carbohydrates

Question 1

what atoms are carbohydrates made out of

Answer 1

carbon, hydrogen, oxygen atoms

Question 2

what is the H:O ratio in carbohydrate molecules

Answer 2

2:1

Question 3

properties of monosaccharides

Answer 3

simplest form of carbohydrates, soluble in water, sweet
examples:
glucose (fruit)
fructose (fruit)
galactose (dairy products)

Question 4

properties of disaccharides

Answer 4

formed by condensation of 2 molecules of monosaccharides, soluble in water, sweet
examples:
maltose (malt)
sucrose (sugarcane)
lactose (milk)

Question 5

properties of polysaccharides

Answer 5

formed by condensation of 3 or more monosaccharide molecules, insoluble in water, tasteless
examples:
starch (cereals)
glycogen (liver)
cellulose (vegetables)

Question 6

can disaccharides and polysaccharides be absorbed directly

Answer 6

no, they cannot be directly absorbed and need to be broken down into monosaccharides for digestion

Question 7

what milk can lactose be found in

Answer 7

cow’s milk only

Question 8

where can glycogen be found in the human body

Answer 8

liver and muscles

Question 9

what is cellulose used for

Answer 9

structural support in plant cell walls

Question 10

what is starch used for

Answer 10

major storage form of carbohydrates in plants, major energy source in most diets

Question 11

what is condensation

Answer 11

a reaction where a bond is formed and water is produced (energy is absorbed overall and energy is stored in the bond)

Question 12

what is hydrolysis

Answer 12

a reaction where a bond is broken using water and energy is released overall

Question 13

monosaccharide + monosaccharide

Answer 13

disaccharide + water

Question 14

what is the bond between 2 monosaccharides called

Answer 14

glycosidic bond

Question 15

glucose + glucose

Answer 15

maltose + water

Question 16

glucose + fructose

Answer 16

sucrose + water

Question 17

glucose + galactose

Answer 17

lactose + water

Question 18

functions of carbohydrates

Answer 18

• energy source (as glucose is oxidised in body cells and releases chemical energy during respiration to provide energy)
• storage material (starch is stored in plants while glycogen is stored in the liver / muscles of animals)
• structural material (cellulose is the main component of cell walls)

Question 19

what are excess carbohydrates converted into

Answer 19

glycogen

Question 20

why can’t we digest cellulose?

Answer 20

our body doesn’t have the enzymes to break it down

Question 21

why do we use polysaccharides for storage

Answer 21

their branched structure allows for them to be stored in a more compact way, and they are also insoluble in water

Question 22

why is cellulose used to form cell walls

Answer 22

as it is composed of long chains of glucose molecules with no branching, with hydrogen bonds forming between adjacent chains, stabilising the molecule. this structure provides high tensile strength so that plant cell walls are strong enough to support plant cells

Question 23

why is carbohydrates the primary energy source

Answer 23

as it can be broken down over time and therefore can provide energy readily