Which group of microorganisms is considered the most abundant on Earth?

• A. Bacteria
• B. Fungi
• C. Protozoa
• D. Algae

Answer: (A)

Verified step by step guidance

1. Understand the question: It asks which group of microorganisms is the most abundant on Earth, meaning which group has the highest number of individual organisms globally.
2. Recall the characteristics and ecological roles of each group: Bacteria are single-celled prokaryotes found in almost every environment; Fungi are mostly multicellular decomposers; Protozoa are single-celled eukaryotes often found in aquatic environments; Algae are photosynthetic organisms, mostly aquatic.
3. Consider the population sizes and distribution: Bacteria are known to inhabit soil, water, air, and even extreme environments, often in enormous numbers, while the other groups have more limited habitats and lower overall abundance.
4. Use scientific knowledge that bacteria dominate microbial biomass and numbers due to their rapid reproduction and adaptability to diverse environments.
5. Conclude that among the options, bacteria are the most abundant group of microorganisms on Earth.