Cell Cycle Phases Practice Questions
20 free Cell Cycle Phases practice questions for the NCERT Biology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
Which phase of the cell cycle is also known as the resting phase, despite being a period of high metabolic activity and preparation for division?
- A Prophase
- B Interphase
- C Cytokinesis
- D M phase
Correct answer: Interphase
Interphase is the phase between two successive M phases. Although called the resting phase, it is the time during which the cell grows and undergoes DNA replication in an orderly manner.
In a typical 24-hour cell cycle of a human cell, approximately how long does the actual M phase (mitosis) last?
- A 23 hours
- B 12 hours
- C 1 hour
- D 90 minutes
Correct answer: 1 hour
Interphase lasts for more than 95% of the duration of the cell cycle. In a 24-hour cycle, the M phase typically lasts for only about one hour.
During which sub-phase of interphase does the actual replication of DNA take place?
- A G1 phase
- B S phase
- C G2 phase
- D G0 phase
Correct answer: S phase
The S (Synthesis) phase marks the period during which DNA synthesis or replication occurs. During this time, the amount of DNA per cell doubles.
If a cell has 2C amount of DNA at the start of the G1 phase, what will be the amount of DNA after the completion of the S phase?
- A C
- B 2C
- C 4C
- D 8C
Correct answer: 4C
During the S phase, DNA replication results in the doubling of the DNA content. Therefore, if the initial amount is 2C, it increases to 4C by the end of the S phase.
What happens to the chromosome number of a cell after the completion of the S phase if the initial number was 2n?
- A It becomes 4n
- B It remains 2n
- C It becomes n
- D It becomes 3n
Correct answer: It remains 2n
While the DNA amount doubles during the S phase, the chromosome number remains the same. If the cell had 2n chromosomes at G1, it will still have 2n chromosomes at the end of S phase.
In animal cells, besides DNA replication in the nucleus, which of the following events occurs in the cytoplasm during the S phase?
- A Spindle fiber polymerization
- B Centriole duplication in cytoplasm
- C Nuclear envelope breakdown
- D Protein synthesis for G1 preparation
Correct answer: Centriole duplication in cytoplasm
During the S phase, DNA replication begins in the nucleus, and the centriole duplicates in the cytoplasm. This is essential for the later formation of the mitotic apparatus.
The phase of the cell cycle where proteins are synthesized in preparation for mitosis while cell growth continues is:
- A G1 phase
- B S phase
- C G2 phase
- D M phase
Correct answer: G2 phase
The G2 phase (Gap 2) follows the S phase. It is characterized by the synthesis of proteins, such as tubulin, which are required for spindle formation during mitosis.
Cells that do not divide further exit the G1 phase to enter an inactive stage called the:
- A Synthesis phase (S)
- B Gap two phase (G2)
- C Quiescent stage (G0)
- D Mitotic phase (M)
Correct answer: Quiescent stage (G0)
Some cells, like heart cells or nerve cells, do not divide frequently and exit G1 to enter G0. In this stage, cells remain metabolically active but do not proliferate unless called upon to do so.
Which of the following is the correct sequence of phases in the cell cycle?
- A S -> G1 -> G2 -> M
- B G1 -> S -> G2 -> M
- C M -> G1 -> G2 -> S
- D G1 -> G2 -> S -> M
Correct answer: G1 -> S -> G2 -> M
The cell cycle follows a specific chronological order. It begins with G1 (Gap 1), followed by S (Synthesis), then G2 (Gap 2), and finally the M phase (Mitosis).
The G1 phase corresponds to the interval between:
- A Mitosis and DNA replication
- B DNA replication and Mitosis
- C S phase and G2 phase
- D Prophase and Metaphase
Correct answer: Mitosis and DNA replication
G1 is the first growth phase that occurs after the cell has divided (Mitosis) and before it begins to synthesize new DNA (S phase).
Mitosis in most animals is usually restricted to:
- A Haploid cells only
- B Diploid somatic cells
- C Diploid germ cells only
- D Both haploid and diploid cells equally
Correct answer: Diploid somatic cells
In animals, mitotic cell division is typically seen only in diploid somatic cells. However, plants can show mitosis in both haploid and diploid cells.
During which phase does the cell grow and carry out normal metabolism but does not replicate its DNA?
- A G1 phase
- B S phase
- C G2 phase
- D M phase
Correct answer: G1 phase
The G1 phase is a period of intense metabolic activity and cell growth. However, DNA replication is strictly reserved for the subsequent S phase.
A cell in the G0 stage is said to be:
- A Dead and degrading
- B Metabolically inactive and dormant
- C Actively dividing with DNA replication
- D Metabolically active but non-dividing
Correct answer: Metabolically active but non-dividing
Cells in G0 are alive and perform their physiological functions. They have simply suspended the cell cycle and will only re-enter it if specific environmental or hormonal signals are received.
How many minutes does the cell cycle of yeast typically take to complete?
- A 24 hours
- B 60 minutes
- C 90 minutes
- D 120 minutes
Correct answer: 90 minutes
The duration of the cell cycle varies between organisms and cell types. Yeast (Saccharomyces cerevisiae) can progress through a complete cell cycle in about 90 minutes.
The 'M' in M phase stands for:
- A Metabolic phase
- B Meiotic phase
- C Mitosis phase
- D Mesophase
Correct answer: Mitosis phase
The M phase represents the Mitosis phase (or Meiosis in germ cells), which is the most dramatic period of the cell cycle involving a major reorganization of virtually all cell components.
Which phase is characterized by the duplication of the cell's organelles and increase in cytoplasm, but not DNA?
- A G1 phase
- B S phase
- C Cytokinesis
- D Interphase
Correct answer: G1 phase
During G1, the cell is metabolically active and continuously grows by increasing its cytoplasmic volume and duplicating organelles, preparing for the DNA replication of the S phase.
The decision for a cell to divide is primarily made in which phase?
- A G1 phase
- B S phase
- C G2 phase
- D M phase
Correct answer: G1 phase
G1 is the 'decision-making' phase. If the environment is favorable and the cell receives growth signals, it passes the G1 checkpoint to commit to DNA replication in the S phase.
Which of the following describes the G2 phase correctly?
- A DNA content is 2C
- B DNA content is 4C
- C Chromosome number is 4n
- D Centrioles are yet to duplicate
Correct answer: DNA content is 4C
Since G2 follows the S phase (where DNA is replicated), the DNA content per cell remains at the doubled level (4C) until the cell finishes mitosis.
Interphase is often called the 'resting phase' because:
- A The cell is fully dormant and inactive
- B Chromosomes show no visible structural change
- C The cell consumes no energy during this phase
- D The nucleus disappears completely
Correct answer: Chromosomes show no visible structural change
It was historically called 'resting' because early microscopists could not see any chromosomal activity. We now know it is a period of intense biochemical preparation for cell division.
In which stage of the cell cycle are tubulin proteins synthesized?
- A G1 phase
- B S phase
- C G2 phase
- D G0 phase
Correct answer: G2 phase
Tubulin is the protein that makes up microtubules, which form the spindle fibers during mitosis. Its synthesis occurs primarily during the G2 phase.