Ch 2: The Cell As the Basic Unit of Life 🔋

• What are the two main inorganic chemical constituents of organisms?

  Water and inorganic ions
• What percentage of body weight does water make up in humans?

  About 60%
• What are the functions of water in organisms?

  1. As a reactant in chemical reactions
  2. Medium for chemical reactions
  3. Medium of transport for substances
  4. Cooling agent through evaporation
  5. Provides support and shape
  6. Component of lubricating fluids
• How is water involved as a reactant in photosynthesis?


  It is produced from carbon dioxide and light
• Why is water considered a medium for chemical reactions?

  It can dissolve many substances
• How does water function as a medium of transport in organisms?

  It carries dissolved substances throughout
• What role does water play as a cooling agent in organisms?

  It removes heat through evaporation
• How does sweating help cool down the human body?

  Evaporation of sweat removes heat
• How does water provide support to plant cells?

  It makes cells turgid and upright
• What is the major component of lubricating fluids in organisms?

  Water
• What is the function of pleural fluid in humans?

  It reduces friction during breathing
• What are the functions of inorganic ions in animals and plants?

  • Activate enzymes
  • Component of haemoglobin
  • Component of bones and teeth
  • Needed for blood clotting and muscle contraction
  • Source of nitrogen for proteins
  • Component of chlorophyll
  • Strengthen cell walls
• What is the function of iron in animals?

  Component of haemoglobin
• What is the function of calcium in animals?

  Needed for blood clotting
• What is the function of phosphate in animals?

  Component of phospholipids and nucleic acids
• What is the function of nitrate in plants?

  Source of nitrogen for proteins
• What is the function of magnesium in plants?

  Component of chlorophyll
• What is the function of iron in plants?

  Activates some enzymes
• What is the function of calcium in plants?

  Helps strengthen cell walls
• What is the function of phosphate in plants?

  Component of phospholipids and nucleic acids
• What are the major organic chemical constituents of organisms?

  • Carbohydrates
  • Lipids
  • Proteins
  • Nucleic acids
• What elements do carbohydrates contain?

  Carbon, hydrogen, and oxygen
• What are four common carbohydrates found in organisms?

  Glucose, starch, glycogen, cellulose
• What is the main energy source for cells?

  Glucose
• Starch acts as an energy reserve in plants.
• Glycogen acts as an energy reserve in animals.
• What is cellulose a major component of?

  Plant cell walls
• What elements do lipids contain?


  Carbon, hydrogen, and oxygen
• What are two common types of lipids?


  Triglycerides and phospholipids
• What do triglycerides act as in organisms?


  Energy reserve
• What is the function of fats stored in adipose tissues under the skin?


  Act as an insulator
• What is the function of fats stored around internal organs?

  Act as a shock absorber
• What are phospholipids a major component of?

  Cell membranes
• What elements do proteins contain?

  Carbon, hydrogen, oxygen, and nitrogen
• What are some functions of proteins in organisms?

  • Make up body tissues (hair, muscles, skin)
  • Act as enzymes to regulate reactions
  • Act as hormones to regulate processes
  • Act as antibodies to protect against pathogens
  • Involved in transport (e.g., haemoglobin)
• What is the genetic material in organisms?

  DNA
• What does DNA carry?

  Genetic information
• What is RNA involved in?

  Synthesis of proteins
• What elements do nucleic acids contain?

  Carbon, hydrogen, oxygen, nitrogen and phosphorus
• The Cell Theory states that

  • All organisms are made up of one or more cells
  • The cell is the basic unit of life
  • All cells come from pre-existing cells