Topic 1A - Biological Molecules

Question 1

What is the theory of evolution?

Answer 1

The theory that all organisms on Earth are descended from one or a few common ancestors and that they have changed and diverged over time.

Question 2

What is the evidence for the theory of evolution?

Answer 2

The fact that a huge variety of different organisms share the same biochemistry (i.e. they all contain the same groups of carbon-based compounds that interact in similar ways) suggests that animals and plants have a common ancestor, which provides indirect evidence for evolution

Question 3

What are polymers?

Answer 3

Polymers are large, complex molecules composed of long chains of monomers joined together

Question 4

What are monomers?

Answer 4

Monomers are small, basic molecular units that can form a polymer

Question 5

How are polymers formed?

Answer 5

Polymers are firmed from their monomers by condensation reactions, which forms a chemical bond between the monomers and releases a molecule of water

Question 6

How are polymers broken down?

Answer 6

Polymers can be broken down into monomers by hydrolysis reactions, which breaks the chemical bond between monomers using a water molecule

Question 7

What are monosaccharides?

Answer 7

Monosaccharides are the monomers that carbohydrates are made of

Question 8

What are the two isomers of glucose?

Answer 8

Alpha glucose

Beta glucose

Question 9

What does alpha glucose look like?

Answer 9

—-

Question 10

What does beta glucose look like?

Answer 10

—-

Question 11

What are disaccharides?

Answer 11

Disaccharides are two monosaccharides joined together by a glycosidic bond

Question 12

How are disaccharides formed?

Answer 12

Disaccharides are formed by condensation reactions; they form a glycosidic bond and release a water molecule

Question 13

What are some examples of monosaccharides? (3)

Answer 13

Glucose
Galactose
Fructose

Question 14

What are some examples of disaccharides? (3)

Answer 14

Sucrose
Lactose
Maltose

Question 15

What are the monosaccharides which make up the common examples of disaccharides?

Answer 15

Maltose - glucose & glucose
Sucrose - glucose & fructose
Lactose - glucose & galactose

Question 16

What are examples of reducing sugars?

Answer 16

All monosaccharides
Some disaccharides (e.g. maltose and lactose)

Question 17

What are examples of non-reducing sugars?

Answer 17

Some disaccharides

Question 18

How do you test for reducing sugars?

Answer 18

Heat sample with Benedict’s reagent

Question 19

What does a positive test look like for reducing sugars?

Answer 19

Sample forms green - yellow - orange - brick red precipitate

Question 20

What does a negative test look like for reducing sugars?

Answer 20

The sample stays blue

Question 21

How do you test for non-reducing sugars?

Answer 21

Heat sample with Benedict’s reagent
Negative result for reducing sugar
Heat a new sample with dilute HCl then neutralise with sodium hydrogencarbonate.
Heat sample with Benedict’s reagent

Question 22

What does a positive result for non-reducing sugars look like?

Answer 22

Sample forms green - yellow - orange - brick red precipitate

Question 23

What does a negative result for non-reducing sugars look like?

Answer 23

Sample stays blue

Question 24

Which elements do all carbohydrates contain?

Answer 24

C - Carbon
H - Hydrogen
O - Oxygen