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INTERMEDIATE 2 BIOLOGY

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.

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INTERMEDIATE 2 BIOLOGY

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  1. 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

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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

  7. 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

  8. 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

  9. 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

  10. 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

  11. 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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