Q: A solution has a pH of 4. What is the concentration of hydrogen ions $$[H^+] in $$this solution?

$$[H^+] = 1 \times 10$$^{-4}$$ \ \mathrm{M}$$

Question 1

Which of the following best describes the relationship between an atom, a molecule, and a cell in the hierarchy of biological organization?

Accepted Answer

A cell is made up of molecules, which are made up of atoms.

Question 2

Which of the following best explains why water is considered a polar molecule?

Accepted Answer

Water has an uneven distribution of charge due to the difference in electronegativity between oxygen and hydrogen.

Question 3

A scientist is testing the effect of a new fertilizer on plant growth. Which of the following is the best example of a dependent variable in this experiment?

Accepted Answer

The height of the plants measured after two weeks.

Question 4

Which of the following best describes a covalent bond?

Accepted Answer

A bond formed by the sharing of electrons between two atoms.

Question 5

Which of the following statements about enzymes is correct?

Accepted Answer

Enzymes lower the activation energy required for a reaction to occur.

Question 6

A solution has a pH of 4. What is the concentration of hydrogen ions $$[H^+] in $$this solution?

Accepted Answer

$$[H^+] = 1 	imes 10$$^{-4}$$ \ \mathrm{M}$$

Question 7

Which of the following best explains why unsaturated fatty acids are typically liquid at room temperature?

Accepted Answer

They contain double bonds that create kinks, preventing tight packing.

Question 8

A student adds hydrochloric acid (HCl) to a beaker of water, causing the pH to drop from 7 to 3. By what factor has the hydrogen ion concentration increased?

Accepted Answer

By a factor of 1,000

Question 9

Which of the following is a correct description of a dehydration (condensation) reaction?

Accepted Answer

A reaction that joins two monomers together by removing a molecule of water.

Question 10

Which of the following best explains the role of buffers in biological systems?

Accepted Answer

Buffers maintain a stable pH by accepting or donating hydrogen ions.

Question 11

A triglyceride is formed from which combination of molecules?

Accepted Answer

Three fatty acids and one glycerol molecule

Question 12

Which of the following best describes the difference between a monosaccharide and a polysaccharide?

Accepted Answer

A monosaccharide is a simple sugar, while a polysaccharide is a complex carbohydrate made of many monosaccharides.

Question 13

Which of the following is the correct sequence of protein structure formation?

Accepted Answer

Primary, secondary, tertiary, quaternary

Question 14

A researcher is studying the effect of temperature on enzyme activity. She finds that enzyme activity increases with temperature up to a point, then sharply decreases. Which of the following best explains the decrease in activity at high temperatures?

Accepted Answer

The enzyme is denatured, losing its three-dimensional structure.

Question 15

Which of the following best describes the function of the R group in an amino acid?

Accepted Answer

It determines the specific properties and function of the amino acid.

Question 16

Which of the following is a correct example of a hydrolysis reaction?

Accepted Answer

Breaking down a polysaccharide into monosaccharides by adding water.

Question 17

Which of the following best explains why phospholipids are well-suited to form cell membranes?

Accepted Answer

They have both hydrophilic heads and hydrophobic tails, allowing them to form bilayers in water.

Question 18

A student is analyzing the following data: The average distance between slugs in a plot increases from 8.0 cm at midnight to 350.5 cm at 4 P.M., then decreases back to 8.0 cm at midnight. Which of the following is the most reasonable hypothesis to explain this pattern?

Accepted Answer

Slugs spread out during the day to avoid heat and predators, then regroup at night for moisture and protection.

Question 19

Which of the following best describes the effect of pH on enzyme activity, using bromelain as an example?

Accepted Answer

Bromelain has an optimal pH range, and activity decreases if the pH is too high or too low.

Question 20

Which of the following is a correct statement about the difference between DNA and RNA?

Accepted Answer

DNA is usually double-stranded, while RNA is usually single-stranded.

General Biology: Foundations, Chemistry of Life, and Macromolecules

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