(a) Photosynthesis It is a process by which green plants having chlorophyll synthesise simple suger (glucose)from water and `CO_(2)` using the energy of sunlight. The light energy is used in splitting of water molecules into hydrogen and oxygen (i.e., chemical energy ).
(b) Autotrophs Those organisms which can make their own food from inorganic substances present in the environment, e.g., green plants , autotrophic bacteria etc. are called autotrophs.
(c ) Chloroplasts Chlorophyll is the green pigment capable of trapping light energy, requried for photosynthesis. This pigment is present in chloroplast present in the leaves.
(d) Guard cells Each stomatal pore is sorrounded by a pair of guard cells , that control their opening and closing by the inflow and outflow of water.
(e) Heterotrophs Those organisms which cannot make their own food from inorganic substances and depend on other organisms for their food . e.g., all animals , yeast , etc.
(f) Pepsin It is a protein digesting enzyme secreted from gastric glands present in the wall of the stomach .