One month ago, a teenage girl stopped eating animal-derived foods and now only consumes vegetables and fruits. She is now experiencing either a cold and/or an infection. This is probably due to inadequate protein intake for:

Synthesizing antibodies.

Explanation:

A person should have a balanced diet which consists of fruits, vegetables, pulses and many more nutritious things.

Escaping from any of these food will cause problem in the body. A girl has skipped the protein intake inside the body by skipping the animal derived food ans is now depending on the plant source for the diet.

Sooner, she was ill and had infection in the body because there was lack of protein in her diet which lead to problem in synthesizing antibodies.

unicellular organisms, like bacteria, are able to perform all life functions within one single cell. multicellular organisms need many different types of cells to carry out the same life processes. each of these special types of cells has a different structure that it perform a specific function.