Cell Biology Lab Exam 1 Questions &
Answers (Grade A+)
pH and Buffers
What is pH? -
correct answer ✅pH=-log[H+]
p means -log
Measured on a scale from 0 to 14
A shorthand way of expressing the hydrogen ion concentration of a
solution
pH and Buffers
What is a useful thing to know about pH and that will always be
true? -
correct answer ✅pOH + pH = 14
pH and Buffers
,Cell Biology Lab Exam 1 Questions &
Answers (Grade A+)
Cells maintain pH either by _________ ________ mechanisms or by
_______ ______ systems -
correct answer ✅active (energy-requiring ) mechanisms or by
complex buffering systems
pH and Buffers
What is a buffer? -
correct answer ✅A substance that in solution resists changes in pH
Any substance that resist changes in pH of a solution
pKa = -log10Ka where Ka is acid dissociation constant
pH and Buffers
A buffer is either a weakly ___________ or weakly _________
compound that _________ in water so that an ___________ exists
between the ___________ substance and its _____________ ions -
correct answer ✅acidic or weakly basic compound that dissociates
in water so that an equilibrium exists between the undissociated
substance and its dissociated ions
,Cell Biology Lab Exam 1 Questions &
Answers (Grade A+)
pH and Buffers
The ______ is a fundamental characteristic of a _________ -
correct answer ✅pKa is a fundamental characteristic of a buffer
pH and Buffers
A buffer must meet the following criteria:
HINT: There are nine requirements -
correct answer ✅1. pKa between 6 and 8
2. High solubility in aqueous systems
3. exclusion by biological membranes
4. minimal salt effects
5. minimal concentration effects
6. well defined or non existent interactions with mineral cations
7. Chemical stability
8. insignificant light absorption between 240 and 700 nm
9. readily available in pure form
, Cell Biology Lab Exam 1 Questions &
Answers (Grade A+)
pH and Buffers
What are two ways you can determine pH? -
correct answer ✅mathematically if we know the hydrogen by
using color indicators
-Color indicators, chemicals that are different colors at different pH
may be used either in solution or impregnated into papers
Using a pH meter
- An accurate and easily used instrument
pH and Buffers
What kind of pH meter did we use for experiment one ? -
correct answer ✅Solid state microprocessor based meter that use
a solid state pH probe
pH and Buffers
How do you pipette correctly? -
correct answer ✅You will pick up the pipette and go down all the
Answers (Grade A+)
pH and Buffers
What is pH? -
correct answer ✅pH=-log[H+]
p means -log
Measured on a scale from 0 to 14
A shorthand way of expressing the hydrogen ion concentration of a
solution
pH and Buffers
What is a useful thing to know about pH and that will always be
true? -
correct answer ✅pOH + pH = 14
pH and Buffers
,Cell Biology Lab Exam 1 Questions &
Answers (Grade A+)
Cells maintain pH either by _________ ________ mechanisms or by
_______ ______ systems -
correct answer ✅active (energy-requiring ) mechanisms or by
complex buffering systems
pH and Buffers
What is a buffer? -
correct answer ✅A substance that in solution resists changes in pH
Any substance that resist changes in pH of a solution
pKa = -log10Ka where Ka is acid dissociation constant
pH and Buffers
A buffer is either a weakly ___________ or weakly _________
compound that _________ in water so that an ___________ exists
between the ___________ substance and its _____________ ions -
correct answer ✅acidic or weakly basic compound that dissociates
in water so that an equilibrium exists between the undissociated
substance and its dissociated ions
,Cell Biology Lab Exam 1 Questions &
Answers (Grade A+)
pH and Buffers
The ______ is a fundamental characteristic of a _________ -
correct answer ✅pKa is a fundamental characteristic of a buffer
pH and Buffers
A buffer must meet the following criteria:
HINT: There are nine requirements -
correct answer ✅1. pKa between 6 and 8
2. High solubility in aqueous systems
3. exclusion by biological membranes
4. minimal salt effects
5. minimal concentration effects
6. well defined or non existent interactions with mineral cations
7. Chemical stability
8. insignificant light absorption between 240 and 700 nm
9. readily available in pure form
, Cell Biology Lab Exam 1 Questions &
Answers (Grade A+)
pH and Buffers
What are two ways you can determine pH? -
correct answer ✅mathematically if we know the hydrogen by
using color indicators
-Color indicators, chemicals that are different colors at different pH
may be used either in solution or impregnated into papers
Using a pH meter
- An accurate and easily used instrument
pH and Buffers
What kind of pH meter did we use for experiment one ? -
correct answer ✅Solid state microprocessor based meter that use
a solid state pH probe
pH and Buffers
How do you pipette correctly? -
correct answer ✅You will pick up the pipette and go down all the
