Which best describes the biological species concept?
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a) sexually reproducing
b) genetic exchange does not occur between reproductively isolated
c) species are populations that interbreed and produce fertile offspring
d) certain factors separate sexually reproducing populations from
asexually reproducing populations

What is the significance of the protein-lined pits? a. protein attracts other proteins needed for atp synthesis within the cell. b. protein-lined pits are able to transport one molecule at a time down the concentration gradient within the cell. c. the polarity of proteins allows other polar molecules to attach and be transported in the cell by transport channels. d. receptors within the pits allow ligands to fuse and be transported into the cell by endocytosis.