Reading Comprehension 73

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What is a Virus Made Of

All viruses are made up of two kinds of substance. First, all viruses contain proteins. Proteins are chemical substances that occur in all living creatures. A particle, or molecule, of a protein consists of a long chain of substances called amino acids. There are about 20 different kinds of amino acid in proteins. These can be arranged in any order on the protein chain. Different kinds of plant or animal contain proteins with different arrangements of amino acids. The protein generally forms the outer coat of a virus. This outer layer of protein encloses the second kind of substance found in all viruses - nucleic acid.

1. It is clear from the passage that ----.

A) proteins are greatly damaged by viruses
B) the amount of proteins differs in each animal or plant
C) few proteins are without amino acids
D) it is impossible to find a living thing with no proteins
E) a virus's resistance depends on the amount of proteins it contains

2. The arrangement of amino acids ----.

A) is very simple in the proteins of the viruses
B) is determined by the kinds of proteins
C) can be harmed if too many viruses confront the proteins
D) has nothing to do with proteins
E) varies among each living thing

3. The second substance of the viruses ----.

A) consists of only amino acids
B) is usually the part covered by proteins
C) protects it from outer effects
D) must contain at least 20 amino acids
E) is not as essential as the first one

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