The picture is not clear !
Answer: D
Explanation:
A change in the amount of polar ice will alter how ocean currents move
Per calendar year (365 days) there are 31536000 seconds
Answer:
Question 17: Silent mutation.
Question 18: Neutral.
Question 19: Beneficial (but see explanation below).
Explanation:
17)
A silent mutation is defined as a change in coding DNA which does not have an effect in the amino acid produced during translation. Silent mutations are possible because the genetic code is degenerate, meaning that a given amino acid may be coded by more than one codon. For instance: a mutation changing AUGCUA to AUGCUG is likely to be silent, since both the CUA and CUG codons code for the same amino acid (Leucine).
Note that a silent mutation may well <em>also</em> be a point mutation (meaning: involving the change of a single nucleotide). In fact, the example given above would meet that criterion. However, the question as stated does not contain enough information for making that call in this particular case.
18)
This particular question asks us to extrapolate from a given level of organization (function of a specific type of protein) to a higher one (overall functioning and/or wellbeing of the whole organism). <em>In general</em>, it can be assumed that mutations which change a given protein’s sequence without altering its function will have a negligible effect on the organism’s fitness. Such mutations are therefore called neutral. Note that the neutrality of a mutation may not always be self-evident, however, due the fact that a given protein may have <em>several</em> functions, the measurement of which may not be feasible.
19)
The answer in this question really depends on which specific example one may happen to be working with. Broadly speaking, higher efficiency tends to be associated with beneficial effects (e.g. assume an increase in the efficiency of an enzyme which breaks down a certain type of toxic substance present in food). One may found counterexamples, however. Picture another enzyme, which normally plays a role in disaggregating blood clots during normal blood coagulation. An increase in its efficiency could potentially lead to premature disaggregation of clots and hence prolonged bleeding.
