Chapter 5 - Nutrients

Question 1

Define nutrients.

Answer 1

Nutrients are chemical substances in food that provide energy and materials needed in the body.

Question 2

Name the 4 functions of water in humans.

Answer 2

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.

Question 3

Name the functions of water in plants. (4)

Answer 3

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

Question 4

What does the amount of water a person needs depend on?(3)

Answer 4

1) how healthy a person is
2) how active a person is
3) environmental conditions

Question 5

Define carbohydrates.

Answer 5

Carbohydrates are organic molecules made up of carbon, hydrogen and oxygen.

Question 6

What is the general formula and ratio of h:o atoms in carbohydrates?

Answer 6

CnH2mOm

2:1

Question 7

How can you categorize carbohydrates into? (3)

Answer 7

Monosaccharides, disaccharides, polysaccharides(complex carbohydrates).

Question 8

Name 3 examples of monosaccharides.

Answer 8

Glucose, fructose, galactose.

Question 9

Name 3 examples of disaccharides.

Answer 9

Maltose, sucrose, lactose.

Question 10

Name 3 examples of polysaccharides.

Answer 10

Starch, glycogen, cellulose.

Question 11

What are reducing sugars?

Answer 11

All monosaccharides and disaccharides except sucrose.

Question 12

Define a condensation reaction.

Answer 12

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.

Question 13

Define hydrolysis.

Answer 13

Hydrolysis is a reaction in which a water molecule is needed to break up a complex molecule into simple molecules, also a catabolic reaction.

Question 14

How can we test for reducing sugars? Describe the procedure. (4)

Answer 14

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.

Question 15

What is starch?

Answer 15

a storage form of carbohydrates in plants found in storage organs in plants

Question 16

Name 2 functions of the cellulose.

Answer 16

1) cellulose cell wall protects plant cells

2) serve as dietary fibers to prevent constipation

Question 17

Name 2 functions of glycogen.

Answer 17

1) storage form of carbohydrates in mammals

2) digested to form glucose when needed

Question 18

How can we test for starch? Describe the procedure.

Answer 18

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.

Question 19

Name the functions of carbohydrates. (6)

Answer 19

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

Question 20

define fats.

Answer 20

Fats are organic compounds made up of carbon, hydrogen and oxygen.

Question 21

Describe the proportion of elements in fats.

Answer 21

Fats contain much less oxygen in proportion to hydrogen, however proportion not fixed.

Question 22

What is a fat molecule made up of?

Answer 22

Glycerol and fatty acid chains

Question 23

How can fats be broken down?

Answer 23

By hydrolysis to produce fatty acids and glycerol.

Question 24

State the 2 differences between saturated and unsaturated fats.

Answer 24

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

Question 25

How do we test for fats? Describe the procedure. (4)

Answer 25

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.

Question 26

List the 5 functions of fats.

Answer 26

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

Question 27

Define proteins.

Answer 27

Proteins are organic compounds made up of carbon, oxygen, hydrogen and nitrogen.

Question 28

What are amino acids made up of?

Answer 28

An amino group, an acid group and a side chain.

Question 29

How are proteins formed?

Answer 29

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.

Question 30

How can we test for protein? Describe the procedure. (4)

Answer 30

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.

Question 31

Name 3 functions of the proteins.

Answer 31

1) synthesis new protoplasm for growth and repair of worn-out cells
2) synthesis of enzymes and some hormones
3) synthesis antibodies

Question 32

What are the nutrients in food needed to? (3)

Answer 32

1) provide energy
2) supply raw materials to make new protoplasm
3) helps us stay healthy