BIOC 3021 Exam 1, Biochem 3021 - Exam 1 BIOC 3021
UMN Questions With Complete Solutions
??? A buffer solution is made from a weak acid, HA (pKa = 6)
and its conjugate base A-. what is the ratio of the base A- to the
acid HA at pH = 5? Correct Answers pH = pK + log
(base/acid)
5 = 6 + log (base/acid)
-1 = log (base/acid)
1/10 = base/acid
??? If the Hydrogen ion [ ] of blood increases 10-fold, how
much does the pH change? Correct Answers For each whole
number change in the pH scale, the actual H+ ion concentration
changes ten-fold. For example, a pH change from 7 to 8
represents a drop in hydrogen ion concentration from 1 in 10
million to 1 in 100 million.
** it is lower by one pH unit
??? If the pH changes from 7 to 6 which amino acid R group is
the most affected? (the most affected R group is the one with
pKa the closest to pH = 7) Correct Answers Histidine
??? Which aa is essentially incompatible with alpha helix and
beta sheet formation? Correct Answers Proline
??? which of the following elements is the LEAST common in
organic compounds within living cells?
Carbon
Hydrogen
,Nitrogen
Sulfur
Fluoride Correct Answers Fluoride
??? which type of bond involves shared electrons and serves as
the basic linkage in organic compounds? Correct Answers
Covalent
??? Which type of interaction is NOT stabilized by H-bonds?
Correct Answers between water and a non-polar R-group
(Nth)peptide Correct Answers 20^n unique sequences
3 parts of Flavin Adenine Dinucleotide Correct Answers
Isoalloxazine, ribitol, riboflavin
20 Common amino acids: Correct Answers all contain H, C, O,
& N atoms
can be (+), (-) or neutral depending on the pH
can occur at any place in a protein sequence
with one exception are all of the L-form when found in proteins
A buffer soltuion is prepared by mixing 10 ml 1M HA with 10
ml of 1M NaA and diluting to a final volume of 100ml. What
will be the pH of this buffer solution? the pK for HA is 4.
Correct Answers 10 ml 1M HA = 0.01 equivalents of HA
When you have .01 equivalents (moles) of acid in a volume of
100ml it is the same as 0.1 equivalent/liter or .1M or 10^-1 M.
10 ml of 1M NaA = .01 equivalents of NaA
,When you have .01 moles of base in a volume of 100 ml it is the
same as 0.1 equivalent/liter or .1M or 10^-1 M
pH = pK + log (base/acid)
= 4 + log (.1M/.1)
= 4 + log 1/1
= 4-0
=4
** at this point you have 50% acid and 50% base and the pH
equals the pK.
A buffer solution is prepared by mixing 1 ml 1M HA with 10 ml
of 1M NaA and diluting to a final volume of 100ml. What will
be the pH of this buffer solution? the pK for HA is 4. Correct
Answers 1 ml 1M HA = .001 equivalents of HA
when you have .001 equivalents of acid in a volume of 100 ml it
is the same as 0.01 equivalent/liter or 0.01M or 10^-2 M
10 ml of 1 M NaA = 0.01 equivalents of NaA
when you have 0.01 equivalents of base in a volume of 100 ml it
is the same as .1 equivalent/liter or .1M or 10^-1 M.
pH = pK + log (base/acid)
pH = 4 + log 0.1M / .01M
= 4 + log (10/1)
=4+1
=5
** at this point you have 90% base and 10% acid and the pH is
one unit above the pK.
, A buffer solution is prepared by mixing 10 mL 1M HA with 1
ml of 1 M NaA and diluting to a final volume of 100ml. What
will be the pH of this buffer solution? The pK for HA is 4.
Correct Answers (Use H-H equation)
10 ml 1M HA = 0.01 equivalents of HA
When you have .01 equivalents (moles) of acid in a volume of
100ml it is the same as 0.1 equivalent/liter or .1M or 10^-1 M.
1ml of 1 M NaA = .001 equivalents of NaA
When you have .001 moles of base in a volume of 100ml it is
the same as .01 equivalents/liter or .01M or 10^-2
pH = pK + log(base/acid)
= 4 + log (.01 M/.1M)
= 4 + log 1/10
= 4-1
=3
** at this point you have 90% acid and 10% base and you are 1
pH unit below the pK.
A carbon atom can form how many single bonds?
Select one:
a. 1
b. 2
c. 3
d. 4
e. 5 Correct Answers 4
UMN Questions With Complete Solutions
??? A buffer solution is made from a weak acid, HA (pKa = 6)
and its conjugate base A-. what is the ratio of the base A- to the
acid HA at pH = 5? Correct Answers pH = pK + log
(base/acid)
5 = 6 + log (base/acid)
-1 = log (base/acid)
1/10 = base/acid
??? If the Hydrogen ion [ ] of blood increases 10-fold, how
much does the pH change? Correct Answers For each whole
number change in the pH scale, the actual H+ ion concentration
changes ten-fold. For example, a pH change from 7 to 8
represents a drop in hydrogen ion concentration from 1 in 10
million to 1 in 100 million.
** it is lower by one pH unit
??? If the pH changes from 7 to 6 which amino acid R group is
the most affected? (the most affected R group is the one with
pKa the closest to pH = 7) Correct Answers Histidine
??? Which aa is essentially incompatible with alpha helix and
beta sheet formation? Correct Answers Proline
??? which of the following elements is the LEAST common in
organic compounds within living cells?
Carbon
Hydrogen
,Nitrogen
Sulfur
Fluoride Correct Answers Fluoride
??? which type of bond involves shared electrons and serves as
the basic linkage in organic compounds? Correct Answers
Covalent
??? Which type of interaction is NOT stabilized by H-bonds?
Correct Answers between water and a non-polar R-group
(Nth)peptide Correct Answers 20^n unique sequences
3 parts of Flavin Adenine Dinucleotide Correct Answers
Isoalloxazine, ribitol, riboflavin
20 Common amino acids: Correct Answers all contain H, C, O,
& N atoms
can be (+), (-) or neutral depending on the pH
can occur at any place in a protein sequence
with one exception are all of the L-form when found in proteins
A buffer soltuion is prepared by mixing 10 ml 1M HA with 10
ml of 1M NaA and diluting to a final volume of 100ml. What
will be the pH of this buffer solution? the pK for HA is 4.
Correct Answers 10 ml 1M HA = 0.01 equivalents of HA
When you have .01 equivalents (moles) of acid in a volume of
100ml it is the same as 0.1 equivalent/liter or .1M or 10^-1 M.
10 ml of 1M NaA = .01 equivalents of NaA
,When you have .01 moles of base in a volume of 100 ml it is the
same as 0.1 equivalent/liter or .1M or 10^-1 M
pH = pK + log (base/acid)
= 4 + log (.1M/.1)
= 4 + log 1/1
= 4-0
=4
** at this point you have 50% acid and 50% base and the pH
equals the pK.
A buffer solution is prepared by mixing 1 ml 1M HA with 10 ml
of 1M NaA and diluting to a final volume of 100ml. What will
be the pH of this buffer solution? the pK for HA is 4. Correct
Answers 1 ml 1M HA = .001 equivalents of HA
when you have .001 equivalents of acid in a volume of 100 ml it
is the same as 0.01 equivalent/liter or 0.01M or 10^-2 M
10 ml of 1 M NaA = 0.01 equivalents of NaA
when you have 0.01 equivalents of base in a volume of 100 ml it
is the same as .1 equivalent/liter or .1M or 10^-1 M.
pH = pK + log (base/acid)
pH = 4 + log 0.1M / .01M
= 4 + log (10/1)
=4+1
=5
** at this point you have 90% base and 10% acid and the pH is
one unit above the pK.
, A buffer solution is prepared by mixing 10 mL 1M HA with 1
ml of 1 M NaA and diluting to a final volume of 100ml. What
will be the pH of this buffer solution? The pK for HA is 4.
Correct Answers (Use H-H equation)
10 ml 1M HA = 0.01 equivalents of HA
When you have .01 equivalents (moles) of acid in a volume of
100ml it is the same as 0.1 equivalent/liter or .1M or 10^-1 M.
1ml of 1 M NaA = .001 equivalents of NaA
When you have .001 moles of base in a volume of 100ml it is
the same as .01 equivalents/liter or .01M or 10^-2
pH = pK + log(base/acid)
= 4 + log (.01 M/.1M)
= 4 + log 1/10
= 4-1
=3
** at this point you have 90% acid and 10% base and you are 1
pH unit below the pK.
A carbon atom can form how many single bonds?
Select one:
a. 1
b. 2
c. 3
d. 4
e. 5 Correct Answers 4
