Come see me in my office to check your scores and make sure they are right.
Answer to question 19 (A codon... may code for one or more amino acids) is wrong, so everybody gets 2 points in addition to their final score (a codon codes only for ONE amino acid, or it works as a stop codon. An amino acid can be coded by more than one codon). That mistake actually boosted the mode from a B to an A. Good job, guys!
Results were good over all. Some stats:
- Mean score: 85.5
- Standard deviation: 8.83
- Mode: 90
Score frequency distribution
Toughest questions (statistically):
26. A conserved gene is...
A gene that accumulates very few mutations
Comment: Every gene has mutated in some way or another. No gene, no matter how conserved it is, is identical accross the tree of life. It may accumulate very, very few mutations, but it has them nevertheless.
27. Mutations will accumulate faster in...
An intron
Comment: Exons and regulatory sequences, specially promoters, have important functions. Most mutations in such sequences will be deleterious. Introns, on the other hand, are free to mutate.
40. Bacteria increase genetic diversity through Horizontal Gene Transfer (HGT). Eukaryotes do it mainly through...
Recombination
Comment: Recombination is what happens after fertilization, and it is when paternal and maternal chromosomes exchange information (recombine). Genetic diversity is thus maintained or increased. There are very few cases of HGT in eukaryotes, and it happens mostly in plants. In prokaryotes HGT is rampant.
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