- A newly discovered unicellular eukaryote contains an organelle that produces ATP. The organelle is surrounded by two membranes; the inner membrane contains proteins similar to bacterial electron transport proteins. The organelle also contains circular DNA and ribosomes that are smaller than cytosolic ribosomes. When treated with an antibiotic that inhibits bacterial ribosomes, synthesis of several organelle-encoded proteins decreases while cytosolic protein synthesis is unaffected. Which evidence best supports an endosymbiotic origin for this organelle?
Answer: The organelle contains circular DNA and bacterial-size ribosomes sensitive to bacterial antibiotics.
This question assesses the analysis of the origins of cell compartmentalization. The correct answer, choice B, is evidenced by the organelle's circular DNA, bacterial-size ribosomes, and sensitivity to bacterial antibiotics, which directly support the endosymbiotic theory where a bacterium was engulfed and retained, contributing its own genetic and protein synthesis machinery. The inner membrane's bacterial-like electron transport proteins and the selective inhibition of organelle protein synthesis further align with the AP Biology concept that mitochondria originated from aerobic bacteria, preserving prokaryotic traits. This evidence distinguishes endosymbiotic organelles from those formed by host membrane infolding, as the organelle maintains autonomy in replication and translation. A tempting distractor, choice A, is incorrect due to a level-of-organization error, confusing shared lipid ratios at the cellular level with specific prokaryotic features like DNA and ribosomes that indicate endosymbiosis. To approach similar questions, prioritize evidence of prokaryotic remnants such as independent DNA and ribosomes over general membrane similarities to identify endosymbiotic origins.
- Scientists observe a modern archaeon that forms internal membrane sheets connected to the plasma membrane. Fluorescent labeling shows newly synthesized membrane lipids appear first at the plasma membrane and later in the internal sheets. The internal sheets lack ribosomes and DNA and do not divide independently; instead, they expand and contract with changes in cell surface area. Which explanation best accounts for the origin of these internal membranes?
Answer: Infolding from the plasma membrane formed internal sheets that share lipid sources and continuity.
This question requires analyzing the origins of cell compartmentalization to explain internal membrane formation in archaea. The correct answer B is supported by direct tracking of membrane biogenesis: fluorescent lipids appear first at the plasma membrane then in internal sheets, demonstrating physical continuity and shared lipid synthesis pathways. The absence of DNA and ribosomes, lack of independent division, and correlation with cell surface area changes all indicate these are extensions of the plasma membrane rather than separate organelles. Answer A incorrectly invokes endosymbiosis, failing to recognize that endosymbionts cannot completely lose all genetic material and ribosomes while maintaining membrane structures—this represents a misconception about the limits of reductive evolution. When evaluating membrane origins, trace the flow of newly synthesized lipids and look for physical connections to distinguish infolding from endosymbiotic capture.
- A eukaryotic lineage contains an organelle that performs aerobic respiration. The organelle has a double membrane, and its inner membrane includes many proteins related to bacterial electron transport proteins. Antibiotics that inhibit bacterial ribosomes reduce protein synthesis inside the organelle but do not affect cytosolic protein synthesis. The organelle contains a small circular genome. Which evidence best supports the origin of this organelle by endosymbiosis?
Answer: Antibiotic sensitivity of organelle translation and circular DNA support bacterial ancestry.
This question requires analyzing the origins of cell compartmentalization to identify endosymbiotic evidence. The correct answer A is supported by the specific antibiotic sensitivity pattern: antibiotics that target bacterial ribosomes inhibit the organelle but not the cytosol, directly demonstrating the organelle contains bacterial-type ribosomes distinct from eukaryotic ones. Combined with circular DNA (bacterial genome organization) and bacterial-related electron transport proteins, this provides strong molecular evidence for bacterial ancestry through endosymbiosis. Answer C incorrectly attributes electron transport proteins to membrane infolding, a structure-function confusion—infolded membranes would contain the host's proteins, not bacterial-type proteins. To confirm endosymbiotic origins, look for molecular markers that specifically link to bacterial ancestry, particularly differential antibiotic sensitivity that reveals the presence of bacterial-type translation machinery.
- A unicellular eukaryote contains a photosynthetic organelle surrounded by four membranes. The two innermost membranes resemble cyanobacterial membranes, and the organelle contains circular DNA. Between the second and third membranes, researchers detect remnants of a membrane-bound compartment with ribosomes distinct from the host cytosol. Which inference best accounts for the origin of this compartmentalization pattern?
Answer: Multiple membranes and distinct ribosomes support serial endosymbiosis involving an engulfed eukaryote.
This question requires analyzing the origins of cell compartmentalization to explain complex membrane arrangements. The correct answer A is supported by the four-membrane structure and intermediate compartment containing distinct ribosomes, indicating serial endosymbiosis: a eukaryote containing a cyanobacterium was itself engulfed by another eukaryote. The innermost membranes' resemblance to cyanobacteria, circular DNA, and the remnant compartment with its own ribosomes between membranes 2 and 3 provide evidence for this secondary endosymbiosis. Answer B incorrectly attempts to explain four membranes through plasma membrane infolding, a level-of-organization error—infolding cannot produce the observed pattern of distinct ribosome types in different compartments. To identify serial endosymbiosis, count membrane layers and look for remnant structures (like ribosomes) between membranes that indicate a previously independent organism.
- Researchers compare two internal compartments in a eukaryotic cell. Compartment X is bounded by a single membrane and is continuous with the outer membrane of the nucleus; proteins in its membrane match plasma membrane proteins in amino acid sequence. Compartment Y is bounded by two membranes, contains circular DNA, and has ribosomes that differ from cytosolic ribosomes. Which claim is best supported about the origin of compartment X?
Answer: Compartment X most likely arose from infolding of the plasma membrane, producing a connected endomembrane system.
This question assesses the analysis of the origins of cell compartmentalization. The correct answer, choice A, is supported by compartment X's single membrane, continuity with the nuclear envelope, and proteins matching plasma membrane sequences, aligning with the infolding hypothesis where plasma membrane invaginations form the endomembrane system including the ER and nuclear envelope in eukaryotes. In contrast, compartment Y's double membrane, circular DNA, and distinct ribosomes suggest endosymbiotic origin, highlighting X's host-derived nature per AP Biology evolutionary models. This distinction emphasizes how infolding creates interconnected compartments without separate genomes, facilitating specialized functions like protein processing. A tempting distractor, choice B, is incorrect due to a level-of-organization error, mistaking nuclear continuity for endosymbiosis, which requires double membranes and independent DNA rather than host membrane extensions. To approach similar questions, contrast membrane number, continuity, and genetic independence to classify compartments as infolded or endosymbiotic.
- A newly discovered unicellular eukaryote contains a small energy-producing organelle. The organelle is surrounded by two membranes, contains circular DNA, and has ribosomes that are similar in size to those of bacteria rather than those in the cytosol. During cell division, the organelle replicates by a process resembling binary fission. Which evidence best supports a mechanism for the origin of this organelle?
Answer: Two membranes and circular DNA support origin by endosymbiosis of a bacterium.
This question requires analyzing the origins of cell compartmentalization to identify evidence supporting endosymbiosis. The correct answer A is supported by the convergence of multiple endosymbiotic signatures: double membranes (indicating engulfment), circular DNA (characteristic of bacteria), bacterial-sized ribosomes (distinct from eukaryotic cytosolic ribosomes), and binary fission reproduction (typical of free-living bacteria). These features collectively indicate the organelle was once a free-living bacterium that became permanently incorporated into the host cell. Answer B incorrectly attributes binary fission to membrane infolding, demonstrating a structure-function confusion—infolded membranes lack independent replication machinery and divide only when the cell divides. To identify endosymbiotic origins, look for the complete package of bacterial characteristics: independent genome, distinct ribosomes, autonomous division, and double membranes from the original engulfment event.
- In a lab model of early protocells, repeated cycles of membrane growth and division produced inward folds that pinched off into internal vesicles. Enzymes that bind membranes were found concentrated on the inner surfaces of these vesicles, while the outer plasma membrane retained transport proteins. No DNA was detected inside the vesicles, and each vesicle membrane had the same lipid composition as the cell's plasma membrane. Over many cycles, vesicles remained connected to the plasma membrane in some cells, forming continuous internal sheets. Which explanation best accounts for the origin of these internal membranes?
Answer: Infolding of the plasma membrane generated internal membranes with matching lipid composition and continuity.
This question requires analyzing the origins of cell compartmentalization to determine how internal membranes formed in protocells. The correct answer B is supported by multiple lines of evidence: the vesicles have the same lipid composition as the plasma membrane, they remain connected to the plasma membrane forming continuous sheets, and no DNA is detected inside them, ruling out endosymbiosis. The infolding mechanism explains how membrane-bound enzymes concentrate on inner surfaces while transport proteins remain on the outer membrane through differential protein sorting during membrane deformation. Answer A is incorrect due to the misconception that all internal membranes arise from endosymbiosis—this teleological error ignores that endosymbiotic organelles contain their own DNA and have distinct lipid compositions from the host membrane. When evaluating compartmentalization origins, look for continuity with existing membranes, matching lipid compositions, and absence of independent genetic material as indicators of infolding rather than endosymbiosis.
- In a cell lineage with an extensive endomembrane system, the nuclear envelope is continuous with the ER, and both have a similar lipid composition to the plasma membrane. Genes encoding nuclear pore proteins are homologous to genes encoding proteins involved in vesicle coating and budding. No organelle-like DNA is associated with the nucleus or ER. Which evidence best supports a model for the origin of the nuclear envelope?
Answer: Homology between pore and vesicle-coat proteins supports origin via plasma membrane infolding and budding.
This question requires analyzing the origins of cell compartmentalization to explain nuclear envelope evolution. The correct answer A is supported by molecular homology: genes for nuclear pore proteins share ancestry with vesicle coat proteins, indicating the nuclear envelope arose through the same membrane-budding mechanisms that generate other endomembrane compartments. The continuity with ER, matching lipid composition with plasma membrane, and absence of organellar DNA all support origin through membrane dynamics rather than endosymbiosis. Answer E commits a teleological error by suggesting the nucleus evolved "to control gene expression more effectively"—evolution cannot anticipate future benefits, and structures arise through available mechanisms regardless of eventual function. When evaluating nuclear origins, examine protein homologies that reveal shared evolutionary mechanisms with other membrane-trafficking systems.
- Scientists examine a lineage of single-celled organisms that lacks mitochondria but contains internal membrane sacs that store ions. These sacs are bounded by a single membrane and are connected to the plasma membrane via narrow tubules. Lipid analysis shows the sacs and plasma membrane share the same sterol composition, and no circular DNA is detected in the sacs. Which evidence best supports plasma membrane infolding as the origin of these sacs?
Answer: The sacs are single-membraned and physically continuous with the plasma membrane through tubules.
This question assesses the analysis of the origins of cell compartmentalization. The correct answer, choice B, is supported by the sacs' single membrane, physical continuity with the plasma membrane via tubules, and shared sterol composition, directly evidencing plasma membrane infolding as a mechanism for internal compartment formation in non-mitochondrial lineages per AP Biology evolutionary concepts. The absence of circular DNA further confirms these are not endosymbiotic but host-derived structures for ion storage. This connectivity allows for direct exchange with the exterior, consistent with infolding increasing internal complexity without symbiosis. A tempting distractor, choice C, is incorrect due to a level-of-organization error, confusing bacterial-like enzymes at the molecular level with organelle-level endosymbiosis, which requires double membranes and independent genomes. To approach similar questions, prioritize structural continuity and compositional similarity over functional analogies to identify infolding origins.
- A newly identified organelle in a unicellular eukaryote has two membranes and contains enzymes for anaerobic ATP production. Sequencing reveals a small circular genome inside the organelle, and phylogenetic analysis groups several organelle genes with bacterial genes rather than nuclear genes. The organelle's ribosomes resemble bacterial ribosomes in size. Which evidence best supports the mechanism by which this organelle originated?
Answer: The organelle contains circular DNA and bacterial-like ribosomes, consistent with endosymbiosis.
This question assesses the analysis of the origins of cell compartmentalization. The correct answer, choice B, is evidenced by the organelle's circular DNA, bacterial-like ribosomes, and genes grouping with bacteria, which are key indicators of endosymbiotic origin as described in AP Biology for organelles like mitochondria adapted for anaerobic conditions. The double membrane and phylogenetic analysis further confirm that an engulfed bacterium contributed its genome and translation machinery, distinguishing it from host-derived compartments. This supports the theory that eukaryotic complexity arose through symbiosis, allowing specialized ATP production in isolated environments. A tempting distractor, choice A, is incorrect due to structure-function confusion, as membrane folds for surface area do not imply origin mechanism and overlook the prokaryotic genetic evidence essential for endosymbiosis. To approach similar questions, focus on genetic and ribosomal similarities to prokaryotes to identify endosymbiotic origins over structural adaptations.
- A protist contains an energy-processing organelle with two membranes. Sequencing shows several genes inside the organelle are most similar to genes in modern alphaproteobacteria, while the host nuclear genome lacks these gene versions. The organelle's membranes contain transport proteins that import many nucleus-encoded proteins. Which evidence best supports endosymbiosis as the origin of this organelle?
Answer: Similarity of organelle genes to alphaproteobacterial genes supports endosymbiotic origin.
This question requires analyzing the origins of cell compartmentalization to identify evidence supporting endosymbiotic origin. The correct answer A is supported by the organelle genes being most similar to alphaproteobacterial genes, providing direct molecular evidence that the organelle descended from an alphaproteobacterium ancestor that was engulfed and retained. The presence of these bacterial-like genes inside the organelle, absent from the host nucleus, demonstrates the organelle brought its own genetic material—a definitive marker of endosymbiosis. Answer B incorrectly interprets protein import as evidence for membrane infolding, but this actually shows how endosymbiotic organelles evolved to depend on their hosts after gene transfer—this represents a derived feature confusion error. For endosymbiotic evidence, prioritize genetic similarity to specific bacterial groups over secondary adaptations like protein import.
- A student claims the nucleus originated when an ancient bacterium was engulfed and became the nuclear compartment. However, in a cell lineage being studied, the nuclear envelope is continuous with an internal membrane network, and both membranes have similar lipid composition to the plasma membrane. The nuclear compartment contains linear chromosomes and no bacterial-like ribosomes. Which evidence best supports an alternative origin of the nuclear envelope?
Answer: Continuity of nuclear membranes with internal membranes and similarity to plasma membrane lipids support infolding
This question assesses the analysis of the origins of cell compartmentalization. The correct answer, choice A, is supported by the continuity of nuclear and internal membranes with similar lipid composition to the plasma membrane, aligning with the autogenous infolding model in AP Biology for nuclear envelope formation from plasma membrane invaginations. The presence of linear chromosomes and absence of bacterial-like ribosomes contradict a prokaryotic ancestor, favoring an internal evolutionary process. This evidence refutes the student's engulfment claim by demonstrating integrated membrane systems without symbiotic remnants. A tempting distractor, choice B, is incorrect because it misinterprets linear chromosomes as modified bacterial DNA, representing a level-of-organization error by ignoring the distinction between prokaryotic circular and eukaryotic linear genomes. To address similar claims, evaluate membrane lipid similarities and chromosomal structure to support or refute proposed origins.
- In a eukaryotic alga, mitochondria have double membranes and contain circular DNA and 70S ribosomes. Proteins encoded by nuclear genes are imported into the mitochondria through membrane transport complexes. Which evidence best supports an endosymbiotic origin for mitochondria?
Answer: Mitochondria contain circular DNA and 70S ribosomes inside a double membrane
This question requires analyzing the origins of cell compartmentalization to identify evidence supporting mitochondrial endosymbiosis. The presence of circular DNA and 70S ribosomes within a double membrane (option B) provides the strongest evidence for endosymbiotic origin, as these are bacterial characteristics retained by mitochondria after engulfment of an ancestral bacterium. These features directly reflect the bacterial ancestry of mitochondria—circular DNA resembles bacterial genomes, 70S ribosomes match bacterial ribosome size, and the double membrane resulted from the original bacterial membrane plus the host's phagocytic membrane. Option C (protein import) is incorrect as a primary evidence because while mitochondria do import proteins, this evolved after endosymbiosis as genes transferred to the nucleus, representing a consequence-as-cause error where students confuse later adaptations with original evidence. To identify endosymbiotic origins, prioritize bacterial-like features (circular DNA, 70S ribosomes, binary fission) over derived characteristics.
- A eukaryotic cell contains an organelle that divides by fission and has a double membrane. However, extensive sequencing detects no DNA inside the organelle, and its ribosomes match cytosolic ribosomes rather than bacterial ribosomes. The organelle's membrane proteins are encoded in the nucleus and resemble proteins found in the endomembrane system. Which conclusion is best supported about this organelle's origin?
Answer: It likely originated from infolding and remodeling of host membranes, despite having two membranes.
This question assesses the analysis of the origins of cell compartmentalization. The correct answer, choice B, is indicated by the absence of internal DNA, cytosolic-matching ribosomes, and nuclear-encoded proteins resembling endomembrane system components, suggesting origin from host membrane infolding and remodeling despite the double membrane, as per AP Biology discussions of non-endosymbiotic organelles like peroxisomes. The fission division aligns with host-controlled replication, not independent prokaryotic traits, supporting a derived endomembrane origin. This evidence challenges the typical double-membrane endosymbiosis association, highlighting gene loss or transfer in evolution. A tempting distractor, choice A, is incorrect due to structure-function confusion, overemphasizing double membranes as exclusively endosymbiotic while ignoring the lack of prokaryotic DNA and ribosomes. To approach similar questions, weigh genetic and ribosomal evidence against membrane structure to resolve atypical organelle origins.
- A protist contains a chloroplast-like organelle with two membranes and circular DNA. Sequencing shows several genes in the organelle are most similar to cyanobacterial genes, while other related genes are located in the host nucleus and encode proteins imported into the organelle. The organelle divides independently of the host cell cycle. Which inference best connects these observations to the origin of the organelle?
Answer: The organelle originated by endosymbiosis because cyanobacterial genes and circular DNA persist.
This question requires analyzing the origins of cell compartmentalization to determine how a photosynthetic organelle arose. The correct answer B is supported by multiple endosymbiotic signatures: cyanobacterial genes in the organelle genome, circular DNA organization, independent division from the host cell cycle, and gene transfer to the nucleus with subsequent protein import. These features indicate the organelle descended from an engulfed cyanobacterium that became integrated with the host through gene transfer and protein targeting evolution. Answer D commits a teleological error by suggesting the organelle evolved "to provide glucose"—evolution lacks foresight and organelles arise through mechanistic processes, not purposeful design. To identify endosymbiotic origins, look for phylogenetic evidence (gene similarities to free-living bacteria), genetic integration (gene transfer to nucleus), and retention of bacterial features like circular DNA and autonomous division.
- A eukaryotic cell's mitochondria and chloroplasts each have double membranes and their own circular DNA. The cell's nucleus has a double membrane but contains only the cell's linear chromosomes and no separate genome. Which conclusion is best supported by these observations about compartment origins?
Answer: Mitochondria and chloroplasts likely arose by endosymbiosis, unlike the nuclear envelope
This question requires analyzing the origins of cell compartmentalization to compare different organelle origins based on their characteristics. The presence of circular DNA in mitochondria and chloroplasts but not in the nucleus, despite all having double membranes, supports option A that mitochondria and chloroplasts arose by endosymbiosis while the nuclear envelope arose differently (likely by infolding). The circular DNA in mitochondria and chloroplasts represents retained bacterial genomes from endosymbiotic events, while the nucleus contains only the cell's own linear chromosomes, indicating it formed by membrane reorganization around existing genetic material rather than incorporating a separate organism. Option C (nuclear endosymbiosis) is incorrect because it assumes double membranes alone indicate endosymbiosis, representing a single-feature error where students focus on membrane number rather than the complete evidence package including genome presence/absence. To distinguish organelle origins, evaluate multiple features together—endosymbiotic organelles have their own DNA while infolding-derived structures do not.
- An archaeal species is observed under electron microscopy to have extensive internal membrane folds that increase over generations in a stable environment. The folds are continuous with the plasma membrane and share the same membrane proteins, including transporters found at the cell surface. No separate genome is detected inside the folded regions, and the folds do not divide independently of the cell. Which inference best explains how these compartments could have arisen?
Answer: Plasma membrane infolding generated internal surfaces that retained surface proteins and lacked separate DNA.
This question assesses the analysis of the origins of cell compartmentalization. The correct answer, choice B, is supported by the stimulus showing internal membrane folds continuous with the plasma membrane, sharing the same transporters and lacking a separate genome, which fits the infolding model where plasma membrane extensions create internal surfaces without independent replication. The observation that folds do not divide separately from the cell reinforces that these are extensions of the host membrane, consistent with AP Biology discussions of archaeal membrane complexity evolving through invagination. This mechanism allows for increased surface area for reactions while maintaining connectivity to the cell surface, unlike endosymbiotic organelles. A tempting distractor, choice A, is incorrect due to structure-function confusion, as it attributes the folds to an engulfed bacterium despite the absence of double membranes or internal DNA, which are hallmarks of endosymbiosis. To approach similar questions, evaluate membrane continuity and the absence of independent genetic material to differentiate infolding from endosymbiotic processes.
- In a lab model of early cells, repeated osmotic swelling causes the plasma membrane to invaginate and pinch off, forming internal vesicles. After many cycles, microscopy shows a stable network of internal membranes that remains continuous with the plasma membrane in some regions, and the internal compartments contain the same lipid composition as the cell surface. No internal compartment contains its own DNA, and all ribosomes observed are free in the cytosol. Which explanation best accounts for the origin of these internal membranes?
Answer: Infolding of the plasma membrane produced internal membranes with matching lipids and occasional continuity.
This question assesses the analysis of the origins of cell compartmentalization. The correct answer, choice A, is supported by the stimulus describing internal membranes formed through invagination and pinching off of the plasma membrane, resulting in vesicles with matching lipid composition and occasional continuity, which aligns with the infolding hypothesis for the endomembrane system's origin in eukaryotic cells. The absence of internal DNA and the presence of only free cytosolic ribosomes further indicate that these compartments did not arise from endosymbiotic events, as they lack independent genetic material typical of organelles like mitochondria. This mechanism reflects how early eukaryotic cells could have developed internal compartments to separate biochemical reactions without engulfing prokaryotes, consistent with AP Biology concepts of eukaryotic evolution. A tempting distractor, choice B, is incorrect due to a structure-function confusion, as it assumes endosymbiosis despite the lack of internal DNA or separate ribosomes, which would be expected in an engulfed bacterium. To approach similar questions, compare the presence of independent genomes and membrane continuity to distinguish between infolding and endosymbiotic origins.
- A plant cell organelle is found to have two surrounding membranes and its own circular genome. When treated with antibiotics that inhibit bacterial ribosomes, protein synthesis inside the organelle decreases, while cytosolic protein synthesis is unaffected. The organelle also divides independently by constriction. Which explanation best accounts for the origin of this organelle's compartmentalization?
Answer: Endosymbiosis of a bacterium produced a double-membraned organelle retaining bacterial traits.
This question requires analyzing the origins of cell compartmentalization to explain how a plant organelle with specific characteristics formed. The correct answer B is supported by the combination of double membranes, circular genome, sensitivity to antibiotics targeting bacterial ribosomes, and independent division by constriction—all hallmarks of endosymbiotic origin from an engulfed bacterium. These bacterial-like features indicate the organelle (likely a chloroplast or mitochondrion) retained characteristics from its free-living ancestor after being incorporated into the host cell. Answer A incorrectly suggests nuclear envelope infolding could produce circular DNA, but the nucleus contains linear chromosomes and infolding doesn't introduce new genetic material—this represents a mechanism-product mismatch error. To identify endosymbiotic organelles, look for the complete package of bacterial traits: circular DNA, prokaryotic ribosomes, and independent division.
- In a lab model of early cells, a population of membrane-bound vesicles forms when the plasma membrane repeatedly infolds and pinches off. Microscopy shows that the new internal sacs remain continuous with the plasma membrane in many cells, and their membrane lipids match the plasma membrane lipid composition. No internal compartment contains its own DNA. Over time, some vesicles become densely packed near the cell's genetic material, creating a double-membrane boundary around it that is still connected to the outer membrane at a few points. Which explanation best accounts for the origin of these internal membranes?
Answer: Infolding of the plasma membrane followed by vesicle formation, producing internal membranes with similar lipids
This question assesses the analysis of the origins of cell compartmentalization. The correct answer, choice B, is supported by the stimulus describing repeated infolding and pinching off of the plasma membrane to form internal vesicles that remain continuous with it, aligning with the autogenous model in AP Biology where endomembrane systems arise from invaginations of the cell membrane. The matching lipid composition between internal sacs and the plasma membrane further indicates they originated from the same source without external incorporation, and the formation of a double-membrane boundary around genetic material suggests an evolutionary step toward nuclear compartmentalization. Additionally, the absence of DNA in these compartments rules out endosymbiotic origins, consistent with the infolding mechanism for non-autonomous organelles. A tempting distractor, choice A, is incorrect because it confuses endosymbiosis with infolding by assuming lipid matching implies bacterial engulfment, representing a structure-function confusion where membrane similarity is misinterpreted as evidence of independent origin rather than shared derivation. To approach similar questions, evaluate evidence for membrane continuity and genetic independence to distinguish between autogenous and endosymbiotic origins.
