Q: A solution has a hydrogen ion concentration of $$1 \times 10$$^{-4}$$ M. What is its pH?

$$pH = -\log(1 \times 10$$^{-4}$$) = 4$$

Question 1

Which of the following statements best explains why water is an excellent solvent for most cellular chemistry?

Accepted Answer

Water has polar covalent bonds, enabling it to interact with and dissolve other polar substances.

Question 2

A solution has a hydrogen ion concentration of $$1 	imes 10$$^{-4}$$ M. What is its pH?

Accepted Answer

$$pH = -\log(1 	imes 10$$^{-4}$$) = 4$$

Question 3

Which of the following best describes an amphipathic molecule?

Accepted Answer

A molecule that contains both hydrophobic and hydrophilic regions.

Question 4

Which type of chemical bond is primarily responsible for the secondary structure of proteins, such as alpha-helices and beta-pleated sheets?

Accepted Answer

Hydrogen bonds

Question 5

A patient receives an intravenous solution labeled as 0.9% saline. How many grams of NaCl are present in 500 mL of this solution?

Accepted Answer

4.5 grams

Question 6

Which of the following is a correct statement about isotopes?

Accepted Answer

Isotopes have the same number of protons but different numbers of neutrons.

Question 7

Which of the following best describes the difference between saturated and unsaturated fatty acids?

Accepted Answer

Saturated fatty acids lack double bonds and are solid at room temperature; unsaturated fatty acids contain double bonds and are liquid at room temperature.

Question 8

Which of the following functional groups is found in all amino acids?

Accepted Answer

A carboxyl group (COOH)

Question 9

A scientist is analyzing a bacterial cell wall and finds a carbohydrate-based structure that helps the bacteria adhere to surfaces. What is this structure most likely called?

Accepted Answer

Capsule

Question 10

Which of the following best explains why ionic compounds are considered strong bonds in dry conditions but weak in aqueous solutions?

Accepted Answer

Water molecules surround and shield the ions, reducing the electrostatic attraction between them.

Question 11

Which of the following is a correct description of a dehydration synthesis reaction?

Accepted Answer

A reaction that builds larger molecules by removing a water molecule.

Question 12

Which of the following is a function of carbohydrates in cells?

Accepted Answer

Providing structural support and energy storage

Question 13

A molecule of DNA is composed of which of the following components?

Accepted Answer

Deoxyribose sugar, phosphate group, and thymine

Question 14

Which of the following best describes the quaternary structure of a protein?

Accepted Answer

The combination of two or more polypeptide chains into a functional protein

Question 15

Which of the following molecules is a major component of the Gram-negative bacterial cell wall and is toxic to humans?

Accepted Answer

Lipopolysaccharide (LPS)

Question 16

Which of the following best describes the role of ATP in cells?

Accepted Answer

ATP is a ribonucleotide that serves as a primary energy source for cellular processes.

Question 17

A researcher is studying a molecule that contains a long hydrocarbon chain with a carboxylic acid group. This molecule is most likely a:

Accepted Answer

Fatty acid

Question 18

Which of the following best explains why proteins can perform such a wide variety of functions in cells?

Accepted Answer

Proteins are made from 20 different standard amino acids, allowing for diverse structures and functions.

Question 19

Which of the following statements about phospholipids is correct?

Accepted Answer

Phospholipids are a major component of cell membranes and are amphipathic.

Question 20

A solution is prepared by dissolving 50 mg of glucose in 10 mL of water. What is the weight-volume concentration of this solution?

Accepted Answer

$$5 \ \mathrm{mg/mL}$$

Biochemistry Basics for Microbiology

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