The intracellular stimulus for secretion of neurotransmitters into the synaptic cleft is an increase in
A) potassium ion levels.
B) chloride ion levels.
C) sodium ion levels.
D) calcium ion levels.
E) acetylcholine levels.
Answer: D
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Darwin observed an orchid flower with petals arranged in very long, thin tubes, rather than broad and flat, as we might see in other common flowers. What is the advantage to the orchid having an 11-inch-long nectar tube arrangement of the petals?
A. The long tube can trap insects as a source of nutrients. B. The flower can collect more sunlight for photosynthesis. C. The flower can produce nectar more easily spread over a larger area to attract more pollinators. D. The flower nectar tube can collect more rainwater to maintain health of the flower. E. The flower can only be pollinated by a specifically adapted pollinator, reducing cross-fertilization among orchid species.
Which of the following statements applies to sexually reproducing species but not asexually reproducing species?
A. Reproduction can occur with either one or two parents. B. The two "daughter" cells that result from cell division following mitosis are genetically identical to each other and to the original "parent" cell. C. Two kinds of cell division are required. D. Offspring are able to reproduce.
What useful information can you derive from the protein/lipid ratio of the following?nerve cell plasma membrane 0.23inner mitochondrial membrane 3.54
A. Nerve cell plasma membrane requires relatively more lipid that the inner mitochondrial membrane for its function B. Nerve cell plasma membrane probably use the lipid as insulation C. The inner mitochondrial membrane is probably involved in considerable metabolic activity D. The nerve cell plasma membrane and the inner mitochondrial membrane have widely different functions. E. all of the above
Tunde is abnormally slender. Which of the following conditions is she more likely to have compared to an obese person, given the information in this chapter?
A) hypothermia and injury due to trauma B) heartburn and indigestion C) heart disease and stroke D) cancers