Compare total antibody yields over 10 days for two cultures: Culture A starts with 1.0 × 10⁶ primary B cells that do not divide and secrete 1.0 × 10⁴ molecules/cell/day for 5 days before dying; Culture B starts with 1.0 × 10⁵ hybridoma cells that double every 48 hours (2 days) and secrete 2.0 × 10⁴ molecules/cell/day during the entire 10-day period. Calculate total molecules produced by each culture over the 10 days and determine the fold difference (Culture B / Culture A). Show your calculation steps.

• A. Culture B produces far less antibody than Culture A because hybridomas secrete negligible amounts per cell; therefore Culture B is approximately 0.1-fold of Culture A.
• B. Culture B ~6.2 × 10¹⁰ molecules and Culture A ~5.0 × 10¹⁰ molecules; fold ≈ 1.24, because secretion rates average out to nearly equal production.
• C. Culture B ~1.24 × 10¹¹ molecules; Culture A ~5.0 × 10¹⁰ molecules; fold ≈ 2.48 (Culture B/Culture A).
• D. Total yields are identical for both cultures because doubling only compensates for the shorter lifespan of primary cells, so fold = 1.0 in all realistic systems.

Answer: (C)