Fish fossils occur in sediments deposited underwater. That could be sea bottom, lakes, or rivers. Generally, seabottom sediments are raised to the surface by tectonic uplift. Also, when sea level falls during ice ages, sea bottom sediments are exposed to the atmosphere.
The cells that were involves in the process of spermatogenesis is
primary spermatocyte.
Klinglers iron agar medium is used to find the enterobacteria which can ferment glucose , lactose and hydrogen Sulphide . They are H₂S producing bacteria .
This media have phenol red as an indicator. When the glucose is fermented to acid , the production of acid turn the indicator from red to yellow, but it is then reoxidised and turns red again . When lactose is fermented it produce large amount of acid , and turn indicator yellow . Hence the slant will become yellow.And combination of ferrous sulphate and sodium thiosulphate helps in detection of H₂S which produce black color at the butt .
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Seafloor spreading is the answer