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Genetics Test 1 with answer


Test 1   Test 1a*
Test 2   Test 3
Quiz 1   Quiz 2
Quiz 3   Test 4

*including answer

All questions are ranked out of five and then the section is prorated. (e.g., every question in Part B is worth equal value.  Same applies to every question is A and C.)

Part A: Easy Stuff. If you read the book and followed the study guide, this stuff should be a cinch.  Worth 20% of the test. Use the box at the bottom of the next page.

1)      Look at Figure 14.4. Which characteristics could be used to do the sort of experiments Mendel did?

a)      None.

b)      All.

c)      Only the ones involving colour.

d)      Only the ones involving shape.

e)      Cannot be solved.


2)      Look at Figure 14.5 (supplied for you). From this picture, it can be deduced that

a)      Yellow is dominant

b)      Green is dominant

c)      Neither is dominant

d)      Both are dominant

e)      Cannot be solved.


3)      A geneticist is studying two different kinds of animals.  Animal "a" is found to have a diploid number of 10.  Animal "b" is found to have a diploid number of 44.  Which conclusion is best?

a)      The animals are identical twins.

b)      Animal "b" is more intelligent than animal "a."

c)      Animal "b" is less intelligent than animal "a."

d)      Animal "b" is more evolved than animal "a."

e)      None of the above are good conclusions.


4)      For human blood types (A, B, AB, and O), the situation is best described as:

a)      A and B are codominant, O is recessive to both A and B.

b)      A, B and O are all co-dominant.

c)      A and B are recessive to O.

d)      AB is dominant to AA and BB.

e)      None of the above.


5)      Which of the following are examples of multiple allelism?

a)      Eye colour in Drosophila melanogaster (Fruit flies).

b)      Wing type in Drosophila melanogaster.

c)      Human ABO blood type.

d)      All of the above.

e)      None of the above.



6)      If a cell's genome is 18% guanine, what percentage of it should be adenine?

a)      18%

b)      32%

c)      36%

d)      64%

e)      82%


7)      DNA replication is

a)      Conservative

b)      Semi-conservative

c)      Sometimes conservative, sometimes semi-conservative

d)      Liberal

e)      Green

Part B: Do only 4 of these. Keep it short.  50 words should be more than enough, otherwise you'll run out of time.  This section is worth 40%.

1)      There is a connection between Mendel's compensating mechanism, the diploid number, and chromosomes.  What it the connection?

When a baby is made one egg and one sperm join to make the first cell.  If the sex cells had diploid number of chromosomes then the baby would have double that, and the number of chromosomes would double every generation.   The compensation mechanism is where the sex cells contain half the number of chromosomes as the adult cells.  This insures that the offspring will have the same number of chromosomes as the adult.

2)      Suppose a trait for baldness is carried on the x-chromosome (sex-chromosome) in humans.  Suppose also that the allele codes for either baldness or not. Does this explain why more men are bald that women?  (Sinead O'Connor notwithstanding.)

Males have a XY and females have XX.  Since the trait for baldness is carried on the x-chromosome and if the trait was recessive the the not bald trait, then males have a better chance of being bald. Females have two X’s so they need to receive two alleles for baldness to express the trait, while if men received one allele for baldness they will be bald.

3)      Explain albinism is genetic and molecular terms.

Albino’s do not produce melanin.  For melanin to be made the enzyme tryosinase must be present.  People who are albino are aa which means they do not have the gene that codes for tryosinase (A). Since they do not have the information (DNA) to make this enzyme they cannot make melainin. Another reason could also be that the ribosomes did not read the mRNA because of a frameshift substitution or a base pair substitution could have occurred in the DNA and the protein that was made was significantly different then tryosinase.

4)      What is the connection between crossing over, map units, and independent and dependent segregation? It may help you in answering this to know that Mendel's dihybrid crosses of (yellow smooth peas X wrinkled green) yielded yellow smooth and yellow wrinkled ratios that were not equal.

When genes are located on the same chromosome they sort dependently.  The genes on different chromosomes independently they segregate. Map units determine how far apart genes are and therefore measure the degree of cross over. During cross over chromosome swap genetic material by physically over lapping each other resulting in the change of independent and dependent assortment.

5)      There are 2 classes of types of mutations.  One class have four sub-types, one class has only one subtype.  Name the 2 major classes and the 5 sub-classes.  Pick one and explain in 25 words or less.

Base pair substitution: i) missense

                                    ii) silent

                                    iii) reversion

                                    iv) chain termination

Frameshift: i) frameshift mutations-this occurs when one or more base pairs are added of deleted (but not in multiples of three). When a nucleotide is added to the sequence then there is a disruption in the reading of the codons in proper frames. There is a dramtic change in the codons from the point of mutation to the end of the gene. When three base pairs are added then the mRNA can be read in properly, but the protein formed will be different from the DNA blueprint.

Part C: Do all of these.  This section is worth 40%.

1)      It has been said that about 40% of all human pregnancies "spontaneously abort shortly after implantation" (i.e., somewhere between the first day of implantation in the uterine wall and the second week of gestation, "something" happens). Ruling out interference from factors outside the womb, propose some molecular and genetic reasons why spontaneous abortions may occur.

2)      Give the molecular genetics explanation for sickle-cell anemia.  Talk about the molecular basis for the allele and the basis for the altered function.

3)      Would Hershey & Chase been able to arrive the same conclusions had they used radioactively-labeled nitrogen instead of sulphur?  Use diagrams of the amino acids and nucleotides in your answer.

4)      Sketch & label Figure 16.4.  What is the relevance to these ideas in prokaryotic (no nuclear membrane) versus eukaryotic cells?