Environmental Science

1. Environmental Science Final Review CHS Academy

2. Defining an Ecosystem • Ecosystems are communities of organisms and their abiotic environment. • Examples are an oak forest or a coral reef. CHS Academy

3. The Components of an Ecosystem • In order to survive, ecosystems need five basic components: energy, mineral nutrients, water, oxygen, and living organisms. • Plants and rocks are components of the land ecosystems, while most of the energy of an ecosystem comes from the sun. • If one part of the ecosystem is destroyed or changes, the entire system will beaffected. CHS Academy

4. The Components of an Ecosystem • Factors affecting an ecosystem can be divided into two types: • Biotic-living • Abiotic-nonliving CHS Academy

5. Habitat • Habitats are places where an organism usually lives. • Every habitat has specific characteristics that the organisms that live there need to survive. If any of these factors change, the habitat changes. • Organisms tend to be very well suited to their natural habitats. If fact, animals and plants usually cannot survive for long periods of time away from their natural habitat. CHS Academy

6. An Organism’s Niche • A niche is the unique position occupied by a species, both in terms of its physical use of its habitat and its function within an ecological community. • A niche is different from a habitat. An organism’s habitat is a location. However, a niche is an organism’s pattern of use of its habitat. • A niche can also be though of as the functional role, or job of a particular species in an ecosystem. CHS Academy

7. Evolution by Natural Selection • Natural selection is the process by which individuals that have favorable variations and are better adapted to their environment survive and reproduce more successfully than less well adapted individuals do…”Survival of the fittest.” • Variations are different traits found within a species ex. Fur color • English naturalist Charles Darwin observed that organisms in a population differ slightly from each other in form, function, and behavior. • Darwin proposed that over many generations, natural selection causes the characteristics of populations to change. • Evolution is a change in the characteristics of a population from one generation to the next. • Adaptation is the process of becoming adapted to an environment. It is an anatomical, physiological, or behavioral change that improves a population’s abilityto survive. CHS Academy

8. Nature Selects CHS Academy

9. Evolution by Artificial Selection • Artificial selection is the selective breeding of organisms, by humans, for specific desirable characteristics. • Dogs have been selectively bred for certain characteristics. • Fruits, grains, and vegetables are also produced by artificial selection. Humans save seeds from the largest, and sweetest fruits. By selecting for these traits, farmers direct the evolution of crop plants to produce larger, sweeter fruit. CHS Academy

10. Life Depends on the Sun • Energy from the sun enters an ecosystem when plants use sunlight to make sugar molecules. • Solar energy converted into chemical energy • This happens through a process called photosynthesis. • Photosynthesis is the process by which plants, algae, and some bacteria use sunlight, carbon dioxide, and water to produce carbohydrates and oxygen. CHS Academy

11. From Producers to Consumers • Because plants make their own food, they are called producers. • A producer is an organism that can make organic molecules from inorganic molecules. • Producers are also called autotrophs, or self-feeders. CHS Academy

12. From Producers to Consumers • Organisms that get their energy by eating other organisms are called consumers. • A consumer is an organism that eats other organisms or organic matter instead of producing its own nutrients or obtaining nutrients from inorganic sources. • Consumers are also called heterotrophs, or other-feeders. CHS Academy

13. What Eats What? • Organisms can be classified by what they eat. • Types of Consumers: • Herbivores-plants • Carnivores-other animals • Omnivores-both plant and animal • Decomposers-dead material • With mouth-Scavenger • Without mouth-Saprophyte CHS Academy

14. The Water Cycle • Water is a renewable resource because it is circulated in the water cycle. • In the water cycle, water molecules travel between the Earth’s surface and the atmosphere. Water evaporates at the Earth’s surface. Water vapor rises into the air. As the vapor rises, it condenses to form clouds. Eventually the water in clouds falls back to the Earth as precipitation. • Water can also runoff the earth’s surface percolating through the soil. • Plants can release water to the atmosphere through transpiration while animals return water through respiration. CHS Academy

15. The Water Cycle CHS Academy

16. Burning the Fuel • An organism obtains energy from the food it eats. • This food must be broken down within its body. • The process of breaking down food to yield energy is called cellular respiration. CHS Academy

17. Energy Transfer • Each time an organism eats another organism, an energy transfer occurs. • This transfer of energy can be traced by studying food chains, food webs, and trophic levels. CHS Academy

18. Food Chains • A food chain is a sequence in which energy is transferred from one organism to the next as each organism eats another organism. CHS Academy

19. Food Webs • Ecosystems, however, almost always contain more than one food chain. • A food web shows many feeding relationships that are possible in an ecosystem. CHS Academy

20. Trophic Levels • Each step in the transfer of energy through a food chain or food web is known as a trophic level. • A trophic level is one of the steps in a food chain or food pyramid; examples include producers and primary, secondary, and tertiary consumers. • Each time, only 10 % of the energy is transferred, while 90% of the energy is lost as heat CHS Academy

21. What is a Biome? • Biomes are large regions characterized by a specific type of climate and certain types of plant and animal communities. • Climate-temperature and precipitation patterns over a long period of time • Each biome is made up of many individual ecosystems. CHS Academy

22. Temperature and Precipitation CHS Academy

23. Tropical Rain Forests • Tropical rain forests are forests or jungles near the equator. They are characterized by large amounts of rain and little variation in temperature and contain the greatest known diversity of organisms on Earth. • They help regulate world climate an play vital roles in the nitrogen, oxygen, and carbon cycles. • They are humid, warm, and get strong sunlight which allows them to maintain a fairly constant temperature that is ideal for a wide variety of plants and animals. CHS Academy

24. Temperate Deciduous Forests CHS Academy

25. Taiga • The taiga is the region of evergreen, coniferous forest below the arctic and subarctic tundra regions. • The taiga has long winters and little vegetation. • The growing season can be as short as 50 days with most plant growth occurring during the summer months because of nearly constant daylight and larger amounts of precipitation. CHS Academy

26. Savannas Savannas are plains full of grasses and scattered trees and shrubs that are found in tropical and subtropical habitats. Found mainly in regions with a dry climate, such as East Africa and western India. CHS Academy

27. Temperate Grasslands • Temperate grasslands are communities (or biomes) that are dominated by grasses, have few trees, and are characterized by hot summers and cold winters, with rainfall that is intermediate between that of a forest and a desert. • Heavy precipitation is rare in the grasslands, allowing the hot temperatures in the summer to make the grasslands susceptible to fires. CHS Academy

28. Chaparral • Chaparral is a type of temperate woodland biome with vegetation that includes broad leafed evergreen shrubs and is located in areas with hot, dry summers and mild, wet winters. • Chaparrals are located in the middle latitudes, about 30° north and south of the equator. • Chaparrals are located primarily in coastal areas that have Mediterranean climates. CHS Academy

29. Deserts CHS Academy

30. Tundra • The tundra is a treeless plain that is located in the Arctic or Antarctic and that is characterized by very low winter temperatures, short, cool summers, and vegetation that consists of grasses, lichens, and perennial herbs. • Summers are short in the tundra, so only the top few centimeters of soil thaw. • Permafrost is the permanently frozen layer of soil or subsoil and can be found in the tundra regions. CHS Academy

31. The Carbon Cycle • The carbon cycle is the movement of carbon from the nonliving environment into living things and back CHS Academy

32. The Carbon Cycle • Carbon exists in air, water, and living organisms. • Producers convert carbon dioxide in the atmosphere into carbohydrates during photosynthesis. • Consumers obtain carbon from the carbohydrates in the producers they eat. • During cellular respiration, some of the carbon is released back into the atmosphere as carbon dioxide. • Over long periods of time, once living organisms may form deposits of coal, oil, or natural gas, which are known as fossil fuels. • The burning of fossils fuels which releases carbon into the atmosphere is called combustion • Humans are affecting this cycle by deforestation and combustion of fossil fuels CHS Academy

33. The Nitrogen Cycle • The nitrogen cycle is the process in which nitrogen circulates among the air, soil, water, plants, and animals in an ecosystem. • All organisms need nitrogen to build proteins, which are used to build new cells. • Nitrogen makes up 78 percent of the gases in the atmosphere. CHS Academy

34. The Nitrogen Cycle • Nitrogen must be altered, or fixed, before organisms can use it. • Only a few species of bacteria can fix atmospheric nitrogen into chemical compounds that can be used by other organisms. • These bacteria are known as “nitrogen-fixing” bacteria. • Nitrogen-fixing bacteria are bacteria that convert atmospheric nitrogen into ammonia. • These bacteria live within the roots of plants called legumes, which include beans, peas, and clover. CHS Academy

35. The Nitrogen Cycle CHS Academy

36. The Phosphorus Cycle • The phosphorus cycle is the cyclic movementof phosphorus in different chemical forms from the environment to organisms and then back to the environment. • Plants get the phosphorus they need from soil and water, while animals get their phosphorus by eating plants or other animals that have eaten plants. • Phosphorus may enter soil and water when rocks erode. Small amounts of phosphorus dissolve as phosphate, which moves into the soil. CHS Academy

37. The Phosphorus Cycle CHS Academy

38. Fertilizers and the Nitrogen and Phosphorus Cycles • Fertilizers, which people use to stimulate and maximize plant growth, contain both nitrogen and phosphorus. • Excessive amounts of fertilizer can enter terrestrial and aquatic ecosystems through runoff. • Excess nitrogen and phosphorus can cause rapid growth of algae. • Excess algae can deplete an aquatic ecosystem of important nutrients such as oxygen, on which fish and other aquatic organisms depend. CHS Academy

39. Ecological Succession Ecological succession is a gradual process of change and replacement of the types of species in a community. • Primary succession is a type of succession that occurs on a surface where no ecosystem existed before. It begins in an area that previously did not support life. Ex. rock after glacier retreats • Primary succession can occur on rocks, cliffs, or sand dunes. • Secondary succession occurs on a surface where an ecosystem has previously existed. It is the process by which one community replaces another community that has been partially or totally destroyed. • Secondary succession can occur in ecosystems that have been disturbed or disrupted by humans, animals, or by natural process such as storms, floods, earthquakes, or volcanic eruptions. CHS Academy

40. Ecological Succession • A pioneer species is a species that colonizes an uninhabited area and that starts an ecological cycle in which many other species become established. Ex. Lichens • A climax community is the final, stable community in equilibrium with the environment. • Even though a climax community may change in small ways, this type of community may remain the same through time if it is not disturbed. CHS Academy

41. Ecological Succession CHS Academy

42. What Is a Population? • A population is a group of organisms of the same species that live in a specific geographical area and interbreed. • A population is a reproductive group because organisms usually breed with members of their own population. • The word population refers to the group in general and also to the size of the population, or the number of individuals it contains. CHS Academy

43. Populations • Populations are groups of organisms of the same species that live in a specific geographical area and interbreed. • Members of a species may not all live in the same place. Field mice in Maine will not interact with field mice in Texas. However, each organism lives as part of a population. • For example, all the field mice in a corn field make up a population of field mice. CHS Academy

44. How Does a Population Grow? • Growth rate is an expression of the increase in the size of an organism or population over a given period of time. It is the birth rate minus the death rate. • Overtime, the growth rates of populations change because birth rates and death rates increase or decrease. • For this reason, growth rates can be positive, negative, or zero. CHS Academy

45. Exponential Growth • In exponential growth, a large number of individuals is added to the population in each succeeding time period. CHS Academy

46. Carrying Capacity • Carrying capacity is the largest population that an environment can support at any given time. • A population may increase beyond this number but it cannot stay at this increased size. CHS Academy

47. Carrying Capacity CHS Academy

48. World Population Over Time CHS Academy

49. Histograms • Age structure is the classification of members of a population into groups according to age or the distribution of members of a population in terms of age groups and helps demographers make predictions. • Countries that have high rates of growth usually have more young people than older people. • In contrast, countries that have slow growth or no growth usually have an even distribution of ages in the population. CHS Academy

50. Age Structure • Age structure can be graphed in a population pyramid, a type of double sided bar also referred to as a histogram . CHS Academy