Biology- Section 9

  • Created by: emmaaaaa
  • Created on: 18-05-13 09:59

Increasing Crop Yield

You can artificially create ideal conditions for photosynthesis for a better crop yield:

  • Keeping plants in glasshouses to keep free from pests and diseases
  • Give artificial light after Sun goes down so plants have more time to photosynthesise
  • Glasshouses trap Sun's heat keep warm, in winter also use heater keep temperature ideal
  • increase level carbon dioxide using paraffin heater, as carbon dioxide a by-product

Fertilisers can be used to ensure the crops have enough nutrients:

  • Plants need some elements to make compounts like proteins
  • If not enough available, their growth and life processes are affected
  • Sometimes elements not in soil as been used by previous crop
  • Fertilisers replace missing elements or provide more to increase crop yield

Pest control can stop pests eating crops:

  • Pesticides- often poisonous to humans, used carefully on food can harm other wildlife
  • Biological control- use other organisms reduce number of pests can have longer lasting effects
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Yeast and Making Beer

Yeast respires aerobically (with oxygen) to turn sugar into carbon dioxide.

Yeast respires anaerobically (without oxygen) to turn sugar into carbon dioxide and alcohol.

  • Beer usually made from grail- e.g. barley
  • Grains allowed germinate and starch broken into sugar and enzymes
  • Dried in a kiln, called malting then mashed and water added make sugary solution
  • Solution sieved and hops added give bitter flavour
  • Yeast added and mixture incubated, ferments sugar into alcohol
  • Rise concentration of alcohol starts kill yeast so fermentation slow down
  • Different yeast tolerate different levels alcohol make stronger/weaker beer
  • Beer drawn off, sometimes clarifying agent added make it clearer
  • Beer pasteurised- heated kill any yeast left then ready to sell
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Selective Breeding

Organisms are selectively bred to develop the best features:

  • Maximum yield of meat, milk, grain etc.
  • Good health and disease resistance
  • In animals: temperament, speed, fertility, mothering skills
  • In plants: pretty flowers, nice smell

Increase productivity of cows:

  • Cows selectively bred produce offspring higher yield in meat
  • Animal characteristics increase meat yield selected and bred together
  • The offspring best characteristics then bred, continued several generations

Increase crop yield:

  • Combine 2 desired characteristics
  • Tall wheat good grain but easily damaged, dwarf wheat resist damage lower grain yield
  • Plants cross-bred and best resulting cross-bred again, new variety wheat good characteristics
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Fish Farming

Fish Farming cages in the sea like in Scotland:

  • Fish in cages in sea stop using energy swimming
  • Also protects from interspecific predation- being eaten by birds and seals
  • Fed on food pellets carefully controlled maximise amount energy get
  • Better quality food, quicker and bigger fish will grow
  • Young fish reared special tanks ensure many as possible survive
  • Keep younger fish separate big fish so not eat small fish
  • Fish kept in cages more prone to disease and parasites e.g. sea lice
  • Can use pesticides but avoid pollution biological control used instead e.g. wrasse fish eat lice
  • Fish can be selectively bred, produce less agressive, faster growing fish

Fish can be farmed in tanks:

  • Fresh water fish e.g. carp farmed in ponds/ tanks so conditions controlled
  • Water monitored check temperature and pH and oxygen levels good
  • Easy control how much food supplied and give exactly right sort food
  • Water can be removed or filtered to get rid of waste to keep clean and to avoid pollution
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Genetic Engineering

Enzymes often used to cut DNA and join it back together:

  • Restriction enzymes recognise certain sequences of DNA and cut the DNA there
  • Ligase enzymes join the DNA together
  • When 2 different parts of DNA are joined together it is known as recombinant DNA

Vectors are used to insert DNA to other organisms:

  • Vector used transfer DNA into a cell- plasmids and viruses
  • DNA want to insert cut out with restriction enzyme, vector DNA cut open using same enzyme
  • Vector DNA and DNA inserting mixed with ligase enzyme- joins to form recombinant DNA
  • Recombinant DNA inserted other cells
  • Cells can use gene inserted to make protein you want e.g. bacteria contain gene human insulin be grown in fermenter produce insulin people with diabetes
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Genetic Engineering

Plants can be genetically modified to improve food production:

  • Insect resistant- spray less pesticides so less wildlife harmed
  • Herbicide resistant- spray herbicides kill weeds not affect crop itself
  • Concerns over GM food- transplanted genes may get into environment- weed pick up herbicide resistant gene and make new 'superweed'
  • Transplanted genes could affect food chains or human health also
  • Changing genes could cause unforseen problems which are passed on to future generations
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Tissue culture (micropropagation) is used to clone plants

  • Plant with desirable characteristics selected to be cloned, small pieces taken from tips of stems and side shoots of plant
  • The explants are sterelised to kill microorganisms
  • They are then grown in vitro- placed in petri dish with nutrients and growth hormones
  • Cells divide and grow into small plants, if large quantity needed further explants can be taken from spall plants until enough produced
  • Small plants planted in soil and put into glasshouses and develop genetically identical to orginal plant

Cloning adult mammals can be done by transplanting a cell nucleus like Dolly the sheep:

  • Nucleus of sheep egg cell removed making enucleated cell
  • Diploid nucleus inserted in its place- nucleus mature udder cell different sheep
  • Cell stimulated to start dividing via mitosis as if normal fertilized cell
  • Dividing cell implanted into uterus of another sheep to develop until ready to be born
  • Result was dolly, clone of sheep- other animals can be cloned similar method.
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