📌Definition Table

Term	Definition
Growth	Increase in size and mass of organisms, requiring cell proliferation.
Reproduction	Biological process of producing offspring; may be sexual or asexual.
Differentiation	Process by which cells become specialised for particular functions.
Regeneration	Replacement or repair of damaged tissue through cell division.
Asexual reproduction	Production of offspring genetically identical to parent via mitosis.
Sexual reproduction	Production of genetically diverse offspring via meiosis and fertilisation.

📌Introduction

Cell division underpins growth, development, reproduction, and tissue maintenance in all organisms. Mitosis drives somatic growth and repair, while meiosis ensures genetic diversity in sexual reproduction. Together, these processes sustain life, enable adaptation, and explain fundamental biological patterns.

📌 Role in Growth and Development

• Growth results from repeated mitotic divisions.
• Embryonic development depends on rapid cycles of cell division.
• Differentiation follows division, producing specialised tissues.
• Cell division continues through adolescence to maintain growth.
• Controlled by genetic and hormonal signals.

🧠 Examiner Tip: Don’t just say “cell division causes growth” — always mention mitosis specifically.

📌 Role in Asexual Reproduction

• Mitosis produces identical clones of parent cells.
• Common in unicellular organisms (binary fission in bacteria, mitosis in protists).
• Also occurs in multicellular organisms (vegetative propagation in plants, budding in yeast).
• Advantages: rapid, efficient, no mate required.
• Disadvantage: lack of genetic diversity reduces adaptability.

🧬 IA Tips & Guidance: Students could observe budding in yeast or regeneration in planaria as examples of mitosis in reproduction.

📌 Role in Sexual Reproduction

• Meiosis produces haploid gametes.
• Fertilisation restores diploid chromosome number.
• Crossing over and independent assortment → variation.
• Variation enhances survival in changing environments.
• Errors in division impact fertility and offspring viability.

🌐 EE Focus: An EE could explore the evolutionary significance of meiosis in generating variation vs the efficiency of asexual reproduction.

📌 Repair and Regeneration

• Mitosis replaces damaged or dead cells in tissues (e.g., skin, gut lining).
• Regeneration capacity varies: high in salamanders, low in mammals.
• Stem cells enable replacement and repair.
• Controlled cell division prevents scarring or overgrowth.
• Imbalances lead to cancer or degenerative diseases.

❤️ CAS Link: Students could volunteer in health awareness programs on tissue regeneration and healing.

📌 Evolutionary and Ecological Importance

• Asexual reproduction enables rapid colonisation of habitats.
• Sexual reproduction drives adaptation via variation and natural selection.
• Cell division supports population dynamics by enabling reproduction.
• Errors in meiosis can reduce fitness but also drive evolution.
• Division processes explain diversity of life strategies.

🔍 TOK Perspective: Reproduction is often simplified into “asexual = identical, sexual = diverse.” TOK issue: Are such binary categories too simplistic, given cases like parthenogenesis or horizontal gene transfer?

📝 Paper 2: Questions may involve explaining roles of mitosis and meiosis in growth and reproduction, evaluating advantages of sexual vs asexual reproduction, or analysing micrographs.