carbohydrates 3.1.2

Question 1

what 3 elements does carbohydrates contain?

Answer 1

carbon, hydrogen and oxygen

Question 2

what is always in the ratio 2:1

Answer 2

hydrogen : oxygen

Question 3

what are monosaccharides?

Answer 3

monomers that larger carbohydrates are made from

Question 4

what are the three common monosaccharides?

Answer 4

glucose, galactose and fructose

Question 5

what is the bond between two monosaccharides called?

Answer 5

glycosidic bonds

Question 6

glucose is the main…

Answer 6

respiratory substrate

Question 7

what are isomers?

Answer 7

when something has the same molecular formula but different structural formula.

Question 8

What are the two isomers of glucose?

Answer 8

alpha and beta glucose.

Question 9

what is the difference in the structure of ‘alpha’ glucose compared to ‘beta’?

Answer 9

In alpha, carbon 1 has H at the top of the ring and OH at the bottom of the ring.
In beta, carbon 1 has OH at the top of the ring and H at the bottom of the ring.

Question 10

what are disaccharides?

Answer 10

2 monosaccharides joined together by condensation.

Question 11

name 3 disaccharides:

Answer 11

maltose, sucrose and lactose

Question 12

how is maltose formed

Answer 12

by the condensation of two alpha glucoses

Question 13

how is sucrose formed?

Answer 13

by the condensation of a glucose and fructose molecule

Question 14

how is lactose formed?

Answer 14

by the condensation of glucose and galactose

Question 15

describe the biochemical test that could be used to test for reducing sugars

Answer 15

heating the sample with benedicts solution -> brick red precipitation will be formed

Question 16

How does the structure of starch link to it’s function? [3]

Answer 16

the molecules are tightly coiled~allowing a considerable amount of starch to be packed into a small volume (compact)
insoluble~no osmosis can occur, won’t affect water potential of cell
readily broken down~to glucose by enzymes

Question 17

which glucose is used in starch? and what are the two types of chain in starch [with other name] And what other bond does it have and why?

Answer 17

alpha glucose is used
straight chain (glycosidic bond only between C1and4) - amylose
branched chain (glycosidic bond between C1and4 and C1and6) - amylopectin
Hydrogen bond to keep it in a specific shape.

Question 18

Explain glycogen (include structure and function)

Answer 18

Energy store in animals. It is built from alpha glucose. It is a highly branched chain (glycosidic bond between 1-4 and 1-6), this increases surface area for rapid hydrolysis back to glucose.

Question 19

Explain the role of cellulose and how it links to its structure.

Answer 19

cellulose has a structural function in plants. It is made from Beta glucose. Every other glucose molecule is upside down forming long straight parallel chains. These chains are then joined together by hydrogen bonds into bundles. This also forms fibres, fibrils and microfibrils. Making them extremely strong, completely permeable and flexible.

Question 20

How can u test for starch?

Answer 20

Add iodine solution(iodine/potassium iodide) to the sample and the colour should change from yellow to blue/black.

Question 21

name a non reducing sugar

Answer 21

sucrose