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Noushi 9
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GCSE Biology Note on Biology iGCSE Notes, created by Noushi 9 on 28/03/2016.

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Noushi 9
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Section 5
a) Food production
  • Pesticides : +ve = Very effective. Kill all the pests. -ve = Expensive, pests can become resistant, cause env. damage as some remain in soil and food chain, kills other organisms too
  • Biological control : +ve = Cheap. Self regulating as predator won't kill itself + reproduces. -ve = does not kill ALL the pests. Predator may enter the wild and affect biodiversity

  • CO2 production by yeast experiment - Add sucrose solution + oil layer (blocks air) andplace in different temp water baths. Collect Co2 over water in measuring cylinder to measure rate. Use limewater to test
  • Lactobacillus bulgaricus
  • Fermenter: aseptic conditions = Sterile. Filter air and sterilise the fermenter
  • Intraspecific predation - Fish of the same species eat each other. Separate different age, gender & feed often
  • Interspecific predation - different species eat the fish
b) Selective breeding

  • Selective breeding - Individuals with desired characteristics are bred together to produce offspring that express both desired characteristics.
  • Plants - Higher yields, more nutritional to humans, resistant to diseases and pests, hardier to survive in harsher climates and conditions for longer year production
  • Animals - More meat/eggs/milk, more fur/higher quality fur, more offspring, resistant to diseases
c) Generic modification
  • Restriction enzymes - Cutting + Ligase enzymes - Sticking
  • Recombinant DNA - DNA from 2 different organisms that has been recombined
  • Transgenic Organism - The organism that receives the new gene from a different species
  • GM Plants are : Increased resistance to pests,pathogens,heat,drought, high salt. Extended shelf lives,contain more vitamins, higher yields, easier to eat/process
  • -ve = Could be more vulnerable to change in conditions or diseases as they are GM
d) Cloning
  • Micropropagation/tissue culture - Explants, Sterile, tissue culture, grown in vitro, clones, hormones + nutrients (optimum growing conditions), agar medium, controlled conditions (temp., light, humidity)
  • +ve = Large numbers produced rapidly, planted all year round, species that are hard to grow can be reproduced, GM only small no. of plants but then introduced into thousands quickly, plants can be stored easily
  • -ve = Plants could be vulnerable to change in conditions or a new disease
  • Dolly the Sheep - Diploid nucleus from body/stem/udder cell electrically zapped with enucleated egg cell, divided by mitosis to form an embryo, implanted into surrogate mother
  • transgenic animals - Can produce antigens of a specific bacteria/virus for vaccines given to people, grow human antigens on their organs for transplant as body is less likely to reject them, sheep produce milk with specific proteins for humans needed to treat diseases like cystic fibrosis