Biology Lab 2

Question 1

4 main macromolecules

Answer 1

Carbohydrates (sugars),
Lipids (fats),
Proteins,
Nucleic Acids

Question 2

Reducing sugar

Answer 2

Has an Aldehyde group on it.

Can reduce copper ions (at proper pH)

Question 3

Copper ions react with glucose to form a precipitate of ?

Answer 3

Copper oxide

Question 4

Which precipitate has more sugar? Green or brownish red?

Answer 4

Brownish red

Question 5

Benedict’s solution is used to test for ?

Answer 5

Presence of simple sugars (in food, blood, urine)

Question 6

Reducing sugars are either monosaccharides or?

Answer 6

Disaccharides

Question 7

If Benedict’s reagent is added to a solution and it turns blue, is there a reducing sugar?

Answer 7

No

Question 8

If Benedict’s reagent is added to a solution and it turns orangish brown, is reducing sugar present?

Answer 8

Yes

Question 9

A single or simple sugar is called a

Answer 9

Monosaccharide (mono=1) (saccharine=sugar)

Question 10

2 or more monosaccharides bonded together are called?

Answer 10

Oligosaccharides (oligo=few)

Question 11

Barfoed’s reagent is used to

Answer 11

Distinguish between monosaccharides and oligosaccharides.

Question 12

Benedict’s reagent and Barfoed’s reagent both contain?

Answer 12

Copper ions

Question 13

Which reagent is more acidic? Benedict’s or Barfoed’s?

Answer 13

Barfoed’s

Question 14

If Barfoed’s reagent is added to a solution and a reddish precipitate forms at the bottom of the test tube, are monosaccharides present?

Answer 14

Yes

Question 15

List 3 monosaccharides.

Answer 15

Glucose, Fructose, Sprite

Question 16

________is a polysaccharide used for storing energy in plants

Answer 16

Starch

Question 17

Starch reacts w/ Lugol’s iodine (IKI) to produce what color?

Answer 17

Dark blue/black

Question 18

List 2 characteristics of LIPIDS (oils, fats, waxes, steroids)

Answer 18

Do not dissolve well in water

Do not all have similar chemical structures (like carbohydrates do)

Question 19

Name 2 types of tests for lipids

Answer 19

Brown paper test

Sudan IV test

Question 20

Sudan IV is a ______________ that dissolves in_____________ but not in water.

Answer 20

Red powder

Lipids

Question 21

Biuret is prepared from?

Answer 21

Urea

Question 22

Biuret contains 2?

Answer 22

Peptide bonds

Question 23

When Biuret reacts with copper sulfate, what color forms?

Answer 23

Purple

Question 24

A reaction between copper ions and peptide bonds causes what color?

Answer 24

Purple

Question 25

Proteins give a strong reaction to Biuret because?

Answer 25

Proteins contain many peptide bonds, which link individual amino acids in the polypeptide chain.

Question 26

Name something that reacted with Biuret.

Answer 26

Albumin solution.

Question 27

If a sample tests positive with Benedict’s reagent but not with Barfoed’s reagent, what can you tell about that sample?

Answer 27

That it contains a reducing sugar, but it is not a monosaccharide, it is an oligosaccharide.

Question 28

Benedict’s reagent and Barfoed’s reagent are both blue because?

Answer 28

They both contain copper ions

Question 29

Draw 2 different isomers of the chemical C2H6O

Answer 29

Draw

Question 30

List 2 foods that would react with Benedict’s reagent but not with IKI

Answer 30

Soda (Sprite), Apple?

Question 31

Macromolecules

Latin -> macro = large

Answer 31

Large molecules that make up important parts of the cell