Figure 29.1 Use the Following Information to Answer the Corresponding Question(s)

question 14

Multiple Choice

Figure 29.1
Use the following information to answer the corresponding question(s) .
Giardia intestinalis can cause disease in several different mammalian species,including humans.Giardia organisms (G.intestinalis) that infect humans are similar morphologically to those that infect other mammals;thus they have been considered a single species,though other species in the Giardia genus infect other organisms.However,G.intestinalis has been divided into different subgroups based on their host and a few other characteristics.
In 1999,a DNA sequence comparison study tested the hypothesis that these subgroups actually constitute different species.The following phylogenetic tree was constructed from the sequence comparison of rRNA from several subgroups of G.intestinalis and a few other morphologically distinct species of Giardia.The researchers concluded that the subgroups of Giardia are sufficiently different from one another genetically that they could be considered different species.

-By examining the phylogenetic tree diagrammed in Figure 29.1,what conclusion can you draw about the species G.microti?

• A)It evolved before G.intestinalis.
• B)It is more closely related to G.muris than to G.intestinalis.
• C)It should not be labeled a species distinct from G.intestinalis.
• D)It is part of a monophyletic group that also includes G.intestinalis.

Discuss the impact of environmental cues on circadian rhythms.

Link the secretion of melatonin to sleep regulation and circadian rhythms.

Explain the historical and cultural significance of altered states of consciousness.

Analyze the physiological basis of circadian rhythms and their impact on human behavior.

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Definitions:

Muscle Relaxants

Drugs that relieve muscle spasms, pain, and tightness.

Electroconvulsive Therapy (ECT)

A medical treatment most commonly used for severe depression, involving electrical stimulation of the brain while the patient is under anesthesia.

Barbiturates

A class of drugs used as sedatives and hypnotics, which can also provide relief from anxiety, insomnia, and seizures.