Friday, May 25, 2007

PLANT NUTRITION PART 2: MODES OF NUTRITION

Living things may be classified according to their modes of nutrition. They may be HETEROTROPHS or AUTOTROPHS.

AUTOTROPHS
  • These are organisms that can synthesize their organic materials from inorganic materials in the environment (OR in other words, they are able to make their own food).
  • GREEN PLANTS must have come to you mind at this moment right? You are right. Yes green plants are examples of autotrophs but there are other organisms which can be considered as autotrophs like some bacteria.
  • BUT for some bacteria, they are using chemical energy instead of light energy so for these bacteria we say that they are chemo-synthesizing instead of photosynthesizing (Remember, since green plants are using light energy from the sun, we say that they are photosynthesizing)
  • An autotroph can be a multicellular organism or unicellular organism such as Euglena (Notice the chloroplasts containing chlorophyll?)

HETEROTROPHS
  • These are organisms which cannot make their own food.
  • A heterotroph obtains its food (hence source of energy) from the organic molecules that have already been produced by the autotrophs.