other organisms • Clumped- resources such as food or living space are clumped

9. Limiting factors • Any biotic or abiotic factor that limits the number of individuals in a population • Competitors • Weather • Predators • Fires • Available habitat • Disease/parasites

10. Carrying Capacity • The largest number of individuals of a species that an environment can support and maintain for a long period of time • If a population gets bigger than the carrying capacity, some individuals are left without adequate resources and will either die or be forced to move elsewhere • Biotic potential • The maximum rate at which a population increases when plenty of food and water are available, the weather is ideal, and no disease or enemies exist

11. Symbiosis and Other interactions • Symbiosis: any close interaction between two or more different species • Mutualism: two different species of organisms cooperate and both benefit (+ +) • Lichens = fungus + algae • Commensalism: one organism benefits without affecting the other organism (+ 0) • Flatworm that lives in a horseshoe crab’s gills • Parasitism: two different species in which one species benefits and the other species is harmed (+ -) • Mistletoe grows into a tree’s roots and takes away nutrients

12. Symbiosis and Other interactions • Predation is a way to regulate population size • Act of hunting, killing and feeding on another organism • Habitats and niches • Habitat: place where an organism lives • Niche: role, or job, of an organism in the ecosystem

13. Classwork Questions • On a separate sheet of paper answer the following questions. You do not have to write these questions, but the answers should be in complete sentences. • Compare and contrast abiotic factors and biotic factors. Give five examples of each that are in your ecosystem. • Describe a population and a community. • Explain how biotic factors change in an ecosystem that has flooded.

14. Classwork Questions • Write down the following questions. Answer them as you watch the videos. • Name three pairs of animals that work together in the video. • Describe what each animal offers its partner (if anything). http://www.youtube.com/watch?v=uxVMeLWzB_o

15. Energy Flow Through Ecosystems • Organisms interact with members of their own species and other species • Food chains or food webs consist of: • Producers- organisms that take in and use energy from the Sun or some other source to produce food • Consumers- organisms that take in energy when they feed on producers or other consumers • Decomposers- take in energy as they break down the remains of organisms

16. Food chains • Simple way of showing how energy, in the form of food, passes from one organism to another • Arrows indicate the direction of energy transfer • Usually only have three or four links because energy decreases/is lost as it is transferred • Lost as heat*

17. Food Webs • Series of overlapping food chains that exist an ecosystem • Provides more complete model of energy transfer in an ecosystem • More accurate, because they show more organisms

18. Ecological Pyramids • Most of the energy in the biosphere comes from the Sun • Producers take in and transform only a small part of the energy that reaches the Earth’s surface • Primary consumers eat producers • Secondary consumers eat other consumers • Tertiary consumers eat only secondary consumers (usually at the top of the food chain/web)

19. Ecological Pyramids • Organisms can be classified as: • Autotrophs- can produce their own food • Heterotrophs- cannot produce their own food • Carnivore- must eat other organisms • Herbivore- must eat producers (plants) • Omnivore- can eat both plants and other organisms

20. Energy Pyramids Only about 10% of the energy at each level of the pyramid is available to the next level

21. Classwork questions • On a separate sheet of paper answer the following questions. You do not have to write the question, but the answers should be complete sentences. • Draw and label a food web that includes you and what you’ve eaten today (or yesterday). • Compare and contrast producers, consumers and decomposers. • Use your knowledge of food chains and the energy pyramid to explain why fewer lions than gazelles live on the African plains.

22. Videos • http://www.vtaide.com/png/symbiosis.htm

23. Resources • Florida Science Grade 8 Glencoe Science & McGraw Hill Publishing • Google Images