Question

Pollen grain can be stored in a viable condition for many years in which of the following conditions?
a. Anaerobic conditions in 0°C
b. Liquid nitrogen (-196°C)
c. Liquid nitrogen (0°C)
d. Liquid nitrogen (196°C)

Answer 1

Hint: A liquid nitrogen at a very low temperature (below 0°C). It is manufactured industrially by liquid air fractional distillation. It is a low viscosity, colourless liquid that is commonly used as a coolant.

Complete answer:
> Option A is incorrect. Anaerobic conditions arise whenever oxygen uptake or disappearance is greater than its output by photosynthesis or diffusion from the surrounding environment through physical transport. As a result of the availability of organic matter, oxygen is typically absorbed by microbial respiration.

> Option B is correct. Pollen grains have been preserved in liquid nitrogen for several years and have a temperature of -196°C. Cryopreservation is the name of this form of saving. The low temperature allows for a longer period of storage as it decreases the rate of cell growth. The cryoprotective agents delay the plants ageing and protect the plants from cold-related damage.

> Option C is incorrect. There is a temperature known as absolute zero (0°C) that is as cold as anything can get, then one would know. Liquid nitrogen is around three-quarters of the way to absolute zero if we arrive at the freezing point of water and move towards absolute zero.

> Option D is incorrect. At temperatures of -210°C and -196°C, which is equal to -346°F and -320.44°F, nitrogen exists as a liquid under normal atmospheric pressure. Liquid nitrogen found in unpressurized containers such as the tanks sold here is slowly boiling away, so the temperature is -196 ° C or -320.44 ° F. Thus, this option is incorrect.

Hence, the correct answer is option (B).

Note: As a cryogenic fluid which freezes cells or tissues quickly, it needs thermal insulation for its handling and storage. This can be preserved and exported in vacuum flasks; the temperature is maintained constant at 77 K by slowly boiling the liquid.