Answer:
Variations are caused by mutation. random mating between organisms.
Explanation:
The study of how living things are classified is called dichotomous key
Answer:
The pH of gastric acid is 1.35 to 3.5 in the human stomach, the acidity being maintained by the proton pump H+/K+ ATPase. The small intestine has a pH of around 7 to 8, that is, it is either neutral or slightly alkaline in nature. The pancreas secretes the bicarbonate ions through bile juice in the small intestines.
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I forgot what it was called but its in the nerv.
Two different types of succession—primary and secondary—have been distinguished. Primary succession occurs in essentially lifeless areas—regions in which the soil is incapable of sustaining life as a result of such factors as lava flows, newly formed sand dunes, or rocks left from a retreating glacier.