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

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

Question 1

Which of the following best describes the central dogma of molecular biology?

Accepted Answer

DNA is transcribed into RNA, which is then translated into protein.

Question 2

A scientist observes a new organism and wants to determine if it is alive. Which of the following properties would NOT be sufficient alone to confirm it is living?

Accepted Answer

The organism can move from one place to another.

Question 3

Which of the following correctly lists the levels of biological organization from smallest to largest?

Accepted Answer

Atom, molecule, organelle, cell, tissue, organ, organism, population, community, ecosystem, biosphere

Question 4

Which of the following is NOT one of the four most abundant elements in living organisms?

Accepted Answer

Phosphorus

Question 5

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}$$~	ext{M}$$

Question 6

Which type of chemical bond is primarily responsible for the secondary structure of proteins?

Accepted Answer

Hydrogen bonds

Question 7

Which functional group is found in all amino acids and is responsible for their acidic properties?

Accepted Answer

Carboxyl group $$(-COOH)$$

Question 8

Which of the following statements about water is FALSE?

Accepted Answer

Water molecules are held together by ionic bonds.

Question 9

Which of the following best describes the difference between DNA and RNA?

Accepted Answer

DNA contains deoxyribose sugar, while RNA contains ribose sugar.

Question 10

Which of the following reactions is responsible for breaking down polymers into monomers?

Accepted Answer

Hydrolysis

Question 11

A patient is experiencing acidosis (blood pH below 7.35). Which of the following best explains how a buffer system in the blood helps restore normal pH?

Accepted Answer

The buffer absorbs excess $$H^+$$ ions, minimizing changes in pH.

Question 12

Which of the following best describes an isomer?

Accepted Answer

Molecules with the same molecular formula but different structures

Question 13

Which of the following is a correct pairing of a macromolecule and its monomer?

Accepted Answer

Protein – Amino acid

Question 14

Which of the following best explains why enzymes are highly specific for their substrates?

Accepted Answer

The active site of an enzyme has a unique shape that fits only specific substrates.

Question 15

Which of the following statements about lipids is TRUE?

Accepted Answer

Lipids are hydrophobic and do not dissolve in water.

Question 16

A researcher mixes sodium chloride (NaCl) in water. What type of bond is broken when NaCl dissolves, and what type of bond forms between Na+ and water molecules?

Accepted Answer

Ionic bonds are broken; ion-dipole interactions form between Na+ and water.

Question 17

Which of the following is an example of a polar covalent bond?

Accepted Answer

The bond between oxygen and hydrogen in a water molecule

Question 18

Which of the following best describes the role of dehydration synthesis in biological systems?

Accepted Answer

It joins monomers together by removing a molecule of water.

Question 19

Which of the following is a correct statement about the structure of DNA?

Accepted Answer

DNA is a double helix with complementary base pairing between adenine and thymine, and between guanine and cytosine.

Question 20

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

Accepted Answer

The $$[H^+]$$ increased by a factor of $$10^4 = 10$$,000$$

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