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birds wind insects substrate bacteria precipitation fungi sunlight reptiles temperature plants disturbances (fire, hurricanes) mammals amphibians nutrients fish All things on Earth can be classified into one of two categories BIOTIC ABIOTIC
BIOLOGY = the study of living things What things make something “living” vs. “nonliving”? 1. reproduction (DNA) 2. movement 3. metabolism 4. growth 5. stimulus response to the environment
Hierarchy of Life Earth biosphere ecosystems communities populations organisms organ systems organs tissues cells molecules atoms subatomic particles
a community of species combined with their abiotic (nonliving) environment populations of all the different species occupying a particular place at the same time a group of interacting organisms of the same species that occupy a specific area at the same time any single life form ecosystem community population organism
ENERGY FLOW IN BIOLOGICAL SYSTEMS E = energy The single most essential requirement for living things. Without it, cells cannot work and all biological processes stop.
CO2 H2O The ultimate source of energy for life on Earth is the sun yields sugar + O2 photosynthesis converts the radiation E of the sun into chemical bond E stored in sugar (glucose)
Living things access this stored E by breaking these bonds during metabolism RESPIRATION
Living organisms are either: AUTOTROPHS HETEROTROPHS
so…. • energy comes to our planet from the sun • is converted into chemical bond energy by photosynthetic organisms • is accessed for use by organisms through aerobic or anaerobic respiration - all life is linked in food chains and webs -
FOOD CHAIN Secondary consumers eat primary consumers. They are also known as carnivores (“meat eaters”). Primary consumers eat producers (green things). They are also known as herbivores (“herb eaters”). Green plants are called producers because they “produce” food for the rest of the planet The sun = E source
tertiary consumer secondary consumer primary consumer primary producer
DECOMPOSERS… turning a food chain into a food cycle • feed on dead producers and consumers • are necessary for the renewal of life because they • recycle nutrients and biological molecules making • them available to be used again by producers
Energy flows along the chains in one direction from the sun. At each link in the chain, there is energy loss.
10% 10% 10% Only about 10% (5%-20% range) of the E stored in biological mass at one level of the food pyramid is converted to biological mass at the next level The other 90% of energy is lost in transfer – largely as heat
The main food of sea otters = sea urchins Kelp forest Sea Urchins Sea Otter all species dependent on kelp forest 1. Understanding food webs allows us to better understand and predict how impacts to ecosystems will influence all species. In the 1800’s, sea otters were hunted to near extinction The main food of sea urchins = kelp kelp creates kelp forests critical habitat: providing food and shelter for hundreds of marine species As Sea Otter population recovered, this trend was reversed
As global warming diminishes Antarctic sea ice, the algae that inhabit the substructure of the sea ice disappear. In turn, krill that feed on the algae decline, leaving little food for the penguins that feed on krill. sea algae krill Adelie penguins
2. They allow us to trace the movement of materials through ecosystems foodwebs are often used to trace the bioaccumulation of toxins in wildlife Methylmercury is absorbed by algae and plankton in the ocean and biomagnifies/ bioconcentrates as it moves up the food chain.
Life on Earth is sustained by: • the flow of E from the sun through living things by their feeding interactions • the cycling of matter (the atoms and molecules needed for survival) through the biosphere