Ignicoccus has several unique structural features that have lead scientists to propose that it may be the modern descendent of the ancestral cell type that gave rise to the origin of eukaryotic cells
What are the unique features of Ignicoccus and why do they support this hypothesis?
What will be an ideal response?
Answer: Ignicoccus lacks a cell wall, but has both an inner and outer cellular membrane. The space between the two membranes, called the intermediate compartment, is abnormally larger than its cytoplasm and contains membrane-bound vesicles that may function to export substances from the cell. This cell structure resembles some of the membranes in Eukarya and supports the idea that Ignicoccus may be a modern descendent of the ancestral eukaryote cell. Ignicoccus also has a hydrogen- and elemental sulfur-based metabolism and has a temperature optimum of 90 °C, thus it also possesses a metabolism that would have been well-adapted for conditions on early earth.
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The force necessary to fill the lungs in a mammal is provided by the
A. diaphragm. B. intercostal muscles. C. buccal muscles. D. diaphragm and buccal muscles. E. diaphragm and intercostal muscles.
The notochord is most closely associated with the:
a. nervous system b. spinal cord c. skeletal system d. skin system e. nervous system and spinal cord only
Explain the importance of information transfer in living systems. Include three specific examples. What will be an ideal response?
How did Lutzoni and Pagel (1997) conclude that the entire genome of mutualistic fungi evolved faster than the genome of free-living fungi?
a. They based their estimate on the branch lengths in the phylogeny of a single gene. b. They compared the evolutionary rates of multiple genes. c. They conducted a genome scan at a great number of variable loci using microarray technology. d. Their "conclusion" is mere speculation and is not backed up by data.