Question 1

Which of the following statements best describes the difference between an element and a compound?

Accepted Answer

An element is a pure substance made of only one type of atom, while a compound contains two or more different elements chemically bonded together.

Question 2

A neutral atom of oxygen has an atomic number of 8 and a mass number of 16. How many neutrons does it contain? Use the formula $$	ext{Number of neutrons} = 	ext{Mass number} - 	ext{Atomic number}.$$

Accepted Answer

$$16 - 8 = 8$$ neutrons

Question 3

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

Accepted Answer

Oxygen is more electronegative than hydrogen, resulting in an unequal sharing of electrons and partial charges on the molecule.

Question 4

Which of the following is a property of water that is essential for life and results from hydrogen bonding?

Accepted Answer

High specific heat, allowing water to resist temperature changes.

Question 5

A solution has a pH of 4. Which of the following statements is true about this solution?

Accepted Answer

It has a higher concentration of hydrogen ions ($$[H^+]) $$than a solution with pH 7.

Question 6

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

Accepted Answer

Buffers minimize changes in pH by accepting or donating hydrogen ions ($$H^+) as $$needed.

Question 7

Which of the following statements about covalent bonds is correct?

Accepted Answer

Covalent bonds involve the sharing of electrons between atoms.

Question 8

A sodium atom loses one electron to become a sodium ion ($$Na^+). $$What type of ion is this and why?

Accepted Answer

A cation, because it has more protons than electrons.

Question 9

Which of the following best describes the difference between a dehydration synthesis reaction and a hydrolysis reaction?

Accepted Answer

Dehydration synthesis builds polymers by removing water, while hydrolysis breaks polymers by adding water.

Question 10

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

Accepted Answer

Protein – Amino acid

Question 11

Which of the following statements about enzyme function is correct?

Accepted Answer

Enzymes lower the activation energy ($$E_A) $$required for a reaction to proceed.

Question 12

Which of the following best explains why ice floats on liquid water?

Accepted Answer

Stable hydrogen bonds keep water molecules in ice farther apart, making ice less dense than liquid water.

Question 13

Which of the following is a function of carbohydrates in living organisms?

Accepted Answer

Short-term energy storage and structural support.

Question 14

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

Accepted Answer

The specific sequence of amino acids in a polypeptide chain.

Question 15

Which of the following statements about ATP is true?

Accepted Answer

The energy released from ATP hydrolysis comes from breaking the bond between the second and third phosphate groups.

Question 16

Which of the following is an example of a competitive inhibitor in enzyme regulation?

Accepted Answer

A molecule that binds to the active site of an enzyme, preventing substrate binding.

Question 17

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

Accepted Answer

Saturated fatty acids have only single bonds between carbons, while unsaturated fatty acids have one or more double bonds.

Question 18

Which of the following is a property of exergonic reactions?

Accepted Answer

They proceed with a net loss of free energy ($$\Delta G \u003c 0).$$

Question 19

Which of the following best describes the role of phospholipids in biological membranes?

Accepted Answer

They form a bilayer with hydrophilic heads facing outward and hydrophobic tails facing inward.

Question 20

Which of the following is a correct description of a nucleotide?

Accepted Answer

A molecule consisting of a phosphate group, a pentose sugar, and a nitrogenous base.

The Chemistry of Life: Foundations for Anatomy & Physiology

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