Dr. Reichler’s Bio 301L MWF 11am-noon
Exam #1 February 16, 2007
Read each question carefully and don’t hesitate to
ask if a question seems unclear. If possible, answer each
question in the space provided, but if needed, continue on the
back. If you use a drawing as part of your answer, be sure to
also include a written explanation. These questions have specific
answers, although for some, more than one answer is possible. To
receive full credit you must clearly and fully answer the question
being asked. This exam is worth 103 points with the points for
each question noted in parentheses.
1. Using rules one and two of Strong Inference answer the following
question: Who are people in the Middle East most closely related
Should propose at least two
hypotheses and one experiment to eliminate the hypotheses. For
example: Hypos- Middle Easterners are most closely related to
Europeans. Middle Easterners are most closely related to
Asians. Middle Easterners are most closely related to
Africans. Expt- Compare the mtDNA of people from these regions
and see who has the fewest differences with Middle Easterners.
2. You read a report stating that someone’s sense of humor is
genetically determined. The researchers only tested twins that
lived apart. Did these researchers use Strong Inference?
Why or why not? (6pts)
No. Because they did not try to
disprove any hypothesis, they only have data from twins in different
environments. OR They did not get reliable results because
they have no controls. OR They only had a single hypothesis.
3. Both ionic bonds and covalent bonds can lead to atoms with positive
and negative charges. What is different about the formation of
charged atoms in ionic and covalent bonds? (6pts)
Ionic bonds involve the donation or
acceptance of electrons leading to charged atoms (ions). Covalent
bonds involve sharing of electrons, but the sharing can be unequal
leading to charged atoms.
4. Describe how all four bimolecules are involved in determining ABO
blood type. (8pts)
Nucleotides/DNA code for proteins
(amino acids) that give rise to the different carbohydrates (sugars) on
the membrane (lipids) of the RBC.
5. Below is a cartoon of a protein embedded in a membrane. The
protein has both polar and non-polar amino acids. Show where the
polar and non-polar amino acids are located, and explain why they are
located where you indicated. (6pts)
Polar amino acids on the outside near
the polar water and polar heads of the lipids. Non-polar amino
acids on the inside near the non-polar tails of the lipids.
6. What would be the effect on a protein if three nucleotides were
added to the coding region of the gene? (8pts)
There would be an additional amino
7. Relate the Y chromosome to two of the perspectives about genes.
Any two of:
Y chromosome has genes that code for
proteins that cause maleness.
Y chromosome does not have the same
genes as the X chromosomes, and therefore males are more likely to
suffer from defects (diseases) on the X chromosome.
The Y chromosome is inherited from
Genes on the Y chromosome change the
development of the fetus from female to male.
8. If a haploid cell replicates its DNA, is it now diploid? Why
or why not? (6pts)
No. The DNA is an exact copy,
so there are not pairs of similar information. The DNA is
identical, not diploid.
9. Identical twins should have identical DNA. If one of the twins
has a viral infection, how could this viral infection cause a
difference between the twins’ DNA? (8pts)
The virus could have entered the
lysogenic cycle in which it inserted its DNA into the host cell’s DNA.
10. Would vole monogamy be explained as having a more genetic or
environmental cause? Why? (8pts)
Genetic- different levels of the
oxytocin/vasopressin receptor, which is coded for by a gene, can
explain differences in prairie and montane vole monogamous
behavior. But these differences arose from the different species
evolving in different environments with different availability of
11. Give two possible genotypes of parents that could lead to offspring
with AB blood type. (8pts)
Any two of: AA x BB, AO x BO,
AO x BB, AO x BO…
12. If a male is colorblind, a recessive allele on the X chromosome,
does that tell us about his father’s or mother’s DNA? Why? (8pts)
Males inherit their X chromosome from
mom, so male X linked traits tell us about mom’s DNA.
13. Why do you have more of your mom’s DNA than your dad’s DNA? (6pts)
MtDNA is inherited only through the
egg. OR Males have a small Y chromosome from Dad and a
larger X chromosome from mom.
14. When researchers compared individual’s mitochondrial DNA, they
found people from different geographic locations with similar
mitochondrial DNA sequences. What does this indicate about our
ancestors’ behavior? (6pts)
They must have commonly
migrated. The spread of different DNA throughout the planet shows
this pattern of ancient migration.
Bonus: Over the same period of time, why would the number of
mutations present in nuclear DNA be higher than in mitochondrial
DNA? (3 pts)
Because the nuclear DNA has more
non-coding DNA. Mutations in coding regions are typically fatal,
and therefore not passed on. So since mtDNA has very little
non-coding DNA, the number of mutations for a given time that gets
successfully passed on would be lower.