Nutrition in Animals - SS1 Biology Past Questions and Answers - page 3

Autotrophic and heterotrophic nutrition are two contrasting modes of obtaining energy and nutrients in organisms. Autotrophic nutrition refers to the ability of certain organisms, such as plants and some bacteria, to synthesize their own organic molecules using inorganic substances like carbon dioxide and water, with the help of sunlight or chemical energy. These organisms are capable of photosynthesis or chemosynthesis, converting raw materials into energy-rich organic compounds.

On the other hand, heterotrophic nutrition involves organisms that are unable to produce their own organic molecules. They rely on consuming preformed organic compounds derived from other organisms for their energy and nutrient needs. Heterotrophs, including animals, fungi, and most bacteria, obtain nutrition by consuming and digesting complex organic substances, breaking them down into simpler molecules that can be utilized for energy production, growth, and maintenance.

Enzymes are biological catalysts that accelerate chemical reactions without being consumed in the process.