Mod 4 Energy Eco

Autotroph

An organism that uses radiant or chemical energy to synthesize organic carbon from inorganic $CO_2$.

Heterotroph

An organism that obtains required organic carbon by consuming live or dead organic matter.

Photosynthesis vs. chemosynthesis energy sources

Photosynthesis derives energy from radiant sunlight, whereas chemosynthesis derives energy from chemical oxidation reactions.

Light compensation point

The light level at which photosynthetic $CO_2$ uptake exactly balances $CO_2$ loss from cellular respiration.

Light saturation point

The light level at which the maximum photosynthetic rate is reached, beyond which increased light does not increase $CO_2$ uptake.

Photorespiration

A metabolic process where RuBisCO binds $O_2$ instead of $CO_2$, consuming energy ($ATP$) and releasing $CO_2$ without producing carbohydrates.

C4 photosynthesis

A photosynthetic adaptation using spatial separation, fixing $CO_2$ with PEPcase in mesophyll cells before transporting it to bundle sheath cells.

CAM photosynthesis

A photosynthetic adaptation using temporal separation, opening stomata at night to store $CO_2$ as organic acids for use during the day.

Kleptoplasty

The process by which certain heterotrophs ingest photosynthetic organisms and retain functional chloroplasts to produce energy.

C3 photosynthesis

The standard photosynthetic pathway where CO2​ combines with a 5-carbon molecule (RuBP) via the enzyme RuBisCO to form two 3-carbon molecules during the Calvin cycle.