Dr. Reichler’s Bio 301L MWF 9-10am Print
Exam #1 September 27, 2006
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. Apply rules 1 and 2 of Strong Inference (the parts prior to actually
doing any experiments) to answer the following question: How do
cells maintain membrane fluidity in cold temperatures? (8pts)
Must use Strong Inference and make
multiple hypotheses and experiments to eliminate hypotheses.
Ex: hypo’s- Cells change from saturated to unsaturated
lipids. Cells add choloesterol. Cells no not change the
lipids. Expt- Lower the temperature and measure ratio of
saturated and unsaturated lipids before and after cold temperature.
2. Explain how using controls and doing statistical analysis relates to
Strong Inference. (4pts)
Rule three of Strong Inference states
that we need reliable results if we are to eliminate the correct
hypotheses. Using statistics and doing controls is part of
getting reliable results.
3. Phosphorous has 15 protons. Would a radioactive phosphorous
atom decay into silicon with 14 protons or sulfur with 16
protons? Why? (8pts)
Sulfur, an electron leaves from one
of the neutrons from phosphorous and that neutron becomes a proton
making the 16 protons which is sulfur.
4. What two characteristics of lipids make them effective in forming
A hydrophilic, water soluble head,
and a hydrophobic, water insoluble tail.
5. How are carbohydrates used differently in plant and animal cells?
Any one of: The plant cell wall
is carbohydrates while the animal Extracellular matrix is
protein. Plants produce carbohydrates in the chloroplast while
animal cells must take in carbohydrates from the environment.
6. How could you determine what climate a plant lived in based on the
lipids in its membrane? (8pts)
Plants from a colder climate should
have more unsaturated lipids, while a plant from a warmer climate
should have more saturated lipids.
7. Transposons are examples of genes acting as replicating units.
Relate transposons to two other gene definitions. (8pts)
Any two of:
Genes code for proteins- some
transposons make transposase, a protein, that is involved in moving the
Genes are units of heredity-
transposons are inherited from the parents.
Genes cause diseases- when a
transposon disrupts another gene, that can cause a disease by
disrupting the normal function of the gene product.
Genes are switches- transposons can
disrupt genes thereby disrupting normal development.
8. If a transposon moved once from one part of your DNA to another
part, is it likely to cause a problem? Why or why not? (8pts)
No, most of our DNA is non-coding, so
the chance of damage to a gene is low.
6/8 pts Yes, If the transposon
inserts into a gene, it would disrupt the proper coding of the protein
made from that gene.
9. What are two parts of a cell where you would find RNA? What is
it doing in each place? (8pts)
Any two of: Nucleus- being
transcribed. Cytoplasm- being translated. Endoplasmic
reticulum- being translated into a membrane protein. Cytoplasm-
as rRNA (ribosome) or tRNA.
10. A nucleotide is changed in the coding region of the gene that codes
for transposase, but the transposase protein still functions
properly. How is this possible? (8pts)
Redundancy in the genetic code means
that some nucleotides can be changes, but still code for the same amino
11. Most multicellular organisms are diploid. What is one
disadvantage to being haploid? (8pts)
Any one of: There is no other
copy of the genes. So if there is any problem or mutation, there
is only the one copy that is now damaged.
Haploid organisms cannot reproduce
sexually thereby limiting genetic diversity.
12. A woman has a mutation on her mitochondrial DNA that causes a
protein to not be produced, and that causes her to have low energy
levels. Her husband does not have this mutation. Will their
offspring have low or normal energy levels? Why? (8pts)
All children will have low
energy. MtDNA is inherited only from mom. Dad will not pass
on any of his MtDNA.
13. You are breeding kittens, and you want kittens with short
tails. One gene controls tail length with long tails being
dominant and short tails recessive. Mom is heterozygous and the
dad is homozygous recessive. What percent of the kittens will
have short tails? (8pts)
50%. Mom is Tt. Dad is
tt. Possible offspring Tt, Tt, tt, tt.
14. Male humans inherit less DNA from their fathers than their
mothers. Give two reasons why this is true. (8pts)
MtDNA is maternally inherited.
The Y chromosme is smaller than the X chromosome, and males inherit the
X from mom and the Y from dad.
Bonus: If DNA does not directly cause diseases, what does? (3pts)
Proteins or RNA that are improperly