FRQ AP BIO UNIT 4 PROGRESS CHECK
ACTUAL EXAMINATION TEST 2026
QUESTIONS WITH ANSWERS GRADED A+
>> Part A: Describe the importance of the inner membranes separating different regions of the
mitochondrion and the chloroplast.
Answer: The importance of the inner membranes separating different regions of the mitochondrion and
the chloroplast is that they allow for different reactions to occur in different regions of the organelles.
Without them, the mitochondrion and the chloroplasts wouldn’t be able to complete their functions as
efficiently. The inner membranes permit a higher level of organization and control in the cell to exist.
>> Part B: Based on the diagram, describe how the structure of these organelles controls movement
across the membranes.
Answer: The compartmentalized structure of the mitochondrion and the chloroplast allow for a higher
surface area to volume ratio, in turn making transport across the membranes more efficient. Different
materials have more areas to enter from and they don’t need to cross as much space to get to their
destination, which allows for the cell to work at its necessary rate.
>> Part C: Complete the table to represent the relationship between volume and surface area of a
spherical structure surrounded by a membrane.
Answer: 4.19 cubed, 12.56 squared, 1:3 113.04 cubed, 113.04 squared, 1:1
>> Part D: Explain how the folding of the mitochondrial inner membrane and the many individual
chloroplast thylakoids are beneficial to a cell that is carrying out chemical reactions.
Answer: The folding of the mitochondrial inner membrane and the many individual chloroplast
thylakoids are both beneficial to a cell that is carrying out chemical reactions because the folding
increases the surface area, providing optimal conditions for enzyme reactions and ATP production.
This is because the folding creates distinct environments for each process.
ACTUAL EXAMINATION TEST 2026
QUESTIONS WITH ANSWERS GRADED A+
>> Part A: Describe the importance of the inner membranes separating different regions of the
mitochondrion and the chloroplast.
Answer: The importance of the inner membranes separating different regions of the mitochondrion and
the chloroplast is that they allow for different reactions to occur in different regions of the organelles.
Without them, the mitochondrion and the chloroplasts wouldn’t be able to complete their functions as
efficiently. The inner membranes permit a higher level of organization and control in the cell to exist.
>> Part B: Based on the diagram, describe how the structure of these organelles controls movement
across the membranes.
Answer: The compartmentalized structure of the mitochondrion and the chloroplast allow for a higher
surface area to volume ratio, in turn making transport across the membranes more efficient. Different
materials have more areas to enter from and they don’t need to cross as much space to get to their
destination, which allows for the cell to work at its necessary rate.
>> Part C: Complete the table to represent the relationship between volume and surface area of a
spherical structure surrounded by a membrane.
Answer: 4.19 cubed, 12.56 squared, 1:3 113.04 cubed, 113.04 squared, 1:1
>> Part D: Explain how the folding of the mitochondrial inner membrane and the many individual
chloroplast thylakoids are beneficial to a cell that is carrying out chemical reactions.
Answer: The folding of the mitochondrial inner membrane and the many individual chloroplast
thylakoids are both beneficial to a cell that is carrying out chemical reactions because the folding
increases the surface area, providing optimal conditions for enzyme reactions and ATP production.
This is because the folding creates distinct environments for each process.
