2.1.2 Biological molecules

Question 1

What happens due to the sharing of the electrons in water being uneven between the oxygen and hydrogen atoms?

Answer 1

The oxygen atom attracts the electrons more strongly than the hydrogen atoms, resulting in a weak negatively charged region on the oxygen atom (δ-) and a weak positively charged region on the hydrogen atoms (δ+), this also results in the asymmetrical shape

Question 2

What is a polar molecule?

Answer 2

When a molecule has one end that is negatively charged and one end that is positively charged

Question 3

As a result of the polarity of water, … form between the positive and negatively charged regions of adjacent water molecules

Answer 3

Hydrogen bonds

Question 4

Ice is … dense than water

Answer 4

less

Question 5

Benefits of ice being less dense than water

Answer 5

ice floats on water, creating an insulating layer and insulating the water below, increases chance of survival of organisms in large bodies of water as it prevents them from freezing and allows aquatic animals to move

Question 6

Strong … between water molecules enables effective transport of water in tube like cells

Answer 6

cohesion

Question 7

What property of water allows it to act as a medium for chemical reactions and transport dissolved compounds?

Answer 7

water is a solvent

Question 8

What is the benefit of water having a high specific heat capacity?

Answer 8

It requires a lot of energy to warm it up which minimises temperature fluctuations and allows it to act as a buffer (enzymes, living organisms= remain a constant environment)

Question 9

Condensation reaction definition:

Answer 9

a reaction which joins monomers by chemical bonds and it involves the elimination of a water molecule.

Question 10

Hydrolysis reaction definition:

Answer 10

when water is added to break a
chemical bond between two molecules.

Question 11

What elements do carbohydrates contain

Answer 11

carbon, hydrogen and oxygen

Question 12

What is a monosaccharide?

Answer 12

a single sugar unit

Question 13

Examples of a monosaccharide:

Answer 13

glucose, fructose, ribose

Question 14

Glucose formula:

Answer 14

C6H12O6

Question 15

What type of sugar is glucose?

Answer 15

a hexose sugar (6 carbon sugar)

Question 16

What are the 2 types of glucose?

Answer 16

alpha and beta glucose

Question 17

What is the difference between alpha and beta glucose?

Answer 17

In alpha glucose the hydroxyl (OH) group is below on carbon 1, whereas in beta glucose the hydroxyl group is above on carbon 1

Question 18

Properties of glucose:

Answer 18

soluble in water, bonds store large amounts of energy

Question 19

What is a disaccharide?

Answer 19

2 monosaccharides joined together via a condensation reaction

Question 20

What bond is formed during the condensation reaction?

Answer 20

a glycosidic (covalent) bond

Question 21

Name 3 disaccharides:

Answer 21

maltose, sucrose and lactose

Question 22

How is maltose formed?

Answer 22

a condensation reaction between two glucose molecules

Question 23

How is sucrose formed?

Answer 23

a condensation reaction between glucose and fructose molecules

Question 24

How is lactose formed?

Answer 24

a condensation reaction between glucose and galactose

Question 25

What is a polysaccharide?

Answer 25

formed from many monosaccharides joined via glycosidic bonds

Question 26

Glycogen and starch are examples of polysaccharides formed from .... glucose

Answer 26

alpha

Question 27

What two polysaccharides is starch made of?

Answer 27

amylose and amylopectin

Question 27

Cellulose is an example of a polysaccharide formed from .... glucose

Answer 27

beta

Question 28

Is amylose branched?

Answer 28

No it is a long, unbranched chain

Question 29

What bonds are found in amylose?

Answer 29

1-4 glycosidic bonds only

Question 30

What do the 1-4 glycosidic bonds in amylose cause?

Answer 30

They cause the chain to coil into a helix due to the angle of the bonds

Question 31

What does the coiling of the amylose chain cause?

Answer 31

It makes it compact meaning a lot of energy is stored in a small space

Question 32

Is amylopectin branched?

Answer 32

Yes it is a long, branched chain

Question 33

What bonds are found in amylopectin?

Answer 33

1-4 and 1-6 glycosidic bonds

Question 34

What does the branching in amylopectin cause?

Answer 34

it means that it can be rapidly digested by enzymes so energy can be released quickly

Question 35

Features of starch:

Answer 35

insoluble, large, coiled, branched

Question 36

What does it mean if starch is insoluble?

Answer 36

it doesn't affect water potential

Question 37

What does it mean if starch is large?

Answer 37

it cannot diffuse out of cells

Question 38

What bonds are found in glycogen?

Answer 38

1-4 and 1-6 glycosidic bonds

Question 39

Is glycogen branched?

Answer 39

Yes it is highly branched (more branches than amylopectin)

Question 40

Glycogen is .... meaning it doesn't affect water potential

Answer 40

insoluble

Question 41

How does glycogen maximise the amount of energy that is stored?

Answer 41

it is large but compact

Question 42

What bonds are found in cellulose?

Answer 42

1-4 glycosidic bonds

Question 43

How does cellulose form 1-4 glycosidic bonds?

Answer 43

every other beta glucose molecule is inverted 180 degrees (flipped upside down) to bring the OH groups close enough to react

Question 44

Properties of cellulose:

Answer 44

long, straight, unbranched chains, lots of hydrogen bonds and made of microfibrils

Question 45

What do lots of hydrogen bonds in cellulose cause?

Answer 45

high tensile strength