Consider the given two statements:
I. | Sex chromosomes in male mammals also undergo synapsis in meiosis I |
II. | Sex chromosomes are homologous chromosomes |
1. | Both I and II are correct and II explains I |
2. | Both I and are correct but II does not explain I |
3. | I is correct and II is incorrect |
4. | Both I and II are incorrect |
If a cell in S phase is fused with a cell in G1:
1. | The G1 nucleus immediately enters the S phase |
2. | The S nucleus stops DNA replication |
3. | The G1 nucleus directly enters G2 phase |
4. | Both nuclei enter the M phase immediately |
Cyclins and cyclin-dependent kinases (CDKs) are:
1. | Two key classes of regulatory molecules that determine a cell's progress through the cell cycle |
2. | The products of the proto-oncogenes in a eukaryotic cell |
3. | Two very important promoters that are involved in oncogenes |
4. | Mediators of apoptosis |
A cell passes the G1/S transition. This cell will:
1. | be allowed to replicate DNA only if there is adequate nutrients and growth signaling. |
2. | progress through S-phase even if environmental conditions become unfavorable. |
3. | become quiescent if the environmental conditions become unfavorable. |
4. | not be subjected to any control check point during the completion of the cycle. |
Apart from tissue stem cells, which of the following cells in the human body are good examples of being in reversible G0 phase?
1. | Mature hepatocytes |
2. | Senescent cells |
3. | Differentiated muscle |
4. | Differentiated bone |
If an organisms lives in an environment that increases the risk of damage to chromosomes, which of the following would be beneficial?
1. | Development of gametes into individuals without fertilization |
2. | Reproduction by binary fission |
3. | Syngamy |
4. | A life cycle excluding meiosis |
Destruction of both centrosomes with a laser beam in an animal cell:
1. | will prevent both mitosis and cytokinesis |
2. | prevents cytokinesis even if mitosis has been completed normally |
3. | permits cytokinesis but the daughter cells fail to enter a new S phase |
4. | prevents mitosis but permits cytokinesis |
Anaphase is characterized by two distinct motions. The second motion, anaphase B:
1. | moves chromosomes to either pole of a dividing cell and this movement is primarily generated by the action of kinetochore microtubules. |
2. | moves chromosomes to either pole of a dividing cell and this movement is primarily generated by the action of interpolar microtubules. |
3. | involves the separation of the two poles from each other and the movement for this is primarily generated by the action of kinetochore microtubules. |
4. | involves the separation of the two poles from each other and the movement for this is primarily generated by the action of interpolar microtubules. |
A bacterium divides every 35 minutes. If a culture containing 105 cells per mL is grown for 175 minutes, what will be the cell concentration per mL after 175 minutes ?
1. 175 × 105 cells
2. 85 × 105 cells
3. 35 × 105 cells
4. 32 × 105 cells
During which phase of the cell cycle does a mature human RBC replicate its DNA?
1. S phase
2. G1 phase
3. G2 phase
4. None