Class 10 Science - ICSE-BIOLOGY
Cell Cycle, Cell Division and Structure of Chromosomes
This chapter explores the fundamental biological processes of life: how cells grow, divide, and pass on genetic information. Students will learn about the cell cycle stages (Interphase and M-phase), mitosis and meiosis with their biological significance, and the detailed ultrastructure of a chromosome, including DNA, histones, and centromeres. For ICSE Class 10 Biology board exams, this is a high-scoring and conceptually vital unit. Examiners frequently test the phases of cell division, differences between mitosis and meiosis, chromosome terminology (chromatids, chromatin, centromere), and diagram-based questions identifying specific stages of division.
Start Learning FreeKey Concepts
Cell Cycle
The regular sequence of growth and division that a cell undergoes, consisting of Interphase (resting/growth phase) and M-Phase (cell division).
Mitosis
Equational cell division occurring in somatic cells, resulting in two genetically identical daughter cells with the same number of chromosomes as the parent cell.
Meiosis
Reductional cell division occurring in reproductive cells, producing four genetically diverse haploid daughter cells essential for sexual reproduction.
Structure of Chromosome
Condensed chromatin threads made of DNA and histone proteins, visible during cell division, featuring sister chromatids joined at a primary constriction called the centromere.
DNA and Genes
DNA (Deoxyribonucleic acid) is the genetic material carrying hereditary information, organized into functional segments called genes on chromosomes.
Important Formulas
Board Exam Info
In ICSE Biology (Class 10), this chapter typically carries around 8 to 12 marks. Questions frequently appear as diagram-based identification of cell division phases, structural labeling of chromosomes, direct differences between mitosis and meiosis, and reasons for biological phenomena like crossing over or genetic variation.
Frequently Asked Questions
Why is mitosis called equational division?
Mitosis is called equational division because the chromosome number in the parent cell remains equal to the chromosome number in the resulting daughter cells.
What is the main difference between chromatin and chromosomes?
Chromatin is the long, thin, uncoiled thread-like form of DNA found during interphase, whereas a chromosome is the highly condensed and tightly coiled form visible during cell division.
Why does meiosis result in haploid cells?
Meiosis involves two nuclear divisions with only one DNA replication phase, which halves the chromosome number to ensure that the fusion of gametes during fertilization restores the normal diploid number of the species.
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