predicted

• co-transport

  • sodium ions actively transported out of the epithelial cell into blood
  • reduces sodium ion conc in epithelial cell
  • sodium ions diffuse down lumen down conc grad into epithelial cell
  • diffuse through a co-transporter protein
  • glucose and amino acids also attach and transported to epithelial cell against conc grad
  • glucose moves by facilitated diffusion from epithelial cell into blood
• biodiversity

  • species diversity = number of different species in a community
  • genetic diversity = variety of genes amongst all the individuals in a population in one species
  • ecosystem diversity = range of different habitats
  • species richness = number of different species in a particular area at a particular time
  • measured by index of diversity
  • N(N-1)/n(n-1)
  • N = total number of organisms of all species
  • n = total number of organisms of one species
• natural selection types

  • directional = one of the extremes has the selective advantage due to a change in environment
  • stabilising = modal trait has selective advantage as environment doesnt change but standard deviation decreases
  • anatomical, physiological or behavioural adaptations
• meiosis

  • produces 4 genetically different haploid daughter cells by two divisions from one diploid parent
  • independent segregation and crossing over introduce variation
  • independent segregation = random separation of homologous chromosomes in meiosis 1
  • crossing over = chromatids become twisted around each other so break and then recombine with another chromatid creating new combinations of alleles
• capillaries

  • connect arterioles to veins
  • no muscle or elastic layer
  • wall is one cell thick for short diffusion distance
  • no valves
• arteries

  • carry blood away from heart into arterioles
  • thick muscle layer for constriction and dilation to control volume of blood
  • thick elastic layer to maintain blood pressure
  • thick walls to prevent vessels bursting due to high pressure
  • no valves
• arterioles

  • smaller than arteries and connect to capillaries
  • thick muscle layer to restrict blood flow
  • thin elastic layer and walls as low pressure
  • no valves
• veins

  • carry blood back into the heart
  • thin muscle layer so it cant control blood flow
  • thin elastic layer and walls as pressure is lower
  • valves
• adaptations of fish gills

  • lamellae on filaments gives large sa for diffusion
  • thin epithelium so short diffusion pathway between water and blood
  • lots of capillaries maintains diffusion pathway
  • counter current maintains diffusion gradient
  • circulation replaces blood saturated with oxygen
  • ventilation replaces water
• flow of water maintained over gills

  • mouth opens and operculum shuts
  • floor of mouth lowered
  • water enters due to decreased pressure
  • mouth closes and operculum opens
  • floor raised as increased pressure
  • high pressure forces water over gills
• fish counter current system

  • blood and water flow in opposite directions
  • blood passes water with a higher oxygen concentration
  • diffusion gradient of oxygen maintained along length of lamellae
  • diffusion occurs across whole length of lamellae
  • more oxygen diffuses into blood
  • more aerobic respiration releasing energy for swimming
  • one way flow of water needs less energy
• herd immunity =
if enough if the population are vaccinated, the pathogen cannot spread easily amongst the population which protects those not vaccinated
• • artificial active immunity

  • following the weakened version of the pathogen via a vaccine
• • natural active immunity

  • following infection and the creation of the bodies own antibodies and memory cells
• • active immunity

  • immunity created my own immune system due to pathogen exposure
• • passive immunity
  • antibodies are introduced into the body and the pathogen doesnt enter the body so no plasma or memory cells are made giving no long-term immunity
• why cant viruses be destroyed by antibiotics?

  they have different mechanisms to replicate and no cell wall
• lipids

  • triglycerides
  • phospholipids
  • ester bond = condensation between glycerol and fatty acid
  • saturated fatty acid = no double carbon bonds
  • unsaturated fatty acid = double carbon bonds
  • emulsion test = add ethanol and water then shake, cloudy-white emulsion
• triglycerides

  • 1 glycerol and 3 fatty acids
  • high ratio of carbon-hydrogen bonds to carbon atoms so good energy store
  • low mass to energy ratio so lots of energy in small volume
  • non-polar so insoluble in water
• phospholipids

  • 1 glycerol, 2 fatty acids and 1 phosphate group
  • polar so forms bilayer in aqueous environment
  • hydrophillic heads to hold at surface of cell membrane
  • form glycolipids with carbohydrates for cell recognition
• non-competitive inhibitors = inhibitors increase so rate decreases as shape of enzyme is altered by inhibitors
• • competitive inhibitors 

  • inhibitors increase so rate decreases as active sites are blocked by inhibitors so substrates cant bind