Biological molecules

Question 1

What is covalent bonding?

Answer 1

Atoms share a pair of electrons in their outer shell.

Question 2

What is ionic bonding?

Answer 2

Ions with opposite charges attract one another in an electrostatic attraction.

Question 3

What is a hydrogen bonding?

Answer 3

the negative region of one polarised molecule (electrons are evenly distributed) is attracted to the positive charged region of another, in a weak electrostatic bond.

Question 4

What are monomers?

Answer 4

the smaller units from which large molecules are made.

Question 5

What are polymers?

Answer 5

Molecules made from a large number of monomers joined together.

Question 6

What is polymerisation?

Answer 6

Process by which polymers are made.

Question 7

What is a condensation reaction?

Answer 7

Joining of two molecules together with the formation of a chemical bond and involves the elimination of a molecule of water.

Question 8

What is a hydrolysis reaction?

Answer 8

Breaking of a chemical bond between two molecules and involves the use of a water molecule.

Question 9

What is metabolism?

Answer 9

All the chemical reactions that take place in living organisms.

Question 10

What is a molar solution?

Answer 10

A solution that contains one mole of solute in each litre of solution.

Question 11

What is the importance of carbons?

Answer 11

Carbon atoms readily form bond with other carbons, allowing sequence of carbon atoms of various lengths to be built up, forming a ‘backbone’ along which other atoms can be attached.

Question 12

Name 3 examples of monomers?

Answer 12

Monosaccharides, amino acids, nucleotides.

Question 13

Name 3 examples of polymers?

Answer 13

Carbohydrates, proteins, lipids.

Question 14

What are the 4 main elements made up from polymers?

Answer 14

Carbon, hydrogen, oxygen, nitrogen.

Question 15

What are monosaccharides?

Answer 15

The monomers from which carbohydrates are made, e.g. glucose, galactose, and fructose.

Question 16

Name the characteristics of monosaccharides?

Answer 16

• Sweet-tasting
• Soluble substances
• (CH2O)n

Question 17

What is a glycosidic bond?

Answer 17

A condensation reaction between two monosaccharides.

Question 18

What is maltose formed from?

Answer 18

A disaccharide formed by condensation of two glucose molecules.

Question 19

What is sucrose formed from?

Answer 19

A disaccharide formed by condensation of a glucose molecule and a fructose molecule.

Question 20

What is lactose formed from?

Answer 20

Is a disaccharide formed by condensation of a glucose molecule and a galactose molecule.

Question 21

What are polysaccharides?

Answer 21

Polymers formed by combing together many monosaccharide molecules in a glycosidic bond by condensation reactions.

Question 22

What are the characteristics of polysaccharides?

Answer 22

Large molecules
Insoluble- makes them suitable for storage.
When hydrolysed, break down into momsaccarides and disaccharides.

Question 23

What are the 3 main polysaccharides?

Answer 23

Starch, cellulose, glycogen

Question 24

What is a reducing sugar?

Answer 24

A sugar that can donate electrons to another chemical.

Question 25

What is reduction?

Answer 25

A chemical reaction involving the gain of electrons or hydrogen.

Question 26

What is the test for reducing sugars?

Answer 26

The Benedict’s test:

1. Add 2cm of the food sample (if not already in liquid form, grind it up in water) into a test tube.
2. Add an equal volume of Benedict’s reagent.
3. Heat the mixture in a gently boiling water bath for 5 minutes.
   4.If reducing sugar is present the solution turns orange- brown.

Question 27

What is a non-reducing sugar?

Answer 27

Do not act as reducing agents in chemical reactions.

Question 28

What is the test for a non-reducing sugar?

Answer 28

(Must be hydrolysed into its monosaccharide component by hydrolysis)
1. Add 2cm of the food sample (must be in liquid form, if not ground up in water) into a test tube.
2. Add equal amounts of Benedict’s reagent into the test tube and filter.
3. Place in a gently boiling water bath for 5 minutes, if it does not change colour, non-reducing sugar is not present