AP BIO FRQS. EXAM 2025 QUESTIONS
AND ANSWERS
Describe the role of carbon in biological systems. - ANS The response indicates that carbon is
used to build biological macromolecules such as carbohydrates, proteins, nucleic acids, and
lipids.
Explain how, when the membranes are fused, the polar parts of the phospholipids from one cell
will interact with the phospholipids from the other cell and how the nonpolar parts of the
phospholipids from one cell will interact with the phospholipids from the other cell. -
ANS The response indicates that the polar part of the phospholipids from one cell will align
or interact with the polar parts of the phospholipids from the other cell, and nonpolar parts of
the phospholipids from one cell will align or interact with nonpolar parts of the phospholipids
from the other cell.
Make a claim about the most immediate effect on the fused B-cancer cells if the fused cells are
transferred to a growth medium that lacks a source of nitrogen. - ANS The response
1 Copyright ©2025 FYNDLAY ALL RIGHTS RESERVED.
,indicates that the cells will die OR that they will be unable to synthesize DNA and RNA/nucleic
acids/nucleotides and amino.
Provide reasoning with evidence based on the composition of biological macromolecules to
support your claim. - ANS The response indicates that nucleic acids (DNA, RNA, or
nucleotides) and amino acids (polypeptides, or proteins) contain nitrogen.
Identify the process used to form the covalent peptide bonds that join amino acids into a
polypeptide. - ANS The response indicates that the process that joins amino acids into a
polypeptide is a dehydration synthesis OR a condensation reaction.
The change in the amino acid sequence illustrated in Figure 1 caused a change in the shape of
Receptor X. Based on the R groups of the original and substituted amino acids, explain why
Receptor X changed shape. - ANS The response indicates that two amino acids with charged
or ionic or hydrophilic R-groups were replaced by two amino acids with uncharged or nonpolar
or hydrophobic R-groups.
Using the template below that represents the four levels of protein structure, place an X on
each level that is expected to be altered as a result of the amino acid substitutions shown in
Figure 1. - ANS The response indicates primary and tertiary structure.
2 Copyright ©2025 FYNDLAY ALL RIGHTS RESERVED.
, Explain how the amino acid substitution shown in Figure 1 is most likely to affect the function
of Receptor X. - ANS The response indicates that because function is determined by shape,
the function of receptor X is likely to change OR that the structural change might alter the
binding of the molecule to receptor X OR that the structural change might alter the ability of
receptor X to cause a cellular response.
Identify the most likely mode of transport across the membrane for substance L. Explain how
information provided helps determine the most likely mode of transport. - ANS The response
indicates that substance L most likely crosses the membrane by active transport. The response
indicates that the cells maintain an intracellular concentration of 120 mM, which is always
greater than the concentration of substance L in the culture medium.
Determine the external concentration of substance L that will result in one-half of the maximal
entry rate. - ANS The response indicates that the external concentration of substance L that
will result in one-half of the maximal entry rate is a value other than one between 31 mM and
34 mM.
Predict the likely effect on the ability of substance L to enter the cells if substance L is attached
to a large protein instead of free in the culture. - ANS The response indicates that substance
3 Copyright ©2025 FYNDLAY ALL RIGHTS RESERVED.
AND ANSWERS
Describe the role of carbon in biological systems. - ANS The response indicates that carbon is
used to build biological macromolecules such as carbohydrates, proteins, nucleic acids, and
lipids.
Explain how, when the membranes are fused, the polar parts of the phospholipids from one cell
will interact with the phospholipids from the other cell and how the nonpolar parts of the
phospholipids from one cell will interact with the phospholipids from the other cell. -
ANS The response indicates that the polar part of the phospholipids from one cell will align
or interact with the polar parts of the phospholipids from the other cell, and nonpolar parts of
the phospholipids from one cell will align or interact with nonpolar parts of the phospholipids
from the other cell.
Make a claim about the most immediate effect on the fused B-cancer cells if the fused cells are
transferred to a growth medium that lacks a source of nitrogen. - ANS The response
1 Copyright ©2025 FYNDLAY ALL RIGHTS RESERVED.
,indicates that the cells will die OR that they will be unable to synthesize DNA and RNA/nucleic
acids/nucleotides and amino.
Provide reasoning with evidence based on the composition of biological macromolecules to
support your claim. - ANS The response indicates that nucleic acids (DNA, RNA, or
nucleotides) and amino acids (polypeptides, or proteins) contain nitrogen.
Identify the process used to form the covalent peptide bonds that join amino acids into a
polypeptide. - ANS The response indicates that the process that joins amino acids into a
polypeptide is a dehydration synthesis OR a condensation reaction.
The change in the amino acid sequence illustrated in Figure 1 caused a change in the shape of
Receptor X. Based on the R groups of the original and substituted amino acids, explain why
Receptor X changed shape. - ANS The response indicates that two amino acids with charged
or ionic or hydrophilic R-groups were replaced by two amino acids with uncharged or nonpolar
or hydrophobic R-groups.
Using the template below that represents the four levels of protein structure, place an X on
each level that is expected to be altered as a result of the amino acid substitutions shown in
Figure 1. - ANS The response indicates primary and tertiary structure.
2 Copyright ©2025 FYNDLAY ALL RIGHTS RESERVED.
, Explain how the amino acid substitution shown in Figure 1 is most likely to affect the function
of Receptor X. - ANS The response indicates that because function is determined by shape,
the function of receptor X is likely to change OR that the structural change might alter the
binding of the molecule to receptor X OR that the structural change might alter the ability of
receptor X to cause a cellular response.
Identify the most likely mode of transport across the membrane for substance L. Explain how
information provided helps determine the most likely mode of transport. - ANS The response
indicates that substance L most likely crosses the membrane by active transport. The response
indicates that the cells maintain an intracellular concentration of 120 mM, which is always
greater than the concentration of substance L in the culture medium.
Determine the external concentration of substance L that will result in one-half of the maximal
entry rate. - ANS The response indicates that the external concentration of substance L that
will result in one-half of the maximal entry rate is a value other than one between 31 mM and
34 mM.
Predict the likely effect on the ability of substance L to enter the cells if substance L is attached
to a large protein instead of free in the culture. - ANS The response indicates that substance
3 Copyright ©2025 FYNDLAY ALL RIGHTS RESERVED.
