Multiple Choice
The optimum pH for an alkaliphile would be at:
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10. Dynamics of Microbial Growth
pH Requirements for Microbial Growth
3:17 minutesProblem 4
Textbook Question
The optimum pH of Acidithiobacillus bacteria (pH 3) is _______________ times more acid than blood (pH 7).
a. 4
b. 10
c. 100
d. 1000
e. 10,000
Verified step by step guidance1
Understand that pH is a logarithmic scale that measures the concentration of hydrogen ions (H\(\textsuperscript{+}\)) in a solution. Each unit change in pH represents a tenfold change in acidity.
Identify the pH values given: Acidithiobacillus bacteria have an optimum pH of 3, and blood has a pH of 7.
Calculate the difference in pH between blood and the bacteria's optimum pH: \(\Delta pH = 7 - 3\).
Use the formula to find how many times more acidic the bacteria's environment is compared to blood: \(\text{Acidity difference} = 10^{\Delta pH}\).
Substitute the pH difference into the formula to express the acidity difference as a power of 10, which will give the factor by which the bacteria's environment is more acidic than blood.
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Video duration:
3mKey Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
pH Scale and Its Logarithmic Nature
The pH scale measures acidity or alkalinity on a logarithmic scale, where each unit change represents a tenfold difference in hydrogen ion concentration. A decrease of one pH unit means the solution is ten times more acidic. This logarithmic property is essential for comparing acidity levels between substances.
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Acidity Comparison Between pH Values
To compare acidity between two pH values, subtract the lower pH from the higher pH and calculate 10 raised to that difference. For example, a pH of 3 is 10^(7-3) = 10,000 times more acidic than a pH of 7, reflecting the exponential increase in hydrogen ion concentration.
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Biological Relevance of Acidithiobacillus Optimum pH
Acidithiobacillus bacteria thrive in highly acidic environments, with an optimum pH around 3. Understanding this helps explain their ecological niche and metabolic adaptations, as well as the significance of comparing their acidity preference to neutral pH environments like human blood (pH 7).
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