Caves of Death ■ 17(d) Let the control group choose whether or not to take any pills.(e) Expose the control group to the cold virus.Tr y Something New
(^9) If a virus was discovered that had the ability to reproduce itself
without the help of a cell and its machinery, several experiments
could be performed in order to show that it should be categorized
as “alive.” For each experiment, specify which one of the six criteria
for being classified as “alive” would be tested.
a. Place a set number of viral particles in a nutrient broth
and check for an increase in viral particles after several
days.
b. Place a set number of viral particles in a broth where all
the nutrients are corralled to one side of the container and
check for viral particle accumulation in the nutrient-rich
area of the container.
c. Place a set number of viral particles in a nutrient broth and
check for waste products (broken-down nutrients) in the
broth after several days.
d. Place a set number of viral particles in a nutrient broth
for several months, adding different nutrients daily.
Randomly isolate viral particles and sequence their
DNA to determine whether there have been changes in
genetic characteristics of this population of viral parti-
cles compared to the DNA of the original population
before culturing.
e. Perform biochemical and microscopic analyses on a
number of viral particles to determine whether they have
the main components of a living cell, including a plasma
membrane, ribosomes, and DNA.
(^10) Mad cow disease, or bovine spongiform encephalopathy,
appears to be caused by a novel infectious agent: a protein that
replicates by causing related proteins to modify their structure
from a harmless shape to a dangerous one. These prions (short
for “proteinaceous infectious particles”) also appear to be the
cause of several other spongiform encephalopathy diseases,
such as scrapie in sheep, and kuru and Creutzfeldt-Jakob disease
in humans. Which of the following observations or experiments
would not support the hypothesis that a prion causes spongiform
encephalopathy?
(a) The brains of many sheep with scrapie contain prion
proteins, but the brains of most sheep without scrapie
do not.
(b) There is a high incidence of kuru in populations of people who
consume brain tissue from prion-infected animals.
(c) Coyotes that feed on cows with mad cow disease do not
subsequently develop spongiform encephalopathy.
(d) When introduced into sheep brain cells in culture, prions cause
the normal proteins to change shape into dangerous prion
proteins.
(e) When prions are fed to sheep, most of them subsequently
develop scrapie, whereas sheep not fed prions do not develop
scrapie.
(prediction / observation) about the natural world. A scientist
then proposes a (hypothesis / prediction), which is the basis of
one or more testable (observations / predictions).
(^4) Place the following steps of the scientific method in the
correct order by numbering them from 1 to 7.
a. Make observations about the natural world.
b. Test the predictions by designing an experiment or collect-
ing observational data.
c. Run the experiment and analyze the results.
d. Generate predictions to test the hypothesis.
e. Share the results with fellow scientists so that they can
review and evaluate them.
f. Develop a hypothesis to explain the observations.
g. Accept, reject, or modify your hypothesis depending on the
results.
(^5) Identify the level of biological organization for each of the
following.
a. the kidney of a bat
b. an oak tree outside a cave in upstate New York
c. bats in a cave in upstate New York
d. the physical and biological components of a cave in
upstate New York
e. the respiratory system of a bat
f. all the species living and interacting within a cave in
upstate New York
Challenge Yourself
(^6) Describe one observation, one hypothesis, and one experiment
from the white-nose syndrome research discussed in this chapter.
(^7) Which of the following statements is a scientific hypothesis
(that is, it makes testable predictions)? (Select only one.)
(a) Even though no one else can see him, the ghost of my dog lives
in my backyard.
(b) The Atkins diet helps people lose more weight and keep it off
than Weight Watchers does.
(c) People born under the sun sign Aquarius are kinder and cuter
than those born under Scorpio.
(d) It is unethical to text while driving.
(e) none of the above
(^8) Consider an experiment in which subjects are given a pill to
test its effectiveness in reducing the duration of a cold. Which of
the following is the best way to treat the control group?
(a) Give the control group two pills instead of one.
(b) Do nothing with the control group.
(c) Give the control group a pill that looks like the test pill but does
nothing.