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

Question 1

Which property of water allows insects to walk on its surface, and what is the molecular basis for this property?

Accepted Answer

Cohesion; water molecules stick together via hydrogen bonds, creating surface tension

Question 2

Why does ice float on liquid water, and what is the biological significance of this phenomenon?

Accepted Answer

Ice is less dense than water due to hydrogen bonds forming a lattice structure, which insulates aquatic life below

Question 3

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}$$ M

Question 4

Which statement best explains why water is called the 'universal solvent'?

Accepted Answer

Water can dissolve many substances because its polar molecules surround and separate solute ions or molecules

Question 5

Which functional group is responsible for acting as an acid by donating hydrogen ions in a chemical reaction?

Accepted Answer

Carboxyl group

Question 6

A buffer system in blood helps maintain pH homeostasis. If a strong acid is added to blood, which reaction will occur to minimize pH change?

Accepted Answer

$$HCO_3^- + H$$^+ \rightarrow H_2CO_3$$

Question 7

Which of the following best describes a structural isomer?

Accepted Answer

Molecules with the same molecular formula but different covalent arrangements of atoms

Question 8

What is the main reason carbon is able to form such a diversity of organic molecules?

Accepted Answer

Carbon has four valence electrons, allowing it to form up to four covalent bonds with a variety of atoms

Question 9

Which property of water is most important for the transport of water from roots to leaves in plants?

Accepted Answer

Cohesion and adhesion

Question 10

Which statement about pH is correct?

Accepted Answer

A solution with pH 5 is more acidic than a solution with pH 9

Question 11

Which functional group is found in molecules called 'thiols' and helps stabilize protein structure?

Accepted Answer

Sulfhydryl group

Question 12

Which of the following is an example of a cis-trans isomer?

Accepted Answer

Molecules with the same formula but different spatial arrangement around a double bond

Question 13

Which experiment demonstrated that organic molecules could be synthesized abiotically under early Earth conditions?

Accepted Answer

Stanley Miller's classic experiment

Question 14

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

Accepted Answer

Buffers resist changes in pH by accepting or donating $$H^+$$ ions

Question 15

Which functional group is most likely to make a molecule more polar and able to dissolve in water?

Accepted Answer

Hydroxyl group

Question 16

What is the correct name for a hydrocarbon with seven carbon atoms and only single bonds?

Accepted Answer

Heptane

Question 17

Which property of water allows it to moderate Earth's climate by absorbing and releasing heat slowly?

Accepted Answer

High specific heat

Question 18

Which statement about acids and bases is correct?

Accepted Answer

Acids donate hydrogen ions, bases accept them

Question 19

Which functional group is most likely to be involved in energy transfer reactions in cells?

Accepted Answer

Phosphate group

Question 20

Which of the following molecules is an enantiomer?

Accepted Answer

Molecules that are mirror images of each other

Water, Carbon, and the Molecular Basis of Life: Key Concepts in General Biology

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