Assignment 2 due date has changed to Oct 21
Assignment 1 part 1 for tmrw.
1) Energy and Nutrients
1) Energy sources:
a. Autotrophs – self feeders
b. Heterotrophs – other feeders
i. Where does the carbon come from? Photosynthesis
Photons hitting pigments of plants and those pigments focus electrons that generate
ATP/NADPH and with them they create sugars with the C02 that is in the atmosphere.
Considering two types of plants: C3 plants & C4 plants – dif. evolutions of photosynthesis.
C3: most trees are C3plants. Carbon is taken in and it is C3 because the product has 3
carbons in it. It all happens in the mesophyll cell (outer layer of plant). The Stoma must be
open to create energy (sugar/ATP) but in the process it loses water – so temperature and
moisture is very important: high transpiration – the process of moving water through the
plant (costs involved – lose water through stoma). Lower productivity
C4: In the case of C4 plants they’ve evolved an additional pathway that allows them to
create C4 molecules (4 C). The making of the sugars happens somewhere eles & this allowed
C4 plants to exist and undergo photosynthesis is got climates without losing water (stoma
can stay open w/o losing water). Low transpiration and higher productivity.
The exponential increase in CO2 output by industry has only stopped 3 times in the 20 C.
High C: N ration shows that plants are relatively rich in carbon and poor in nitrogen
Low C: N rations shows that animals, fungi and bacterial are relatively rich in nitrogen
Detritivore: key in nutrient cycling food – rich C, low N. Soil moisture and temperature are
very important to detritivores
Heterotrophs: herbivores eat plants and eat a lot of plants to get the energy they need (low
Nutrition and plant defenses (thorns, etc).
Bottom on the sea: chemosynthetic organisms get hydrogen sulfide and transfer it into
Carnivores: eat other things and depending on the carnivore the C;N ratio varies widely.