Viruses are small, infectious particles. They have a genome of either DNA or RNA, but no
organelles characteristic of cells. They do not divide by mitosis but are duplicated by
having their constituent parts produced and assembled by the infected cell. Viruses can
evolve in the same way as living things, by changes in their genome due to random
mutation and selection. Would a virus be considered alive? What are the criteria on which
you base your answer? Answer
Natural antifreeze molecules allow many animals to exist in conditions cold enough to
freeze the blood (or equivalent fluid) of animals without these additives. The usual
explanation about how these molecules work is that they bind to tiny ice crystals in the
blood and prevent them from getting larger. However, the exact mechanism is still not
completely understood. Knowing the role of hydrogen bonding in the transition from liquid
water to ice, how might these "natural antifreeze" molecules interact with ice/water to
prevent crystal growth? Answer
DNA is a large molecule that is made of two long, thin strands. All of the atoms within each
strand are held together by covalent bonds, but the two strands are held together by
hydrogen bonds only. Knowing that individual hydrogen bonds are weaker than covalent
bonds, but that many hydrogen bonds together make a strong connection, what would you
predict about the stability of the DNA molecule? Answer
