T1

Question 1

Why does water have a high latent heat of evaporation?

Why is this important?

Answer 1

A polar molecule
so many hydrogen bonds between molecules
takes a large amount of energy to break all the bonds
so takes a lot of energy to change from a liquid to a gas

makes sweat an efficient cooling mechanism, evaporation of a small amount of water= takes with it a lot of heat
important mechanism to cool the body down and maintain optimum temp

Question 2

Cohesive forces between water molecules importance

Answer 2

water is a polar molecule so many hydrogen bonds between molecules
makes water molecules stick together

important in transpiration, allows water to move up the xylem in a continuous column

Question 3

structure of water

Answer 3

a polar molecule:
hydrogen atoms with slight positive charge
oxygen atoms with slight negative charge

many hydrogen bonds form between water molecules

Question 4

Importance of Hydrogen ions

Answer 4

Maintenance of optimal pH for enzyme action
the higher the conc of H the lower the pH

ATP synthesis, pass through ATP synthase during aerobic respiration and photosynthesis to provide energy for the reaction of ADP+Pi- ATP

Oxygen delivery
Bohr effect- CO2 enters the blood reacts with water and produces H. Increasing con of H more H binds to amino acid side chains on haemoglobin
reduces its affinity of oxygen, more readily unloads and disassociates with oxygen, more O2 for respiring cells

Question 5

Importance of sodium ions

Answer 5

Generation of nervous impulses, depolarisation

Co-transport of glucose and amino acids- absorption @illium and reabsorption at the PTC

Sodium ions are involved in initiating and controlling the rhythmic contractions of the heart
the rhythmic nerve impulses are continuously generated in the SA node without any stimulus due to the slow influx of sodium ions

Question 6

Structure of ATP (adenosine triphosphate)

Answer 6

Base: adenine
Sugar: ribose
3 phosphate groups, 2 high-energy phosphoanhydride bonds

Question 7

Why is ATP a suitable immediate source of energy?

Answer 7

ATP-ADP+Pi releases small amounts of manageable amounts of energy
only one bond is hydrolysed- so energy realise is immediate