The mussel Mytilus edulis thrives in saline habitats, in both the highly salty seawater of tidal zones and the less salty estuaries. This results in two kinds of populations: one adapted to the higher salt concentrations of the tidal zone, and one adapted to the lower salt concentrations of the estuary. It has been found that the more salt-tolerant populations have high frequencies of an allele that produces an enzyme involved in maintaining osmotic equilibrium. Conversely, estuarine mussels having the same enzyme seem to be disfavoured and have a much higher death rate than mussels without the allele. Adult estuarine populations do have lower frequencies of this allele. Each spring, large numbers of larvae from  the salty habitats pour into the estuaries.

The invasion of the seawater larvae would be expected to facilitate change in the genetic structure of the estuarine population by a process called

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#Question id: 13119

#Unit 2. Cellular Organization

Ions, small metabolites, and globular proteins up to about ---------- can diffuse passively through the central aqueous region of the nuclear pore complex.

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#Question id: 2059

#Unit 2. Cellular Organization

For a protein to be an integral membrane protein, it would have to be:

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#Question id: 2060

#Unit 2. Cellular Organization

An animal cell lacking carbohydrates on the external surface of its plasma membrane would likely be impaired in which function?

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#Question id: 2061

#Unit 2. Cellular Organization

Which of the following types of molecules are hydrophilic and therefore excluded from the hydrophobic portion of the phospholipid bilayer?

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#Question id: 2063

#Unit 2. Cellular Organization

In what way do the membranes of a eukaryotic cell vary?

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#Question id: 2065

#Unit 2. Cellular Organization

Which of the following are least likely to diffuse through the phospholipid bilayer of a cell membrane?