When two protein chains combine to form an active protein, the structural level is quaternary.
<h3>What is a quaternary structure?</h3>
The quaternary and tertiary structure of a protein is the tridimensional shape of the protein, which involves protein domains.
The quaternary protein structure refers to the different arrangements generated by different protein subunits.
The primary structure of a protein involves its amino acid sequence, whereas the second structure involves protein chains.
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A hydrogen bond forms from the attractive force between a hydrogen atom covalently bonded to a very electronegative atom.
Species have similar characteristics, but they are rarely, if not never, identical; the difference between them is variation!
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C. Single events or several causes working together to produce extinction in a short period is referred to as mass extinction.
<span>Example:
</span><span>Destruction of forests, mountains, and bodies of water to satisfy human needs result to the imbalance of nature which also give rise to global warming.
</span><span>Animals and plants have lost their habitats. They lost their means to live. They lost their food sources and they suffer and die because of humans irresponsible acts.</span>
It should be natural selection since there is no external influence implied. (like environment or genetic mutations.)