Q: As the pH of a solution changes from 7 to 5, what happens to the hydrogen ion concentration? Select the correct answer and the best explanation.

The hydrogen ion concentration increases by $$100\times$$

Q: A graph shows the Gibbs free energy of reactants at 8 kcal/mol, increases to 12 kcal/mol, then drops to 4 kcal/mol. What is the value of $$\Delta G$$ for this reaction?

$$\Delta G = -4\ \text{kcal/mol}$$

Question 1

Refer to the diagram of bonds within and between three molecules (see $$image_1). $$Which of the labeled bonds are hydrogen bonds? Select the correct answer.

Accepted Answer

Bonds 6, 7, 8, and 9

Question 2

Water molecules are polar due to the type of bond that forms between oxygen and hydrogen atoms. Which property of water is NOT a result of water being a polar molecule?

Accepted Answer

None of these; all are properties resulting from water's polarity

Question 3

As the pH of a solution changes from 7 to 5, what happens to the hydrogen ion concentration? Select the correct answer and the best explanation.

Accepted Answer

The hydrogen ion concentration increases by $$100	imes$$

Question 4

Which functional group is correctly labeled in the molecule shown in $$image_2$$?

Accepted Answer

Amino

Question 5

Which property best matches the sulfhydryl functional group?

Accepted Answer

Nonpolar; two of this functional group can form a covalent bond called a disulfide bond

Question 6

The energy in a covalent bond is an example of which type of energy?

Accepted Answer

Chemical potential energy

Question 7

What is true of energy transformations in living organisms?

Accepted Answer

At each transformation, some energy is converted to forms that are no longer useful to do work in the organism.

Question 8

Reaction A has $$G = 3.85\ 	ext{kJ/mol}$$ and Reaction B has $$G = -1.54\ 	ext{kJ/mol}. $$Can these reactions be coupled so that the energy released by one is used as the energy input for the other?

Accepted Answer

No. Reaction B releases less energy than reaction A requires, so they cannot be coupled.

Question 9

A graph shows the Gibbs free energy of reactants at 8 kcal/mol, increases to 12 kcal/mol, then drops to 4 kcal/mol. What is the value of $$\Delta G$$ for this reaction?

Accepted Answer

$$\Delta G = -4\ 	ext{kcal/mol}$$

Question 10

Which of the molecules shown in $$image_4 is a $$single amino acid, one of the building blocks of proteins?

Accepted Answer

Molecule 2

Question 11

Match the level of protein structure to its description: 'Alpha helices and beta pleated sheets.'

Accepted Answer

Secondary

Question 12

What interactions are generally the most important in determining the secondary structure of a protein?

Accepted Answer

Interactions between partially charged regions of the backbone

Question 13

What is the major breakthrough method for predicting protein folding, as reported in 2021?

Accepted Answer

Software that utilizes artificial intelligence

Question 14

How does the addition of an enzyme affect the progress of a reaction as shown in a Gibbs free energy graph?

Accepted Answer

It lowers the activation energy required for the reaction.

Question 15

Which of the following mechanisms could be used by a cell to change an enzyme's activity and regulate the rate of a reaction?

Accepted Answer

All of these

Question 16

Researchers extract an enzyme from cells that grow in thermal hot springs. The activity of the enzyme increases as temperature goes from 55°C to 75°C. What is the most likely explanation?

Accepted Answer

The activity of the enzyme increases because the enzyme functions more effectively at 75°C.

Question 17

A protein is composed of a single polypeptide strand. If negatively charged chloride ions (Cl-) are added to the solution, which level(s) of protein structure would be likely to be affected?

Accepted Answer

Secondary

Question 18

Which of the following statements about transport proteins and their impact on human health are accurate?

Accepted Answer

When aquaporin 2 mis-folds, it doesn't work, causing a condition in which a person cannot retain water and becomes dehydrated.

Question 19

A reaction has reactants with Gibbs free energy of 10 kcal/mol and products with Gibbs free energy of 3 kcal/mol. What is the $$\Delta G$$ for this reaction, and is it exergonic or endergonic?

Accepted Answer

$$\Delta G = -7\ 	ext{kcal/mol}$$; exergonic

Biology Study Guide: Molecular Bonds, Water Properties, pH, Functional Groups, Protein Structure, Enzyme Activity, and Transport Proteins

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