A modular model integrating metabolism, growth, and cell cycle predicts that fermentation is required to modulate cell size in yeast populations. - Marco Vanoni; Pasquale Palumbo; Federico Papa; Stefano Busti; Laura Gotti; Meike T. Wortel; Bas Teusink; Ivan Orlandi; Alex Pessina; Cristina Airoldi; Luca Brambilla; Marina Vai; et al. (PLoS Comput. Biol., 2025)