Cell cycle and Cell Divisions MCQs for NEET — Botany Questions with Answers

In the cell cycle, the G1 phase is the first gap phase where the cell grows and synthesizes proteins and organelles but does not synthesize DNA (q). The S phase (synthesis phase) is where DNA replication occurs (p). The G2 phase is the second gap phase where the cell prepares for mitosis, and DNA synthesis stops (r). Therefore, the correct matching is: G1 phase - Synthesis of DNA does not occur (q), G2 phase - DNA synthesis stops (r), S phase - Synthesis of new DNA (p).

During anaphase, spindle fibers shorten, which helps pull the sister chromatids toward the opposite poles of the cell. This is a critical step in ensuring that each daughter cell will receive an identical set of chromosomes.

During telophase-I of meiosis, the nuclear envelope reforms around each set of chromosomes. This marks the end of the first meiotic division and the beginning of the formation of two separate nuclei.

DNA replication occurs during the S-phase (Synthesis phase) of the cell cycle. This phase follows the G1 phase and precedes the G2 phase and is essential for ensuring that the genetic material is accurately copied before cell division.

During telophase, the nuclear membrane and nucleolus reappear. This stage marks the end of nuclear division, where the chromosomes reach opposite poles, and the cell prepares to divide its cytoplasm, resulting in the formation of two daughter cells.

Meiosis is a type of cell division that reduces the chromosome number by half, resulting in four daughter cells. This process is crucial for sexual reproduction and involves two consecutive divisions: meiosis I and meiosis II. Each of the four daughter cells has half the number of chromosomes as the original cell, making them haploid.

Crossing over occurs during prophase I of meiosis at specific points called chiasmata. These are the locations where homologous chromosomes exchange genetic material, which increases genetic diversity in the offspring.

Higher plant cells typically do not have centrioles. Centrioles are involved in the formation of spindle fibers during cell division in animal cells, but plant cells form spindle fibers without centrioles. Instead, they use other microtubule-organizing centers.

In mitosis, each cell divides into two. So starting from a single cell, the increase in a number of cells will occur as per the following progression- 1->2->4->8->16->32->64->128.

The correct order of stages in cell division is prophase, metaphase, anaphase, and telophase. In prophase, the chromatin condenses into visible chromosomes. During metaphase, the chromosomes align at the cell's equatorial plane. In anaphase, the chromatids are pulled apart to opposite poles of the cell. Finally, during telophase, the chromosomes de-condense, and the nuclear envelope re-forms around each set of chromosomes.