Low air pressure is usually associated with D. Cloudy, wet weather.
Eukaryotic cells are theorized to have evolved from prokaryotes called the endosymbiotic theory. This explains that the most primitive eukaryotic cell engulfed a prokaryotic cell (by the process of phagocytosis) that is capable of cellular respiration and another prokaryotic cell that is capable of photosynthesis. These prokaryotic cells eventually became organelles and these organelles are the mitochondria and the chloroplast.
The outer skeleton provides protection due to the fact that invertebrates do not have backbones
The correct answer to the question stated above is the first option: <span>an instinctive behavior was tied to a different stimulus.
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Pavlov's experiment was a typical case of classical conditioning because an instinctive behavior was tied to a different stimulus.
