11-17-09 - Biology 330 Class Notes Chemotrophs or...

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Biology 330 – Class Notes – 11/17/09 Chemotrophs or lithotrophs – can capitalize on redox reactions for energy. This would be organisms that appear at the thermal vents. Oxogenic photosynthesis Food chain or food web analysis What is it that causes disparity in primary productivity? 1. Light a. Light on forest floor is quite small. b. Suspended particles, clay, plankton, compounds dissolved in water (ocean) i. If you are a phytoplankton cell and you spend a lot of time fixing light for food (energy), most of the time you are in poor light environment – difficult for light to penetrate Photosynthetic efficiency – energy produced / energy available Example: (carbohydrate Joules / solar radiation) * 100% Expect 2-3% efficiency The more light we get, the lower the efficiency 0.01 to 0.1 to 1.0 – there is a 2 magnitude change in efficiency that explains efficiency of conversion of light into energy o THUS, THERE ARE REASONS OTHER THAN LIGHT TO EXPLAIN THIS CHANGE IN EFFICIENCY Length of photosynthetic period average time for last frost in spring to first frost in fall growing season positive relationship between net productivity and photosynthetic period. The longer the photosynthetic period, the higher the productivity Hectare- metric equivalent of an acre Length of growing season as it affects the availability of water Temperature affects the availability of water. At lower temperatures, we get lower net productivity. There is a positive but at a decreasing rate - productivity versus precipitation Highest productivity: Moderately long growing season and abundant water As we move away from the equator, the growing season gets shorter.
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We expect to find deserts at 30o north latitude and 30o south latitude. This is because the heat is falling back to earth. Global circulation of air masses low relative humidity but no water. The mid-latitudes around 45o we get more precipitation than at 30o (the deserts), but the air masses can hold less because it’s cooler As long as water isn’t frozen and it’s abundant, then temperature and water are not limiting factors.
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11-17-09 - Biology 330 Class Notes Chemotrophs or...

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