Answer:
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Explanation:
ANSWER OF 1ST QUESTION -
1) it protects the nucleic acid from digestion by enzymes, 2) contains special sites on its surface that allow the virion to attach to a host cell, and 3) provides proteins that enable the virion to penetrate the host cell membrane and, in some cases, to inject the infectious nucleic .
ANSWER OF 2ND QUESTION -
Mutations can produce viruses with a reduced pathogenicity, altered host range, or altered target cell specificity but with intact antigenicity. Such viruses can sometimes be used as vaccine strains.
The type of immunity that provides lifetime immunity for the body against a specific pathogen is called acquired immunity. It is also referred to as adaptive or specific immunity.
Acquired immunity is not present at birth. it is learned. As a person's immune system encounters foreign substances (antigens) the components of acquired immunity learn the best way to attack each antigen and begin to develop a memory for that antigen. Acquired immunity is also called specific immunity because it tailors its attack to a specific antigen previously encountered. Its uniqueness lies in its ability to learn, adapt and remember.
Acquired immunity takes time to develop after first exposure to a new antigen. However afterward, the antigen is remembered, and subsequent responses to that antigen are quicker and more effective than those that occurred after first exposure. Memory of a particular antigen is kept by the B and T lymphocytes.
The answer that best completes the statement above is 30-60 seconds. This is the rest interval needed in between sets for hypertrophy training. The purpose of this rest interval is to optimize the anabolic hormone response. So basically, this hypertrophy training aims in growing the muscles faster with great efficacy.
