Which best describes the class Halobacteria?
A) archaeans that require highly saline environments
B) archaeans that require methane-rich environments
C) bacteria that require highly arid environments
D) bacteria that require highly saline environments
Answer: A) archaeans that require highly saline environments
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The last common ancestor of all bilaterians is thought to have had four Hox genes. Most extant cnidarians have two Hox genes, except Nematostella (of ?-catenin fame), which has three Hox genes. On the basis of these observations, some have proposed that the ancestral cnidarians were originally bilateral and, in stages, lost Hox genes from their genomes. If true, this would mean that _____.
A) the Radiata should be a true clade B) the radial symmetry of extant cnidarians is secondarily derived, rather than being an ancestral trait C) Hox genes play little actual role in coding for an animal's "body plan" D) the Cnidaria may someday replace porifera as the basal bilaterians B) the radial symmetry of extant cnidarians is secondarily derived, rather than being an ancestral
Provide a brief description of segment polarity genes, including their regulation and their molecular and developmental effects
What will be an ideal response?
In photosynthetic cells, synthesis of ATP by the chemiosmotic mechanism occurs during _____
A) photosynthesis only B) respiration only C) photosynthesis and respiration D) neither photosynthesis nor respiration
Natural selection can be defined as ________
A) the evolution of a population of organisms B) a process in which changes in gene frequencies result from evolution C) the production of more offspring than can survive in a given environment D) a process in which organisms with certain inherited traits are more likely to survive and reproduce than individuals with other traits