7. Answer the following questions using the diagrams provided, which represent cross sections of bacterial cell walls. A. Which diagram represents a gram-positive bacterium? How can you tell? B. Explain how the Gram stain works to distinguish these two types of cell walls. C. Why does penicillin have no effect on most gram-negative cells? D. How do essential molecules enter cells through each wall? E. Which cell wall is toxic to humans? .

1. 7. Answer the following questions using the diagrams provided, which represent cross sections
of bacterial cell walls. A. Which diagram represents a gram-positive bacterium? How can you
tell? B. Explain how the Gram stain works to distinguish these two types of cell walls. C. Why
does penicillin have no effect on most gram-negative cells? D. How do essential molecules enter
cells through each wall? E. Which cell wall is toxic to humans?