Final answer:
An organism that needs to ingest food to get energy and organic compounds is known as a heterotroph. These organisms rely on other sources for nutrition since they cannot synthesize their own food. The energy they obtain from ingestion can be traced back to photosynthesis, the process by which plants convert solar energy into chemical energy.
Step-by-step explanation:
An organism that must ingest or eat to acquire energy and organic compounds is called a heterotroph. These organisms cannot produce their own food, so they rely on the intake of nutrition from other sources of organic compounds, often by consuming plants or other organisms. The energy stored in food, which heterotrophs access by ingestion, can ultimately be traced back to the sun, since plants use photosynthesis to convert solar energy into chemical energy.
Heterotrophs obtain energy through a series of processes—beginning with ingestion, followed by digestion, absorption, and elimination.
During digestion, complex molecules in food are broken down into simpler compounds that the body can use. Finally, these simpler substances are absorbed by cells and converted into necessary forms of energy to fuel metabolic processes.