Chapter 5 - Nutrients Flashcards
Define nutrients.
Nutrients are chemical substances in food that provide energy and materials needed in the body.
Name the 4 functions of water in humans.
1) solvent which chemical reactions take place
2) essential component of cell tissue fluids, digestive juices and blood.
3) helps control body temperature
4) helps transport dissolved substances around the body.
Name the functions of water in plants. (4)
1) essential for photosynthesis
2) helps keep plant upright through turgor pressure in plant cells
3) is needed for transport of dissolved mineral salts up to xylem
4) needed for transport of food substances from leaves to other parts of plant
What does the amount of water a person needs depend on?(3)
1) how healthy a person is
2) how active a person is
3) environmental conditions
Define carbohydrates.
Carbohydrates are organic molecules made up of carbon, hydrogen and oxygen.
What is the general formula and ratio of h:o atoms in carbohydrates?
CnH2mOm
2:1
How can you categorize carbohydrates into? (3)
Monosaccharides, disaccharides, polysaccharides(complex carbohydrates).
Name 3 examples of monosaccharides.
Glucose, fructose, galactose.
Name 3 examples of disaccharides.
Maltose, sucrose, lactose.
Name 3 examples of polysaccharides.
Starch, glycogen, cellulose.
What are reducing sugars?
All monosaccharides and disaccharides except sucrose.
Define a condensation reaction.
A condensation reaction is a chemical reaction in which two simple molecules are joined together to form a larger molecule with the removal of one molecule of water, an anabolic reaction.
Define hydrolysis.
Hydrolysis is a reaction in which a water molecule is needed to break up a complex molecule into simple molecules, also a catabolic reaction.
How can we test for reducing sugars? Describe the procedure. (4)
Benedict’s test
1) add 2cm3 of Benedict’s solution to 2cm3 of food sample in a test tube.
2) shake the mixture.
3) heat contents in boiling water bath for 2-3min.
4) a green, yellow or orange-red PRECIPITATE is formed if reducing sugar is present in trace, moderate or large amounts respectively.
What is starch?
a storage form of carbohydrates in plants found in storage organs in plants
Name 2 functions of the cellulose.
1) cellulose cell wall protects plant cells
2) serve as dietary fibers to prevent constipation
Name 2 functions of glycogen.
1) storage form of carbohydrates in mammals
2) digested to form glucose when needed
How can we test for starch? Describe the procedure.
Iodine test.
1) add 2cm3 of food sample to a clean test tube.
2) add a few drops of iodine solution to test tube.
3) a blue black solution is formed if starch is present.
Name the functions of carbohydrates. (6)
1) broken down in respiration to release energy for CELL ACTIVITIES
2) form supporting structures like cell wall
3) converted into other organic compounds like fats
4) form part of nucleic acids
5) used to synthesize lubricants
6) synthesize nectar in flowers
define fats.
Fats are organic compounds made up of carbon, hydrogen and oxygen.
Describe the proportion of elements in fats.
Fats contain much less oxygen in proportion to hydrogen, however proportion not fixed.
What is a fat molecule made up of?
Glycerol and fatty acid chains
How can fats be broken down?
By hydrolysis to produce fatty acids and glycerol.
State the 2 differences between saturated and unsaturated fats.
1) saturated fats have straight fatty acid chains while unsaturated fatty acid chains have kinks
2) saturated fats most solid at room temperature like butter while unsaturated fats usually liquid at room temperature
How do we test for fats? Describe the procedure. (4)
Ethanol emulsion test.
1) add 2cm3 of ethanol to 2cm3 of food sample in a test tube.
2) shake contents of tube vigorously.
3) decant 3cm3 of water into test tube and shake the mixture.
4) cloudy white emulsion would be formed if fats are present.
List the 5 functions of fats.
1) source and store of energy
2) insulating material to prevent excessive heat loss
3) solvent for fat soluble vitamins and some hormones
4) form main part of cell membrane
5) help reduce water loss from skin surface
Define proteins.
Proteins are organic compounds made up of carbon, oxygen, hydrogen and nitrogen.
What are amino acids made up of?
An amino group, an acid group and a side chain.
How are proteins formed?
Amino acids are building blocks of proteins. Peptide bonds link amino acids to form a polypeptide. Two or more polypeptide chains fold to form a three dimensional molecule called protein.
How can we test for protein? Describe the procedure. (4)
Biuret test.
1) add 2 cm3 of sodium hydroxide solution to 2cm3 of food sample into a test tube.
2) shake mixture thoroughly.
3) add 1% copper(II) sulfate solution drop by drop, shaking the mixture after each drop.
4) a violet solution is formed if proteins are present.
Name 3 functions of the proteins.
1) synthesis new protoplasm for growth and repair of worn-out cells
2) synthesis of enzymes and some hormones
3) synthesis antibodies
What are the nutrients in food needed to? (3)
1) provide energy
2) supply raw materials to make new protoplasm
3) helps us stay healthy
