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Ch. 2 - Chemical Principles
Tortora - Microbiology: An Introduction 14th Edition
Tortora14th EditionMicrobiology: An IntroductionISBN: 9780138200398Not the one you use?Change textbook
All textbooksTortora 14th EditionCh. 2 - Chemical PrinciplesProblem 4
Chapter 2, Problem 4

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 guidance
1
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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Key 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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Related Practice
Textbook Question

The best definition of ATP is that it is

a. A molecule stored for food use.

b. A molecule that supplies energy to do work.

c. A molecule stored for an energy reserve.

d. A molecule used as a source of phosphate.

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Textbook Question

What type of bond holds the following atoms together?

a. Li+ and Cl- in LiCl

b. Carbon and oxygen atoms in methanol

c. Oxygen atoms in O2

d. A hydrogen atom of one nucleotide to a nitrogen or oxygen atom of another nucleotide in:

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Textbook Question

Radioisotopes are frequently used to label molecules in a cell. The fate of atoms and molecules in a cell can then be followed. This process is the basis for the following question.


If E. coli were grown in a medium containing the radioactive isotope 32P, the 32P would be found in all of the following molecules of the cell except

a. ATP.

b. Carbohydrates.

c. DNA.

d. Plasma membrane.

e. Complex lipids.

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Textbook Question

Diagram the electronic configuration of a carbon atom.

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Textbook Question

Bacteria use the enzyme urease to obtain nitrogen in a form they can use from urea in the following reaction:

What purpose does the enzyme serve in this reaction? What type of reaction is this?

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Textbook Question

Classify the following types of chemical reactions.

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