1.1 - monomers and polymers 1.2 - carbohydrates

Question 1

Define monomer

Answer 1

smaller units that join together to form larger molecules.

Question 2

Examples of monomers

Answer 2

monosaccharides (glucose, fructose, galactose)

amino acids

nucleotides

Question 3

Define polymer

Answer 3

molecules formed when many monomers join together

Question 4

Examples of polymers

Answer 4

polysaccharides

proteins

DNA/RNA

Question 5

What happens in a condensation reaction?

Answer 5

a chemical bond forms between 2 molecules & a molecule of water is produced

Question 6

What happens in a hydrolysis reaction?

Answer 6

a water molecule is used to break a chemical bond between 2 molecules

Question 7

name the 3 hexose monosaccharides

Answer 7

glucose, fructose, galactose

Question 8

name the type of bond formed when monosaccharides react

Answer 8

(1,4 or 1,6) glycosidic bond

Question 9

name 3 disaccharides

Answer 9

maltose, sucrose, lactose

Question 10

how do the 3 disaccharides form?

Answer 10

glucose + glucose = maltose
glucose + fructose = sucrose
glucose + galactose = lactose

Question 11

describe the functions of starch

Answer 11

storage polymer of a-glucose in plant cells

-insoluble = no osmotic effect

-large = does not diffuse out of cells.

Question 12

describe the structure of starch related to its function

Answer 12

energy store in plant cells
-polysaccharide of a-glucose
-1,4 and 1,6 glycosidic bonds so branched (rapidly hydrolysed)
large molecule (can’t leave cell)
-insoluble, no osmotic effect, water potential isn’t affected
-helical, compact, good for storage

Question 13

describe the structure and functions of glycogen

Answer 13

-1,4 and 1,6 glycosidic bonds

-branched - more enzymes can act of these branches for hydrolysis

-insoluble - no osmotic effect & does not diffuse out of cells

-compact

Question 14

describe the structure and functions of cellulose

Answer 14

polymer of b-glucose gives rigidity to plant cell walls

-1,4 glycosidic bonds

-straight chain, unbranched molecule

-H- bond crosslinks between parallel strands form microfibrils = high tensile strength.

Question 15

Describe the benedict’s test for reducing sugars.

Answer 15

1. add and equal volume of benedict’s reagent to a sample
2. heat the mixture in a water bath at 100°C for 5 mins
3. Positive result: colour change from blue to orange/brown

Question 16

describe the Benedict’s test for non-reducing sugars

Answer 16

1. Negative result: Benedict’s reagent remains blue
2. Hydrolyse non-reducing sugars e.g. sucrose into their monomers by adding 2cm³ of HCl. Heat in boiling water bath 5mins
3. Neutralise the mixture using sodium carbonate solution.
4. proceed with the Benedict’s test as usual.

Question 17

describe the test for starch

Answer 17

1. add iodine
2. positive result: colour change from orange to blue-black