biology paper 1

• Nucleus


  Animal, plant
• Prokaryotic cells


  No nucleus, bacteria cells
• Mitosis process


  1. Nucleus dissolves

  2. Genetic material is duplicated

  3. 2 sets of chromosomes move to different sides

  4. Mitochondria, ribosomes & other organelles are duplicated

  5. Cell divides producing 2 identical diploid cells
• Stem cells


  Aren't specialised, can specialise to perform specific functions, found in embryos and plant meristems
• Blood cells


  Some are made in bone marrow, only specialise in blood cells
• Diffusion


  Movement of particles from high to low concentration
• Osmosis


  Diffusion of water across a semi-permeable membrane to balance the solution concentration inside and outside of the cell
• Active transport


  Movement of particles through a membrane via carrier proteins
• Levels of organisation


  • Cell
  • Tissue
  • Organ
  • Organ system
• Organ system


  • Circulatory system
  • Digestive system
• Digestive system


  1. Teeth break down food mechanically

  2. Saliva contains amylase

  3. Stomach contains hydrochloric acid and enzymes

  4. Liver produces bile

  5. Pancreas secretes amylase

  6. Water absorbed into bloodstream in large intestine

  7. Glucose absorbed into bloodstream by villi in small intestine
• Enzymes


  Biological catalysts
• Enzymes


  • Carbohydrases break down carbohydrates into simple sugars
  • Proteases break down proteins into amino acids
  • Lipases break down lipids into glycerol and fatty acids
• Enzyme activity (rate of reaction)

  Increases with temperature until the enzyme denatures
• Food tests


  • Starch turns iodine from orange to black
  • Sugars turn Benedict's solution from blue to orange
  • Protein turns biuret's reagent from blue to purple
  • Lipids turn cold ethanol cloudy
• Respiratory system


  • Trachea
  • Bronchi
  • Bronchioles
  • Alveoli
• Alveoli


  • Large surface area to allow gas exchange to occur
  • Oxygen diffuses into bloodstream and binds to haemoglobin in red blood cells to be transported
• Double circulatory system


  Blood enters heart twice every time it is pumped
• Parts of the heart

  • Right atrium
  • Right ventricle
  • Left atrium
  • Left ventricle
  • Valves
  • Electrical pulse from cells near right atrium causes heart to contract
• Left side of heart

  • Has thicker walls due to the higher pressure needed to pump blood to the body
• Arteries


  Carry blood away from the heart, have thick walls and narrow lumen to withstand high pressure
• Veins


  Carry blood back to the heart, have thin walls and wide lumen, have valves to prevent backflow
• Arteries splitting to form capillaries

  Arteries split to form capillaries which are one cell thick to allow fast diffusion between blood and tissues
• Coronary heart disease is caused when the artery supplying blood to the heart becomes blocked
• Fats can build up in arteries, restricting blood flow, causing cardiovascular disease
• Stents can be inserted to open up blocked vessels
• Statins are drugs that reduce fatty deposits in arteries
• Communicable disease


  Caused by a pathogen
• Non-communicable disease


  Caused from within the body
• Non-communicable diseases


  • Diabetes
  • Heart disease
  • Liver disease
  • Lung disease
  • Cancer
• Diabetes


  Caused by obesity, poor diet
• Heart disease


  Caused by poor diet, smoking, lack of exercise
• Liver disease


  Caused by alcohol
• Lung disease


  Caused by smoking
• Cancer


  Auto-immune condition resulting from genetic mutation causing cells to multiply uncontrollably, forming a tumour
• Benign tumour


  Doesn't spread
• Malignant tumour


  Spreads through the body
• Carcinogens


  Increase risk of developing cancer
• Leaf


  • Photosynthesis, gas exchange, water evaporates out
• Xylem


  Continuous tubes that carry water and dissolved minerals upwards, transpiration rate increased by increased air movement, temperature, and decreased humidity