Dr. Reichler’s Bio 301M
MWF 9-10am Print Name:____________KEY_______________
Exam #1 February 13, 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. Why is using disproof more certain than looking for proof? (8 pts)
Positive proof can be misleading as
positive data does not always mean something is true.
Additionally, using positive proof can lead us to favor a single
hypothesis. Disproof is more certain because once something is
shown to be false, it is always false. Plus using disproof leads
us to look for multiple hypotheses thereby not getting stuck on one.
2. Using rules 1 and 2 of Strong Inference, the parts prior to doing an
experiment, answer the following question: What is the function
of the non-coding part of human DNA? (8 pts)
Create multiple hypotheses:
Non-coding DNA controls gene expression. Non-coding DNA is used
as an energy source. Non-coding DNA has no information at
all. Design an experiment or experiments to disprove the
hypotheses: Eliminate the non-coding DNA and check if cell what
functions are lost.
3. If nine nucleotides are deleted in the coding region of a gene, what
will be the effect on the protein produced? (8 pts)
Three amino acids will be missing,
the rest of the sequence will be normal.
4. Is a cell with 11 chromosomes haploid or diploid? How do you
know? (4 pts)
Haploid. Diploid chromosomes
come in pairs, which would mean an even number of chromosomes.
5. Relate two of the five definitions of genes that we discussed in
class to each other. Do not simply list the definitions, but
describe how they can be related together. (8 pts)
Any of: Genes code for proteins
that when they malfunction can cause diseases. Genes code for
proteins that lead to heritable traits. When genes are replicated
that leads to heritable traits. Genetic diseases can be inherited
and/or replicated. Genes code for proteins that control
6. Would a species that reproduces sexually or asexually have an
advantage in an environment that is not changing? Why? (4 pts)
Asexual reproduction would be favored
because it can produce more offspring, and this constant environment
does not require much genetic diversity. OR What works now
will work later so diversity might be bad while consistency is good.
7. If the trait for liking chocolate is controlled by a single gene
with two alleles (L= likes chocolate; H= hates chocolate) and two
parents who like chocolate have a child who hates chocolate, which
allele is dominant, and what are the genotypes of the parents?
(Show your work for partial credit.) (8 pts)
Hating chocolate is recessive.
Both parents are heterozygous.
8. Female A has a mutation in her mitochondrial DNA. In the third
generation, which individuals will inherit this mutation?
Explain. (8 pts)
2 Male B
3 Male D Female E
Male F and Female G. MtDNA is
inherited only through the mother, Female C.
9. A single gene codes for baldness with two alleles (B= dominant not
bald; b= recessive bald). Two parents who are not bald have 100
children, 50 girls and 50 boys. None of the daughters are bald
while half of the sons are bald. How is this possible? What
are the genotypes of the parents? (Show your work for partial
credit.) (8 pts)
The baldness gene is on the X
chromosome (sex-linked). XB Y and XB Xb.
note: Many students answered Bb x Bb. This will yield 25%
bald children, but no difference in the chance of baldness in boys or
10. What effect would there be on evolution if DNA replication made no
errors? (8 pts)
The number of individuals with a
certain trait could change, but no new traits (genes or alleles) would
11. How can one quantify the most evolutionarily successful individuals
in a population? (4 pts)
The individual who passes on the most
genes OR who reproduces the most.
12. One group of scientists publishes a paper showing that two
populations of rabbits can produce fertile offspring and are therefore
the same species. Another group subsequently publishes a paper
showing that the two populations of rabbits are not the same
species. The data of the first group is correct. What data
did the second group present? (8 pts)
That in nature the two populations of
rabbits do not reproduce.
13. If someone is studying a population of wild pigs, and they notice
that there has been a decrease in genetic diversity, what are two
explanations for the population’s decrease in genetic diversity? (8 pts)
A bottleneck occurred or stabilizing
selection occurred. (Directional selection can also sometimes
lead to decreased genetic diversity.)
14. Are humans evolving? Why or why not? (8 pts)
Yes. We have genetic diversity,
and not everyone can reproduce. 6/8 for No, we do have genetic
diversity, but there is little limit on reproduction.
Bonus: Humans and chimpanzees share about 98% of our DNA.
Would you expect to find the differences in coding regions or
non-coding regions of the DNA? Why? (3 pts)
Non-coding regions. Coding
regions code for proteins, etc and changes will likely lead to
problems. Changes in non-coding DNA would not have a direct
effect on the organism.