Essays – Genetic Engineering to Evolution

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Dec 11, 2012 (4 years and 6 months ago)

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Essays


Genetic Engineering to Evolution



Name:

AP Biology







Date:


1.

You hope to study a gene that codes for a neurotransmitter protein in human brain
cells. You know the amino acid sequence of the protein. Explain how you might
(a) identify the gen
es expressed in a specific type of brain cell, (b) identify the
gene for the neurotransmitter, (c) produce multiple co
p
ies of the gene for study,
and (d) produce a quantity of the neurotransmitter for evaluation as a potential
medication.


2.

If DNA
-
based tec
hnologies become widely used, how might they change the way
evolution proceeds, as compared with the natural evolutionary mechanisms of the
past 4 billion years?


3.

Genes important in the embryonic development of animals, such as homeobox
-
containing genes, h
ave been relatively well conserved during evolution; that is,
they are more similar among different species than are many other genes. Why is
this?


4.

How does evolution account for the similar mammalian forelimbs with different
functions such as found in h
umans, cats, whales and bats and the similar lifestyle
of two distantly related mammals like the sugar glider (Australia) and the flying
squirrel (N. America)?


5.

The fossil record shows that dinosaurs originated 200
-
250 million years ago.
Would you expect
the geographic distribution
of early dinosaurs to be broad (on
many continents) or narrow (on one or a few continents only)?


6.

Explain why genetic variation within a population is a prerequisite for evolution.
What factors can produce genetic variation amo
ng populations?


7.

Of all the mutations that occur in a population, why do only a small fraction
become widespread among the population’s members?


8.

If a population stopped reproducing sexually (but still reproduced asexually0,
how would its genetic variation

be affected over time? Explain.


9.

For a locus with two alleles (A and a) in a population at risk from an infectious
neurodegenerative disease, 16 people had genotype AA, 92 had genotype Aa, and
12 had genotype aa. Use the Hardy
-
Weinberg equation to determ
ine whether this
population appears to be evolving.


10.

In what sense is natural selection more “predictable” than genetic drift?


11.

Distinguish genetic drift from gene flow in terms of how they occur and their
implications for future genetic variation in a pop
ulation.


12.

Suppose two plant populations exchange pollen and seeds. In one population,
individuals of genotype AA are most common (9000 AA, 900 Aa, 100 aa), while
the opposite is true in the other population (100 AA, 900 Aa, 100 AA). If neither
allele has

a selective advantage, what will happen over time to the allele and
genotype frequencies of these populations?


13.

How is the process of evolution revealed by the imperfections of living
organisms?


14.

To

what extent are humans who live in a technological socie
ty exempt from
natural selection? Justify your answer.


15.

Which species concept(s) could you apply to both asexual and sexual species?
Which would be most useful for identifying species in the field?


16.

Summarize between allopatric and sympatric speciation.
Which type of
speciation is more common why?


17.

What are hybrid zones, and why can they be viewed as “natural laboratories” in
which to study speciation?


18.

Speciation can occur rapidly between diverging populations, yet the length of
time between speciation e
vents is often more than a million years. Explain this
apparent contradiction.


19.

In the United States, the rare red wolf (Canis lupus) has been known to hybridize
with coyotes (Canis latrans), which are much more numerous. Although red
wolves and coyotes
differ in terms of morphology, DNA and behavior, genetic
evidence suggests that living red wolf individuals are actually hybrids. Red
wolves are designated as an endangered species and hence receive legal
protection under the Endangered Species Act. Some

people think that their
endangered status should be
withdrawn

because the remaining red wolves are
hybrids, not members of a “pure” species. Do you agree? Why or why not?


20.

Describe an example from the fossil record that shows how life has changed over
t
ime.


21.

What factors promote adaptive radiations?


22.

If mass extinction were caused by a single, catastrophic event (such as an asteroid
impact), what pattern would you expect regarding the dates when formerly
common species lost in the extinction are last obs
erved in the fossil record?


23.

Given that changes in morphology are often caused by changes in gene
regulation, predict whether noncoding DNA is likely to be affected by natural
selection. (Noncoding DNA includes the sequences called control elements that
re
gulate gene expressin by binding to transcription factors.)


24.

Describe how gene flow, genetic drift, and natural selection all can influence
macroevolution.


25.

Decide whether the following pairs of structures more likely represents analogy or
homology and exp
lain your reasoning: (a) a porcupine’s quills and a cactus’s
spines; (b) a cat’s paw and a human’s hand; (c) an owl’s wing and a hornet’s
wing.