The temperature (°C) of liquid nitrogen used for cryopreservation of plant samples is
The temperature (°C) of liquid nitrogen used for cryopreservation of plant samples is
Select an option to attempt
Correct Answer: Option D
Explanation
Liquid nitrogen (LN) boils (liquefies) at(77.36 K = 77 K) at standard atmospheric pressure (1 atm = 101.325 kPa). It is produced industrially by fractional distillation of liquefied air. At, biological processes, enzymatic reactions, ice crystal formation, and molecular diffusion are effectively halted — providing indefinite preservation of cells, tissues, seeds, embryos, and microorganisms. Vitrification (ice-free cryopreservation using cryoprotectants like DMSO or glycerol) prevents damaging ice crystal formation. The International Society for Biological and Environmental Repositories (ISBER) recommends storage in vapour phase () rather than liquid phase () to prevent cross-contamination.