GED Science Practice

In microbiology, what are single-celled or noncellular spherical or spiral or rod-shaped organisms lacking chlorophyll that reproduce by fission known as?

1. Autotroph

2. Auxin

3. Bacillus

4. Bacteria

The correct answer is: Bacteria

The term for single-celled or noncellular spherical, spiral, or rod-shaped organisms that lack chlorophyll and reproduce by fission is bacteria. Bacteria are prokaryotes, which means they do not have a membrane-bound nucleus or organelles. They can take on various shapes, including spherical (cocci), rod-like (bacilli), and spiral (spirilla), aligning with the description provided in the question. Bacteria reproduce asexually through a process known as binary fission, where one cell divides into two identical daughter cells. This efficient method of reproduction contributes to the rapid growth of bacterial populations under favorable conditions. Understanding that bacteria lack chlorophyll is important, as it differentiates them from autotrophic organisms, which can perform photosynthesis or chemosynthesis. Other options in the question, such as auxin, refer to plant hormones that regulate growth, and bacillus specifically identifies a genus of bacteria that are rod-shaped. Thus, they do not encompass the full range of organisms described in the question. The correct answer encompasses the broader category of these diverse microorganisms.