Answer: board-certified "pathologist" (physician).
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Seeing as Peter is male, he's seeing a counselor (which indicates mental/emotional/psychological issues) and has been referred to a urologist, I'd say his problem is erectile dysfunction, or choice #2.
Answer: Nonpolar lipid layers
Explanation:
Natural selection can cause speciation, which increases the biodiversity of an ecosystem. Several bacterial colonies are placed on a petri dish that contains agar with antibiotics. After 24 hours, ninety percent of the original bacteria die, but the remaining ten percent survive and later reproduce.
When a human dies, his corpses gets decomposed by decomposing bacteria. What's produced by the decomposing bacteria is the "fertilizer" for plants.