Answer:
F-: StrR, his+ and met+
Explanation:
the strain Hfr is a high-frequency strain of recombination that includes the F plasmid (fertility factor). Therefore, the whole genome sequence is able to be passed via Hfr to its receiver, but it needs a long duration of physical contact with the recipient because the recipient gets a gene (long time physical contact is seldom attained) and retains the F strain. Also, genomes from the F-cells are not passed backwards to the HF cells. Therefore, only F strain with tolerance to Streptomycin and capable of synthesizing its amino acids on limited media can thrive in this situation. Which is F-: StrR, his+ and met+ recombining.
Punctuated equilibrium is a theory biology<span> which proposes that once </span>species<span> appear in the fossil record they will become stable.
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So according to above explanation
<span>C. puncated equilibrium</span> , is the correct
answer
Explanation:
The DNA could be dried -through the process of lyophilization- or stored, as a precipitate of ethanol, in liquid nitrogen (temperatures below -80 degrees Celsius). The aim is to reduce water in the stored samples as much as possible because the water can be involved in natural hydrolytic reactions (depurination, depyrimidination, deamination, and hydrolytic cleavage) that could degrade the nucleic acids of the DNA.
If the DNA is stored while being used regularly it is not advisable to store it as a precipitate of ethanol. It should be stored in aqueous form but in a slightly alkaline pH of about 8.5 to prevent acid-catalysed degradation processes.
Learn More:
For more on DNA storage check out;
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