Bio paper1

• Microscopes


  Normal light microscope can see cells and nucleus, electron microscope can see subcellular structures in more detail
• Calculating cell size


  1. Measure image size

  2. Divide by magnification
• Eukaryotic cells


  Have a nucleus containing DNA
• Prokaryotic cells


  Do not have a nucleus, DNA is in a ring called a plasmid
• Cell structures


  • Cell membrane
  • Cell wall (in plants and bacteria)
  • Cytoplasm
  • Mitochondria
  • Ribosomes
  • Chloroplasts (in plants)
• Bacterial binary fission


  1. Number doubles every 10 minutes

  2. Practical: Grow culture on agar plate, use aseptic technique, calculate growth rate
• Diploid cells


  Have 23 pairs of chromosomes
• Haploid cells


  Have 23 single chromosomes
• Mitosis


  1. Genetic material duplicated

  2. Nucleus breaks down

  3. Chromosomes pulled to opposite sides

  4. New nuclei form
• Specialised cell types


  • Nerve
  • Muscle
  • Root hair
  • Xylem
  • Phloem
  • Stem cells
• Stem cells


  Unspecialised cells that can differentiate into different cell types
• Diffusion


  Movement of molecules/particles from high to low concentration, down concentration gradient, passive process
• Osmosis


  Diffusion of water across a semi-permeable membrane
• Practical: Osmosis


  1. Cut potato cylinders

  2. Weigh

  3. Place in sugar solutions

  4. Reweigh

  5. Calculate % change in mass

  6. Plot against concentration
• Active transport


  Using energy to move substances against a concentration gradient
• Tissues


  • Heart
  • Digestive system
• Enzymes


  Biological catalysts that are specific to certain substrates, work on a lock and key principle
• Practical: Enzyme activity


  1. Mix amylase and starch

  2. Test for starch every 10 seconds with iodine

  3. Calculate time for complete breakdown

  4. Plot against temperature or pH
• Food tests


  • Iodine for starch
  • Benedict's solution for sugars
  • Biuret's reagent for proteins
  • Ethanol for lipids
• Breathing and gas exchange

  1. Air moves down trachea, bronchi, bronchioles to alveoli

  2. Oxygen diffuses into blood, carbon dioxide diffuses out
• Double circulatory system


  Blood enters heart twice per cycle, deoxygenated blood to lungs, oxygenated blood to body
• Blood vessels


  • Arteries (thick walls, narrow lumen)
  • Veins (thin walls, valves)
  • Capillaries (one cell thick)
• Coronary artery


  Supplies blood to heart muscle
• Stents


  Tubes inserted into blood vessels to keep them open
• Non-communicable diseases


  • Cardiovascular disease
  • Autoimmune conditions
  • Cancer
• Communicable diseases


  Diseases caused by pathogens that can be transmitted between organisms
• Coronary artery


  Delivers blood to the heart muscle to supply oxygen
• Heart attack


  Occurs when coronary arteries are blocked by buildup of fatty deposits, causing coronary heart disease (CHD)
• Stents


  Little tubes inserted into blood vessels to keep them open and allow blood flow
• Statins


  Drugs that reduce cholesterol, which reduces fatty deposits
• Heart valves


  Can become faulty, resulting in backflow, and may need to be replaced with artificial ones
• Cardiovascular disease (CVD)


  An example of a non-communicable disease, caused by factors within the body
• Examples of non-communicable diseases

  • CVD
  • Autoimmune conditions
  • Cancer
• Communicable disease


  Caused by a pathogen that enters the body, resulting in viral, bacterial or fungal infection
• Carcinogen


  Anything that increases the risk of cancer
• Benign cancer


  Doesn't spread through the body and is relatively easy to treat
• Malignant cancer


  Cancerous cells spread through the body, much worse
• Photosynthesis


  Process in plant cells that uses chlorophyll to produce food (glucose) from light, water and carbon dioxide
• Photosynthesis is an endothermic reaction, requiring energy in the form of light
• Transpiration

  The diffusion of water out of leaves, allowing water and mineral ions to be drawn up from the roots