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Bonus Questions
Page 237 challenge question # 2
Many species can reproduce either asexually or sexually. It is often when the environment
changes in some way that it is unfavorable to an existing population that the organisms
begin to reproduce sexually. Speculate about the evolutionary significance of this switch
from asexual to sexual reproduction.
Page 323 science, technology and society #1
As part of the Human Genome Project (discussed in Chapter 19), researchers are
determining the nucleotide sequence of human genes and identifying the proteins coded by
the genes. Labs in the U.S. National Institutes of Health (NIH), for example, have worked
out thousands of sequences, and similar analysis is being carried out by many private
companies. Knowing the nucleotide sequence of a gene and identifying its product can be
useful; this information might be used to treat genetic defects or produce life-saving
medicines. U.S. law allows the first person or research group to isolate a pure protein or a
gene to patent it, whether or not a practical use for the discovery has been demonstrated.
The NIH and biotechnology companies have applied for patents on their discoveries. What
are the purposes of a patent? How might the discoverer of a gene benefit from a patent?
How might the public benefit? What kinds of negative impacts might result from patenting
genes? Do you think individuals and companies should be able to patent genes and gene
products? Why or why not? Under what conditions should such patenting be permitted?
Page 257 (if confidentially…), answer page 261 science, tech and society #1 and #3
Imagine that one of your parents had Huntington’s disease. What would be the probability
that you, too, would someday manifest the disease? There is no cure for Huntington’s.
Would you want to be tested for the Huntington’s allele? Why or why not?
In the near future, gene therapy may be an option of the treatment and cure of many
inherited disorders. What do you think are the most serious ethical issues that must be dealt
with before human gene therapy is used on a large scale? Why do you think these issues are
important?
Page 280 science tech and society #1, 2
A chromosome test is used to determine whether women Olympic competitors are actually
female. In the past, the test checked for the presence of a Barr body. The method used in
the 1992 Olympics checked for genes found on the Y chromosome. Athletes who fail the
test—about one in 500—are barred from competition. Some XY individuals are anatomically
female, although they lack ovaries and a uterus; their Y chromosome fails to cause the
development of testes, or their cells are insensitive to the effects of the male hormone
testosterone. Athletes and physicians argue that the chromosome test unfairly bars XY
females from competition. What is the purpose of the test? Is it fair? Can you suggest an
alternative?
Gregor Mendel never saw a gene, yet he concluded that these “heritable factors” were
responsible for inheritance in peas. Similarly, Morgan and Sturtevant never actually saw
linked genes on chromosomes; their maps were deduced from patterns of inheritance. Is it
legitimate science for biologists to claim the existence of things and processes they cannot
actually see? Why or why not?
Page 280 science tech and society #3
Opinions differ about weather children with learning disorders should be tested by
karyotyping for the presence of a fragile X chromosome. Some argue that it’s always better
to know the cause of the problem so that education specialized for that disorder can be
prescribed. Others counter that attaching a specific biological cause to a learning disability
stigmatizes a child and limits his or her opportunities. What is your evaluation of these
arguments?
Page 350 science tech and society #2
Explain how the excessive or inappropriate use of antibiotics poses a health hazard for a
population.
Read about cancer, pg 364 and answer page 323 science tech and society #2
Our civilization generates many potentially mutagenic chemicals (pesticides, for example)
and modifies the environment in ways that increase exposure to other mutagens, notably UV
radiation. What role should government play in identifying mutagens and regulating their
industrial causes?
Page 323 challenge question #2
The base sequence of the gene coding for a short polypeptide is CTACGCTAGGCGATTAGC.
What would be the base sequence of the mRNA transcribed from this gene? Using the
genetic code chart (figure 17.5), give the amino acid sequence of the polypeptide translated
from this mRNA.
Page 395 science, tech and society #1, 3
Which uses of DNA technology do you think will prove to be of most value in the coming
decades? Why do you think so? What safety and ethical issues do you think are most
important? Why? How do you think we should deal with these concerns?
Under pressure from the biotechnology industry, the U.S. government recently loosened up
some regulations affection DNA technology in order to make the possible introduction of
new products and procedures more rapid and less costly. What trade-offs do you see
between government regulation of biotechnology and the desire of U.S. industry to remain
competitive with other nations in this field?
Page 237 Science and Technology #2
It is possible to grow seedling of pine trees from short pieces of their needles. A few of the
straightest, fastest-growing trees are selected for this treatment. By this method,
thousands of genetically identical trees can be grown and transplanted to create a forest
that is a superior producer of lumber. What are the short-term and long-term advantages
and disadvantages of this technology?
Page 415 challenge question #2
An orange grower discovered that most of his trees were infested with destructive mites. He
sprayed the trees with insecticide, which killed 99% of the mites. Five weeks later, most of
the trees were infested again, so he sprayed again, using the same quantity of the same
insecticide. This time, only about half the mites were killed. Explain why the spray did not
work as well the second time.
Page 415 Science, Tech and Society # 1
To what extent are humans in a technological society exempt from natural selection?
Explain your answer.
Page 435 Science, Tech and Society #3
Give a few historical example of how gene flow has affected human populations.
Page 481 challenge question #1; Science, Tech and Society #3
In the “DNA clock,” some nucleotide changes cause amino acid substitutions in the encoded
protein (nonsynonymous changes), and others do not (synonymous changes). In a
comparison of rodent and human genes, rodents were found to accumulate synonymous
changes 2.0 times faster than humans and nonsynonymous substitutions 1.3 times as fast.
What factors could explain this difference? How do such data complicate the use of
molecular clocks in absolute dating?
Experts estimate that human activities cause the extinction of hundreds of species every
year. The natural rate of extinction is thought to be a few species per year. The natural rate
of extinction is thought to be a few species per year. As we continue to alter the global
environment, especially by cutting down tropical rain forests, the resulting extinction will
probably rival that at the end of the Cretaceous period. Most biologists are alarmed at this
prospect. What are some reasons for their concern? Consider that life has endured
numerous mass extinctions and has always bounced back. How is the present mass
extinction different from previous extinctions? Why? What might be the consequences for
the surviving species? For humans?
Page 435 challenge question #1
Some species have been rescued from near extinction by conservationists. In terms of
evolutionary theory, what problems do such species face as their populations rebound from
a small size?
Page 962 Science, Tech and Society #3
New technology has made it possible for doctors to save a small percentage of babies born
16 weeks prematurely. A baby born this early weighs just over a pound and faces months of
treatment in an intensive care nursery. The cost for care may be hundreds of thousands of
dollars per infant. Many of the surviving infants have mental and physical disabilities. Some
people wonder whether such a huge technological and financial investment should be
devoted to such a small number of babies. They feel that the resources might better be
directed at providing prenatal care that could prevent many premature births. What is your
opinion in this controversy? Defend your position.