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

The text states: 'Meiosis involves two sequential cycles of nuclear and cell division called meiosis I and meiosis II but only a single cycle of DNA replication.' and 'Meiosis I is initiated after the parental chromosomes have replicated to produce identical sister chromatids at the S phase.'

The context clearly states: 'It is called the reduction division since it reduces the chromosome number by half while making the gametes.'

The NCERT text explicitly highlights: 'It also increases the genetic variability in the population of organisms from one generation to the next. Variations are very important for the process of evolution.'

The text describes: 'This is followed by anaphase I in which homologous chromosomes move to the opposite poles with both their chromatids. Each pole receives half the chromosome number of the parent cell.'

The context starts the section on meiosis by stating: 'The production of offspring by sexual reproduction includes the fusion of two gametes, each with a complete haploid set of chromosomes.'

The text states: 'Four haploid cells are formed at the end of meiosis II.' and 'cytokinesis follows resulting in the formation of tetrad of cells i.e., four haploid daughter cells (Figure 10.4).'

The NCERT text states: 'During metaphase I the bivalents arrange on the equatorial plate.'

According to the NCERT text, 'In animals, mitotic cell division is only seen in the diploid somatic cells.' This implies that the resulting daughter cells will also be diploid, maintaining the chromosome number. Therefore, mitosis in animal somatic cells always produces diploid cells.

The NCERT states, 'Cell growth results in disturbing the ratio between the nucleus and the cytoplasm. It therefore becomes essential for the cell to divide to restore the nucleo-cytoplasmic ratio.' This disturbance occurs because cell growth (in terms of cytoplasmic increase) is a continuous process, leading to a larger cytoplasmic volume relative to the nucleus. Mitosis then divides the cell, restoring the optimal ratio.

The context mentions, 'These cells that do not divide further exit $G_1$ phase to enter an inactive stage called quiescent stage ($G_0$) of the cell cycle. Cells in this stage remain metabolically active but no longer proliferate unless called on to do so depending on the requirement of the organism.'