Question

Bull semen is stored in
(a)Liquid carbon dioxide
(b)Liquid oxygen
(c)Liquid nitrogen
(d)Ice

Answer 1

Hint: The low temperature $-196℃$ of this liquid and the inert characteristics prevent the biological content from degrading. It is created by fractional distillation of liquid air in an industrial way. It is a colorless liquid of low viscosity that is commonly used as a coolant.

Complete answer:
Low pH, hyperosmotic pressure, warm temperature, and low oxygen tension with high sperm density are ideal conditions for semen storage. This makes liquid carbon dioxide incorrect as sperm is lethal in an anaerobic climate. Liquid oxygen is also wrong, as high oxygen tension is not appropriate for sperm. Freeze drying technique used in sperm storage stores bull sperms in dry ice at 4 degrees Celsius which maintains their viability and design rate up to 3-4 years. Store bull sperm in liquid nitrogen, however, gives the rate of conception as high as that of fresh semen and is also a faster, less costly technique than freeze-drying. The method of storing semen in a liquid state only allows for a few days of intermediate storage while the deep-frozen process allows for years of storage without any noticeable drop in semen quality. So ice is an incorrect answer, too.
Deep-frozen semen may be preserved in liquid nitrogen or in a cold liquid form.
So, the correct answer is, ‘liquid nitrogen’.

Note: An artificial insemination is a form of breeding cattle that is recognized worldwide, and is also successful for other animals. When bull ejaculates, fluids from the additional sex glands from the testes are applied to the sperm. The resulting mixture of sperm/fluid is called semen. The industry word for extracting this mixture is "Collecting semen."