Chapter 1: Biological Molecules

Question 1

What is a covalent bonding?

Answer 1

Atoms share a pair of electrons in their outer shells. As a result, the outer shell of both atoms is filled and a molecule is formed.

Question 2

What is an ionic bonding?

Answer 2

The electrostatic attraction between ions with opposite charges which attract one another.

Question 3

What is hydrogen bonding?

Answer 3

The electrons within a molecule are not evenly distributed. One region is more negatively charged than the rest of the molecule - a polar molecule

Question 4

Monomers?

Answer 4

Single small sub-units

Question 5

Polymers?

Answer 5

Many monomers linked together to form long chains

Question 6

What is a condensation reaction?

Answer 6

A reaction that joins molecules together and release water. e.g. glucose into starch

Question 7

What is a hydrolysis reaction?

Answer 7

A reaction that breaks molecules with the addition of water e.g. lipids into glycerol and fatty acids

Question 8

What is metabolism?

Answer 8

All the chemical processes that happen in living organisms

Question 9

What is the mole?

Answer 9

It is a SI unit for measuring the amount of a substance and is abbreviated to mol
6/02x10^23

Question 10

Molar solution?

Answer 10

A solution that contains one mol of solute in each litre of solution

Question 11

Monosaccharides

Answer 11

A single monomer

Question 12

Polysaccharides

Answer 12

Combined monosaccharides joined together

Question 13

Test for reducing sugars?

Answer 13

Benedict’s reagent added to food sample solution.
Heat gently in boiling water.
If a reducing sugar is present, the solution will change from blue to red.

Question 14

Maltose

Answer 14

Glucose + Glucose

Question 15

Sucrose

Answer 15

Glucose + Fructose

Question 16

Lactose

Answer 16

Galactose + Glucose

Question 17

A glycosidic bond?

Answer 17

The bond formed between two monosaccharides when they join together.

Question 18

Test for non-reducing sugars?

Answer 18

Conducts Benedict’s test
Then add a bit more food sample and add HCl, put the tube in gently boiling water for 5 mins
Slowly add some sodium hydrogen-carbonate solution to the test tube - test with pH paper to check the solution is alkaline
Retest the solution with Benedict’s reagent
If the solution turns orange-brown then a non reducing sugar was present (it was hydrolysed)

Question 19

Test for starch?

Answer 19

Add iodine to the liquid form of the food sample

If the sample turns from yellow to blue-black then iodine is present

Question 20

Starch?

Answer 20

Found it parts of plants
Made up of alpha glucose monosaccharides linked by glycosidic bonds
May be branched or unbranched
Large and insoluble 
Compact

Question 21

Glycogen?

Answer 21

Found in animals and bacteria
Made up of alpha monosaccharides but has a shorter chain
It is more highly branched
Insoluble and Compact

Question 22

Cellulose?

Answer 22

Found in plants
Made from Beta glucose
Unbranched straight chains which run parallel to each other with hydrogen bonds
Molecules are grouped to form microfibrils- these form fibres for more strength