biology

• Genetic engineering


  Modifying an organism's genome by adding a new helpful gene
• Genetic engineering process


  1. Find desirable gene

  2. Cut out gene using enzymes

  3. Insert gene into vector (virus or bacterial plasmid)

  4. Introduce vector to target organism

  5. Organism cells take up vector and produce protein coded for by gene
• Genetically engineered organisms


  • Sheep producing drugs in milk
  • Bacteria producing human insulin
• Genetically modified crops


  • Improved fruit size and quality
  • Disease resistance
  • Insect resistance
  • Herbicide resistance
• Gene therapy


  Giving a person a healthy version of a gene to fix an inherited disorder
• Gene therapy is difficult because the faulty gene is in all of the person's cells, so the new gene would have to be transferred to every cell</b>
• A potential solution is to transfer the gene at an early stage of development, such as at the egg or embryo stage
• Biotic factors


  Any living factor that affects another organism or that shapes the ecosystem in some way
• Abiotic factors


  The non-living parts of the environment that can affect organisms
• Abiotic factors


  • Light intensity
  • Temperature
  • Carbon dioxide concentrations
  • Moisture levels
  • Wind intensity and direction
  • pH
  • Mineral content of soil
• Increase in temperature


  Increases the rate of photosynthesis
• Increase in temperature


  Animals have to spend less energy staying warm, so they can use more energy for growth or spend less time searching for food
• Biotic factors affecting a clownfish

  • Predation by bigger fish or eels
  • The sea anemone (habitat)
  • Competition for plankton and algae
  • Disease
• Factors like light intensity and carbon dioxide concentration might not affect the clownfish directly, but they might affect other species around them like the sea anemone, which will in turn affect the clownfish
• The heart acts as the pump for the circulatory system
• Blood vessels


  1. Arteries carry blood away from the heart

  2. Capillaries exchange nutrients and oxygen with tissues

  3. Veins carry blood back to the heart
• Arteries


  • Carry blood directly from the heart
  • Blood inside is at high pressures
  • Have thick layers of muscle and elastic tissue to be strong and elastic
• Capillaries


  • Very small vessels that come into close contact with cells
  • Walls are only one cell thick and permeable
  • Total cross-sectional area is much higher than arteries, so blood flows more slowly
• Veins

  • Relatively large vessels with big lumens
  • Walls are thin with small layers of elastic and muscle tissue
  • Have valves to prevent backwards blood flow
• Calculating rate of blood flow


  Divide volume of blood by time taken
• 2500 ml of blood passes through the aorta in 8 minutes
• Chromosomes are made up of genes that determine characteristics such as eye colour and height.
• The nucleus is the control centre of the cell, containing DNA.
• light microscopes are easy to use, cheap and rely on light
• electron microscopes are expensive, hard to use and use electrons also better resolution
• cardi vascular disease has treatments, stent tubes, heart donor
• genotype the genetic makeup of an organism
• phenotype the humans visible traits
• alleles different versions of a gene
• dominant allele masks recessive allele
• female chromosones are XX
• male chromosones are XY
• platelets help blood clotting
• red blood cells can change shape, allows transport of oxygen around body
• white blood cells ( many different types)

  make antibodies, fight infection
• mitochondria 


  where most of the aroebic respirtaion takes place
• chloroplasts


  these are where photosynthesis occurs which makes food
• nucleus


  contains genetic material in cell
• parts of a light mircroscope

  eye lens,objective lens,stage,microscope slide,light source,coarse focusing knob,fine focuisng knob
• image 


  what we see when we look into microscope