T1: Biological Molecules

Question 1

What are monomers?

Answer 1

Small molecular units that join to make polymers

Question 2

Define polymer

Answer 2

A molecule made from long chains of monomers

Question 3

What is a condensation reaction?

Answer 3

The joining of two monomers together with the release/elimination of a
molecule of water (forming a chemical bond)

Question 4

What is a hydrolysis reaction?

Answer 4

The breaking of a chemical bond between two molecules involving the use of a water molecule

Question 5

Two monosaccharides = ?

Answer 5

A disaccharide (joined by a condensation reaction forming a glycosidic bond)

Question 6

More than two monosaccharides = ?

Answer 6

Polysaccharide (joined together by condensation reactions forming glyosidic bonds)

Question 7

Name 3 monosaccharides

Answer 7

glucose
galactose
fructose

Question 8

Name one non reducing sugar?

Answer 8

sucrose

Question 9

glucose + glucose = ?

Answer 9

maltose

Question 10

glucose + galactose = ?

Answer 10

lactose

Question 11

glucose + fructose = ?

Answer 11

sucrose

Question 12

Name the 2 types of glucose

Answer 12

Name the 2 types of glucose

Question 13

In alpha glucose the OH is…

Answer 13

below

Question 14

In beta glucose the OH is…

Answer 14

above

Question 15

How are glycogen and starch formed?

Answer 15

by the condensation of alpha glucose

Question 16

How is cellulose formed?

Answer 16

by the condensation of beta glucose

Question 17

Where is starch located in organisms?

Answer 17

Many parts of plants in the form of small grains + large amounts found in seeds & storage organs

Question 18

What is the purpose of starch?

Answer 18

Plants store excess glucose as starch

Question 19

How is starch produced?

Answer 19

Condensation of many α-glucose sub units, which then form hydrogen bonds with molecules in the same chain

Question 20

Starch is a mixture of…

Answer 20

2 polysaccharides of alpha-glucose
amylose + amylopectin

Question 21

Describe the structure of amylose

Answer 21

Long, UNbranched chain of α-glucose

Question 22

Describe how the structure of amylose relates to its function

Answer 22

Angles of the glycosidic bonds = coiled structure → makes it compact = can fit more into a small space (= good for storage)

Question 23

Describe the structure of amylopectin

Answer 23

Long, BRANCHED chain of α-glucose

Question 24

Describe how the structure of amylopectin relates to its function

Answer 24

Its side branches allow the enzymes that break down starch to get at the glycosidic bonds easily = glucose can be released quickly

Question 25

α-glucose molecules are formed by what type of glycosidic bonds?

Answer 25

1,4 & 1,6 glycosidic bonds

Question 26

How is cellulose formed?

Answer 26

by the condensation of beta glucose

Question 27

Where is glycogen located in organisms?

Answer 27

Stored as small granules mainly in liver and some in muscles

Question 28

What is the purpose of glycogen?

Answer 28

In animals: excess glucose is stored as glycogen

Question 29

Glycogen is a p______…

Answer 29

Polysaccharide of α-glucose

Question 30

Describe glycogen’s structure

Answer 30

Chain of α-glucose with many side branches coming off it + short chains

Question 31

Describe how glycogen’s structure relates to its function

Answer 31

1. Loads of branches & shorter chains = stored glucose can be released even quicker than in starch → important for energy releases in animals
2. Very compact molecule, making it good for storage

Question 32

Why is starch suited for its role? 3x

Answer 32

1. Insoluble in water = doesn’t affect water potential (doesn’t cause water to enter cells by osmosis)
2. Compact = lots of it can be stored in small space
3. When hydrolysed, alpha glucose can be easily transported & used in respiration

Question 33

Describe the structure of cellulose

Answer 33

1. Long, unbranched chains of beta-glucose
2. Straight cellulose chains run parallel to each other in cell walls = allows hydrogen bonds to form cross-linkages between chains

Result: formation of bundles called micro fibrils which then join together to make macro fibrils

Question 34

What is the purpose of cellulose?

Answer 34

To provide rigidity to plant cells

Question 35

Describe the test for reducing sugars

Answer 35

Add Benedict’s reagent (blue) to sample & heat it in a boiling water bath (5 mins)
Positive result = orange/red precipitate
Higher the concentration of reducing sugar = further the colour change goes
blue - green - yellow - orange - brick red

Question 36

Describe the test for non-reducing sugars

Answer 36

Heat a new sample with dilute HCl in a boiling water bath
Neutralise with alkali
Repeat Benedicts test for reducing sugars

Question 37

Describe the structure of a triglyceride

Answer 37

3 fatty acids attached to a single glycerol

Question 38

What do fatty acids have?

Answer 38

Have long ‘tails’ made from hydrocarbons

Question 39

Describe the structure of a phospholipid

Answer 39

2 fatty acids attached to a glycerol + a phosphate group

Question 40

Name two kinds of fatty acids

Answer 40

saturated
unsaturated

Question 41

Describe how a triglyceride forms

Answer 41

1) A fatty acid joins to a glycerol molecule
2) When ester bonds are formed a molecule of water is released (condensation)
3) This process repeats twice to form a triglyceride

Question 42

Why are triglycerides good energy storage molecules?

Answer 42

Long hydrocarbon tails of fatty acids contains lots of chemical energy SO lots of energy is released when they are broken down

Question 43

Describe how the structure of triglyceride makes them insoluble?

Answer 43

Triglycerides clump together as insoluble droplets in cells due to the fatty acids which are hydrophobic

Tails face inwards shielding themselves from water with their glycerol heads