Answer:
Viral proteins can modify the most superficial portion in such a way that it is complementary to the receptor of the human cell.
Generally this happens due to a genetic recombination between an avian virus and a human virus within the respiratory epithelium of the pig: this process underlies the emergence of new, more virulent strains of the influenza virus and underlies the emergence of influenza pandemics
A; Carbon’s atomic number is 6, atomic number indicates the amount of protons in an atom. The number of protons (positively charged particles) is equal to the number of electrons (negatively charged particles). Because atoms have a neutral charge. The average atomic mass of carbon is 12.011; this is the amount of protons plus the amount of neutrons because electrons are so small they weigh almost nothing compared to protons and neutrons. To find the number of neutrons you subtract the number of protons from the average atomic mass. 12.011-6=6.011 (which can just be rounded to 6). So a carbon atom has 6 neutrons. Answer A is correct because it correctly states that an atom of carbon has 6 protons 6 neutrons and 6 electrons
