Read the summary and the most important questions on Biology for the IB Diploma : standard and higher level | 9780199151431 | Andrew Allott.

• 2 Chemistry of life

• 2.1 Chemistry of life

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• What are the most frequent occurring chemicals?

  1. Carbon 
  2. Hydrogen 
  3. Oxygen 
  4. Nitrogen 

  Calcium: bones

  Iron: Hemoglobin 

  Sulphur: Amino acids

  Sodium: nerves 

  Phosphorus: ATP

• How is water used  in living organisms?

  Coolant

   

  High specific heat capacity --> can absorb heat without significant rise in temp.Homeostasis:

  maintaining a consistent internal environment eg temp

   

  High latent heat of vaporization--> Heat energy needed to brak hydrogen bond for H2) to evaporate

  -Carries heat away from body eg sweating.  

   

  Transport in plants --> cohesive properties 

  Allows long columbs of water to be drawn up xylem 

   

  Metabolic reactions + Transport --> solvent properties

  -As water allows substances to dissolve into it and be transported e.g.. glucose in blood.

• State one function of glucose, lactose and glycogen  in animals and fructose, sucrose and cellulose in plants

  Animals

  • Glucose: aerobic respiration 
  • Lactose: milk for young
  • Glycogen: carbohydrates storage 

  Plants 

  • Fructose: fruit sugar + flower nectar
  • Sucrose: transport of sugar 
  • Cellulose: cell wall structural support

• State the functions of lipids

  1. Thermal insulation 
  2. Energy storage 
  3. Impact protection 

• Compare the use of carbohydrates and lipids in energy storage 

  • Lipids have twice the energy content of carbs per unit of mass 
  • Carbs used for short term --> lipids long term 
  • Carbs stored as:

  Plants--> starch 

  animals --> glycogen

  • Carbs are more soluble than lipids : more readily converted to glucose for respiration when needed 
  • Lipids have less mass than carbohydrates, more effective storage

• 3 Digestion

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• Explain why digestion f large molecules is essential 

  • Digestion breaks down large complex insoluble molecules that could not pass from the digestive system to the blood
  • Once large molecules are broken down they become simple soluble molecules that can easily pass from the digestive system into the blood

• State the source, substrate, product and optimum PH for amylase, protein and lipase

  Enzyme	Source	Substrate	Product	PH
  Amylase	Slavia	Starch	Maltose	7
  Protease	Stomach cell	Proteins	Amino acids	3
  Lipase	Pancreas juice	Fats	lipids (tryglicerides)	7 (neutral)

• Functions of the small intestine 

  Digestion: all types of digestion 

  • Carbohydrates 
  • Protease 
  • Lipase 

  Absorption:

  • vili

• Function of the large intesine 

  • water absorption 
  • undigested food compacted to faeces 
  • bacteria which synthesize vitamin K

• Differences between absorption and assimilation 

  Absorption: means taking in substances through cell membranes or layers of cells, in particular from the lumen of the gut into the blood or lymph capillaries 

   

  Assimilation:  involves the conversion of nutrients into fluids or solid parts of the organism. Assimilation can ONLY OCCURE after absorption