The answer is "D"
The body's first line of defense is also known as Innate immunity and incudes mucous membranes. Both the intact skin and mucous membranes of the body offer a high degree of protection against pathogens.
A good example is the mucous membrane of the respiratory tract. It is lined up with cilia and covered with mucus. The coordinated beating of the cilia drives the mucus up to the nose and mouth where the trapped bacteria can be expelled.
(Lymph nodes and white blood cells belong to the second line of defense, not the first)
Virions are physical entities containing nucleocapsid, capsid and sometime envelop. It exists extracellularly. Viruses are genetic material that occur intracellularly
The atoms are going through decomposition.They are breaking apart into the elements they are made of.
Suppose that part of an amino acid sequence of a protein changed from tyrosine-proline-glycine-alanine to tyrosine-histidine-glycine-alanine. This change was most likely caused by a point mutation called a <u>substitution</u>.
<u>Explanation:</u>
Any protein is synthesized by joining a number of amino acids together. This amino acid is placed based on the sequences of the DNA , for every 3 sequence there is an amino acid that is synthesized and therefore it is called as a triplet codon, since there may be many sequence for a single amino acid we call it as degenerate codon.
