As viruses cannot reproduce by themselves, they depend on the host cells that they infect to reproduce
Natural selection act directly upon <u>Alleles</u>
Explanation:
Genes, such as that of fur color, have many variants called alleles. Natural selection act on the alleles and chooses the best fit for an environment and eliminates the disadvantageous ones from the population over generations. Mutations are a rare occurrence that increases the number of allelic variants of a genes on which natural selection can act upon.
Answer:
<h2><em><u>Base</u></em><em><u> </u></em><em><u>isolated</u></em><em><u> </u></em><em><u>system</u></em></h2>
Explanation:
<u>Fixed based system:- </u>
A fixed-base building (built directly on the ground) will move with an earthquake’s motion and can sustain extensive damage as a result.
<u>Base isolated system:-</u>
A base isolation system is a method of seismic protection where the structure (superstructure) is separated from the base (foundation or substructure).
<em><u>Hence</u></em><em><u>,</u></em>
<em><u>A</u></em><em><u> </u></em><em><u>base</u></em><em><u> </u></em><em><u>isolated</u></em><em><u> </u></em><em><u>system</u></em><em><u> </u></em><em><u>is</u></em><em><u> </u></em><em><u>much</u></em><em><u> </u></em><em><u>more</u></em><em><u> </u></em><em><u>better</u></em><em><u> </u></em><em><u>in</u></em><em><u> </u></em><em><u>a</u></em><em><u> </u></em><em><u>area</u></em><em><u> </u></em><em><u>where</u></em><em><u> </u></em><em><u>there</u></em><em><u> </u></em><em><u>are</u></em><em><u> </u></em><em><u>a</u></em><em><u> </u></em><em><u>lot</u></em><em><u> </u></em><em><u>of</u></em><em><u> </u></em><em><u>earthquakes</u></em><em><u>.</u></em><em><u> </u></em>