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(also called selectively permeable membrane) a membrane which allows some substances to cross it, but not others.
a graphical representation of the evolutionary relationship between taxonomic groups based on...
a duct through which saliva passes from the salivary gland into the mouth.
an alkaline watery fluid containing digestive enzymes, which is secreted into the mouth by...
consists of the pectoral and pelvic girdles together with the arms and legs.