Question 1

Which property of carbon allows it to form the backbone of organic molecules essential for life?

Accepted Answer

Its outer shell has 4 electrons, allowing it to form covalent bonds with up to four atoms

Question 2

Which reaction type is responsible for breaking down starch into glucose molecules in the human digestive system?

Accepted Answer

Hydrolysis

Question 3

A scientist is studying a molecule with the formula $$\mathrm{C_6H_{12}O_6$}. $$Which class of biomolecule does this most likely represent?

Accepted Answer

A monosaccharide

Question 4

Which polysaccharide is found in the cell walls of plants and is indigestible to most animals?

Accepted Answer

Cellulose

Question 5

What is the main difference between saturated and unsaturated fatty acids?

Accepted Answer

Unsaturated fatty acids have one or more double bonds, causing kinks that prevent tight packing

Question 6

Which of the following best describes the structure of a phospholipid?

Accepted Answer

A hydrophilic head with a phosphate group and two hydrophobic fatty acid tails

Question 7

A mutation replaces glutamate with valine in the sixth position of the beta globin chain of hemoglobin. What is the most likely consequence?

Accepted Answer

Red blood cells will become sickle-shaped due to altered hemoglobin structure

Question 8

Which level of protein structure is directly determined by the sequence of amino acids?

Accepted Answer

Primary structure

Question 9

Which process forms peptide bonds between amino acids during protein synthesis?

Accepted Answer

Condensation (dehydration synthesis)

Question 10

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

Accepted Answer

Building and strengthening tissues, catalyzing reactions, and transporting substances

Question 11

Which molecule is the primary energy carrier in cells and is a nucleotide?

Accepted Answer

ATP

Question 12

What is the main structural difference between DNA and RNA?

Accepted Answer

DNA is double-stranded and contains deoxyribose; RNA is single-stranded and contains ribose

Question 13

Which type of reaction is represented by the equation $$\mathrm{HCl + NaOH \rightarrow NaCl + H_2O}$$?

Accepted Answer

Exchange reaction

Question 14

Which of the following is true about the ratio of hydrogen to oxygen in carbohydrates?

Accepted Answer

The ratio of H:O is approximately 2:1

Question 15

Which molecule is a polysaccharide that contains nitrogen and is found in the exoskeletons of invertebrates?

Accepted Answer

Chitin

Question 16

What is the result of denaturation of a protein?

Accepted Answer

The protein loses its 3-D shape and function

Question 17

Which of the following is NOT a function of lipids in living organisms?

Accepted Answer

Catalyzing chemical reactions

Question 18

Which of the following best describes a reversible reaction in biological systems?

Accepted Answer

A reaction where products can revert to reactants, such as $$\mathrm{CO_2$ + H_2O \leftrightarrow H_2CO_3 \leftrightarrow $$HCO_3$$^- + H^+}$$

Question 19

Which of the following is true about the quaternary structure of proteins?

Accepted Answer

It consists of multiple polypeptide chains linked together, as seen in hemoglobin

Question 20

Which of the following is a correct example of a redox reaction in biological systems?

Accepted Answer

A is oxidized (loses electrons) and B is reduced (gains electrons)

Chapter 3: The Molecules of Life – Biomolecules in Living Systems

Study Guide - Practice Questions