Lab 10 (Chapter 26)

Question 1

How are most foods we eat broken down?

Answer 1

Hydrolysis

Question 2

Define enzyme

Answer 2

Speeds up a reaction but doesn’t get used up

Question 3

Name 2 factors that can denature enzymes

Answer 3

1) High heat
2) pH changes

Question 4

1) Where does carbohydrate digestion begin?
2) What do the salivary glands release and what does it do?

Answer 4

1) In the oral cavity
2) Saliva with salivary amylase, which breaks down starch

Question 5

1) Excluding the oral cavity, where else does carbohydrate digestion occur?
2) What enzyme is involved?

Answer 5

1) In the duodenum of the small intestine
2) Pancreatic amylase

Question 6

What is the optimal pH for amylase?

Answer 6

7

Question 7

Name the 2 tests used for carbohydrate digestion and what they measure

Answer 7

1) IKI test: Only for starch presence
2) Benedict’s test: Only for maltose presence

Question 8

1) Name a polysaccharide
2) Name a disaccharide

Answer 8

1) Starch
2) Maltose

Question 9

1) What is a negative result on an IKI test?
2) What is a positive result on an IKI test?

Answer 9

1) Negative: Tan/Brown (no starch present)
2) Positive: Black (starch present)

Question 10

1) Where does protein digestion begin and end?
2) What are proteins broken down to in order to be absorbed by the small intestine?
3) What enzyme produced by the stomach digests proteins?
4) What enzyme was used in place of this enzyme in the color change experiment?

Answer 10

1) Starts in stomach, ends in small intestine
2) Amino acids
3) Pepsin
4) Trypsin
3) Pepsin

Question 11

1) What is the ideal pH for pepsin?
2) What is the ideal pH for trypsin?
3) What is trypsin released by?

Answer 11

1) Pepsin: 2
2) Trypsin: 7
3) The pancreas

Question 12

1) What is a negative result on a color change (BAPNA) test?
2) What is a positive result on a color change test?

Answer 12

1) Negative: Clear (BAPNA present, negative for enzyme)
2) Positive: Yellow (amino acids present, positive for enzyme)

Question 13

What does a positive color change (BAPNA) test result suggest?

Answer 13

That the enzyme trypsin has broken the bonds between BAPNA and amino acids

Question 14

1) Where does most triglyceride digestion occur?
2) What enzyme digests lipids? Where is it produced?
3) What do triglycerides (fats) break down into?

Answer 14

1) In the small intestine
2) Lipase; produced by the pancreas
3) Monoglycerides and 2 fatty acids

Question 15

1) Due to being hydrophobic, what do triglycerides tend to do in a solution?
2) What is the purpose of bile salts?

Answer 15

1) Form large droplets
2) Emulsification of fas

Question 16

1) What organ makes bile?
2) What organ stores and concentrates bile?

Answer 16

1) The liver
2) The gallbladder

Question 17

1) What triglyceride is used in the pH (triglyceride digestion) experiment?
2) What is the original color of this triglyceride?
3) What color does this triglyceride turn when exposed to acid?

Answer 17

1) Litmus cream
2) Blue
3) Red

Question 18

1) What the two types of negative pH (triglyceride digestion) test result?
2) What is a positive triglyceride digestion result?

Answer 18

1) Negative:
-Clear: No litmus cream present
-Blue/ purple: Litmus cream present, no lipase
2) Positive: Pink (monoglyceride + 2 fatty acids present; positive for enzyme)

Question 19

Triglyceride hydrolysis does what to pH?

Answer 19

Decreases pH (creates acid)

Question 20

1) What does cold do to enzymes?
2) What does heat do to enzymes?

Answer 20

1) Slows them down
2) Denatures them

Question 21

1) What does a positive IKI test indicate?
2) What does a positive Benedict’s reagent test indicate?
3) What does a positive color change test indicate?
4) What does a positive pH change test indicate?

Answer 21

1) Starch is present
2) Maltose is present
3) Amino acids are present
4) Fatty acids are present

Question 22

1) What is a negative result on a Benedict’s test?
2) What is a positive result on a Benedict’s test?

Answer 22

1) Negative: Blue (no maltose, no starch digestion)
2) Positive: Green, orange, red, brown (maltose present, potential starch digestion)