Suppose that in DNA sequence comparisons of a homologous region in various species, the region shows a low level of polymorphism. What could account for this?
What will be an ideal response?
Ans: Several possible factors, or a combination of these factors, might be responsible for this observation. One possibility is that there has been strong purifying selection to eliminate new mutations in that region, or closely linked to that region. Another possibility is that populations for the species being compared have been historically small and genetic drift has been eliminating new, low-frequency mutations by chance. (This is less likely when many species are being compared.)
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Answer the following statements true (T) or false (F)
1. The modification of a limb that was used for walking in a preexisting ancestor to one that is used as a wing for a species today is called proteomics. 2. A bacterial infection such as pneumonia is most likely caused by organisms derived from the kingdom fungi. 3. All genetic mutations are harmful to an organism. 4. Vertical evolution, whereby living organisms evolve from a common ancestor ("tree of life"), is the only mechanism of evolution on Earth.
When bringing water to a boil in the mountains the time needed to reach the boiling point is
What will be an ideal response?
Fill in the blanks to complete the following statements. ?
___________________ are the most common infectious agents in humans. ? Fill in the blank(s) with correct word
A distinctive feature of secondary syphilis is
A) a widespread rash that can include the palms and soles. B) hard, red, painless bumps. C) rubbery, painful lesions. D) soft, painful ulcers. E) blister-like lesions which ulcerate.