A culture of bacteiral cells are spread on a petri plate of complete medium. Both prototrophs and auxotrophs grow on the medium and their colonies appear in a random arrangement. Piece of sterilized velvet is pressed on this plate of colonies, and the velvet pickus up some cells form each colony. The velvet can then be pressed on a number of petri plates, whcih reproduces the same pattern of bacterial colonies. One of these replica plates contains minimal media, and each of the remaining replica plates contain minimal medium supplemented with a different compound. A cplony that grows on minimal media represents a protoroph, whereas a colony tha fails to grow on minimal medium represents an auxotroph.REPLICA PLATING CONTINUED<span>An autotroph that grows on a supplemented minimal medium plate is unable to synthesize either the supplemented compound or a precursor to that compound. the indiviulal clonies of interest can then be isolated and grown out.
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Answer:
In the Cretaceous period, Mesozoic Era forests begin to look like modern day forests and included a variety of conifers and decidous trees.
Explanation:
The Cretaceous period was the last and longest segment of the Mesozoic Era.It lasted approximated 79 million years from the minor extinction events that closed the Jurassic Period about 145.5 million years ago to the Cretaceous - Palogene ( K-Pg) extinction event dated at 65.5 million years ago. This era have seen more dinosaurs than before.The horned Cretaceous dinosaurs appeared, like the Triceratops and Centrosaurus. The armored Ankylosaurus, duckbilled Parasaurolophus, and large carnivore Tyrannosaurus were a few of the quickly evolving dinosaurs.
Answer - A
Semi-conservative model of replication involves the replication of DNA in all the familiar cells in such a way that each newly synthesized daughter cell contains a double helix with one new strand and one old strand.