Frozen semen is stored in what substance and at what temperature?

• A. Liquid Nitrogen at -320 degrees F
• B. Dry Ice at -109 degrees F
• C. Liquid Nitrogen at -196 degrees F
• D. Liquid Oxygen at -320 degrees F

Answer: (A)

Ultra-low-temperature cryogenic storage uses liquid nitrogen to preserve semen. Liquid nitrogen stays at about minus 196 degrees Celsius (roughly minus 321 degrees Fahrenheit). At this extreme cold, cellular processes nearly stop and ice crystals that could damage cells are minimized, helping sperm remain viable when thawed later. That’s why semen is stored in liquid nitrogen for long-term preservation—the temperature is far colder than other common cooling methods.

Dry ice is much warmer (around minus 109 degrees Fahrenheit) and isn’t cold enough for long-term preservation. Liquid oxygen, while also very cold, is an oxidizer and unsafe for storage of biological material, so it isn’t used.