All AP Biology Resources
Example Questions
Example Question #31 : Cellular Division
Which of these is/are point(s) at which the cell cycle is controlled?
I. G1/S
II. S/M
III. G1
IV. G2/M
V. Telophase and cytokinesis
III and V
I, II, III, IV, and V
I and IV
IV only
III only
I and IV
The two major checkpoints that control the cell cell are the transition between G1/S and G2/M phases of the cell cycle. The G1/S checkpoint will monitor DNA damage prior to the cell entering the S phase for replication. Following replication during S phase, the G2/M checkpoint ensures DNA replication happened correctly. At both these checkpoints, the cell will slow down until any problems detected by the checkpoints are resolved so that the cell does not replicate defective cells. Without these checkpoints, mutations and disease processes such as cancer can occur and these diseased cells may replicate freely. There is also another checkpoint in the M phase that will ensure that the spindle fibers are correctly formed and the chromosomes are correctly aligned along the metaphase plate in order for anaphase to follow normally.
Example Question #32 : Cellular Division
The regulatory subunit of maturation-promoting factor __________.
converts ATP to ADP
converts ADP to ATP
transfers a phosphate group to certain serine and threonine residues of specific protein substrates
is called cyclin because its concentration rises and falls predictably as the cell cycle progresses
removes a phosphate group from certain tyrosine residues of specific protein substrates
is called cyclin because its concentration rises and falls predictably as the cell cycle progresses
Cyclin controls the progression since cyclin-dependent kinases (CDK's) are inactive unless bound to cyclins, this is what controls the cell cycle progression. The cyclin levels in the cell will control the activity of CDK's. If they are bound, the CDK's are then phosphorylated by distinct kinases, which leads to their activation and subsequent downstream effects. Cyclins do not directly remove a phosphate from ATP to ADP. They also do not directly phosphorylate anything in the answer choices, they specially bind the CDK and that process regulates if the cell cycle is up or down regulated in the cell.
Example Question #33 : Cellular Division
Which of the following does not regulate cyclin-dependent kinases (CDK's) to influence a cell's progress through the cell cycle?
I. Cyclin concentration
II. CDK phosphorylation/unphosphorylation
III. Subcellular localization
IV. Controlled cell lysis
IV only
I, II, and III
I, II, III, and IV
II only
I and II
IV only
Cell lysis is not regulated by cyclin-dependent kinases (CDK). Cyclin concentration, CDK phosphorylation/unphosphorylation, and subcellular localization all influence a cell's progress through the cell cycle. The main control of the cell cycle speed and regulation is cyclin concentration, which is responsible for regulating CDK activity. CDK is inactive if cyclin concentration is low, and is active if cyclin concentration is high. Also, CDK control phosphorylation/unphosphorylation depending on its activity level based on cyclin concentration, this process also control the cell cycle progression. Lastly, subcellular localization controls concentration by sequestering cyclin/CDK complexes in different locations to control concentration levels that affect cell cycle progression.
Example Question #34 : Understanding The Cell Cycle
__________ are surveillance mechanisms that halt the progress of the cell cycle if any of the various events involved not working correctly or are not happening in the correct order.
Allosteric inhibitors
Chaperones
Activation energies
Monitors
Checkpoints
Checkpoints
Checkpoints are what monitor and control the process of the cell cycle and lower incidence of problems with cell growth and replication. The major three checkpoints in the cell cycle are the checkpoint before the S phase at the end of G1 phase to check for DNA damage. The second checkpoint is in the G2 phase before the M phase. The third major checkpoint in the cell cycle in at the end of M phase before anaphase occurs. Checkpoints are the points of control in the cell cycle regulation that are regulated by cyclin dependent kinases and cyclin levels; each checkpoint has its unique cyclins.
Example Question #35 : Understanding The Cell Cycle
Which of the following is a trait unique to cancer cells?
Density-dependent growth factors limit their division
They have escaped form cell cycle controls and inhibitions
They communicate with other cells through chemical signalling
They do not use glucose as an energy source
They do not undergo interphase
They have escaped form cell cycle controls and inhibitions
Cancer cells are not controlled by cyclins and cyclin-dependent kinases, which regulate the cell cycle. They would not proceed through interphase if the system of checkpoints was still in place. The system of chemical signaling is mostly destroyed, preventing the cancer cells from being controlled by surrounding normal cells. Cancer cells, like virtually all body cells, utilize glucose for energy.
Example Question #36 : Understanding The Cell Cycle
What is the correct order of the cell cycle?
G1, S, M, G2
G1, G2, M, S
S, G1, G2, M
G1, G2, S, M
G1, S, G2, M
G1, S, G2, M
G1 (gap 1 phase) is the first stage of the cell cycle. Growth and some preparation for cell division occurs in this stage. If the cell is not preparing to divide then it enters the G0 stage (gap 0 phase): the resting gap stage where neither growth nor division occurs. The S stage (DNA Synthesis phase) comes next and there chromosome duplication occurs. G2 (gap phase 2) is after the S stage and there cell growth continues and everything is checked to make sure the cell can divide. Finally, M stage (mitotic stage) is last and there mitosis occurs and two new daughter cells begin the cell cycle again. Keep in mind that at the end of each stage there are "checkpoints" that the cell needs to pass in order to keep going forward. Cancer occurs when a cell bypasses those checkpoints and continues to replicate without those controls.
Example Question #34 : Understanding The Cell Cycle
When does chromosome duplication occur?
Prophase
G0 Stage
Prometaphase
Metaphase
Interphase
Interphase
It is important to note that chromosome duplication happens before mitosis, so interphase is correct. More specifically, it happens in the S stage of interphase.
Example Question #264 : Cellular Biology
In which of the following cell cycle phases does DNA replication occur?
G1 phase
G2 phase
M Phase
S phase
G0 phase
S phase
The "S" phase, known as the synthesis phase, is the portion of the cell cycle where DNA is replicated. The other stages listed do not contain DNA replication. G0 is a cell cycle arrest phase, where a cell remains dormant, awaiting signals to re-enter the cell cycle.
Example Question #34 : Cellular Division
Which of the following terms is used to describe programmed cell death?
Procaspases
Caspases
Necrosis
Anaphase
Apoptosis
Apoptosis
Caspases are proteases that initiate apoptosis. Procaspases are inactive caspases that are stored in the cell. Necrosis is when the cell body dies due to cell injury. Apoptosis is programmed cell death. The cell uses it to control the rate of cell division. Anaphase is a phase in the cell cycle in which the chromosomes are pulled to opposite poles of the cell.
Example Question #1 : Understanding Mitosis
How is metaphase of mitosis defined?
Sister chromatids begin to separate and form independent chromosomes.
DNA begins to replicate.
Two distinct cells begin to form and separate from one another.
Centrioles begin to move towards opposite poles of the cell.
Chromosomes move towards the center or equator of the cell. Chromatids have not separated.
Chromosomes move towards the center or equator of the cell. Chromatids have not separated.
Metaphase is defined when chromosomes move towards the equator of the cell.
Other answers refer to other stages of mitosis. Sister chormatids separate during anaphase, two distinct cells form during telophase, centrioles move towards opposite poles of the cell during prophase, and DNA replication happens during interphase.
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