Life Processes: Respiration, Movement of Substances, and Cell Differentiation

Respiration

  • Respiration releases energy; cell processes use it.

  • Aerobic respiration: Glucose + Oxygen → Carbon Dioxide + Water (+ Energy)

    • C6H{12}O6 + 6O2 \rightarrow 6CO2 + 6H2O (+ energy)

    • Occurs in mitochondria.

  • Anaerobic respiration:

    • In yeast: Glucose → Ethanol + Carbon Dioxide (+ some energy)

    • In muscle cells: Glucose → Lactate (+ some energy)

  • ATP (Adenosine Triphosphate): Energy 'currency' of the cell.

    • ATP → ADP + Phosphate (+ Energy) when energy is needed.

    • ADP + Phosphate → ATP during respiration.

Movement of Materials In and Out of Cells

  • Cell membrane: Selectively permeable.

  • Diffusion: Net movement from high to low concentration.

    • Affected by: concentration gradient, surface area to volume ratio, distance, temperature.

  • Active transport: Movement against concentration gradient, using energy (ATP).

  • Osmosis: Net movement of water from dilute to concentrated solution across a partially permeable membrane.

    • Water moves from high to low water potential.

Specialised Exchange Surfaces

  • Adaptation: Structure suited to function (e.g., alveoli, villi, spongy mesophyll, root hairs).

Osmosis in Plant Cells

  • Partially permeable membranes: Cell surface membrane and membrane around sap vacuole.

  • Turgid: Cell swollen due to water intake (high water potential).

  • Flaccid: Cell losing water (lower water potential).

  • Plasmolysed: Cell membrane pulls away from cell wall due to water loss.