Question

which of the following is an accurate characteristic of bacterial cell walls? they are primarily made of chitin. they have peptidoglycan only if they are gram - negative. they prevent cells from shrinking in hypertonic environments. they prevent cells from bursting in hypertonic environments.

Explanation:

• Chitin is mainly in fungal cell walls, not bacterial ones.
• Both Gram - positive and Gram - negative bacteria have peptidoglycan (Gram - positive has more).
• In hypertonic environments, water leaves the cell. The cell wall doesn't prevent shrinking (osmosis is due to solute concentration).
• The cell wall provides structural support. In hypotonic environments (where water enters), it prevents the cell from bursting. But in hypertonic, it's about maintaining shape against internal turgor (when there is turgor, like in less hypertonic relative to cell interior). Wait, actually, cell walls prevent cells from bursting in hypotonic (by providing a counter - pressure to the influx of water). But in hypertonic, the main issue is water leaving. However, among the options:
• Option 1: Wrong (chitin in fungi).
• Option 2: Wrong (both have peptidoglycan).
• Option 3: Osmosis (water leaving) in hypertonic is due to solute gradient, cell wall doesn't stop that (shrinking is a result of water loss).
• Option 4: Although the better description is for hypotonic (preventing bursting from water influx), but among the given options, if we consider that cell walls maintain cell shape and integrity. When in a less extreme hypertonic (where there is still some internal pressure relative to very outside), the cell wall provides a structure. Also, by elimination (first three options are clearly wrong).

Answer:

They prevent cells from bursting in hypertonic environments.