Acids, Bases, and Buffers (Intro)

Question 1

What charge does water have and why?

Answer 1

Water is a “polar” molecule, meaning that there is an uneven distribution of electron density. Water has a partial negative charge near the oxygen atom due the unshared pairs of electrons, and partial positive charges near the hydrogen atoms.

Question 2

The ability of ions and other molecules to dissolve in water is due to

Answer 2

polarity

Question 3

Unique physical properties due to hydrogen bonding

Answer 3

high heat of vaporization, strong surface tension, high specific heat, and nearly universal solvent properties of water

Question 4

H+ in regards to acids and bases

Answer 4

Acids release H⁺, bases accept H⁺

Question 5

Alcohol

Answer 5

hydrocarbon with a hydrogen replaced by “OH”

Question 6

Acid

Answer 6

hydrocarbon with a hydrogen replaced by a carboxyl “COOH”.

COOH -> COO⁻ + H⁺

Question 7

Amine

Answer 7

hydrocarbon with a hydrogen replaced by an amine “NH₂”. Basic- accepts protons. NH₂ + H⁺ -> NH₃⁺

Question 8

Phosphate

Answer 8

addition of -PO₄⁼ (switch)

Question 9

Amino Acid

Answer 9

hydrocarbon with amino and carboxyl groups

Question 10

The pH of a solution indicates

Answer 10

how much acid (acidity) or base (alkalinity) exists in a solution

Question 11

An acid is….

Answer 11

a substance that increases the concentration of hydrogen ions (H⁺) in a solution, usually by having one of its hydrogen atoms dissociate

Question 12

A base…

Answer 12

provides either hydroxide ions (OH⁻) or other negatively charged ions that combine with hydrogen ions, reducing their concentration in the solution and thereby raising the pH. In cases where the base releases hydroxide ions, these ions bind to free hydrogen ions, generating new water molecules

Question 13

The stronger the acid, the more readily it donates

Answer 13

H⁺

Question 14

Strong bases are those substances that readily donate

Answer 14

OH⁻ or take up hydrogen ions

Question 15

Buffers…

Answer 15

readily absorb excess H⁺ or OH⁻, keeping the pH of the body carefully maintained in the narrow range required for survival

Question 16

Examples of buffers

Answer 16

carbonic acid (H₂CO₃), bicarbonate ion (HCO₃⁻), and carbon dioxide (CO₂)

Question 17

Viruses

Answer 17

• Viruses are composed of
nucleic acids covered by a
proteinaceous coat. 
• They rely on the host cell
to divide. They do not
burn any fuels. 
• The DNA or RNA sequence
changes over time  in
response to
antivirals/human immune
systems.

Question 18

Evolution has been directly observed on…

Answer 18

short time scales

Question 19

What do biologists study?

Answer 19

Biosphere: all environments inhabited by life
Ecosystems: All the living (biotic) and non-living (abiotic e.g. light, oxygen etc) components of an area
Communities: all organisms in an ecosystem
Populations: all individuals of a species
Organisms: individual living things
Organs and organ systems: carry out particular functions in the organism
Tissues: groups of similar cells; make up organs
Cells: fundamental unit of life, all organisms are made of cells
Organelles: components of cells
Molecules: chemical structure

Question 20

Properties of water : polarity

Answer 20

• Oxygen is more electronegative
• Stronger pull on shared electrons
• Partial negative charge
• Hydrogen has a partial positive charge

Question 21

Bond type and molecular shape

Answer 21

determine whether a molecule is polar or nonpolar

Question 22

Hydrogen bonds…

Answer 22

stabilize biological molecules and allows them to perform their biological function

Question 23

Water molecules have a ____ attraction to each other than to the air

Answer 23

higher

Question 24

Solution

Answer 24

liquid that is a homogeneous mixture of

substances

Question 25

Aqueous solution

Answer 25

solutes dissolved in the solvent water

Question 26

Cations

Answer 26

(+ve ions)- attracted to oxygen of water

Question 27

Anions

Answer 27

(-ve ions)- attracted to hydrogen of water

Question 28

Concentration

Answer 28

number of solute molecules for a given volume of solvent

Question 29

Presence of solutes \_\_\_\_\_\_ the freezing point of
aqueous solutions (freezing point depression)

Answer 29

decreases

Question 30

Freezing point of seawater (-1.8C) is ____ than

freshwater

Answer 30

lower

Question 31

Some organisms ____ solutes in body fluids

to _____ freezing point

Answer 31

Some organisms increase solutes in body fluids

to lower freezing point

Question 32

Equilibrium of water

Answer 32

• H atom in a H-bond between two water molecules can shift from one to the other: (rare but important)
• H₂O molecules dissociate at the same rate at which they are being reformed
• Rare but very important to biology
• Concentration of hydronium and hydroxides can vary over orders of magnitude
• Concentration of hydronium denoted as [H⁺]

Question 33

Buffers contain….

Answer 33

Buffers contain a weak acid and corresponding base,
which combine reversibly with H⁺ ions
Acid ↔ Base + H⁺

Question 34

An organelle is releasing protons into the cytoplasm. How will the buffers of the cytoplasm respond to this input?

Answer 34

Lowering pH