Biological Molecules

Question 1

What is a monomer

Answer 1

Smaller units from which larger molecules are made

Question 2

What are polymers

Answer 2

Molecules made from a large number of monomers joined together

Question 3

Examples of monomers

Answer 3

Monosaccharides, amino acids, nucleotides

Question 4

What is a condensation reaction

Answer 4

Reaction that joins two molecules together, with the formation of a chemical bond, and involves the elimination of a molecule of water

Question 5

What is a hydrolysis reaction

Answer 5

Reaction that breaks a chemical bond between two molecules and involves the use of a water molecule

Question 6

What is a monosaccharide

Answer 6

The monomer from which larger carbohydrates are made

Question 7

Examples of a monosaccharide

Answer 7

Glucose, galactose and fructose

Question 8

What is the bond between 2 monosaccharides called

Answer 8

A glycosidic bond

Question 9

How are disaccharides formed

Answer 9

The condensation of 2 monosaccharides

Question 10

Examples of disaccharides

Answer 10

Maltose, sucrose and lactose

Question 11

What is maltose formed of

Answer 11

Condensation of 2 glucose molecules

Question 12

What is sucrose formed of

Answer 12

A condensation of glucose and fructose

Question 13

What is lactose formed of

Answer 13

A condensation of a glucose molecule and a galactose molecule

Question 14

What are the 2 isomers of glucose

Answer 14

Alpha and beta

Question 15

What is the structural difference of the isomers of glucose

Answer 15

Alpha glucose has its oh group at the bottom on the far right whereas beta glucose has its oh group at the top on the far right

Question 16

How are polysaccharides formed

Answer 16

The condensation of many glucose units

Question 17

Examples of polysaccharides

Answer 17

Glycogen, starch and cellulose

Question 18

What is a structural difference between glycogen + starch and cellulose

Answer 18

Glycogen + starch are formed by the condensation of alpha glucose whereas cellulose is formed by the condensation of beta glucose

Question 19

Function of starch

Answer 19

Energy storage (main plant storage sugar)

Question 20

How is starch’s structure suited to its function

Answer 20

1. It is insoluble and so doesn’t affect water potential (water isn’t drawn into cells)
2. It is large and insoluble so doesn’t diffuse out of cells
3. It is compact (alpha helical) so a lot can be stored in a small place
4. Forms alpha glucose when hydrolysed, which is easily transported and used in respiration
5. Branched so has many ends which can be acted on simultaneously by enzymes so glucose monomers are released rapidly

Question 21

Structure of starch

Answer 21

Chains of alpha glucose which form a coiled chai

Question 22

Structure of glycogen

Answer 22

Similar to starch but had shorter chains and is more highly branched so is more compact

Question 23

Function of glycogen

Answer 23

Carbohydrate storage

Question 24

How is the structure of glycogen suited to its function

Answer 24

1. Insoluble so doesn’t tend to draw water into cells by osmosis
2. Is compact so lots stored in a small space
3. Insoluble so doesn’t diffuse out of cells
4. More highly branched than starch so has more ends to be acted on by enzymes and releases glucose which are used in respiration (animals have a higher metabolic rate)

Question 25

What is the structure of cellulose

Answer 25

Straight up branched chains, every other monomer is rotated 180, have hydrogen bonds that from cross bridges

Question 26

What is the function of cellulose

Answer 26

Provides rigidity to the plant cell (cell wall)

Question 27

How is the structure of cellulose suited to its function

Answer 27

1. Made of beta glucose so form long straight un branched chains 2. Cellulose molecular chains run parallel to each other and have hydrogen cross links which add collective strength 3. Molecules are grouped to form microfibrils which in turn are grouped to form fibres which adds strength

Question 28

What is the formula of a carbohydrate

Answer 28

(CH2O)n

Question 29

What is a reducing sugar

Answer 29

Include all monosaccharides and some disaccharides such as maltose It is a sugar that can donate electrons to another chemical

Question 30

What is Benedict’s solution

Answer 30

Copper II sulfate

Question 31

What are the names of 2 groups of lipid

Answer 31

Triglycerides and phospholipids

Question 32

How is triglyceride formed

Answer 32

The condensation of one molecule of glycerol and 3 molecules of fatty acid

Question 33

What type of bond is formed between glycerol and a fatty acid

Answer 33

Ester bond (coo)

Question 34

What are the roles of lipids

Answer 34

1. Energy storage 2. Insulation 3. Protection 4. Water proofing

Question 35

What elements are lipids made of

Answer 35

Oxygen, carbon, hydrogen

Question 36

What is a saturated fatty acid

Answer 36

Single carbon bonds, solid

Question 37

What is an unsaturated fatty acid

Answer 37

Double carbon bonds, more liquid due to double bind lowering the melting point (as double bond causes kink in chain, so can’t be closely packed together)

Question 38

What are phospholipids made up of

Answer 38

Phosphate, glycerol and 2 fatty acids

Question 39

Why do phospholipids have a hydrophilic head

Answer 39

Phosphate molecules attract water, has a charge

Question 40

Why do phospholipids have a hydrophobic tail

Answer 40

Fatty acids repel water

Question 41

What 3 ways do phospholipids arrange themselves

Answer 41

1. A monolayer 2. A micelle 3. A bilayered sheet (inside cell membrane)

Question 42

What is the test for lipids

Answer 42

The emulsion test - add ethanol to food, then add distilled water, if lipid present a white emulsion will be floating at or near the top of the water

Question 43

Test for non-reducing sugar

Answer 43

Negative Benedict’s test then acid hydrolyse by adding hydrochloric acid, then re do Benedict’s and it’s positive