Eubacteria are classified primarily based on which of the following characteristics?

• A. Ability to photosynthesize
• B. Type of locomotion
• C. Presence of a nucleus
• D. Cell wall composition

Answer: (D)

Verified step by step guidance

1. Understand that Eubacteria, also known as true bacteria, are prokaryotic organisms, meaning they lack a nucleus. So, the presence or absence of a nucleus is not a primary classification characteristic for them.
2. Recognize that while some bacteria can photosynthesize or move using various types of locomotion (like flagella), these traits are not the main basis for their broad classification.
3. Focus on the cell wall composition, which is a fundamental and distinctive feature used to classify Eubacteria. For example, the Gram stain technique differentiates bacteria based on the structure and chemical makeup of their cell walls.
4. Recall that Gram-positive bacteria have a thick peptidoglycan layer in their cell walls, whereas Gram-negative bacteria have a thinner peptidoglycan layer and an outer membrane, which is a key classification criterion.
5. Therefore, the primary characteristic used to classify Eubacteria is their cell wall composition, as it reflects important structural and biochemical differences among bacterial groups.