Paper 2

• The Linnaean System


  1. Kingdom
  2. Phylum
  3. Class
  4. Order
  5. Family
  6. Genus
  7. Species
• The bacteria Fusarium is used to make mycoprotein (eg. quorn)
• The Brain

  • Cerebral cortex - outer wrinkly layer. Responsible for: consciousness, intelligence, memory, language
  • Medulla - top of spinal chord, bottom of brain - unconscious activities
  • Cerebellum - back of brain - muscle coordination
• Eye

  Structure:

  • Sclera - tough, supporting wall
  • Cornea - transparent outer layer. Refracts light into the eye
  • Pupil - light enters
  • Iris - muscles controlling the diameter of the pupil
  • Retina - contains light receptors
  • Lens - focusses light onto retina
• Eye

  Near object:

  • ciliary muscles contract
  • suspensory ligaments slack
  • lens becomes fatter
  • Light is refracted more

  Distant object:

  • ciliary muscles relax
  • suspensory ligaments tighten
  • lens become thinner
  • light is refracted less
• Hormone glands

  • Pituitary - master gland - controls others
  • Pancreas - insulin
  • Thyroid - thyroxine (metabolism, temperature, heart rate)
  • Adrenal - adrenaline - fight or flight response
  • Ovaries - oestrogen
  • Testes - testosterone
• Blood glucose

  When too high

  • Insulin secreted by pancreas
  • Causes cells to take up more glucose
  • Muscles and liver convert glucose to glycogen

  When too low

  • Glucagon secreted by pancreas
  • Causes glycogen to be converted back to glucose
• Controlling water in the body

  • Anti-diuretic hormone is released from the pituitary gland. More ADH increases permeability of kidney tubules meaning more water is reabsorbed making urine more concentrated
  • Excess amino acids are converted into fat and carbohydrates by the process of deamination with the waste product ammonia which is converted into urea in the liver and excreted
• Menstrual Cycle

  No fertilised egg:

  • Oestrogen and progesterone levels fall
  • Pituitary gland releases FSH causing egg maturation and release of oestrogen
  • Ovaries release oestrogen causing the uterus lining to thicken, inhibits FSH production and stimulates LH production
  • Pituitary gland releases LH which causes ovulation
  • Ovaries release progesterone which maintain the lining of the uterus

  Fertilised egg:

  • Oestrogen and progesterone stay high

  Contraceptive:

  • Oestrogen and progesterone

  Fertility:

  • FSH and LH
• DNA

  • 3 bases code for one amino acid
  • A sequence of amino acids to form one protein is coded by 1 gene
  • DNA repeating unit - nucleotide - phosphate molecule, a sugar (sugar-phosphate backbone) and a base (A T G C)
• DNA


  • mRNA copies 3 bases from nucleus to ribosomes
  • Carrier molecules bring amino acids which are ordered in accordance with the mRNA producing a protein
  • Mutations - insertion, deletion, substitution
• Reproduction

  Gamete are produced by meiosis

  • 2 divisions
  • Genes doubled, one to each new cell
  • Each of these new cells is split again, taking half of the genes

  .

  • Sexual reproduction includes variation due to meiosis
  • Asexual reproduction just needs one parent and desirable characteristics can be copied

  BOTH

  • Malaria - sexual in mosquito, asexual in human
  • Fungi - can choose depending on conditions
  • Some plants
• • Genotype - combination of alleles
  • Phenotype - the characteristics the alleles code
• • Mendel - "hereditary unit", either dominant or recessive passed onto offspring - couldn't be proven as no knowledge of DNA and chromosomes
  • Lamark - opposing Darwin - characteristics are developed by constant use
• Genetic engineering

  • desirable allele is isolated
  • added to a vector
  • vector is introduced to target organism
• Artificial cloning

  • Tissue culture - tissue from plant placed in growth hormones
  • Cuttings
  • Embryo transplant - prize egg and sperm produced. Artificially fertilised. Embryo cloned. Placed in host mothers
  • Adult cell cloning - unfertilised egg's nucleus removed and replaced with nucleus from body you want to clone. Placed in surrogate mother - clone
• Fossils

  • gradual replacement by minerals
  • casts and impressions
  • preservation in places where no decay occurs

  .

  Lack of evidence for where life began. Theories:

  • original organisms soft-bodied
  • fossil destroyed by tectonic plate movement
• Alfred Russel Wallace independently came up with the idea of natural selection
• Carl Wose


  • added another level on top of Carl Linnaeus' system:
  • Archaea - prokaryotic extremophiles
  • Bacteria - true bacteria
  • Eukaryotes - everything else. Subdivided by Linnaeus' Linnaean system
• Required Practical - Decay

  • test tube 1 - 5cm³ lipase
  • test tube 2 - 5cm³ milk and 5 drops of phenolphthalein. Add 7cm³ sodium carbonate
  • Heat both test tubes to temperature being tested (eg. 30°C) in a water bath
  • Transfer 1cm³ from test tube 1 to test tube 2. Start stopwatch
  • Stop stopwatch when there is colour change from pink to colourless
  • Repeat at different temperatures
• Trophic levels


  • Level 1 - producer
  • Level 2 - herbivore
  • Level 3 - Carnivore
  • Level 4 - Carnivore - possibly apex predator
• Biomass

  • Pyramids of biomass show trophic level 1 at the bottom and shows relative mass of organic material
  • ~1% suns energy hitting producers is transferred by photosynthesis
  • ~10% of biomass is passed onto next level
  • Lost through - uneaten material, waste products
  • efficiency = biomass transferred to next level / biomass available at previous level
• Factory farming is more efficient as less energy is lost from movement of animals but is seen as cruel
• Human Insulin

  • Plasmid removed from bacteria
  • Insulin gene removed from human chromosome with restriction enzyme
  • Plasmid cut open with restriction enzyme
  • Insulin gene added to plasmid
  • Inserted back into the bacteria which is cloned
• Plant hormones

  
  

  Auxin

  • gravitropism, phototropism
  • stimulates growth in shoots
  • inhibits growth in roots
  • Used for killing weeds, growing cuttings, growing cells in tissue culture

  Gibberellins

  • induce flowering after dormancy growing larger fruit

  Ethene

  • controls cell division and stimulates fruit ripening enzymes
  • used to speed up ripening
  • Ethene's affect can be blocked to delay ripening