1. (b) IV is incorrect; RNA has uracil substituted for thymine in terms of base composition. (As we
will see later, it can also contain modified bases). The other statements are correct; see pp. 5-7.
2. (e) only IV is correct; see pp. 7-9
o There are only 20 amino acids
o There are ~660 times more DNA, but the number of genes is only ~10x more
o A gamete cell contains only 23 chromosomes…they are NOT paired
3. (c) I and III are correct; see pp. 7-8
o Age of earth estimated at ~4.5 billion years
(http://pubs.usgs.gov/gip/geotime/age.html)
o There is a much closer interval between the origin or prokaryotic and eukaryotic
life; see fig.
o Cambrian Explosion refers to rapid divergence (20-50 million year window) of
animal life forms, not global extinction event
4. (c) I and III are correct; see pp. 16-28
o II and IV are false; Mendel attended college, corresponded with several famous
botanists of his day and published his work in 1862.
o
5. True; see “fast forward” box on p. 22
6. P(AaBbccDdEe) =
o ½ x ½ x 1 x ½ x ½ = 1/16 ans (e)
7. P (A_B_ccD_E_) =
o ¾ x ¾ x1 x ¾ x 1 = 27/64 ans (c)
8. P (A_B_ccD_E_) = Although this would fall within the sum rule if the parental phenotypes were
different (i.e. the probability of different phenotypes would be additive), this probability
includes the phenotype of BOTH parents…therefore
P (neither parent) = (1- probability of (A_B_ccD_E_) = (1-27/64) = 37/64
ans (d)
Aa
aa
aa
Aa
AA
aa
AA
AA
½ Aa
aa
a
(a)
½ x ½ = ¼ ans 9: (b)
½ aa
Aa
Aa
Aa
a
aa
aa
aa
AA
AA
Aa
½ Aa
½ x 2/3 x 1/4 =
(d)
1/12 ans 10: (e)
A
aa
Aa
2/3
Aa
¼ aa
AA
A
a
A
Aa
a
A
a
A
a
a
a