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Transcript
Biology I Comp 3 Review Organisms and Their Environments Introduction to Ecology Ecology is the study of organisms and their interactions with their environment. The environment includes 2 types of factors: Biotic factors – the living parts of the environment Plants, animals, bacteria, fungi, etc Abiotic factors – the nonliving parts of the environment Water, oxygen, light, temperature, etc. Nutrient Cycles Some abiotic factors are nutrients that are needed by plants and animals to survive. These nutrients are cycled through the ecosystem. Helps maintain homeostasis, or balance, within the environment. The 3 main nutrient cycles are: Water Carbon Nitrogen Water Cycle Evaporation – water changing from a liquid to a gas Transpiration – water evaporating from the leaves of plants Condensation – water changing from a gas to a liquid Precipitation – water returning to the land in the form of rain, sleet, hail, or snow Water Cycle Carbon Cycle Photosynthesis and Cellular Respiration cycle carbon and oxygen through the environment Photosynthesis uses CO2 and produces O2 Respiration uses O2 and produces CO2 Carbon may be returned to the soil through decomposition Carbon may also returned to the atmosphere through volcanic activity and burning fossil fuels Carbon Cycle e Nitrogen Cycle Most Nitrogen is found in the atmosphere, but organisms can’t use it in that form Atmospheric Nitrogen is made usable for living things through Nitrogen Fixation Nitrogen-fixing bacteria on the roots of some plants Lightning strikes Denitrification – other bacteria in the soil can convert “fixed” nitrogen back into Nitrogen gas (N2) Nitrogen Cycle Assimilation – Plants use Nitrogen in the soil to form amino acids and other organic compounds Consumers obtain Nitrogen from eating producers When plants and consumers die, decomposers return the Nitrogen to the soil Nitrogen Cycle Levels of Organization - Ecologists can look at the world in levels of increasing complexity Biosphere Biome Organism Population Community Ecosystem Levels of Organization Organism – Any unicellular or multicellular form that exhibits all the characteristics of life An individual Example: A zebra Population – A group of organisms of the same species that live together in a certain area Interbreed and compete for resources Example: A herd of zebras Levels of Organization Community – Groups of organisms of different species that live together in a certain area Example: A herd of zebras, a pride of lions, & a pack of hyenas Ecosystem – All the living and nonliving things in a certain area Communities and the abiotic factors with which they interact Example: Zebras, lions, hyenas, rocks, air, water, etc. Levels of Organization Biome a group of ecosystems that have similar climates and communities Example: Savanna Biosphere the entire portion of the planet that supports life Biomes Aquatic Terrestrial Tundra Taiga Tropical Forest Savanna Desert Temperate Grassland Temperate Deciduous Forest Tundra Arctic Little precipitation: 15-25 cm/year Average winter temp. -30 degrees C Summer < 10 degrees C Long winter; very short summer Permafrost – almost permanently frozen snow/ice Artic fox Tundra Small plants with short roots, a few DWARF shrubs Migratory animals or animals with High tolerance for very harsh conditions Adaptations: Animals may have white fur for camouflage. Plants have short roots because of permafrost. Caribou Polar bear Bearberry Taiga (Northern Coniferous Forest) Seasonal rainfall: 30-80 cm; some much more Winters -50 degrees C in winter Summer 20 degrees C Long winter; short summer Taiga (Northern Coniferous Forest) Spruce Plants: cone-bearing trees, diverse shrubs, lichens & mosses Animals: Migratory animals, large herbivores & predatory animals Adaptations: Plants with waxy needles to help retain water. Animals may hibernate during coldest months Moose Bear Timber wolves Tropical Rain Forest Seasonal rainfall: 200-400 cm/yr 25-29 degrees C year round Located along the equator Summer year round Sloth Orchids Tropical Forest Most diverse species of plants & animals Plants: Broad leaves, vines, orchids, bromeliads. Soil lacks nutrients Animals: Lots of insects and tree dwellers Adaptations: Many forms of camoflauge, bright colors, diet heavy on fruits Toucan Boa constrictor Poison Dart Frog Jaguar Savanna Seasonal rainfall; 50-120 cm/yr, with a long drought season Temperature: 20-30 degrees C (warm!) Distinct wet and dry seasons Frequent fires during dry season Aardvark Savanna Plants: Tall grasses, scattered small trees and shrubs Animals: Lots of herbivores (grazers), and carnivores (hunters) Adaptations: Drought tolerant & fire-resistant Cheeta Giraffe Elephant Lion Desert Rainfall < 25 cm/yr (arid/dry) Hot deserts > 50 degrees C Cold deserts (Antarctica) <-30 degrees C Extreme changes in temperature Ex: Very hot during the day & cold at night Rattlesnake Desert Plants: Cacti, creosote bushes, succulents Animals: small nocturnal carnivores, reptiles, birds & insects Adaptations: Plants with deep roots and thick leaves to obtain and hold water. Reptiles with thick, waterproof skin to hold water. Many nocturnal animals. Roadrunner Kangaroo Rat Cactus Fennec Fox Temperate Grassland Dry winters, wet summers: 30-100 cm/yr.; seasonal drought Cold winters < -10 degrees C; Hot summers 30 degrees C Seasonal drought & periodic fires Dark rich soil Blazing stars Temperate Grassland Plants: Lush grasses & wildflowers Animals: Large herbivores & predators, burrowing mammals Adaptations: Drought & fire-resistant plants. Pronghorn antelope Black-tailed prairie dog Bison Coyotes Temperate Deciduous Forest Rainfall: 75-150 cm/yr Cold Winters & hot summers. 0-35 degrees C 4 distinct seasons Our biome! Skunk Temperate Deciduous Forest Maple Plants: Deciduous & coniferous trees, shrubs, mosses, ferns Animals: variety of mammals, birds, insects Adaptations: Deciduous trees lose their leaves in winter to keep from freezing. Some migratory animals & birds. Turkey Squirrel Deer Bobcat Raccoon Types of Interactions Between Organisms Competition – when resources are scarce, only some organisms will survive Food Chains & Webs – diagrams showing the feeding relationships in an ecosystem Predator/Prey Relationship – some animals hunt others for food Symbiotic Relationship – close interaction between two or more organisms of different species Competition When resources are limited, competition for those resources results. Intraspecific competion – between organisms of the same species Interspecific competition – between organisms of different species Competition Limiting Factor – any biotic or abiotic resource that limits the growth of an organism or population in a specific environment Availability of water Availability of food Availability of habitat Temperature Competition Density Dependent Limiting Factors – depend on the number of organisms in a population Food, Water, Predation, Disease Density Independent Limiting Factors – do Not depend on the number of organisms in a population Weather, Natural Disasters, Human Activities Competition Habitat – the place where an organism lives Niche – the role an organism plays in its environment If two organisms occupy the same niche they will compete for resources until one species is forced out Niche Partitioning for Warblers Food Chains & Webs Producers (Autotrophs) – Produce their own food through Photosynthesis or Chemosynthesis Ex: Plants, algae Consumers (Heterotrohps) – Must consume other organisms for food & energy Food Chains & Webs Types of Consumers Herbivores – Primary consumers Eat Plants Carnivores – Secondary & higher consumers Eat other animals Omnivores Eat both plants and animals Food Chains & Webs Types of Consumers (continued) Detritivores – Feed on organic waste (dead plants and animals) Ex: Earthworms – Breakdown dead plants & animals into simpler molecules that can be absorbed Decomposers Ex: Bacteria, Fungi Food Chains & Webs The arrows in a food chain/web show the flow of energy from one organism to the next Only 10% of the available energy is transferred from one trophic level to the next. The rest is lost as heat. The Trophic Level of an organism is the position it holds in a food chain/web/pyramid (Primary, Secondary, Tertiary, etc.) Food Chains & Webs Food Chain – a linear representation of energy transfer between organisms Food Chains & Webs Food Web – a network of interconnected food chains in an ecosystem Food Chains & Webs Food Pyramids Pyramid of Energy – Shows the amount of energy available at each trophic level Biomass Pyramid – Shows the amount of biomass at each trophic level Pyramid of Numbers – Shows the number of individual organisms at each trophic level Food Chains & Webs Energy Pyramid Pyramid of Numbers Biomass Pyramid Predator/Prey Relationships Predator populations can control the size of Prey populations, and vice versa. The Top Predator in an ecosystem has no natural predators. Symbiotic Relationships Symbiosis – two organisms of different species living closely together. There are 3 types of Symbiosis Commensalism Mutualism Parasitism Symbiotic Relationships Mutualism – Both species benefit Commensalism – One species benefits and the other is not affected Parasitism – One species benefits and the other is harmed (parasite & host) Biological Magnification Chemicals or toxins may be introduced into an ecosystem through human actions. As they move up through a food chain, they have a more severe affect on each higher trophic level. Ex: DDT Ecological Succession Ecological Succession – the predictable and orderly changes in the composition or structure of an ecological community over time. Pioneer species – the first species to populate an area Climax community – the final community of organisms in an ecosystem once it becomes stable Ecological Succession Primary Succession – occurs on surfaces where no soil exists Ex: Volcanic rock surfaces after an eruption Ecological Succession Secondary Succession – occurs on preexisting soil Ex: A forrest after being burned or cleared for construction Human Impact on Ecosystems Biodiversity is the variety of life in an ecosystem It may be decreased by human activities such as: Use of pesticides and chemical fertilizers Deforestation and clearing land for construction Introducing non-native species Exploitation of wildlife