3.1.7/8 Water and inorganic ions

Question 1

Why is water a polar molecule

Answer 1

O is more electronegative than H, so attracts the electron density in the covalent bond more strongly
Forms O delta negative and H delta positive

Question 2

State 4 biologically important properties of water

Answer 2

Metabolite
High specific heat capacity
High latent heat of vaporisation
Cohesion between molecules

Question 3

Why water is significant to living organisms

Answer 3

Solvent for polar molecules during metabolic reactions
Enables organisms to avoid fluctuations in core temperature
Cohesion-tension of water molecules in transpiration stream

Question 4

What are inorganic ions and where are they found in the body

Answer 4

Ions that do not contain carbon atoms
Found in cytoplasm and extracellular fluid
May be in high or very low concentrations

Question 5

Explain the role of hydrogen ions in the body

Answer 5

High concentration of H+ = low pH
H+ ions interact with H-bonds and ionic bonds in tertiary structure of proteins which can cause them to denature

Question 6

Explain the role of iron ions in the body

Answer 6

Fe2+ bonds to porphyrin ring to form haem group in haemoglobin
Haem group has binding site to transport 1 molecules of O2 around body in bloodstream
4 haem groups per haemoglobin molecule

Question 7

Explain the role of sodium ions in the body

Answer 7

Involved in cotransport for absorption of glucose and amino acids in lumen of gut
Involved in propagation of action potentials in neurons

Question 8

Explain the role of phosphate ions in the body

Answer 8

Component of
DNA

Question 9

Explain the role of phosphate ions in the body

Answer 9

Component of
DNA
ATP
NADP
cAMP