Do you mean when nucleotides get damaged or when they match to each other incoreectly? (which cuases mutants) Specialized Enzymes repair, different one respond to help different types of damage. Detail the question more, maybe then i can help more.
<u>Answer:</u>
The Answer is <em><u>Option D. </u></em>
<em>Exchange of respiratory gases, oxygen and carbon dioxide take place in the alveoli of the lungs. Oxygen which is inhaled from the atmosphere diffuses through the walls of the alveoli and reaches to the adjacent capillaries into the red blood cells.</em>
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Virus is the only organism which has only one strand
C: primary Consumer
<em>primary consumers</em> are typically animals that eat plants aka herbivores.
<em>producers </em>would be plants
<em>secondary consumers </em>are typically ones that eat meat or eat meat and plants aka omnivores.
<em>decomposers, </em>I believe are like your fungus or anything that feeds off of dead organisms or eat the waste of that organism.
Hopefully this helped. I remember learning about this in college.