Class 11 Biology - PUNJAB
Cell Cycle and Cell Division
The chapter 'Cell Cycle and Cell Division' in Class 11 Biology explores the fundamental biological process of how a single cell divides to form daughter cells. Punjab (PSEB) students will learn about the phases of the cell cycle, including Interphase and M-phase, and study the two major types of cell division: Mitosis (equational division) and Meiosis (reductional division). Understanding this chapter is crucial as it forms the basis of growth, repair, and reproduction in living organisms. It consistently carries significant weight in board exams through direct questions on chromosomal movements, phases of mitosis/meiosis, and the biological importance of crossing over.
Start Learning FreeKey Concepts
Cell Cycle
The series of events that take place in a cell leading to its replication and division, consisting of Interphase and M-phase.
Interphase
The resting or preparatory phase of the cell cycle divided into G1 phase, S phase (DNA synthesis), and G2 phase.
Mitosis
A type of cell division resulting in two daughter cells each having the same number and kind of chromosomes as the parent nucleus, known as equational division.
Meiosis
A specialized type of cell division that reduces the chromosome number by half, creating four genetically distinct haploid cells, essential for sexual reproduction.
Crossing Over
The exchange of genetic material between non-sister chromatids of homologous chromosomes during pachytene of meiosis I, leading to genetic variation.
Important Formulas
Board Exam Info
In Punjab (PSEB) Class 11 Biology exams, this chapter typically carries around 5 to 7 marks. Questions usually include short-answer questions on phases like anaphase or prophase I, differences between mitosis and meiosis, and long-answer questions detailing the events of meiosis with diagrams.
Frequently Asked Questions
What is the difference between mitosis and meiosis?
Mitosis is equational division producing two identical diploid cells for growth and repair, while meiosis is reductional division producing four genetically different haploid cells for sexual reproduction.
Why is S phase important in the cell cycle?
S phase (Synthesis phase) is crucial because DNA replication takes place during this time, doubling the amount of DNA without increasing the chromosome number.
What is synapsis and when does it occur?
Synapsis is the pairing of homologous chromosomes, which occurs during the zygotene stage of Prophase I in meiosis.
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