Unit A

• Dynamic equilibrium

  changing but not disturbing entire system
• Degrees of risk

  Threatened

  Endangered

  Extirpated

  Extinct
• Frogs

  indicator species because sensitive to changes

  lives two different lives (tadpole, frog)
• Frog vs. tadpole

  frogs live in forest and grassland

  frogs eat insects and small fish (carnivore)

  frogs get eaten by large fish, birds, reptiles, and small mammals

  tadpoles live in ponds

  tadpoles eat algae (herbivore)
• Frog vs. tadpole food chain

  Frog's food chain includes producers, herbivores, carnivores, and omnivores

  Tadpole's food chain includes producers, detritus, decomposers
• Detritus

  waste from plants and animals (including dead remains)

  decomposers break down detritus to release nutrients into environment

  plants + algae uses these nutrients
• Disappearing frogs

  Frogs existed before dinosaurs, but human activity is reducing population

  In danger in heavily populated areas (loss of habitat)

  breathe using frog skin (air pollution)

  acidity affects reproduction & growth, slows sperm cells (water pollution)

  frogs can't be in direct sunlight/away from freshwater (climate change)

  frogs can get cell damage (UV radiation)
• Trophic levels

  Food chain levels

  producers - autotrophs

  primary consumers - second trophic

  secondary consumers - third trophic

  consumers in general - heterotrophs
• Poles vs. equator

  Less sunlight + heat at poles

  Less producers at poles

  Less biodiversity at poles

  Less dynamic equilibrium at poles
• Chemosynthesis

  Bacteria (called chemoautrophs) make complex compounds without solar energy

  Requires carbon dioxide, water, and energy source (doesn't have to be sunlight)

  Chemical energy extracted from inorganic chemicals
• Limits on energy transfer

  Energy transfer up food web is not 100% efficient

  Energy is wasted along the way

  That's why only about five trophic levels per ecosystem
• Laws of Thermodynamics

  Thermodynamics - study of energy transformations

  First law: Energy cannot be created/destroyed

  Second law: Some energy will always be wasted during transformation
• Biomass

  Total mass of all organisms in an ecosystem

  Organisms store energy as molecules, so biomass is a measure of energy

  Rainforest has more biomass than tundra e.g.
• Humans in ecosystems

  People move between trophic levels (we eat vegetables and meat)

  We affect ecosystems through:

  Hunting & Fishing (Population control)

  Monoculture crops (Less biodiversity)
• Organic compounds

  Contains carbon and hydrogen

  Matter on earth must be recycled
• Properties of Water

  Absorbs and releases heat (moderates temperature)

  Metabolic reactions happen in water

  Universal solvent

  Makes up over sixty percent of cell's mass

  Supplies hydrogen to producers during photosynthesis, oxygen during cellular respiration

  Involved in many metabolic reactions
• Water's molecular properties

  Polar molecule - Positive hydrogen and negative oxygen

  Hydrogen bond - Polar molecule attracts to each other

  More energy to break bonds, leads to high melting and boiling point
• Water cycle

  AKA hydrological cycle

  Transpiration - loss of water through plant leaves
• Forestry on water cycle

  Less forests means less water in atmosphere

  Surface runoff disturbed, soil holds less water
• Water in the soil

  Percolation - Liquid falling through a porous material, e.g. soil

  Percolation stops when water hits the water table (impermeable bedrock/clay)

  Leaching - Water moving organic matter down during percolation

  Roots prevent leaching, extend deep into soil to bring them back up
• Acid rain

  Fossil fuels + metal ores release sulfur dioxide and nitrous oxides when burned

  Gases mix with water in atmosphere to form acid

  Acid rain is forty times more acidic than normal rain
• Dry deposition

  Sometimes sulfur dioxide and nitrous oxides released in the air and remains airborne

  Mixes with moisture on surfaces, such as lake or humidity in lungs

  Scrubbers - Removes harmful gases from smokestacks

  Lime used to neutralize acids
• Carbon cycle

  Carbon cycled through photosynthesis and cell respiration and many other forms

  Inorganic carbon can be found in the atmosphere, oceans, and Earth's crust

  The atmosphere stores the least amount of inorganic carbon

  The oceans hold the most amount of inorganic carbon
• Inorganic carbon in oceans

  Dissolved carbon dioxide for photosynthesis for water plants

  Some carbon dioxide reacts with water to make carbonate ion (2-) and bicarbonate ion (1-)

  Carbonate + Calcium = Calcium Carbonate (CaCO3)

  Sediment crushes and heats up calcium carbonate into limestone

  Volcanoes and acid rain break down carbonate rocks
• Bogs

  Stores lots of organic carbon

  Low oxygen meaning less decomposition

  Carbon stored in peat (plant matter) for years

  Sediment crushes and heats peat, turning it into coal
• Oxygen cycle

  Exists in carbon dioxide, water, glucose, etc.

  Most of Earth's oxygen stored in the lithosphere
• Impacting carbon cycle

  Reducing vegetation lets more carbon dioxide remain in the air

  Carbon dioxide and methane causes greenhouse effect

  Smoke production affects balance between photosynthesis and cellular respiration, and causes global warming
• Albedo

  How much radiation reflected from a surface

  Snow and ice have high albedo, lowering temperatures
• Snow-temperature feedback

  Climate warms, less snow, less albedo, repeat

  Climate cools, more snow, more albedo, repeat
• Equilibrium in atmosphere

  Stromatolite - Limestone with fossilized bacteria

  Bacteria consumed carbon dioxide and released methane
• Earth's early atmosphere

  Greenhouse gases trapped heat on Earth

  Warmer temperatures led to faster water cycle, absorbing carbon dioxide and releasing methane

  Methane haze blocks sunlight, cooling the Earth

  Led to oxygen organisms dominating heat-dependent methane organisms
• Nitrogen Cycle

  Plants use nitrate ion (1-)

  Nitrogen fixation - Converting nitrogen to nitrates through lightning and bacteria

  Energy + nitrogen + oxygen = nitrate

  Decomposers break down nitrogen into nitrites or simpler compounds

  Denitrification - Bacteria breaking down nitrates to nitrites to nitrogen gas, balancing the compounds in environment

  Other bacteria converts it back to nitrates
• Agriculture and nutrient cycles

  Fertilizers - restore nutrients and increase production from land

  Fertilizer runoff into water makes algae grow more

  Bacteria uses up oxygen to decompose algae while converts nitrates to nitrites

  Other fish and animals die from nitrites in bloodstream and oxygen deficit

  Leads to more oxygen usage by decomposers
• Phosphorus Cycle

  Two parts, staying in rocks vs. staying in organisms

  Phosphates soluble in water, absorbed by organisms

  Phosphates released from decomposers breaking down waste
• Nutrient cycling

  Nitrates and phosphates are nutrients

  Decomposition is faster in warm, moist environments with diverse decomposers

  Crucial aspects of decomposition: temperature and oxygen levels

  Other factors: soil chemistry, frequency of fire