Practical Report: 1 full experimental report



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INTERMEDIATE 2 BIOLOGY

  • 3 topics: Living Cells, Genetics & Environmental Biology, Animal Physiology
  • Each unit: 1 unit test (NAB) - 45 mins
  • 65% pass mark (only 1 resit)
  • Practical Report: 1 full experimental report
  • Prelim/Exam : 25 MCQ, 65 short answers, 10 essay

Structure & Function of Cells

  • All cells contain:
  • Nucleus:
  • - controls cell activities
  • - passes on information to next generation
  • Cytoplasm:
  • site of biochemical reactions
  • Cell Membrane:
  • - controls substances moving in & out of cells

Structure & Function of Cells

  • Structures only in plant cells:
  • Chloroplast:
  • - Contains chlorophyll
  • - absorbs light to help photosynthesis
  • Cell Wall:
  • - made of cellulose,
  • - keeps cell shape semi-rigid
  • Vacuole:
  • - regulates water & solute content

Yeast

  • - single celled fungus
  • - doesn’t photosynthesise (no chlorophyll)
  • - reproduces by budding
  • - can feed using oxygen
  • - this is aerobic respiration
  • - or without oxygen
  • - this is anaerobic respiration
  • - respiration is the release of energy from food

Uses of yeast

  • During anaerobic respiration
  • - Sugar Alcohol + CO2 + energy
  • This is known as alcoholic fermentation
  • In baking
  • - sugar in dough is fermented to alcohol & CO2
  • - bubbles of CO2 makes dough rise
  • - alcohol is boiled off by the oven

Brewing/Wine making

  • Beer making uses maltose
  • Maltose produced by germinating barley grains
  • Wine making uses sugar from crushed grapes
  • Alcohol production stops when yeast get poisoned by the alcohol content
  • Dead yeast must be filtered out

Alternative Fuels

  • Gasohol
  • - fuel produced from plant fermentation
  • - mixture of alcohol and petrol
  • Biogas
  • - anaerobic bacteria feed on organic waste
  • - waste converted to methane (‘biogas’)
  • - methane is a useful fuel

Antibiotics

  • A natural chemical produced by micro-organisms
  • These chemicals can kill or stop the growth of other micro-organisms
  • If growth is stopped – micro-organism is sensitive to the antibiotic
  • If it isn’t stopped – it is resistant

Effect of antibiotics on sensitive bacteria

  • Antibiotics damage bacteria in different ways:
  • - damage cell membrane
  • - damage or affect chromosomes
  • - stop synthesis of cell wall
  • - stop chemical reactions in cytoplasm
  • However, many bacteria develop resistance to the antibiotics
  • Some can develop multiple resistance – e.g. MRSA

Need for a wide range of antibiotics

  • No one antibiotic is effective against all bacteria
  • Some people are allergic to certain antibiotics
  • New resistant strains appear to a particular antibiotic, so others may be needed instead
  • - in this example 2 antibiotics have no effect

Lactic Acid

  • Milk is rich in sugar, protein & fat
  • When milk sours, bacteria feed on the milk
  • They convert lactose into lactic acid
  • Lactic acid makes milk proteins clump together (coagulate)
  • This forms a semi-solid food – yoghurt
  • The acid conditions (low pH) acts as a preservative


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