biological molecules

• Why are all living things based on carbon?

  Carbon forms long chains in organic molecules
• What do covalent bonds in carbon molecules store?


  They store a lot of energy
• What are the simplest organic molecules?

  Carbohydrates
• What is a monosaccharide?

  A single sugar unit
• How are large molecules formed in living organisms?

  By joining small molecules with covalent bonds
• What role do enzymes play in molecular reactions?

  They control the breakdown and formation of molecules
• How can monosaccharides be classified?

  By the number of carbon atoms
• Name three main monosaccharides.

  Glucose, fructose, galactose
• How do glucose and fructose differ?

  They have different atomic arrangements
• What is a reducing sugar?

  A sugar that can reduce other chemicals
• What happens to Benedict's solution when heated with a reducing sugar?

  It changes from blue to brick-red
• What is the Benedict's test used for?

  To test for reducing sugars
• What is the significance of the color change in Benedict's test?

  Indicates the presence of reducing sugars
• What is the role of a colorimeter in testing reducing sugars?

  Measures absorbance to estimate sugar concentration
• What is the difference between hydrolysis and condensation?

  Hydrolysis breaks bonds, condensation forms bonds
• Why must non-reducing sugars be hydrolysed for testing?

  They cannot be tested directly with Benedict's test
• What are polysaccharides made of?

  Long chains of monosaccharides
• How do the properties of polysaccharides relate to their functions?

  Structure affects their storage and strength
• What is the test for starch?

  Iodine solution turns blue/black
• Why does iodine turn blue/black in the presence of starch?

  Iodine fits into the coils of amylose
• What is the primary source of energy in plants?

  Starch
• What are the two types of starch?

  Amylose and amylopectin
• How does amylose differ from amylopectin?

  Amylose is less branched than amylopectin
• What is the advantage of starch's branched nature?

  Allows rapid breakdown for energy release
• What is glycogen's role in animals?

  Energy storage molecule
• How does glycogen's structure facilitate its function?

  Highly branched for rapid glucose release
• How does cellulose differ from starch and glycogen?

  Cellulose has unbranched chains of β-glucose
• What is the structural role of cellulose in plants?

  Provides strength to plant cell walls
• What are microfibrils in cellulose?

  Grouped cellulose molecules providing strength
• Why are hydrogen bonds important in cellulose?

  They add strength to the structure
• How does the structure of cellulose contribute to plant support?

  Rigid walls resist external pressure
• What is the primary component of plant cell walls?

  Cellulose
• What is the role of lipids in organisms?

  Energy storage and structural functions
• What are fats at room temperature?

  Solid
• What are oils at room temperature?

  Liquid
• What is the function of a plant's cell wall?

  Provides support and stability
• Why does a plant's cell wall need to be strong?

  To withstand stresses from wind and weight
• What structure provides strength in woody plants?

  Cellulose microfibrils
• What color do starches stain with iodine solution?

  Deep blue
• Where is glycogen found?

  In animal cells