water Flashcards
Name the 7 important properties of water, which makes it useful
- cohesive
- high specific heat capacity
- large latent heat of evaporation
- a good solvent so allows ionic compounds to separate = good for chemical reactions and good for transport
- transparent= making water a good habitat
- lower density when ice
Why does water have a high specific heat capacity?
Water molecules are attracted to the positive and negative poles of other water molecules (hydrogen bonding), so they stick together = takes more energy to separate them = high bp
What is the definition of latent heat of vaporisation?
heat taken in by a liquid in order to transform it into a vapour
What is the definition of cohesion?
the tendency of molecules to stick together
What is the definition of surface tension?
Surface tension is the cohesion of the molecules on the surface of a fluid to occupy the least possible volume
Describe the cohesion and surface tension in water
Due to hydrogen bonding, water has large cohesive forces. This allows columns of water to move through the xylem of plants and through blood vessels in animals
Water has a high surface tension because hydrogen bonds among water molecules resist stretching or breaking the surface. Water molecules are more strongly cohesive to each other than they are to air. Good for small organisms like pond scaters
Name and explain the properties that help aquatic organisms survive
- ice has a lower density than water = water doesn’t freeze from the bottom, it freezes from the top so aquatic animals will not freeze and can still move. Also, the ice can provide insulation for the aquatic animals
- High specific heat capacity = water rarely fluctuates in temperature , so organisms will not freeze or be warmed to death
- solvent = organisms can easily absorbed dissolved components.
In terms of the chemical structure of water, explain why water is such a good transport medium
Polar molecule = dissolve ionic substances
cohesive due to easily forming hydrogen bonds with other water molecules = flows nicely
solvent
liquid at room temperature.
Water has a high latent heat of vaporisation. Why is this useful?
because so much energy is needed to evaporated water (due to strong hydrogen bonds),as water leaves the surface from which it is evaporating and removes a lot of heat with it. You feel this as a cooling effect on your skin.
Why are new nucleotides only added in a 5 to 3 direction during dna synthesis? (4 marks)
DNA polymerase is the enyzme that joins adjacent nucleotides together
its specific
DNA polymerase only complementary to the 3 end of strand.
5 end and 3 end are different shapes.
Give two features of DNA and explain how each one is important in the semi-conservative replication of DNA? (2 marks, 3 possible answers)
1- Weak hydrogen bonds between bases allow two strands to unzip
2- 2 strands exists, both of them can act as template for replication
3- Complementary base pairing, this allows accurate replication
why may a gene contain more than the necessary amount of bases it needs
because there are regions of the gene that are non-coding
What inorganic ions and where are they found?
An inorganic ion is an ion that does not contain carbon
occur in solution in the cytoplasm and body fluids of organisms, some in high concentration and others in very low concentrations
Describe the role of iron ions in haemoglobin
- an important part of haemoglobin
- Fe2+ binds to the oxygen in haemoglobin
- when bound to oxygen it temporarily becomes fe 3+
Describe the role of sodium ions in terms of glucose and amino acids
A molecule of glucose or an amino acid can be transported into a cell alongside sodium ions = co-transport
During interphase in eukaryotic cells, DNA replication takes place. Explain why one strand of DNA replicates continuously, whereas the opposite strand replicates discontinuously
