Water & Carbohydrates

Question 1

How does hydrogen bonding occur between water molecules?

Answer 1

• Water is polar because oxygen is more electronegative than hydrogen so there are partial positive and negative parts
• positive and negative parts of different molecules attract each other
• forming hydrogen bonds

Question 2

Properties of water

Answer 2

• High boiling point
• less dense when solid than when liquid
• cohesive
• adhesive
• high surface tension

Question 3

Cohesion

Answer 3

The attraction of molecules to each other.

Question 4

Roles of water

Answer 4

Solvent, transport medium, coolant, stable habitat

Question 5

Which properties of water make it a good solvent?

Answer 5

*H+ is attracted to negative ions of solute
* O- is attracted to negative ions
* Ions get surrounded by H2O molecules
* polar substances get dissolved

Question 6

Which properties of water make it a good transport medium?

Answer 6

• Cohesive - water molecules stick together due to its polarity
• Helps water to flow and be transported up plant stems
• Adhesive - helps to transport substances in blood and plants

Question 7

What allows water to do capillary action?

Answer 7

• Adhesion & cohesion
• Surface tension - water contracts to resist forces
• capillary action - Water moves up a tube against the force of gravity - in blood & plant stem

Question 8

Capillary action

Answer 8

Water can move up a tube against the force of gravity

• Escpecially in arms & legs
• So that blood can reach the heart

Question 9

What makes water a good habitat to live in?

Answer 9

• Doesn’t change temperature easily - HSHC
• hydrogen bonds absorb lots of energy.
• less dense as a solid so will float when it freezes

Question 10

What makes water a good coolant?

Answer 10

• It takes a lot of energy to overcome the hydrogen bonds
• lots energy to evaporate
• cools surface of skin

Question 11

Monomer

Answer 11

Molecule that consists of a single unit and can join with others to form a polymer

Question 12

Polymer

Answer 12

Large molecules composed of many similar smaller molecules called monomers

Question 13

Chemical elements in carbohydrates

Answer 13

Carbon, hydrogen, oxygen

Question 14

Chemical elements in lipids

Answer 14

Carbon, hydrogen, oxygen

Question 15

Chemical elements in proteins

Answer 15

Carbon, hydrogen, oxygen, nitrogen, sulfur

Question 16

Chemical elements in nucleic acids

Answer 16

Carbon, hydrogen, oxygen, nitrogen, phosphorus

Question 17

What is glucose an example of?

Answer 17

Hexose monosaccharide

Question 18

Example of a hexose monosaccharide

Answer 18

Glucose

Question 19

What is ribose an example of?

Answer 19

Pentose monosaccharide

Question 20

Example of a pentose monosaccharide

Answer 20

Ribose

Question 21

Difference between alpha and beta glucose

Answer 21

• alpha glucose OH group on carbon 1 is down.
• In beta glucose, it is up.

Question 22

Difference between a hexose and pentose monosaccharide

Answer 22

• hexose sugar = 6 carbons.
• pentose sugar = 5 carbons.

Question 23

How is a disaccharide synthesised?

Answer 23

• OH group removed from one monosaccharide
• H removed from the other in a condensation reaction
• glycosidic bond forms between carbons 1 and 4

Question 24

How are disaccharides broken down?

Answer 24

• Hydrolysis reactions occur
• catalysed by enzymes
• which adds a water molecule to break the glycosidic bond

Question 25

Monosaccharides in sucrose

Answer 25

Glucose, fructose

Question 26

What do glucose and fructose make?

Answer 26

Sucrose

Question 27

Monosaccharides in lactose

Answer 27

Galactose, glucose

Question 28

What do galactose and glucose make?

Answer 28

Lactose

Question 29

Monosaccharides in maltose

Answer 29

Two glucoses

Question 30

What do two glucoses make?

Answer 30

Maltose

Question 31

Structure of starch

Answer 31

Two polysaccharides in amylose and amylopectin,

Question 32

Structure of amylose

Answer 32

Made of alpha glucose molecules joined together by 1-4 glycosidic bonds, the angle of the bond makes it twist to form a helix, stabilised by hydrogen bonding

Question 33

Structure of amylopectin

Answer 33

Made of alpha glucose molecules joined together by 1-4 and 1-6 glycosidic bonds, 1-6 bonds give a branched structure, 1-6 bonds occur every 25 glucose subunits

Question 34

Structure of glycogen

Answer 34

More branched than amylopectin, made of alpha glucose molecules

Question 35

Structure of cellulose

Answer 35

Made of beta glucose molecules, unable to bond like alpha glucose molecules because the OH groups are too far from each other, alternate beta glucose molecules rotate by 180 degrees, straight chain molecule forms, cellulose molecules make hydrogen bonds thus forming microfibrils, the microfibrils join together to form macrofibrils, macrofibrils combine together to form fibres

Question 36

Properties of glucose

Answer 36

Polar, soluble

Question 37

Why it is important that glucose is soluble

Answer 37

Glucose is dissolved in the cytosol of the cell

Question 38

Function of glucose

Answer 38

To be used in aerobic respiration to produce ATP which can provide energy.

Question 39

Why is glucose soluble?

Answer 39

Hydrogen bonds can form between hydroxyl groups and water molecules.

Question 40

Properties of amylose

Answer 40

Compact, insoluble

Question 41

Why is amylose compact?

Answer 41

Hydrogen bonds within the molecule that stabilise it

Question 42

Why is amylose insoluble?

Answer 42

It's compact

Question 43

Why is it important that amylose is compact and insoluble?

Answer 43

Makes it an effective chemical energy store

Question 44

Properties of amylopectin

Answer 44

Insoluble, branched, compact

Question 45

Why is amylopectin compact?

Answer 45

it is branched, made up of glucose molecules joined by 1, 4 and 1, 6 glycosidie bonds

Question 46

Why is the branched nature of amylopectin AND glycogen important for their function?

Answer 46

side branches, rapidly digested by enzymes therefore energy is released quickly.

Question 47

Properties of glycogen

Answer 47

Insoluble, branched, compact

Question 48

Properties of cellulose

Answer 48

Strong, insoluble

Question 49

Functions of cellulose

Answer 49

Cell walls, roughage

Question 50

What makes cellulose so strong?

Answer 50

cellulose chains are linked together by hydrogen bonds to form strong microfibrils. provides structural support for cells

Question 51

Why is cellulose good as roughage?

Answer 51

It is hard to break down into monomers