MCAT Biological and Biochemical Foundations of Living Systems Practice Exam 2026 - Free MCAT Practice Questions and Study Guide

Yeast are a group of unicellular fungi that are often characterized as non-motile organisms. They reproduce asexually by budding or fission and primarily exist as single cells. Unlike some other eukaryotic organisms, such as protozoa, which may exhibit motility through flagella or cilia, yeast remain in a fixed position within their environment as they absorb nutrients and carry out their metabolic processes.

Fungi, while inclusive of yeast, also encompass multicellular forms such as molds and mushrooms, which can have hyphal structures and may not be classified strictly as unicellular. On the other hand, bacteria, though prokaryotic and not eukaryotic, are also unicellular but do not fit the focus of the question regarding eukaryotes. Protozoa are typically unicellular and can be motile, displaying various methods of movement, so they do not align with the characteristics of non-motility specified in the question.

In this context, yeast exemplify the characteristics sought after in the question – they're eukaryotic, unicellular, and non-motile.