Dolly, the sheep, was the first mammal to be cloned from an adult somatic cell. Unexpectedly, she aged prematurely and died at six years old. She had characteristics of a geriatric sheep. Why was this the case?
What will be an ideal response?
Since Dolly was cloned from an adult somatic cell, it is very likely that her telomeres were shorter than those of a normal lamb when born. Therefore, with each cell division the telomeres got shorter and shorter and her cells underwent less cell divisions. The shortened telomeres may have caused her aging.
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A number of species have declined in abundance around Boston, Massachusetts, since Thoreau's time. These tend to be:
A. the plants least able to change their flowering time. B. the plants that have changed their flowering time the most. C. the plants that have the earliest flowering time. D. the plants that have the latest flowering time. E. None of the above.
Respond to items 161–165 in reference to the four cell types
listed below. a. sensory neurons b. interneurons c. motor neurons d. Schwann cells M 161. cells that carry signals to muscle cells M 162. a type of neuroglia cell E 163. cells that form myelin E 164. cells that are restricted to the brain and spinal cord E 165. cells that pick up environmental signals
Species turnover on islands has been observed to be low. What does this suggest about succession on islands?
A. The species that initially colonize islands are random. B. Facilitation is of minor importance on islands. C. The dominant, more important species tend to go extinct during succession on islands. D. Succession on most islands proceeds in a relatively predictable manner.
The energy source of photosynthesis is
A. oxygen. B. sunlight. C. carbon dioxide D. chlorophyll. E. glucose