1.1. Biomolecules — Inorganic ions, water and carbohydrates

Question 1

What is the role of magnesium in a plant cell?

Answer 1

Needed to make chlorophyll
Mg2+

Question 2

Why is iron needed in the body?

Answer 2

A component of haemoglobin, required for binding and transporting oxygen in the blood
Fe2+

Question 3

What is the role of calcium in animals and plants?

Answer 3

A structural component of bones and teeth
Strengthens cell wall in plants
Ca2+

Question 4

What is the role of phosphate within the cell?

Answer 4

component of nucleotides (DNA, RNA, ATP)

A component of phospholipids in cell membranes
PO43-

Question 5

Why is water called a dipolar molecule?

Answer 5

The hydrogen atoms at one end have a slight positive charge; the oxygen atom at the other end has a slight negative charge

Question 6

What causes the dipole in water?

Answer 6

The greater electronegativity of the oxygen atom draws the shared electrons in the covalent bond between the oxygen and hydrogen towards it, giving it a slightly negative charge. The hydrogen atom has a slightly positive charge.

Question 7

What is a hydrogen bond?

Answer 7

A weak attraction between a hydrogen atom with a slight positive charge and another atom with a partial negative charge (oxygen or nitrogen)

Question 8

What is cohesion?

Answer 8

Attraction between dipolar water molecules.
Hydrogen bonds form between the negative oxygen atom of one water molecule and the positive hydrogen atom of an adjacent water molecule

Question 9

What property allows insects to walk on water?

Answer 9

Surface tension due to cohesion

Question 10

What is specific heat capacity?

Answer 10

The amount of energy needed to raise the temperature of 1kg of a substance by 1 degree.

Question 11

What is the latent heat of vaporisation?

Answer 11

The energy needed for a substance to change from liquid to gas (evaporate)

Question 12

Why is it beneficial to have a high latent heat of vaporisation?

Answer 12

For cooling. A large amount of body heat is required to evaporate sweat (energy is needed to break H bonds between water molecules)

Question 13

Why is it beneficial to have a high specific heat capacity?

Answer 13

Gives thermal stability to aquatic environments - bodies of water or cells and tissues, due to the large amount of energy required to raise its temperature

Question 14

What property of water allows it to act as a transport medium?

Answer 14

Its polarity enables it to be a solvent for other polar molecules e.g. plasma transports glucose and ions in animals

Question 15

Give examples of water as a metabolite.

Answer 15

Required for photosynthesis and hydrolysis reactions
Produced during respiration and condensation reactions

Question 16

Give examples of water as a metabolite.

Answer 16

Required for photosynthesis and hydrolysis reactions
Produced during respiration and condensation reactions

Question 17

At what temperature does water have maximum density and why is this advantageous?

Answer 17

4 degrees C
Ice floats insulating water below, protecting aquatic habitats

Question 18

What is the general formula for a monosaccharide?

Answer 18

Cn(H2O)n

Question 19

What are the general properties of all monosaccharides?

Answer 19

Sweet-tasting and soluble

Question 20

Which groups of mononsaccharides have 3, 5 and 6 carbons, respectively?

Answer 20

Triose (3C) pentose (5C), hexose (6C)

Question 21

In which pathways are triose sugars important?

Answer 21

Respiratory pathways - triose phosphate and pyruvate

Question 22

For what purpose are pentose sugars used in the body?

Answer 22

Constituents of ATP (ribose), RNA (ribose) and DNA (deoxyribose)

Question 23

What is glucose used for?

Answer 23

The starting material for respiration
Building block of starch and glycogen (alpha glucose), cellulose and chitin (beta glucose)

Question 24

What are isomers?

Answer 24

Compounds with the same molecular formula but different structural formulae e.g. alpha and beta glucose