Question 1

All forms of life function optimally at a pH of 7.

Accepted Answer

Different forms of life have different optimal pH ranges. For example, human blood functions optimally at a pH of 7.35-7.45, while some bacteria thrive in acidic environments with a pH below 5.5.

Question 2

Covalent bonds are always shared equally.

Accepted Answer

Covalent bonds can be shared equally or unequally, depending on the electronegativity of the atoms involved in the bond. If the atoms have similar electronegativity, the bond will be shared equally. However, if one atom has a significantly higher electronegativity, it will attract the shared electrons towards itself more strongly, resulting in an uneven sharing of electrons and a polar covalent bond.

Question 3

Elements only achieve the full complement of electrons in outermost energy shells by donating away or sharing electrons.

Accepted Answer

Elements achieve the full complement of electrons in their outermost energy shells by accepting or sharing electrons, not just donating them away.

Question 4

Identify the two functional groups that interact to form a peptide bond.

Accepted Answer

A peptide bond is formed between the amino group (-NH2) of one amino acid and the carboxyl group (-COOH) of another amino acid. Therefore, the two functional groups that interact to form a peptide bond are the amino group and carboxyl group.

Question 5

All chemical reactions are,in theory,reversible.

Accepted Answer

All chemical reactions are reversible in theory, meaning that they can be made to go in either direction depending on the conditions. However, in practice, some reactions may be so energetically favorable in one direction that the reverse reaction may not occur under normal conditions.

Question 6

Carbon dioxide is an organic molecule.

Accepted Answer

Carbon dioxide is an inorganic molecule composed of one carbon atom and two oxygen atoms. It does not contain any hydrogen-carbon bonds and therefore cannot be classified as an organic molecule.

Question 7

In terms of similarities,which two molecules would be isomers of each other?

Accepted Answer

Glucose and fructose are isomers of each other because they have the same molecular formula (C6H12O6) but different structural arrangements.

Question 8

You put a spoonful of table salt,NaCl,into a glass of water and it dissolves.You repeat this test,but drop the spoonful of salt into a glass of vegetable oil instead.What happens,and why?

Accepted Answer

Oil is a nonpolar solvent and cannot dissociate the ionic bond between the Na⁺ and Cl⁻ ions in table salt, which requires a polar solvent like water. Therefore, the salt will not dissolve in the vegetable oil.

Question 9

If an amino acid contained a large hydrocarbon (a group of multiple carbons and hydrogens linked together)as its side group,in which of the following categories could it be appropriately designated?

Accepted Answer

A large hydrocarbon side group would contribute to a nonpolar nature of the amino acid, making it hydrophobic. Basic and acidic amino acids have charged side groups, while polar amino acids have polar side groups that are usually not hydrophobic.

Question 10

A basic solution is expected to contain more hydrogen ions than hydroxyl ions.

Accepted Answer

A basic solution contains more hydroxyl ions (OH-) than hydrogen ions (H+).

Question 11

Individual covalent bonds are stronger than individual ionic bonds.

Accepted Answer

Covalent bonds involve the sharing of electrons between atoms, creating a strong attraction between the atoms. In contrast, ionic bonds involve the transfer of electrons, resulting in a weaker electrostatic attraction between positively and negatively charged ions. Therefore, individual covalent bonds are stronger than individual ionic bonds.

Question 12

A friend tells you that he recently read an article claiming that you need to work to restore the alkalinity of your blood to remain healthy.Why is this impossible and impractical (and unhealthy even if you could make it happen)?

Accepted Answer

Both option B and C provide reasons why attempting to restore the alkalinity of your blood is impossible and impractical. Option E combines these explanations, making it the best choice. It states that blood is usually in the neutral range, and also contains buffers that prevent drastic pH changes, making it difficult to alter the pH in a meaningful way. Additionally, attempting to make the blood more alkaline would be unnecessary and potentially harmful.

Question 13

A dehydration synthesis reaction between glucose (C₆H₁₂O₆)and fructose (C₆H₁₂O₆)produces a molecule of sucrose (C₁₂H₂₂O₁₁).Why don't the two individual molecular formulae add up to the same number of atoms in the sucrose product?

Accepted Answer

Dehydration synthesis is a type of chemical reaction in which a water molecule is removed from two smaller molecules to form a larger molecule. In the case of glucose and fructose, a water molecule is removed from them to form sucrose. This means that the final molecule has fewer atoms than the sum of the atoms in the reactants. Therefore, the correct answer is B, as option B correctly describes the process of dehydration synthesis. Option A and D are incorrect because there is no combustion involved in dehydration synthesis, and no atoms are burned or consumed. Option C is also incorrect because a water molecule is removed, not added, in a dehydration synthesis reaction.

Question 14

The density of liquid water is greater than the density of ice.

Accepted Answer

This is because the molecules in liquid water are closer together, making it more dense, while in ice, the molecules are farther apart, making it less dense.

Question 15

What is the main/most important factor that differentiates methanol,ethanol,and isopropanol from each other?

Accepted Answer

The main factor that differentiates methanol, ethanol, and isopropanol from each other is the number of carbon atoms in the molecule. Methanol has one carbon atom, ethanol has two, and isopropanol has three.

Question 16

Which one of the following microbes would grow best at pH 1-3.5?

Accepted Answer

Acidithiobacillus ferrooxidans is an acidophile, which means it thrives in acidic conditions. It is commonly found in acidic environments such as mine drainage water and can grow at pH levels as low as 0.5. Cyanobacteria in ocean water and Propionibacterium acnes on human skin do not grow well in such acidic conditions.

Question 17

Subtle differences exist in the plasma membrane molecules of the organisms in the three Domains._______ functional groups are found in the plasma membrane molecules of bacteria and eukarya,while ________ functional groups are found in the plasma membrane molecules of archaea.

Accepted Answer

Ester linkages are found in the plasma membrane molecules of bacteria and eukarya, while ether linkages are characteristic of the plasma membrane molecules of archaea.

Question 18

The formation of ADP from ATP can be defined as a hydrolytic reaction.

Accepted Answer

In hydrolysis, a molecule is broken down by the addition of water. In this case, ATP is broken down into ADP and inorganic phosphate through the addition of a water molecule.

Question 19

Which one of the following would be the most difficult covalent bond to break in a chemical reaction?

Accepted Answer

The bond between two nitrogen atoms in N₂ involves a triple covalent bond, which is the strongest type of covalent bond. Therefore, it would require the most energy to break this bond in a chemical reaction.

Question 20

Water has recently been discovered to be lying just underneath the soil on Mars.This means it is possible life as we know it may also exist (or may once have existed)on Mars.

Accepted Answer

Scientists have found evidence of liquid water just below the surface of Mars, increasing the chance that life as we know it could exist or have existed on the planet.

Quiz 2: Chemical Principles