Earth s Life-Support Atmosphere- gases surrounding earth s surface. Troposphere= air we breathe; weather 78% nitrogen, 21% oxygen, 0.

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1 Ecosystems APES CH 3 But First: Cells Complex organic compounds called macromolecules make up the basic molecular units found in cells. Complex carbohydrates Cellulose and starch Proteins- made up of amino acids Nucleic acids- made of nucleotides DNA & RNA Lipids- compounds don t dissolve in H 2 O fats, waxes, steroids Next: Genes Genes carry heredity information via the DNA contained in chromosomes. Species- group of organisms that have similar genetic makeup; can mate and reproduce. This genetic information makes you a member of the human species but also allows you to be a unique member of that species. Ecology How organisms interact with biotic and abiotic environment. Biotic is the environment of other organisms. Abiotic is their nonliving environment of soil, water and other forms of matter. It is a study of connections in nature. 5 6 Earth s Life-Support Atmosphere- gases surrounding earth s surface. Troposphere= air we breathe; weather 78% nitrogen, 21% oxygen, 0.033% CO 2 1

2 78% nitrogen, 21% oxygen, 0.033% CO 2 Hydrosphere- earth s water Geosphere- earth s solid surface and deeper layers Lithosphere= upper mantle and crust, resources Biosphere- those parts of the atmosphere, hydrosphere, and geosphere where life is found Classification of the Biosphere Biomes terrestrial regions with distinct climates similar vegetation and also species. Aquatic life zones Almost 75% of the Earth s surface Freshwater life zones Marine life zones Three Factors Sustain Life on Earth One-way flow of high-quality energy from the sun 1 st & 2 nd law of thermodynamics Cycling of matter or nutrients through parts of the biosphere Law of conservation of matter Gravity Enables movement and cycling Natural Capital: Solar Energy Lights the Earth Warms the Earth Natural green house effect Drives the hydrologic cycle Generates winds Enables photosynthesis (less than.03%) Thus, providing food. Range of Tolerance (ROT) 2

3 Each population in an ecosystem has a ROT to variations in its physical and chemical environment. Age, health, & genetic diversity allows some to be more tolerant than others. Optimal range- level of factors in which a population thrives Limiting factors are those abiotic factors that are more important in regulating population growth than other factors. 13 Limiting Factors Limiting factor principle- too much or too little of any abiotic factor can limit or prevent growth of a population, even if all else is in optimal range. Examples On Land: Precipitation Soil nutrients Temperature Aquatic Examples: Dissolved oxygen levels Temperature & sunlight Salinity (Salt) & nutrients Animation: Gause s Competition Experiment Trophic (feeding) Levels Producers autotrophs, chemotrophs Photosynthesis; Plants and algae Chemosynthesis; bacteria in deep ocean Use energy in chemical bonds CH 4 & H 2 S Consumers heterotrophs; animals Primary- eat producers (herbivores) Secondary- eat primary (carnivores) Third-level- eat primary & secondary Omnivores- eat plants and animals Trophic Levels (pt.2) 3

4 Decomposers- digest food outside their bodies, breaking down dead organisms by using enzymes. Perform nutrient cycling by releasing the nutrients once held in those bodies to be used again. Ex. Certain types of bacteria and fungi Detritivores- actually feed on wastes & dead organisms ex. Earthworms, mites, vultures In this way, nature wastes nothing. Nutrient cycling Useless Species? Microbes and microorganisms are everywhere Bacteria Fungi Protozoa Decomposers & detritus feeders complete the cycling of matter by breaking down organic matter into simpler nutrients that can be reused by producers. Only a few microbes cause diseases Consumption of Energy Chemical energy stored in food fuels life processes All organisms get their energy from aerobic or anaerobic respiration, but only plants carry out photosynthesis. Aerobic respiration- carried out in the presence of oxygen Net products are opposite those of photosynthesis Anaerobic respiration- carried out without oxygen a.k.a fermentation Some decomposers can do this 3-4 What Is Biodiversity and Why Is It Important? Biodiversity is all the diversity associated with life, as well as those places & processes that support it. 4

5 those places & processes that support it. The biodiversity found in the earth s genes, species, ecosystems, and ecosystem processes is vital to sustaining life on earth. 22 Biodiversity Genetic diversity- of genes found within a species or population. Allows for adaptation to change Ecosystem diversity- of terrestrial and aquatic ecosystems found in an area or on the earth. Functional diversity- of processes like energy flow and matter recycling 23 Core Case Study: Insects Around for ~400 million years Bad reputation Useful to humans and ecosystems Vital roles in sustaining life Pollinators Natural pest control Renewing soils 24 Ecosystem Diversity Soil varies with its ecosystem. Different soils are supportive of different habitats e.g. desert, grasslands Soil supplies most of the nutrients needed for plant growth and helps purify and store water and control levels of carbon dioxide in the atmosphere by storing it. 25 Soil varies with Age The age of the soil can also cause variety. 5

6 The age of the soil can also cause variety. Immature soil is mostly bedrock Young soil has smaller and smaller rock fragments Mature soils contain 3 horizons (layers); each w/ distinct texture and composition. O horizon= leaf litter, wastes; uppermost layer A horizon= topsoil, more roots, home to detritivores and many decomposers B horizon= subsoil, sand, silt, clay C horizon= parent material; rock, gravel Soil Color & Composition A horizon, topsoil, is composed of decomposed organic matter called humus. Thick= helps hold water & nutrients Dark brown/black= rich in nitrogen & organic matter Gray, yellow, or red topsoils need nitrogen enrichment B & C horizons have inorganic matter Sand, silt, clay, and gravel Soil Texture Sand- largest particles, lots of air, low water holding ability Silt- particles larger than clay, but smaller than sand, drains slowly Clay- smallest particles, poor drainage Loam- best soil, mostly humus, (sand, silt, clay), good infiltration (downward movement of water) Leaching when water dissolves minerals & organic matter water carrying it to lower levels. 29 Higher Percent Clay Soil The finer the texture: the more difficult a soil is to work or till, 6

7 the more difficult a soil is to work or till, the greater the water holding capacity, the slower water will enter and move through the soil profile, more difficult plant root penetration, the more readily surface soil will crust, and the more nutrient rich the soil. 30 Soil Texture & Permeability Gritty= has a lot of sand Sticky= has a lot of clay; retains a lot of water Smooth= soil is silt laden Crumbly/spongy= soil is heavily loam, holds water; good growth & permeability Soil porosity is affected by soil texture. Porosity in soil determines soil permeability Trophic Connections Food Chain- sequence of organisms, each of which serves as a source of food for the next Food web Network of interconnected food chains More complex than a food chain The arrow s point should aim at the organism that eats it (the arrow s end). Animation: Rainforest Food Web What Happens to Energy in an Ecosystem? Law of 10%= The amount of chemical energy available to organisms at each succeeding feeding level decreases. The most energy is at the bottom with producers. Each trophic level in a food web contains a certain amount of biomass, the dry weight of all organic matter contained in organisms. Which would have more energy a vegetarian or a carnivore? 7

8 Which would have more energy a vegetarian or a carnivore? Why do food chains or webs rarely have more than four or five trophic levels? Primary Productivity Gross primary productivity (GPP)- rate producers convert solar into energy stored in biomass. kcal/m 2 /yr Net primary productivity (NPP)- net rate; producers must use some energy to function NPP= GPP R; (R is that used for respiration) Planet s NPP limits number of consumers The amount of biomass that a particular ecosystem can support is determined by the amount of energy captured and stored as chemical energy by the producers of that ecosystem and how fast they can do it What Happens to Matter in an Ecosystem? Biogeochemical cycles- elements & compounds move continually through air, water, soil, rock, and living organisms. These cycles are driven directly or indirectly by solar energy & gravity. Reservoirs are places where nutrients may accumulate in one portion of the cycle. Atmosphere, oceans, waters, underground Water is Important Surface water helps maintain temperature of surrounding areas. 8

9 areas. Due to water s high specific heat. Water is polar; good solvent. Dilutes wastes. Hydrogen bonding; capillary action for transpiration. Humans alter it: withdrawing large amounts, causing erosion, polluting surface & ground water, climate change 40 Carbon Cycle Carbon is obtained from the atmosphere by producers, which are eaten by consumers, which respire, die and decompose. Fast Carbon- part of the carbon cycle that involves processes associated w/ organisms. Slow Carbon- involves carbon held in rocks, in soils, or as petroleum hydrocarbons. May be stored in these forms for millions of years Nitrogen Cycle Multicellular plants and animals cannot utilize atmospheric nitrogen (N 2 ) Nitrogen-fixation- lightning and bacteria combine nitrogen gas with hydrogen to make ammonia. Nitrification- done by bacteria when ammonia & ammonium are converted to nitrates & nitrites, which are easily taken up by the roots of plants. Ammonification= reverse Denitrification- pt.2 of reversal, turning nitrates & nitrites into nitrogen gas/ nitrous oxide How Scientists do Research? Based on Actual Locations Field Research 9

10 Field Research Remote sensing devices Geographic information systems (GIS) Based on Models of a location Simplified model ecosystems Tubes, chambers, aquariums, greenhouse Mathematical models Computer simulations 46 10