In spermatogenesis, reduction division of chromosome occurs during conversion of
spermatogonia to primary spermatocytes
primary spermatocytes to secondary spermatocytes
secondary spermatocytes to spermatids
spermatids to sperms
B.
primary spermatocytes to secondary spermatocytes
Spermatogenesis is the formation and maturation of male gametes or spermatozoan. Sperms are produced in the seminiferous tubules of testes. Diploid spermatogonia present beneath 3 to 5 cells deep from outermost layer of seminiferous tubules, increase their number by ordinary mitotic divisions and each becomes a primary spermatogonial cell or primary spermatocyte. Each primary spermatocyte undergoes first, meiotic (reductional) division and forms two secondary spermatocytes. Each of these, without any intervention undergoes the second meiotic division and gives rise to two spermatids. Each spermatid undergoes the process of spermiogenesis to become a sperm.
The carcinoma, a type of cancer, originates from
blood
connective tissue
epithelial tissue
lymph gland
Melting of DNA at an elevated temperature (70°C) is primarily due to the breakdown of
phosphodiester bonds
glycosidic bonds
disulphide bonds
hydrogen bonds
The expanded name of MRI is
Medical Reserach Instrument
Magnetic Resonance Imaging
Magnetic Research Institute
Medical Resonance Imaging
Which one of the following is not included under in situ conservation?
National park
Wild life sanctuary
Zoological garden
Biosphere reserve
The important gas which was absent during the formation of Earth is
oxygen
hydrogen
nitrogen
carbon dioxide
For a clean environment, which one following is not essential?
Producer
Consumer
Decomposer
Polluter
The usual source of restriction endonucleases used in gene cloning is from
fungi
bacteria
plants
viruses
