Cell Requirements

A comprehensive overview of the requirements essential for cell function, focusing on energy conversion, nutrient acquisition, gas exchange, and waste elimination.

Light Energy (Photosynthesis)

Photosynthesis: The process of converting light energy into chemical energy. This is ecologically significant as it forms the basis for almost all life forms by supplying energy.

• Processes of Photosynthesis

  Light-dependent Reactions (Photolysis):

  • Location: Thylakoid membranes
  • Steps Involved:
    • Splitting of water molecules.
    • Release of oxygen.
    • Production of ATP and NADPH.
  • Provides energy for the subsequent Calvin Cycle.

  Light-independent Reactions (Calvin Cycle):

  • Location: Stroma
  • Steps Involved:
    • Carbon fixation.
    • Synthesis of glucose.

Essential Gases

• Role of Oxygen and CO₂: Oxygen is vital for cellular respiration, converting glucose into energy. Carbon dioxide is essential for photosynthesis, allowing plants to create glucose.
  • Gas Exchange in Plants vs. Animals: Refer to the table comparing gas exchange processes.
  

Simple Nutrients

• Nutrient Building Blocks:

  • Glucose: Essential for energy; crucial in ATP production.
  • Amino Acids: Build proteins for cell structure and function.
  • Fatty Acids & Glycerol: Form lipids, important for cell membranes.
  • Nucleotides: Make up DNA and RNA, which are essential for genetic information.

  

Ions and Transport Mechanisms

• Ion Importance:

  • Sodium: Necessary for nerve signal transmission.
  • Potassium: Maintains electrical charge balance across cell membranes.
  • Calcium: Vital for muscle contractions.

• Transport Types:

  • Diffusion: Movement from areas of high to low concentration.

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    Diffusion: A passive process for substance distribution in cells.

  • Osmosis: Water movement through a semi-permeable membrane.

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    Osmosis: Regulates cell volume and pressure.

  • Active Transport: Utilises energy to move substances against a concentration gradient, such as the sodium-potassium pump.

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    Active Transport: Essential for nutrient uptake and waste elimination.

  

Water as a Crucial Nutrient

• Water Functionality:

  • Acts as a universal solvent, facilitating chemical reactions and nutrient transport.
  • Plays an active role in biochemical reactions.

• Osmosis:

  • Essential for maintaining cells' internal balance; unlike diffusion, it concentrates on water movement. This process is critical for sustaining life functions by keeping conditions stable.

  

Removal of Wastes

Carbon Dioxide Removal

Carbon Dioxide (CO₂): Produced as a cellular respiration waste byproduct.

• Gas Exchange Process:
  • CO₂ moves from a high concentration inside cells into the bloodstream.
  • The bloodstream transports CO₂ to the lungs, where it diffuses into the alveoli and is expelled.

Ammonia and Nitrogenous Waste Removal

Ammonia Conversion: Essential for detoxification.

• Why Conversion?: Ammonia is highly toxic and requires conversion for safe elimination.

• Ureotelism: Conversion of ammonia to urea.

  • Process: Urea is more soluble and less toxic, facilitating easier excretion through urine.
  • Example: Mammals, including humans, utilise ureotelism for ammonia removal.

• Uricotelism: Conversion of ammonia to uric acid.

  • Process: Uric acid is less soluble and expelled as a paste, conserving water.
  • Example: Birds and reptiles commonly employ uricotelism.

Unicellular vs. Multicellular Organism Waste Removal

• Unicellular Organisms: Use simple methods like diffusion and osmosis for waste elimination.

  • Examples: Amoebas and paramecia manage waste effectively using these processes.

• Multicellular Organisms:

  • Specialised Systems: Evolved to manage waste effectively.
    • Respiratory System: Facilitates gas exchange to remove gaseous wastes.
    • Urinary System: Maintains chemical balance and expels liquid waste.
  • Key Role: Lungs and kidneys play essential roles in these systems.

Impact of Waste Removal Failure

Failure to remove waste effectively can lead to significant health issues.

• Health Consequences:

  • Toxicity: Interferes with enzymes, potentially inhibiting biological functions.
  • Accumulation: May result in conditions such as renal failure.

• Renal Failure Case Study:

  • Scenario: Kidneys failure leads to inefficient waste removal.
  • Effects: Increased waste levels in the body (uraemia).
  • Treatment: Dialysis is essential for patients unable to excrete waste naturally.

• Preventive Measures: The significance of maintaining renal health to prevent failures.