4.1 Biological Molecules Food Tests Flashcards
What is the test for starch?
Add iodine solution to the food sample. If starch is present, the color will change from orange-brown to blue-black.
What is the test for reducing sugars?
Add Benedict’s solution to the food sample and heat. If reducing sugars are present, the color will change from blue to green, yellow, orange, or brick red.
What is the test for proteins?
Add Biuret solution to the food sample. If proteins are present, the color will change from blue to violet or purple.
What is the test for fats and oils?
Mix the food sample with ethanol, then add cold distilled water. A positive result will show a cloudy white emulsion.
What is the test for vitamin C?
Add DCPIP solution to the food sample. If vitamin C is present, the blue color of DCPIP will disappear.
Iodine solution test:
For starch – color changes from orange-brown to blue-black.
Benedict’s solution test:
For reducing sugars – color changes from blue to green, yellow, orange, or brick red upon heating.
Biuret test
For proteins – color changes from blue to violet/purple.
Ethanol emulsion test:
For fats and oils – forms a cloudy emulsion.
DCPIP test
For vitamin C – blue color disappears.
Carbohydrates, fats, and proteins all contain?
carbon, hydrogen, and oxygen.
Proteins also contain
nitrogen and sometimes sulfur.
Carbohydrates
Provide energy and structure (e.g., glucose for energy, cellulose for plant cell walls).
Fats:
Store energy, provide insulation, protect organs, and waterproof the body.
Proteins:
Perform a variety of functions, including enzymes, antibodies, and structural components.
DNA:
Carries genetic information necessary for growth and reproduction.
Monosaccharides:
Simple sugars like glucose.
Disaccharides:
Formed when two monosaccharides link together (e.g., maltose).
Polysaccharides:
Formed when many monosaccharides (e.g., glucose) link together (e.g., starch, glycogen, cellulose).
DNA’s structure:
Two strands coiled into a double helix.
Base pairing:
A with T, C with G.
Function of DNA:
Stores genetic information, replicates during cell division, guides protein synthesis.
