1 markWhich of the following is a key structural difference between prokaryotic and eukaryotic cells?
Only eukaryotic cells have ribosomes.
Only eukaryotic cells have membrane-bound organelles.
Prokaryotic cells store DNA inside a nucleus.
Eukaryotic cells lack a plasma membrane.
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1 markWhich of the following lists contains only examples of membrane-bound organelles?
Nucleus, vacuole and ribosomes.
Nucleoid, mitochondria and Golgi apparatus.
Mitochondria, plasma membrane and chloroplasts.
Mitochondria, chloroplasts and rough endoplasmic reticulum.
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1 markWhich of the following correctly describes endosymbiotic theory?
Membrane-bound organelles evolved from once free-living prokaryotic cells via endosymbiosis.
Membrane-bound organelles are prokaryotic cells living with other cells by endosymbiosis
One cell engulfs another cell, taking it into a vacuole within its cytoplasm.
All eukaryotic cells evolved from a common unicellular ancestor.
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1 markEukaryotic cells and prokaryotic cells have many similarities and differences.
Which of the following best describes prokaryotes?
Prokaryotes contain many internal membrane-bound organelles.
Prokaryotic cells have internal regions with specialized structures and functions.
The organelles of prokaryotic cells evolved from once free-living eukaryotic cells via endosymbiosis.
Prokaryotic cells contain organelles that were once free-living prokaryotic organisms such as bacteria.
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1 markResearchers investigated membrane-bound organelles using soft X-ray tomography (SXT), a high-resolution, quantitative imaging technique, to measure cell size and organelle volumes in yeasts during different stages of the cell cycle. Their results are shown in Figure 1.
Which of the following conclusions is best supported by the data shown in Figure 1?
The surface area of organelles does not change between the stages of the cell cycle.
The nucleus has the largest surface area in all stages of the cell cycle.
Lipid bodies have the smallest surface area in all stages of the cell cycle.
The surface area of organelles is highest during mitosis.
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1 markEndosymbiotic theory dates back over 100 years. It states that organelles in eukaryotic cells are thought to have evolved from bacteria through endosymbiosis.
Which of the following lists contains examples of organelles that have arisen by endosymbiosis?
Mitochondria and chloroplasts.
Mitochondria, nucleus and ribosomes.
Chloroplast, mitochondria and lysosomes.
Mitochondria and vacuoles.
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1 markLipid metabolism in the liver is catalyzed by membrane-bound enzymes within the cells.
Scientists investigated the effects of Poria cocos mushroom extracts and protein powders on lipid metabolism in obese mice. Mice were fed different diets, and their lipid metabolism was measured using triglyceride concentration (TG mol/L). The results of the investigation are shown in Figure 1.
Which of the following conclusions is best supported by the data shown in Figure 1?
Diet type has a significant impact on lipid metabolism in mice.
A high fat diet significantly increases triglyceride concentration in obese mice.
A normal diet significantly lowers triglyceride concentration in obese mice.
Any difference in triglyceride concentration between obese mice with different diets is due to chance.
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Membrane-bound organelles allow for compartmentalization within a cell.
Which of the following is not a benefit of having membrane-bound organelles in cells?
The reactions within an organelle can be kept separate from the organelle exterior.
There is increased internal surface area for chemical reactions.
All reactions can take place within organelles.
Lytic enzymes are kept out of the cytoplasm.
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1 markA study investigated the relationship between inner mitochondrial membrane surface area and ATP production in different cell types. Table 1 contains some data from the study:
Table 1. Inner mitochondrial membrane surface area and rate of ATP production in four cell types
Cell type | Inner mitochondrial membrane surface area / µm² | Rate of ATP production / mmol min-1 |
|---|---|---|
Nerve | 210 | 0.9 |
Liver | 310 | 1.4 |
Muscle | 400 | 2.2 |
Skin | 150 | 0.5 |
A student hypothesized that the relationship between membrane surface area and ATP production is directly proportional.
Which of the following statements about the data and the hypothesis is correct?
Muscle cells have the highest ATP production per unit surface area, supporting the hypothesis.
Cells with a higher inner mitochondrial membrane surface area have a higher rate of ATP production, supporting the hypothesis.
This data cannot be used to support or disprove the hypothesis.
Approximately doubling the membrane surface area, e.g. from 210 µm² (nerve cell) to 400 µm² (muscle cell) does not result in a doubled rate of ATP production, disproving the hypothesis.
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1 markThe endoplasmic reticulum (ER) is a cellular compartment that has a crucial role in the production and processing of cellular proteins. During periods of ER stress, e.g. oxygen deprivation or temperature change, unfolded proteins can accumulate inside the ER, leading to the unfolded protein response (UPR). Figure 1 shows how the transfer of Kar2p chaperone proteins to unfolded proteins allows the activation of Ire1p which initiates the UPR.
Which of the following statements about the UPR activation mechanism is most likely to be correct?
Activated Ire1p functions as a channel protein, allowing unfolded proteins to exit the ER.
UPR gene expression is switched on when transcription factors bind to the promoters of UPR genes.
The ER compartment separates the ER stress response from other cellular functions in the cytoplasm.
ER stress activates Ire1p, resulting in the removal of exons by splicing.
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1 markA research team investigating the evolutionary origins of mitochondria compared the folds of the inner mitochondrial membrane (cristae) and folded structures called intracytoplasmic membranes (ICMs) in Alphaproteobacteria.
During this analysis they examined the structure and function of two proteins:
Mic60, part of the Mitochondrial Contact site and Cristae Organizing System (MICOS), which maintains cristae in mitochondria
alphaMic60, found in ICM-forming Alphaproteobacteria
The locations of the two proteins are shown in Figure 1.
Which of the following would be a suitable hypothesis for the protein analysis described above?
Mitochondrial cristae evolved from ICMs via the retention and modification of the alphaMic60 protein.
Cristae evolved in Alphaproteobacteria before the evolution of the first eukaryotic cells.
Alphaproteobacteria function as mitochondria inside modern eukaryotic cells.
The Mic60 protein in MICOS of modern mitochondria is homologous to the alphaMic60 protein in the ICMs of Alphaproteobacteria.
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