Biological molecules 2.1.2

Question 1

What is a carbohydrate?

Answer 1

A molecule containing carbon, hydrogen and oxygen, with a general formula of C_n(H₂O)_n

Question 2

What is the composition of maltose?

Answer 2

Question 3

What is the composition of sucrose?

Answer 3

Question 4

What is the composition of lactose?

Answer 4

Question 5

What is the composition of cellobiose?

Answer 5

Question 6

What is a glycosidic bond?

Answer 6

A bond formed between two monosaccharides by a condensation reaction

Question 7

What are the properties of water?

Answer 7

• Small and polar molecule (lighter than gases like CO₂ and O₂, but liquid at room temperature)
• Unlike most substances, less dense in its solid state, than liquid state
• High boiling point (because of its high specific heat capacity)
• High latent heat of vaporisation
• Universal solvent and a reactant
• Cohesive (resulting in surface tension)
• Adhesive

Question 8

What is a monomer?

Answer 8

An individual molecule that binds to at least two other molecules to make up a polymer

Question 9

What is a molecule?

Answer 9

A particle made up of two or more atoms chemically bonded together

Question 10

What is a polymer?

Answer 10

A large molecule made of many individual molecules (monomers) bonded together

Question 11

What is a condensation reaction?

Answer 11

A reaction that occurs when two molecules are joined together with the removal of water

Question 12

What is a hydrolysis reaction?

Answer 12

A reaction that occurs when a molecule is split into two smaller molecules with the addition of water

Question 13

What is a hydrogen bond?

Answer 13

A weak interaction, relative to a covalent bond, that can occur wherever molecules contain a partially negatively charged atom bonded to a partially positively charged hydrogen atom

Question 14

What are the advantages of water being liquid at room temperature?

Answer 14

• provide a reaction medium for chemical reactions
• provide an effective transport medium, for example, in blood and vascular tissues
• can provide a habitats for livings things in rivers, lakes and seas
• form a major component of the tissues in living organisms

Question 15

What are the advantages of water being less dense in its solid state (ice)?

Answer 15

• ponds and other bodies of water are insulated agaisnt extreme cold, the layer of ice reduces the rate of heat loss from the rest of the pond
• aquatic organisms have a stable environment to live through winter, that does not change temperature easily (due to ice acting as insulation, also meaning that water under the layer of ice do not freeze and organisms can survive)

Question 16

What are the advantages of water being a universal solvent?

Answer 16

• molecules and ions can move around and react together in water. Many such reactions happen in the cytoplasm of cells, which is over 70% water.
• molecules and ions can be transported around living things whilst dissolved in water.