Biology · Cell Cycle and Cell Division · NEET
The cell cycle is the full set of steps a cell goes through from the time it is made until it divides into two new cells. NCERT defines it as the sequence of events by which a cell duplicates its genome (copies its DNA), synthesises the other parts of the cell, and finally divides into two daughter cells. Think of it as one full round: copy, grow, then split.
Cells divide for three main reasons. First, growth: every large organism starts as a single cell, and repeated cycles of growth and division turn that one cell into millions. Second, repair: cells divide to replace cells lost due to injury or cell death. Third, to keep the nucleus-to-cytoplasm ratio balanced, because a cell that grows too big must divide. For NEET, remember growth, repair and replacement.
No, and NTA tests this. Cell division (the M phase, about 1 hour in a human cell) is only the final, short part. The cell cycle is the whole thing, and more than 95% of it is interphase, when the cell grows and copies its DNA. So cell division is one step inside the larger cell cycle, not the whole cycle.
DNA is copied only during the S phase (Synthesis phase) of interphase, not throughout the cycle. Cell growth (cytoplasm increase) is continuous, but DNA synthesis happens only in this one specific stage. This is a very common NEET point: growth is continuous, DNA replication is stage-specific.
No. Some cells, like heart muscle cells, do not divide again. They exit the G1 phase and enter a resting stage called the quiescent stage or G0. These cells stay metabolically active but stop dividing unless the body needs them to. So the cell cycle can pause, and not every cell repeats it.
Following are the stages of cell division: A. Gap 2 phase B. Cytokinesis C. Synthesis phase D. Karyokinesis E. Gap 1 phase Choose the correct sequence of stages from the options given below:
The correct sequence of phases of cell cycle is:
Try the real previous-year questions from this chapter — each with the answer and a full solution.
The cell cycle is the sequence of events by which a cell duplicates its genome, synthesises the other constituents of the cell, and eventually divides into two daughter cells. This is the exact NCERT wording, so use it in exams.
Interphase (the preparation phase, over 95% of the cycle) and the M phase (actual cell division, about 1 hour in a human cell). Interphase is further split into G1, S and G2.
A typical human cell in culture divides about once every 24 hours. But this varies: yeast can complete the cell cycle in only about 90 minutes. Duration changes with organism and cell type.
Because the cell needs a long time to grow and copy all its DNA and cell parts before dividing. The actual division (M phase) is quick, only about an hour, so interphase takes up the rest.
