2. The Biosphere of Life Abiotic Factors contribute to the environment and local ecosystem physical, non-living parts of the environment Ecosystem – all the organisms in an area along with the abiotic factors with which they interact The most important abiotic factor is WATER an essential component of every life form in an ecosystem comprises 70-95% of all cells

3. Other abiotic factors include: ideal temperature ranges amount of sunlight soil composition (nutrients ) Gardeners attempt to provide these through use of fertilizers **most common error  too much fertilizer & insufficient water causes high salt concentrations Habitat - all biotic & abiotic factors in an area that encourage reproduction & survival of a particular organism

4. Run-off & Harmful Algal Blooms Run-off from farmer’s fields containing dissolved nutrients can have unintended effects on nearby bodies of water  It can stimulate the growth of algae - a microscopic, photosynthetic organism that plays a role in marine & freshwater ecosystems Algae can grow to form huge colonies & can result in a population explosion that can lead to: Harmful algal bloom - rapid growth of algae that depletes dissolved O 2 in water & blocks sunlight required by other organisms in the aquatic ecosystem

5. Water – A Finite Resource The impact of human activities on the environment is reducing the supply of clean water The growing population is leading to increased water use Some practices that use water are now being reconsidered : E.g. Removal of petroleum products from the ground using fresh water To save on cost, some petroleum companies obtain water from streams, rivers & lakes near the well site Oilfield injection – water is pumped into the well to create higher pressure to allow petroleum to be pumped to surface

6. Biotic Factors consist of living organisms in the environment Biomass  dry mass of all living organisms occupying a habitat 1)Symbiosis “Living Together” -Relationships formed between organisms that benefit at least one organism of 2 different species that live in close contactE.g. Bison & Prairie Dogs Bison (most numerous grazing animals on planet) Supported by grasses along landscape Nematodes (tiny worms that eat the roots of plants) Microscopic Life Forms (bacteria & fungi convert Nutrients into forms that can be used by grasses

7. When 2 species live close together in a relationship where both species benefit, this is called mutualism e.g. nitrogen-fixing bacteria that live on roots of prairie plants Plants benefit from nitrogen provided by bacteria Bacteria utilize some nutrients in the plant roots Other forms of Symbiosis: Commensalism - form of symbiosis where one organism Benefits & the other organism is neither helped nor harmed e.g. Cowbirds & Bison  insects stirred up in grass from bison’s hooves enhance feeding of cowbirds Parasitism - symbiotic relationship where 1 organism ( the parasite) benefits at the expense of another (the host) e.g. Cowbird & the Yellow Warbler  Cowbird deposits egg into nest of yellow warbler AND yellow warbler incubates Cowbird egg causing it to hatch first & eat most of the food

8. 2) Predator – Prey Interactions Predation – interaction where one organism (predator) kills & eats another organism (prey) e.g. Lynx preys exclusively on snowshoe hare 3) Competition  an interaction where 2 or more organisms compete for the same limited resource e.g. Both the lynx & great horned owl prey on the snowshoe hare

9. Homework  1.1 Homework – p.407-412 Practice #2, 4-6, 7-8, and Questions p.412 #1-4  1.2 Homework – p.415-421 Practice #15, 16, 18-20 Finish Tonight for HOMEWORK Investigation Predator-Prey (p. 420) #1-5 p.422 #1-6