Experiment #10: HYDROLYSIS OF STARCH ( ACID-CATALYZED)

Question 1

Common name to a white, granular or powdery, odorless, tasteless, complex carbohydrates

Answer 1

Starch

Question 2

Formula of Starch

Answer 2

(C6 H10 O5)x

Question 3

Starch is abundant in the ____ of _____ and in _____ and _______

Answer 3

seeds, cereal plants, bulbs, tubers

Question 4

Starch is a ________ found in ______ and deposited in the form of _______ in the______ of the cell

Answer 4

Complex polysaccharide, plants, large granules, cytoplasm

Question 5

2 Components of starch

Answer 5

Amylose, amylopectin

Question 6

The _____ of ______ linked in a ______ by _______ . It has ______ ends and _____ end

Answer 6

Amylose, D-glucose units, linear fashion, a 1-4 linkages. 2 non-reducing, a reducing

Question 7

Branched polysaccharide

Answer 7

Amylopectin

Question 8

In these molecules, shorter chains of glucose units linked by _______ are also joined to each other by _______

Answer 8

a-1,4 linkages, a- 1,6 linkages

Question 9

What happens to starch when placed in a boiling water

Answer 9

Granules rupture, forming a paste that gels on cooling

Question 10

When a small amount of starch is added to the large amount of boiling water,a______ in water is formed

Answer 10

Colloidal dispersion of starch

Question 11

Starch gives a characteristic _______ with ______

Answer 11

Deep blue color, iodine

Question 12

Used to detect the presence of starch

Answer 12

Iodine test

Question 13

When starch is hydrolyzed it forms

Answer 13

Dextrins (amylodextrin, erythrodextrin, achrodextrin), maltose then glucose

Question 14

Iodine test is the test for the_________ with a _______ result

Answer 14

Presence of starch, blue- black positive

Question 15

Starch (insoluble)

Answer 15

Blue-black/dark blue/ blue

Question 16

Starch(soluble)

Answer 16

Blue-black/dark blue/blue

Question 17

Amylodextrin

Answer 17

Blue-purple/ purple

Question 18

Erythrodextrin

Answer 18

Red

Question 19

Achrodextrin

Answer 19

No color/colorless

Question 20

Maltose

Answer 20

No color

Question 21

Glucose

Answer 21

No color

Question 22

When the hydrolysis of starch is complete

Answer 22

The starch solution is colorless once 2 drops of iodine solution is added. The hydrolysis of starch does not occur immediately. The result of the test turns to black to dark purple before it becomes colorless

Question 23

How is complex structure of starch is broken down into a simple carbohydrate, the glucose

Answer 23

Starch (C6 H10 O5) forms dextrins (amylodextrin, erythrodextrin, achrodextrin). Then it slowly forms maltose and finally glucose C6 H12 O6

Question 24

Role of Hydrochloric Acid in Starch Hydrolysis

Answer 24

Acid caused scission of the glycosidic linkages, altering the structure and properties of the starch

Destroys the microcrystals in the starch, hydrolyze the glycosidic bond,
decrease the amount of amylopectin

Question 25

Positive result of Lugol’s test

Answer 25

Blue-black/black

Question 26

Presence of Glucose in Lugol’s test

Answer 26

Colorless

Question 27

Negative result in Lugol’s test

Answer 27

Yellow