All AP Biology Resources
Example Questions
Example Question #28 : Understanding The Cell Cycle
Which of the following is the shortest part of the cell cycle?
G0 phase
Interphase
Mitosis
S phase
G1 phase
Mitosis
Mitosis is the shortest part of the cell cycle. The cell spends most of its time growing in interphase which includes G1, S, and G2 phases. G0 phase involves cells that either very rarely divide, or do not divide at all. An example of a cell type in G0 phase is a neuron.
Example Question #29 : Understanding The Cell Cycle
Interphase is divided in which of the following subphases?
S1 phase and S2 phase
G1 phase and G2 phase
G1 phase, G2 phase, and G3 phase
G1 phase, S phase, and G2 phase
None of these
G1 phase, S phase, and G2 phase
Interphase is divided into G1, S, and G2 phases. It is during interphase that the cell grows by making proteins and cytoplasmic organelles. During S phase, the DNA is replicated, yielding sister chromatids. G2 involves the last bit of growth, and also, DNA proofreading and repair.
Example Question #251 : Cellular Biology
During which subphase of interphase are chromosomes duplicated?
S phase
G2 phase
Metaphase
Prophase
G1 phase
S phase
Interphase consists of the G1 phase, the S phase, and the G2 phase. Only during the S phase (Synthesis) are the chromosomes (DNA) replicated.
Example Question #31 : Understanding The Cell Cycle
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
III only
IV only
I and IV
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 #151 : Cell Functions
The regulatory subunit of maturation-promoting factor __________.
transfers a phosphate group to certain serine and threonine residues of specific protein substrates
converts ATP to ADP
is called cyclin because its concentration rises and falls predictably as the cell cycle progresses
converts ADP to ATP
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 #152 : Cell Functions
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
I, II, III, and IV
I and II
I, II, and III
IV only
II only
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 #261 : Cellular Biology
__________ 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.
Chaperones
Monitors
Activation energies
Checkpoints
Allosteric inhibitors
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 #33 : Cellular Division
Which of the following is a trait unique to cancer cells?
They have escaped form cell cycle controls and inhibitions
Density-dependent growth factors limit their division
They do not use glucose as an energy source
They do not undergo interphase
They communicate with other cells through chemical signalling
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 #262 : Cellular Biology
What is the correct order of the cell cycle?
G1, G2, M, S
S, G1, G2, M
G1, G2, S, M
G1, S, M, G2
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.