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CHAPTER 3 – EcologyThe Biosphere
3.1 What is Ecology?Ecology – study of interactions of organisms with their environment.
Organism – shows ALL characteristics of life:Made of 1or more cells
Reproduce
Based on universal genetic code.
Grow and develop
Evolve
Adapt to their environment.
Metabolism (make and use energy)
Maintain a stable internal environment (homeostasis).
Biosphere – part of the Earth where all life exists – includes land, water & air.
3.1 What is Ecology – Levels of Organization
Species – Group of organisms which can interbreed and produce viable (living) and fertile (able to reproduce) offspring.
Population – Members of the same species living in the same area.
Ex. – “school” population, population of zebra in the Serengeti of Africa.
Community – The different populations living in the same area.
Ex. – Marsh community – all the populations of species that live in a salt marsh.
3.1 What is Ecology – Levels of Organization
Ecosystem – All of the organisms and their non-living surroundings that live in a particular place.
Ex. – Pine Barren ecosystemBiotic factors – all the living parts of an ecosystem.
Ex. – food, shelter, other organims.Abiotic factors – all the NON- living parts of an ecosystem.
Ex. – rocks, air, soil, water, shelter
Biome – all the ecosystems that share similar climate and similar dominant communities.
Ex. – Deciduous Forest, Tundra, Savannah, Marine
3.1 What is Ecology – Ecological Methods
Ecological research uses 3 methods:1. Observing – How ecologists would get their
“problem”2. Experimenting – Testing their hypothesis
a. Artificial environment in the laboratoryb. Field studies – try not to disrupt the organisms.
3. Modeling – Most used methoda. To study events that take place over long periods of time.b. Mathematical formulas based on data collect from experimenting and observing.c. Can be used to try to predict future events.
Ex. Global warming/Climate change.
3.2 Energy FlowSunlight is main source of energy for ALL life on Earth.
Autotroph (Producer) - organisms that make their own food.
Photoauthotroph - make their own food through Photosynthesis (converting sunlight, water and carbon dioxide into sugars & oxygen).
Ex. - Green plants, some algaePhotosynthesis by marine plants is major source of oxygen on Earth.Ps in the rainforest gives approximately 1/3 of Earth’s oxygen supply.
Chemoautotroph - use chemicals to make their own food (chemosynthesis)
Examples – Bacteria that live in hot springs, volcanoes and sulfur bacteria in salt marshes.
3.2 Energy Flow
Consumer - organisms that cannot make their own food.
All animals and fungi (mushroosm, etc.) are consumers.
4 types of consumers: Herbivores Carnivores Omnivores Decomposers
3.2 Energy Flow
Herbivores - Eat only plants (producers).
Examples: cow, buffalo & antelope.
Also called “primary consumers”.
3.2 Energy Flow
Carnivores Capture and eat herbivores and/or other carnivores.
Examples: Lions, snakes, hawks.
Can be secondary or tertiary consumers
Secondary consumers eat herbivores (primary consumers)
Tertiary consumers eat carnivores and/or omnivores (secondary consumers)
3.2 Energy Flow
Omnivores - Eat both producers and carnivores. Examples: humans, bears & chimpanzees.
Can be primary consumers, secondary consumers or tertiary consumers
Primary – eating a salad (producers) Secondary – eating a deer (primary consumer) Tertiary consumer – eating a tuna (secondary consumer)
3.2 Energy Flow
Scavengers - Feed on the dead bodies of other organisms.
They start returning nutrients to the environment.
Examples: Vultures & Hyenas
3.2 Energy Flow
Decomposers - Consume the bodies of dead organisms and wastes.
Examples: Bacteria and fungi (mushrooms).Detritovore – Type of decomposer that feeds on detritus – decaying plant and animal matter.
Ex. – crabs, snails
Put nutrients back into the environment.
Complete the cycle of matter in an ecosystem:Sun Producer Consumer Decomposer Soil
3.2 Energy Flow – Feeding Relationships
Energy (food) travels through an ecosytem from sun to producer to consumer to decomposer to soil and air.
Food chain is a linear (line) transfer of energy by eating and being eaten.
3.2 Energy Flow – Feeding Relationships
Food Web - Network of food chains among organisms inan ecosystem.
ALL the food chains in an ecosystem that link the organisms.
Changes in the population of one organism in an ecosystem affect the entire food web.
3.2 Energy Flow – Feeding Relationships
Trophic Levels - Different feeding levels in an ecosystem.
Producers are the first trophic level (Autotrophs).
Consumers & Decomposers at all other trophic levels:
Heterotroph – organism which cannot make its own food.Must get their food from other sources
3.2 Energy Flow – Feeding Relationships
Autotrophs - organisms that can make their own food.Producers
2 types: Photoautotroph – Green plants – make their food by using photosynthesisChemoautotroph – Bacteria – use chemicals to make their food.
Ex. – Sulfur bacteria – use sulfur to make their food.
3.2 Energy Flow – Feeding Relationships
Heterotroph - Organism which cannot make its own food.
Consumers : Primary, Secondary and/or Tertiary consumers
Decomposers/ Detritivores.
3.2 Energy Flow – Ecological PyramidsDiagram that shows the relative amounts of energy or matter available at each trophic level.
3 types:1. Energy Pyramid2. Biomass Pyramid3. Pyramid of Numbers.
3.2 Energy Flow – Ecological Pyramids
1. Energy Pyramid – Shows the amount of energy available at each trophic level
a. Only about 10% of energy is transferred from one trophic level to the next.
Ex. 10% of the energy stored by green plants is available to the herbivores and 1% of the energy from the herbivores (cow) is transferred to the human that eats it.
3.2 Energy Flow – Ecological PyramidsBiomass Pyramid – Shows the total amount of living tissue (biomass) within a trophic level.
Expressed as grams of organic matter (biomass) per unit of area.Represents the amount of POSSIBLE food available at each trophic level.
3.2 Energy Flow – Ecological Pyramids
Pyramid of Numbers – The number of individuals at each trophic level.
Plants form the base are usually take up the most in the pyramid.
3.3 Cycles of Matter
Matter is recycled within and between ecosystems
Biogeochemical cycles – When elements, chemical compounds, etc., are passed from one organism to another and from one part of the biosphere to another.
Pass the SAME molecules around and around again – no “new” molecules are made and none are destroyed.Law of Conservation of Matter – Matter cannot be created or destroyed. It only changes form.
3.3 Cycles of Matter
Water Cycle:
Water enters atmosphere via evaporation or transpiration (evaporation by plants).
It rises, cools and condenses, forming clouds.
It returns to Earth surface as precipitation – rain, snow, sleet or hail.
It runs off into streams, lakes or oceans.
Some water soaks into the ground and is called “groundwater.”
Groundwater is used by the plants for photosynthesis.
3.3 Cycles of Matter
3.3 Cycles of Matter
Carbon Cycle - Cycling of carbon in the atmosphere & soil.
Photosynthesis removes carbon dioxide (CO2) from the atmosphere and produces Oxygen (O2)
Cell respriation removes O2 from the atmosphere and produces CO2.
Products (end results) for photosynthesis are the starting materials for respiration.
3.3 Cycles of Matter
Carbon is cycled through through 4 main processes:
1. Biological processes – Photosynthesis, respiration, decomposition – cycle CO2 and O2.
2. Geochemical processes – Erosion & volcanic activity – release CO2 into the atmosphere.
3. Mixed biogeochemical processes – burial & decompositon of dead organisms and their conversion under pressure to coal & fossil fuels (petroleum, natural gas) – stores carbon underground.
3.3 Cycles of Matter
4. Human Activities – mining, cutting, burning of forests and burning of fossil fuels – release CO2 into the atomsphere
Largest contributer to global warming and the rise of greenhouse gases (CO2) in the atmosphere.
“Slash & burn” – cutting down and burning of large patches of the rainforests, especially in South America – removes approx. 52,000 acres/day of plants.
3.3 Cycles of Matter
Nitrogen cycle - the cycling of nitrogen through the atmosphere.
“nitrogen-fixing bacteria” change nitrogen from the ari into a form that can be used by plants.
Nitrogen-fixing bacteria live in the soil and in the roots of legumes Ex. - peanuts, beans and clover
Plants also get nitrogen from fertilizers.
Animals get nitrogen from proteins they eat.Provide proteins to animals.
Decomposers return nitrogen to the soil.
Denitrificaion – Soil bacteria that convert nitrates into nitrogen gas – releases nitrogen into the atmosphere again.
3.3 Cycles of Matter
Phosphorus Cycle.Phosphorus is important to all organismsDNA & RNA contain phosphorusNot common in the atmosphereMostly in rock, soil minerals and ocean sediments
As rocks gradually wear down, phosphate is released.
Phosphate moves through the ecosystem via the food web, from producers to consumers, etc.
3.3 Cycles of Matter
3.3 Cycles of MatterNutrient Limitations
Primary (10) production – rate at which organic (carbon containing) matter is created by producers.
Controlled by the amount of available nutrients.
Limiting nutrient – When a nutrient in an ecosystem is in short supply and limits the amount of primary production
Ex. – Nitrogen is a limiting nutrient in the water.Fertilizers added to lawns, etc. contain high amounts of nitrogen. When nitrogen runs-off from the land into the water, creates LARGE algae blooms which can block sunlight to the plants at the bottom, killing them and disrupting the ecosystem.
