Answer the following question given this paragraph: Binary Fission Due to the relative simplicity of the prokaryotes, the cell division process, called binary fission, is a less complicated and much more rapid process than cell division in eukaryotes. The single, circular DNA chromosome of bacteria is not enclosed in a nucleus, but instead occupies a specific location, the nucleoid, within the cell (Figure 10.2). Although the DNA of the nucleoid is associated with proteins that aid in packaging the molecule into a compact size, there are no histone proteins and thus no nucleosomes in prokaryotes. The packing proteins of bacteria are, however, related to the cohesin and condensin proteins involved in the chromosome compaction of eukaryotes. The bacterial chromosome is attached to the plasma membrane at about the midpoint of the cell. The starting point of replication, the origin, is close to the binding site of the chromosome to the plasma membrane (Figure 10.15). Replication of the DNA is bidirectional, moving away from the origin on both strands of the loop simultaneously. As the new double strands are formed, each origin point moves away from the cell wall attachment toward the opposite ends of the cell. As the cell elongates, the growing membrane aids in the transport of the chromosomes. After the chromosomes have cleared the midpoint of the elongated cell, cytoplasmic separation begins. The formation of a ring composed of repeating units of a protein called FtsZ directs the partition between the nucleoids. Formation of the FtsZ ring triggers the accumulation of other proteins that work together to recruit new membrane and cell wall materials to the site. A septum is formed between the nucleoids, extending gradually from the periphery toward the center of the cell. When the new cell walls are in place, the daughter cells separate. Q: The single circular dna chromosome of bacteria is not enclosed in what, but instead occupies a specific location called the nucleoid within the cell? Choices: - atom - molecules - protons - nucleus A:
nucleus
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Answer the following question given this paragraph: Sensory neurons carry nerve impulses from tissues and organs to the spinal cord and brain. Q: What can carry nerve impulses from tissues and organs to the spinal cord and brain? Choices: - healthy neurons - motor neurons - respiratory neurons - sensory neurons A:
sensory neurons
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Answer the following question given this paragraph: Pulmonary gas exchange is the exchange of gases between inhaled air and the blood. It occurs in the alveoli of the lungs. Alveoli (singular, alveolus) are grape-like clusters surrounded by networks of thin-walled pulmonary capillaries. After you inhale, there is a greater concentration of oxygen in the alveoli than in the blood of the pulmonary capillaries, so oxygen diffuses from the alveoli into the blood across the capillaries (see Figure below ). Carbon dioxide, in contrast, is more concentrated in the blood of the pulmonary capillaries than in the alveoli, so it diffuses in the opposite direction. Q: In what part of the lungs is pulmonary gas exchanged? Choices: - bronchioles - trachea - bronchi - alveoli A:
alveoli
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Answer the following question given this paragraph: Q: All enzymes have an optimal temperature and what? Choices: - shapes - weight - ions - ph A:
ph
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