• This assignment consists of 5 questions meant to provide practice with the
material that will have been covered by Jun. 5th.
• You may complete the assignment in the format of your choice (Word, PDF,
plain text, scanned text,… ) provided that it is a format suitable for upload
to Moodle. If you are unsure about the suitability of a format, then please
check with the course director. In your write-up, please clearly indicate
which question/sub-question is being answered. For example, “Q6, part
(b): The article omits the following crucial facts…. ”.
• The completed assignment is to be submitted online through Moodle by
no later than 9 am on Monday, June 13th.
1. Consider the following sequence of nitrogenous bases comprising a hypothetical gene.
A − A − T − G − G − A − G − T − C − T − C − G − G − T − G − G − A − G
a) Reading the gene from left to right, construct the strand of RNA that would be
assembled during the transcription process. [2 Marks]
b) Using the genetic code table below, construct the sequence of amino acids corresponding to this gene. (Use the 3-letter abbreviations shown.) [2 Marks]
c) Mutations occur, creating two new versions of the gene in question. Which of the
two genes below causes no change in the resulting protein? Explain. [1 Marks]
A − A − T − G − G − T − G − T − C − T − C − G − G − T − G − G − A − G
A − A − T − G − G − A − G − T − C − T − C − C − G − T − G − G − A − G
2. In fruit flies, small wings (w) are a recessive trait, while longer ‘normal’ wings (W) are
a) Can two fruit flies with normal wings produce offspring with small wings? Explain.
b) Can two fruit flies each with small wings produce offspring with normal wings?
Explain. [2 Marks]
NATS 1840 33 Marks
3. Corn crops are vulnerable to an insect pest known as the corn borer. This pest can
be controlled using a natural toxin known as BT. The corn borer’s sensitivity to BT
is governed by a single gene. Individuals carrying the dominant allele of that gene
are sensitive to the toxin, while those who do not are immune. Suppose a corn field
has become infested by a population of corn borers in which 5% of the individuals are
immune to BT.
a) What kind of selection pressure will the regular spraying of BT onto the corn
field apply to the corn borer population? Describe how you expect the prevalence
of BT-sensitivity in the corn borer population to change over time? Explain. [2
b) After many years of use, would you expect BT to still be an effective way of
controlling the corn borer population? Explain. [2 Marks]
c) Explain why a farmer might want to always keep a limited portion of their corn
field free of the BT spray. [3 Marks]
4. Human blood comes in four phenotypes: A, B, AB, and O. Types A and B are called
co-dominant because they are manifested whenever the corresponding gene is present,
while the O type is recessive. Having one A gene and one B gene, that is an AB
genotype, leads to the distinct AB phenotype. Consider three siblings: Alice has
blood type A, Bob had blood type B, and Olivia has blood type O.
a) Based only on the information above, list all of the siblings’ possible genotypes.
b) Based on this information, identify their parent’s genotypes. (You do not have
to say which is mother’s and father’s because it isn’t possible to tell with this
information.) [2 Marks]
c) Based on the previous conclusions, can you now identify all of the childrens’
genotypes exactly? [2 Marks]
NATS 1840 33 Marks
5. This exercise is to be completed using a simulation found at
https://phet.colorado.edu/sims/natural-selection/natural-selection en.jnlp. If you are
on an Apple system you may need to run the java file manually. Instructions for you
can be found just below the assignment link on Moodle.
Part A: Reduction of Carrying Capacity
i) After the applet starts to run, press the pause button at the bottom centre, then
familiarize yourself with the controls.
ii) Press “Add a Friend”, zoom out the population chart until 200 is visible on the
vertical axis, prepare for the next step, then resume the simulation run.
iii) When the population first exceeds 200, select the “Food” selection factor. This
makes food scarce and is equivalent to lowering the ecosystem’s carrying capacity
for bunnies. (Don’t wait too long after 200, because at the next step the bunnies
take over the world!)
a) Describe and explain the rabbit population’s behaviour in subsequent generations.
b) Does the bunny population survive in that ecosystem? [1 Mark]
Part B: Microevolution
i) As before, first add a friend, but this time also select the “Long Teeth” mutation
and set long teeth to be recessive. Then, proceed as before introducing food
scarcity once the population reaches/exceeds 200.
ii) Make a note of the relative number of long-toothed bunnies in the generations
before food becomes scarce.
a) Does the bunny population survive? Explain how. [2 Marks]
b) Explain the subsequent behaviour of the bunny population. Is it stable? If so,
then roughly what is the carrying capacity of the ecosystem for bunnies? [3 Marks]
Part C: Conclusions
a) How would you describe the impact of the long-teeth mutation on the bunny
species? What quality did the species gain or lose because of this mutation? [2
b) What do you think this says about the importance of maintaining genetic diversity? Can you think of a practical application? [1 Mark]