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The Economy of Nature 6th Edition by Ricklefs - Test Bank
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The Economy of Nature 6th Edition by Ricklefs - Test Bank
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,NameTest Bank Chapter 01
Description
Instructions The following questions challenge you to think about how ecologists
study and
learn about the natural world. The emphasis of these questions is on application
of the scientific method. Imagine that you are following up on some pioneering
research carried out in the 1930s by the entomologist V. G. Dethier on feeding
behavior of swallowtail butterflies. Dethier observed that larvae of certain
swallowtail butterfly species feed selectively on plants belonging to the carrot
family (Apiaciae). He wondered how the larvae were able to locate such plants.
Using simple but cleverly designed experiments, Dethier was able to
demonstrate that these larvae recognize their preferred food plants based on
their odors.
Question 1
Essay
Question Dethier and other entomologists have spent considerable time
watching the behaviors of butterfly larvae as they move about in natural
habitats and select different plants to eat. Dethier recorded his observations
until he felt he could identify trends that might lead to an understanding of the
processes underlying larval food selection. Which component of the scientific
method did this aspect of Dethier's research represent?
Answer
observation and description
Question 2
Essay
Question Dethier proposed that swallowtail larvae locate their preferred food
plants using their sense of smell. In other words, he believed that the larvae
were able to discriminate among various kinds of plants by detecting
particular kinds of volatile chemicals released by the plants. Which
component of the scientific method did this aspect of Dethier's research
represent? Answer: development of hypotheses and explanations
Answer
development of hypotheses and explanations
Question 3
Essay
Question Dethier conducted experiments to determine if his explanation of
how swallowtail larvae locate their host plants might be correct. Which
component of the scientific method did this aspect of Dethier's research
represent?
Answer
testing of hypotheses
Question 4
Essay
Question You are interested in studying the role of olfaction (using the sense
of smell) in location of host plants by larvae of a particular species of
swallowtail butterfly. You hypothesize that these larvae detect their preferred
host plants in the carrot family by olfaction. Following Dethier's methodology,
,you establish the following experiment. Extracts obtained from various kinds
of plants (including some belonging to the carrot family) are used to moisten
small pieces of paper arranged randomly under a wire screen. Other pieces
of paper are simply moistened with water. Swallowtail larvae are allowed to
crawl about on the wire screen, but the larvae cannot come into direct
physical contact with the pieces of paper. Why do you not simply present the
larvae with a choice among various plants in this experiment?
Answer You want to vary the volatile chemicals presented to the larvae
without giving the larvae other cues as to the "identity" of the plants
from which these chemicals are extracted. Since all the pieces of
paper look alike, you can eliminate the possibility that the larvae use
visual cues to recognize the pieces of paper moistened with extracts
from plants in the carrot family. Separating the larvae from the
pieces of paper also ensures that the larvae cannot use their sense
of taste. The scientific method typically involves manipulating one or
a small number of variables independently of others to reveal their
effects.
Question 5
Essay
Question In your experiment, why do you include pieces of paper moistened
with extracts from plants in other plant families or moistened with water,
among those moistened with extracts from plants in the carrot family?
Answer You expect that the larvae will orient themselves toward the pieces
of paper moistened with extracts from plants in the carrot family.
However, you have to ascertain that larvae are not attracted to just
any piece of moistened paper. The pieces of paper moistened with
extracts from other plants enable you to determine whether or not
larvae are selective in their orientation to pieces of paper moistened
with extracts from plants belonging to the carrot family. The pieces
of paper moistened with water serve as experimental controls.
Question 6
Essay
Question In your experiments with the swallowtail larvae, you indeed find
that these larvae orient toward pieces of paper moistened with extracts from
plants belonging to the carrot family and not toward pieces of paper
moistened with water or extracts of other plants. Does this finding prove your
original hypothesis?
Answer Most scientists agree that it is never possible to prove any
hypothesis in the strictest sense. Although the results of your
experiment are consistent with the predictions of your hypothesis
and offer strong support for it, they do not prove the hypothesis. In
the case described, it would be desirable to subject the hypothesis
to further testing. It would be important, for example, for
experimenters in another laboratory to repeat your experiment to
determine if similar results occur consistently at other times and
places. Other explanations for these results would also have to be
considered and eliminated by further experimentation. It would also
be important to conduct investigations aimed at determining the
mechanism of causation. If the hypothesis held up after additional
evaluation, then it would become more widely accepted by the
scientific community.
, Question 7
Essay
Question Does your study of the feeding preferences of swallowtail larvae
address a "how" or a "why" question?
Answer This study clearly focuses on a "how" question. You are interested
primarily in answering a question dealing with a physiological
process involving sensory perception.
Question 8
Essay
Question Given your answer to the preceding question, decide whether the
kind of question you identified ("how" or "why") addresses a proximate or
ultimate factor.
Answer This study clearly focuses on a "how" question dealing with a
physiological process, or proximate factor.
Question 9
Essay
Question Formulate at least one hypothesis to address a "why" question
applicable to the subject of your study. State your question, then your
hypothesis (or hypotheses).
Answer There are many possible questions. One might ask, "Why do larvae
of swallowtail butterflies select plants belonging to the carrot family
as their food?" There are several possible hypotheses that would
address this question. For example, one might speculate that the
larvae of swallowtail butterflies are capable of safely eating any
plants belonging to the carrot family, but that certain plants
belonging to other plant families might be toxic. One might also
speculate that the larvae of swallowtail butterflies can sequester in
their bodies certain toxic chemicals contained in their preferred plant
foods. Such chemicals could then be used defensively by the larvae.
Question 10
Essay
Question Given your answer to the preceding question, decide whether the
kind of question you identified ("how" or "why") addresses a proximate or
ultimate factor.
Answer This is clearly a "why" question dealing with costs and benefits to
individuals, or ultimate factors that guide evolution.
Question 11
Essay
Question Plants and animals exchange energy and materials with their
physical environments. These exchanges occur across surfaces. In animals.
these surfaces (lungs, for example) tend to be internal, while in plants, these
surfaces tend to be external (leaves, for example). Discuss the principal
reason for this important difference.
Answer Consider energy acquisition. Animals obtain energy by extracting it
from foods they consume. This absorption is best accomplished
internally, where foods can be subjected to appropriate conditions
(presence of enzymes, physical processing, acidic pH, etc.) that
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