Name the 4 key inorganic ions in living organisms
Magnesium ions (Mg2+)
Iron ions (Fe2+)
Calcium ions (Ca2+)
Phosphate ions (PO43-)
What is the role of magnesium ions in plants?
Used to produce chlorophyll
What is the role of iron ions in animals?
Found in haemoglobin and is involved in the transport of oxygen
What is the role of phosphate ions in living organisms?
Used for making nucleotides, including ATP, and are a constituent of phospholipids, found in biological membranes
What is the role of calcium ions in living organisms?
Used to strengthen tissues such as bones and teeth in animals and cell walls in plants
Why is water a polar molecule?
O is more electronegative than H, so attracts the electron density in the covalent bond more strongly, forming O 𝛿- (slight negative charge) & H 𝛿+ (slight positive charge)
Describe hydrogen bonding between water molecules
Weak intermolecular forces of attraction form between a lone pair on a δ- O and a δ+ H on an adjacent molecule
What is a metabolite?
A molecule formed or used in metabolic reactions
Describe the role of water as a metabolite
Water is a reactant in photosynthesis and hydrolysis reactions. Water is a product in aerobic respiration and condensation reactions
What does specific heat capacity mean?
This means a large amount of energy is needed to raise its temperature
Why does water have a high specific heat capacity?
The hydrogen bonds between water molecules restrict their movement, resisting an increase in kinetic energy and therefore resisting an increase in energy
Why is water’s high specific heat capacity important for organisms?
It prevents large fluctuations in water temperature, which is important in keeping aquatic habitats satble, so that organisms do not have to adapt to extremes of temperature. It allows enzymes within cells to work efficiently
What does latent heat of vaporisation mean?
This means a lot of energy is needed to change water from liquid to a vapour
Why is water’s high latent heat of vaporisation important for organisms?
When water evaporates, it has a cooling effect. This is important in temperature control and homeostasis; organisms can lose heat through sweating or panting or from a leaf’s surface
Why is water an important solvent for organisms?
Water is a polar universal solvent. It enables chemical reactions to take place within the cells, the transport of materials (transport medium) in the plasma and the removal of metabolic waste
What is cohension?
The attraction of water molecules for each other, because of the dipole structure of water, producing hydrogen bonds between them
When water molecules undergo cohesion what happens to their structure and what does this mean for plants?
The molecules stick together in a lattice. It allows columns of water to be drawn up xylem vessels in plants
Why does water have a high surface tension?
Due to the ordered arrangement and cohesion of molecules at the surface of water
Why is the high surface tension of water important for organisms?
-Enables the transport of water and nutrients through plant stems and small blood vessels in the body
-Allows small insects to ‘walk’ on water
Why is water being transparent important for aquatic plants?
It allows water to pass through. This lets aquatic plants photosynthesise effectively
What is a monosaccharide?
-Simple sugar
- Building blocks for larger carbohydrates
-General formula Cn(H2O)n
Give 3 examples of monosaccharides
Triose, Pentose, Hexose sugars
Where is the OH group placed on carbon 1 in a-glucose?
At bottom
Where is the OH group placed on carbon 1 in B-glucose?
On top
