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CHAPTER 4 The Organization of Life 4-1 Ecosystems: Everything is Connected 4-1 Objectives • Distinguish between the biotic and abiotic factors in an ecosystem. • Describe how a population differs from a species. • Explain how habitats are important for organisms. 1. What is an ecosystem? • All of the organisms living (biotic parts) in an area together with their physical environment (abiotic parts) • EX: oak forest, coral reef, soil, wetlands, desert • Ecosystems do not have clear boundaries. • Things move from one ecosystem to another. Examples of Ecosystems 2. What are the components of an ecosystem? • In order to survive, ecosystems need five basic components: a) b) c) d) e) Energy Mineral nutrients Water Oxygen Living organisms • If one part of the ecosystem is destroyed or changes, the entire system will be affected. 3. Where does most of the energy in an ecosystem come from? • The sun 4. What are the living or once living things in an ecosystem called? • Biotic factors • EX: plants, animals, leaves, an organism’s waste products 5. What are the nonliving parts of an ecosystem called? • Abiotic factors • EX: air, water, rocks, sand, light, temperature 6. What are the levels of ecological organization of living things? a) b) c) d) e) Organism Population Community Ecosystem Biosphere Levels of Ecological Organization 7. What is an organism? • One individual living thing • EX: a gorilla • You are an organism, as is an ant, an ivy plant, and each of the many bacteria living in your intestines. 8. What is a species? • A group of organisms that can mate and produce fertile offspring, share common genes and that resemble each other in appearance, behavior, and internal structure • EX: humans - Homo sapiens dogs – Canis familiaris gorillas – Gorilla gorilla 9. What is a population? • A group of individuals of the same species that live in the same area and can interbreed • EX: bullfrog population of a pond lion population of a savanna bluebonnet population of a field bacterium population of a petri dish 10. What is a community? • A group of various species that live in the same place and interact with each other. • All the living inhabitants of an ecosystem make up a community. • EX: pond community – includes the populations of all the different plants, fish, insects, amphibians, and microorganisms that live in and around the pond • Land communities are often dominated by a few species of plants. • These plants then determine what other organisms can live in that community. Ecological Communities 11. How is a community different from an ecosystem? • A community includes only the biotic factors whereas an ecosystem includes the biotic and abiotic factors. 12. What is the biosphere? • The layer around the Earth in which life occurs naturally (extends from 8km above the Earth to the deepest part of the ocean 8km below) 13. What is a niche? • The way of life of an organism • It is made up of the animals relationships with its environment. • EX: a lions niche is staking its territory, hunting for zebras to eat, reproducing, etc. 14. What is a habitat? • The actual place an organism lives. • EX: a lions habitat is a savanna • Every habitat has specific characteristics that the organisms that live there need to survive. If any of these factor change, the habitat changes. • Organisms tend to be very well suited to their natural habitats. Animals and plants usually cannot survive for long periods of time away from their natural habitat. 4-2 Evolution 4-2 Objectives • Explain the process of evolution by natural selection. • Explain the concept of adaptation. • Describe the steps by which a population of insects becomes resistant to pesticides. 1. Who is Charles Darwin? • The “father of evolution”. • He observed that organisms in a population differ slightly from each other in form, function, and behavior. • Some of these differences are hereditary (passed on from parent to offspring). Charles Darwin 2. What did Darwin believe? • Natural selection causes the characteristics of a population to change over time. • The environment exerts a strong influence over which individuals survive to produce offspring. • Some individuals, because of certain traits, are more likely to survive and reproduce than other individuals. 3. What is evolution by natural selection? • Natural selection – the process by which individuals that have favorable variations are better adapted to their environment so they survive and reproduce more successfully than less adapted individuals. • Darwin proposed that over many generations, natural selection causes the characteristic of populations to change. • Evolution is a change in the characteristics of a population from one generation to the next. Evolution by Natural Selection 4. What is an example of how nature selects? • Lions with sharp claws survive better than lions with dull claws because lions with sharp claws can get prey better. • Over time, the population includes a greater proportion of lions with sharper claws. • As the populations of a given species change, so does the species. 5. What is an adaptation? • An anatomical, physiological, or behavioral change that improves a population’s ability to survive and reproduce in a certain environment. Nature Selects 6. What is coevolution? • The process of two species evolving in response to long-term interactions with each other. • EX: the Hawaiian honeycreeper, which has a long curved beak to reach nectar at the base of a flower. The flower has structures that ensure that the bird gets some pollen on its head. • When the bird moves to the next flower, some of the pollen will be transferred, helping it to reproduce. • The honeycreeper’s adaptation is a long, curved beak. • The plant has two adaptations: – The first is the sweet nectar, which attracts the birds – The second is the flower structure that forces pollen onto the bird’s head when the bird sips nectar. 7. What is evolution by artificial selection? • Artificial selection is the selective breeding of organisms, by humans, for specific desirable characteristics. • Dogs have been bred for certain characteristics. • Fruits, grains, and vegetables are also produced by artificial selection. 8. What is the evolution of resistance? • Resistance is the ability of an organism to tolerate a chemical or disease-causing agent. • An organism may be resistant to a chemical when it contains a gene that allows it to break down a chemical into harmless substances. • Humans promote the evolution of resistant populations by trying to control pests and bacteria with chemicals. Pesticide Resistance 4-3 The Diversity of Living Things 4-3 Objectives • Name the six kingdoms of organisms and identify two characteristics of each. • Explain the importance of bacteria and fungi in the environment. • Describe the importance of protists in the ocean environment. • Describe how angiosperms and animals depend on each other. • Explain why insects are such successful animals. 1. How many kingdoms are living things classified into? • Six kingdoms • Their classification is based on differences in characteristics. DOMAIN BACTERIA ARCHAEA EUKARYA Kingdom Eubacteria (body) Archaebacteria (hot springs) Protista Fungi Plantae Animalia Cell Type Prokaryotic (no nucleus) Prokaryotic (no nucleus) Eukaryotic (have a nucleus) Eukaryotic (have a nucleus) Eukaryotic (have a nucleus) Eukaryotic (have a nucleus) Cell Structure Cell Walls Cell Walls (cellulose) Some have cell walls Cell Walls (chitin) Cell Walls NO cell walls (cellulose) # of Cells Single Cell (unicellular) Single Cell (Unicellular) Mostly unicellular but some multicellular Mostly multicellular but some unicellular All multicellular All multicellular Nutrition Auto or Heterotrophs Auto or Heterotrophs Auto or Heterotrophs (consumers) Autotrophs (producers) Heterotroph (consumer) Examples Known as the “true bacteria” E. Coli Staph Botulism Dead Sea Hot springs Great Salt Lake Found in extreme environments Algae Amoeba Puff balls Conifers Flowering grasses Mosses Mammals Heterotrops Paramecium Euglena Mushrooms Mold Yeast Arthropods birds Kingdoms of Life 2. What is the difference between a prokaryotic and a eukaryotic cell? • Prokaryotic: – Do NOT have a nucleus or membrane bound organelles – EX: archaebacteria and eubacteria • Eukaryotic: – DO have a nucleus and membrane bound organelles – EX: fungi, protists, plants, animals 3. What are some characteristics of bacteria? • They are extremely small, single-celled organisms • Usually have a cell wall • Reproduce by dividing in half (asexual reproduction) • Lack a nucleus (they are prokaryotes) • Bacteria live in every habitat on Earth 4. What are the two main kingdoms of bacteria? • Archaebacteria – often found in extreme environments, such as hot springs • Eubacteria - most common types of bacteria, such as E. coli 5. Some facts about bacteria: • Some types of bacteria breakdown the remains are wastes of other organisms and return the nutrients to the soil (they are decomposers) • Some types of bacteria recycle nutrients, such as nitrogen and phosphorus. • Certain bacteria can convert nitrogen from the air into a form that plants can use. • This conversion is important because nitrogen is the main component of proteins and genetic material. • Bacteria also allow many organisms, including humans, to extract certain nutrients from their food. • The bacterium, Escherichia coli (E. coli), is found in the intestines of humans and other animals and helps digest food and release vitamins that humans need. 6. What are some characteristics of fungi? • Eukaryotic (have a nucleus) • Have cell walls that act like mini-skeletons that allow fungi to stand up right • Do not contain chlorophyll (so do NOT carry out photosynthesis) 7. What is a mushroom? • The reproductive part of a fungus • The rest of the fungus is an underground network of fibers that absorb food from decaying organisms in the soil. 8. Facts about Fungi: • They are absorptive feeders – they get their food by releasing chemicals that help break down organic matter, then they absorb the nutrients. • The bodies of most fungi are huge networks of threads that grow through the soil dead wood, or other material on which the fungi is feeding • Like bacteria, fungi play an important role in breaking down the bodies of dead organisms. • Some fungi, like some bacteria, cause disease. EX: Athlete’s foot (caused by a fungus) • Other fungi add flavor to food as in blue cheese. The fungus gives the cheese both its blue color and strong flavor. • Yeasts are fungi that produce the gas that makes bread rise. 9. What are some characteristics of protists? • They are mostly unicellular but include some multicellular organisms. • Some are animal-like (ameobas), some are plant-like (kelp), and some resemble fungi. 10. Facts about Protists: • Most are one-celled microscopic organisms, including diatoms, which float on the ocean surface. • Another protist, Plasmodium, is the onecelled organism that causes the disease malaria. • From an environmental standpoint, the most important protists are algae. • Algae are plant-like protists that can make their own food using the energy from the sun. • Protists range in size from the giant kelp to the one-celled phytoplankton, which are the initial source of food in most ocean and freshwater ecosystem. 11. What are some characteristics of plants? • Multicellular organisms that make their own food using the sun’s energy (carry out photosynthesis) • Have cell walls • Most plants live on land where they use their leaves to get sunlight, oxygen, and carbon dioxide from the air and use their roots to absorb nutrients and water from the soil. • Leaves and roots are connected by vascular tissue, which has thick cell walls and serves as a system of tubes that carry water and food. 12. What is the difference between gymnosperms and angiosperms? • Gymnosperms – woody vascular seed plants whose seeds are NOT enclosed by an ovary or fruit. – EX: conifers (gymnosperms that bear cones such as the pine tree) • Angiosperms – flowering plants that produce seeds within fruit. Most land plants are angiosperms. – EX: Daylily 13. What are some characteristics of animals? • Cannot make their own food • No cell walls so their bodies are soft and flexible (some animals have evolved hard exoskeletons) • Animals are more mobile than plants. • All animals move around in their environment during at least one stage in their lives. 14. What are invertebrates? • Animals that do not have backbones. • Many filter their food out of water (corals, worms, mollusks) (these are mobile in their larval stage) • Others move in search of food (squid, insects) • There are more insects on Earth than any other type of animal. 15. What are vertebrates? • Animals that have a backbone. • Include mammals, birds, reptiles, amphibians and fish.