carbohydrates

Question 1

what are carbohydrates made from?

Answer 1

carbon, hydrogen and oxygen

Question 2

what is the general formula for carbohydrates?

Answer 2

CH20

Question 3

what are monosaccharides?

Answer 3

simple sugars (can be trioses, pentoses or hexoses)

Question 4

name three types of hexoses (monosaccharides)

Answer 4

glucose, galactose and fructose

Question 5

what are disaccharides?

Answer 5

molecules made from two monosaccharides

Question 6

name three types of disaccharides

Answer 6

maltose, lactose, sucrose

Question 7

which two monosaccharides make up sucrose?

Answer 7

glucose and fructose

Question 8

which two monosaccharides make up lactose?

Answer 8

glucose and galactose

Question 9

what is a glycosidic bond?

Answer 9

a covalent bond that joins together monosaccharides

Question 10

what is a polysaccharide?

Answer 10

a giant molecule formed from many monosaccharides

Question 11

name three types of polysaccharides

Answer 11

starch, cellulose and glycogen

Question 12

describe starch

Answer 12

main energy store in plants, insoluble, made up of amylose and amylopectin

Question 13

describe glycogen

Answer 13

highly branched molecule, compact, good for storage

Question 14

describe cellulose

Answer 14

long unbranched chains of beta glucose, microfibrils - strong fibres that provide structural support

Question 14

describe cellulose

Answer 14

long unbranched chains of beta glucose, microfibrils - strong fibres that provide structural support

Question 15

describe the benedict’s test for sugars

Answer 15

reducing sugars - add benedict’s reagent to sample and heat in water bath that’s 65°C, positive result: brick red colour

non-reducing sugars - add dilute hydrochloric acid and heat in water bath that’s 65°C, neutralise with sodium hydrogen carbonate, add benedict’s reagent etc

Question 16

describe iodine test for starch

Answer 16

add iodine dissolved in potassium iodide solution, positive result: blue-black colour