Cells
A cell contains abundant rough ER and Golgi apparatus but has unusually few lysosomes. Which cellular function would most likely remain efficient while another becomes impaired?
A. DNA replication would increase while transcription decreases.
B. Protein secretion could remain active while intracellular waste degradation becomes less efficient.
C. ATP production would increase while protein synthesis stops.
D. Photosynthesis would continue while protein secretion stops.
E. Diffusion would stop while osmosis increases.
B. Protein secretion could remain active while intracellular waste degradation becomes less efficient.
A student places an animal cell in three solutions. Cell X swells, Cell Y remains approximately unchanged, and Cell Z shrinks. Which classification is most appropriate?
A. X is isotonic, Y is hypertonic, Z is hypotonic.
B. X is hypotonic, Y is isotonic, Z is hypertonic.
C. X is hypertonic, Y is hypotonic, Z is isotonic.
D. All three solutions are isotonic.
E. X and Z are isotonic while Y is hypertonic.
B. X is hypotonic, Y is isotonic, Z is hypertonic.
A student measures a cell as 5 mm across in a microscope image. The microscope is operating at 400× total magnification. What is the approximate actual diameter of the cell?
A. 0.0125 mm
B. 2 mm
C. 0.125 mm
D. 0.0125 mm or 12.5 μm
E. 20 mm
D. 0.0125 mm or 12.5 μm
A researcher observes homologous chromosomes paired together as tetrads. Which stage is being observed?
Prophase I
A. Carbon dioxide provides all the oxygen released by photosynthesis.
B. Water contributes oxygen atoms that can ultimately be released as molecular oxygen.
C. Glucose is converted directly into oxygen.
D. Oxygen gas enters the chloroplast and is released unchanged.
E. ATP is the source of oxygen gas.
B. Water contributes oxygen atoms that can ultimately be released as molecular oxygen.
A lysosomal enzyme is accidentally released into the cytoplasm and becomes active. Which outcome is most concerning?
Digestion or damage of cellular macromolecules and organelles
A cell is placed in a solution containing a high concentration of sodium ions. However, the cell maintains a much higher sodium concentration outside than inside despite sodium naturally tending to diffuse inward. Which mechanism is most likely responsible?
Active Transport
A student observes a specimen using a 10× ocular lens and a 20× objective. The field of view has a diameter of 1.0 mm. If the objective is changed to 40×, what would be the approximate field-of-view diameter, assuming the relationship is inversely proportional to magnification?
A. 4.0 mm
B. 2.0 mm
C. 0.5 mm
D. 0.25 mm
E. 0.05 mm
C. 0.5 mm
A. DNA replication
B. Cytokinesis
C. Independent assortment
D. Binary fission
E. Chromosome duplication
C. Independent assortment
A muscle cell suddenly requires large amounts of ATP during intense exercise. Oxygen delivery becomes insufficient. Which metabolic response would help the cell continue producing some ATP?
Anaerobic glycolysis followed by fermentation
A researcher observes a cell with an extensive smooth ER network. Which cellular function would most likely be particularly important in this cell?
Lipid synthesis and detoxification
A glucose molecule cannot cross the phospholipid bilayer efficiently because of its size and polarity. However, glucose enters a cell through a membrane protein down its concentration gradient. What type of transport is occurring?
Facilitated Diffusion
A student estimates that four cells fit across a microscope's 1-mm field of view. Assuming the cells are approximately equal in size and arranged edge-to-edge, what is the approximate diameter of one cell?
0.25 mm
A human gamete is found to contain 24 chromosomes instead of the normal 23. Which event could have produced this condition?
Nondisjunction
A. Glycolysis
B. DNA replication
C. ATP production by chemiosmosis
D. Glucose breakdown in the cytoplasm
E. Pyruvate formation
C. ATP production by chemiosmosis
A drug blocks the formation of spindle microtubules during mitosis. Which cellular structure is most directly associated with organizing these microtubules in animal cells?
Centrosome
A scientist adds a drug that prevents vesicles from fusing with the plasma membrane. A cell continues synthesizing a secreted protein, but the protein accumulates inside the cell. Which process has been directly blocked?
Exocytosis
A researcher wants to observe the ultrastructure of mitochondria, including details of their internal membranes that cannot be resolved using visible light. Which instrument would be most appropriate?
Transmission electron microscope (TEM)
Two siblings inherit different combinations of alleles from the same parents. Which meiotic processes best explain this variation?
Crossing over and independent assortment
A mutation prevents pyruvate from entering mitochondria. Which process would be most directly affected?
Transition Reaction or Grooming Stage
A mutation disrupts the mitochondrial inner membrane. Which process would be most directly affected?
Oxidative phosphorylation and efficient ATP production
A cell is placed in a solution with the same effective solute concentration as its cytoplasm. After several minutes, water molecules continue moving across the membrane in both directions, but the cell's overall volume remains nearly constant. Which concept best explains the observation?
Dynamic Equilibrium
A scientist wants to observe the three-dimensional surface features of a pollen grain at very high resolution. Which instrument would be more appropriate?
Scanning electron microscope (SEM)
A species has three homologous chromosome pairs. Assuming independent assortment occurs normally, how many different combinations of maternal and paternal chromosomes can potentially occur in gametes, ignoring crossing over?
23 = 8
A poison prevents oxygen from accepting electrons at the end of the mitochondrial electron transport chain. Why is this especially harmful for normal oxidative phosphorylation?
Oxygen is required as the final electron acceptor to form water