Question

Organisms may be classified into autotrophs or heterotrophs depending on how they obtain their organic molecules?

Answer 1

Yes, organisms are classified into autotrophs and heterotrophs on the basis, these obtain their organic molecules.

Explanation:

Organisms are classified into two categories on the basis of their mode of nutrition (obtaining their food or nourishment). These are:
1. Autotrophs and 2. Heterotrophs.

Autotrophs are those organisms which can synthesize their organic food from simple substances like `CO2` and `H2O` in presence of sunlight.

The autotrophs carry on photosynthesis in presence of light in their green parts like leaves and young stem. Chlorophyll pigment present in green parts of these plants entraps sunlight, that is necessary for the process of photosynthesis. Most of the Angiosperms are autotrophs.

Heterotrophs are the organisms which are incapable of synthesizing their organic food. Heterotrophs are further classified into 2 categories on the basis of the way these derive their nourishment. These are:
( i) Saprophytes and (ii) Parasites.

Saprophytes are the organisms which derive their nourishment from dead and decaying organic matter. These secrete digestive enzymes into the substrate which digest the organic matter into digested form that is absorbed by the organisms. The digestion is thus external. e.g. Rhizopus, Mucor (Fungi), etc.. Even some Angiosperms like Monotropa are saprophytes.

Parasites are the organisms which derive their nourishment from living host. e.g. Cuscutta . It is non-green and derives nourishment of both organic and inorganic matter along with water from the host on which it grows through parasitic roots.