Organisation of the Organism - CIE Biology IGCSE

Overview

• Eukaryotic cells: Plant and animal cells with a nucleus and membrane-bound organelles.
• Prokaryotic cells: Bacteria without a nucleus or membrane-bound organelles.
• Microscopy: Used to view cells and calculate specimen sizes.

Functions of Eukaryotic Cell Structures

• Cytoplasm: Jelly-like material where reactions occur, contains ribosomes and vesicles.
• Cell Membrane: Controls entry and exit of substances.
• Nucleus & DNA: Contains genetic material, site of DNA replication.
• Ribosomes & RER: Site of protein synthesis.
• Mitochondria: Site of respiration, energy production.
• Vesicles: Transport materials within the cell.

Additional Structures in Plant Cells

• Vacuole: Fluid-filled sac with minerals, sugars, and pigments.
• Chloroplasts: Site of photosynthesis, converts light energy to glucose.
• Cell Wall: Provides structure, prevents bursting, controls permeability.

Levels of Organisation

• Tissue: Group of similar cells for a specific process.
• Organ: Group of tissues for a specific function.
• Organ System: Group of organs for body functions.

Specialised Cells

• Ciliated Cells: Line the trachea with cilia to move mucus and bacteria.
• Root Hair Cells: Large surface area for osmosis and mineral uptake.
• Xylem Vessels: Transport water, hollowed-out cells for capillary action.
• Palisade Mesophyll Cells: Photosynthesis, packed with chloroplasts, located at top of leaf.
• Nerve Cells: Transmit electrical impulses, myelinated, contain mitochondria, branched dendrites.
• Red Blood Cells: Carry oxygen, biconcave shape for diffusion, no nucleus.
• Sperm Cells: Contain mitochondria, tail for movement, enzymes for egg penetration.