Study Guides Cycles of Matter

Study Guides Cycles of Matter • • • A handful of elements combine to form the building blocks of all known organisms. Organisms cannot manufacture these elements and do not “use them up,” so where do essential elements come from? How does their availability affect ecosystems? Recycling in the Biosphere ➢ How does matter move through the biosphere? Unlike the one-way flow of energy, matter is recycled within and between ecosystems. Elements pass from one organism to another and among parts of the biosphere through closed loops called biogeochemical cycles, which are powered by the flow of energy. Biogeochemical cycles of matter involve biological processes, geological processes, and chemical processes. As matter moves through these cycles, it is never created or destroyed-just changed. Biogeochemical cycles of matter pass the same atoms and molecules around again and again. Biological Processes Biological processes consist of any and all activities performed by living organisms. These processes include eating, breathing, “burning” food, and eliminating waste products. Geological Processes Geological processes include volcanic eruptions, the formation and breakdown of rock, and major movements of matter within and below the surface of the earth. Chemical and Physical Processes Chemical and physical processes include the formation of clouds and precipitation, the flow of running water, and the action of lightning. The Water Cycle ➢ How does water cycle through the biosphere? Water continuously moves between the oceans, the atmosphere, and land-sometimes outside living organisms and sometimes inside them. Nutrient Cycles ➢ What is the importance of the main nutrient cycles? Every organism needs nutrients to build tissues and carry out life functions. Like water, nutrients pass through organisms and the environment through biogeochemical cycles. The three pathways, or cycles, that move carbon, nitrogen, and phosphorus through the biosphere are especially critical for life. Oxygen participates in parts of the carbon, nitrogen, and phosphorus cycles by combining with these elements and cycling with them through parts of their journeys. The Carbon Cycle Carbon is a major component of all organic compounds, including carbohydrates, lipids, proteins, and nucleic acids. Plants take in carbon dioxide during photosynthesis and use the carbon to build carbohydrates. Carbohydrates then pass through food webs to consumers. Organisms release carbon in the form of carbon dioxide gas by respiration. When organisms die, decomposers break down the bodies, releasing carbon to the environment. Carbon dioxide is released into the atmosphere by volcanic activity or by human activities, such as the burning of fossil fuels and the clearing and burning of forests. The Nitrogen Cycle All organisms require nitrogen to make amino acids, which are used to build proteins and nucleic acids, which combine to form DNA and RNA. Nitrogen gas (𝑁2 ) makes up 78 percent of Earth’s atmosphere. ➢ What role do decomposers have in the nitrogen cycle? Decomposers return 𝑁𝐻4+ to the soil. ➢ What process converts 𝑁2 into 𝑁𝐻3 ? Nitrogen fixation. Pull nitrogen out of the air into a usable form for plants. The Phosphorus Cycle Phosphorus forms a part of vital molecules such as DNA and RNA. Although phosphorus is of great biological importance, it is not abundant in the biosphere. Phosphorus in the form of inorganic phosphate remains mostly on land, in the form of phosphate rock and soil minerals, and in the ocean, as dissolved phosphate and phosphate sediments. As rocks and sediments wear down, phosphate is released. Some phosphate stays on land and cycles between organisms and soil. Plants bind phosphate into organic compounds when they absorb it from soil or water. Organic phosphate moves through the food web, from producers to consumers, and to the rest of the ecosystem. Other phosphate washes into rivers and streams, where it dissolves. This phosphate eventually makes its way to the ocean, where marine organisms process and incorporate it into biological compounds. Nutrient Limitation ➢ How does nutrient availability relate to the primary productivity of an ecosystem? If ample sunlight and water are available, the primary productivity of an ecosystem may be limited by the availability of nutrients. The nutrient whose supply limits productivity is called the limiting nutrient. If any nutrient is in short supply - if any wheel “sticks”- the whole system slows down or stops altogether. Weather and Climate ➢ What is climate? A region’s climate is defined by year-after-year patterns of temperature and precipitation. Climate is rarely uniform even within a region. Environmental conditions can vary over small distances, creating microclimates. For example, in the Northern Hemisphere, south-facing sides of trees and buildings receive more sunlight, and are often warmer and drier, than north-facing sides. These differences can be very important to many organisms. Factors That Affect Climate ➢ What factors determine global climate? Global climate is shaped by many factors, including solar energy trapped in the biosphere, latitude, and the transport of heat by winds and ocean currents. Solar Energy and the Greenhouse Effect The main force that shapes our climate is solar energy that arrives as sunlight that strikes Earth’s surface. Some of that energy is reflected back into space, and some is absorbed and converted into heat. Earth’s temperature is largely controlled by concentrations of 3 atmospheric “greenhouse gases” -carbon dioxide, methane, and water vapor. Latitude and Solar Energy Near the equator, solar energy is intense, as the sun is almost directly overhead at noon all year. That’s why equatorial regions are generally so warm. The curvature of Earth causes the same amount of solar energy to spread out over a much larger area near the poles than near the equator. Earth’s polar areas annually receive less intense solar energy, and therefore heat, from the sun. The difference in heat distribution creates three different climate zones: tropical, temperate, and polar. Temperate and polar zones receive very different amounts of solar energy at different times of the year because Earth’s axis is tilted. As Earth revolves around the sun, solar radiation strikes different regions at angles that vary from summer to winter. During winter in the temperate and polar zones, the sun is much lower in the sky, days are shorter, and solar energy is less intense. Heat Transport in the Biosphere The unequal distribution of heat across the globe creates wind and ocean currents, which transport heat and moisture. Earth has winds because warm air is less dense and rises, and cool air is more dense and sinks. Air that is heated by warm areas of Earth’s surface — such as near the equator — rises, expands, and spreads north and south, losing heat along the way. As the warm air cools, it sinks. Wind In cooler regions, near the poles, chilled air sinks toward Earth’s surface, pushing air at the surface outward. This air warms as it travels over the surface and rises. Similar patterns of heating and cooling occur in the oceans. Surface water is pushed by winds. Ocean currents, like air currents, transport enormous amounts of heat. Warm surface currents add moisture and heat to air that passes over them. Cool surface currents cool the air that passes over them. Deep ocean currents are caused by cold water near the poles sinking and flowing along the ocean floor. This water rises in warmer regions through a process called upwelling.