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• 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 (plant cells and bacteria)
  • Cytoplasm
  • Mitochondria
  • Ribosomes
  • Chloroplasts (plant cells)
• 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


  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 graph to find no change concentration
• Active transport


  Using energy to move substances against a concentration gradient
• Digestive system processes


  • Stomach acid
  • Bile
  • Enzymes
• Enzymes


  Biological catalysts, 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. Plot time to complete reaction against temperature or pH

  4. Find optimum conditions
• Food tests


  • Iodine for starch
  • Benedict's solution for sugars
  • Biuret's reagent for proteins
  • Ethanol for lipids
• Breathing vs respiration


  Breathing provides oxygen for respiration to occur in cells
• Gas exchange in lungs

  1. Air enters trachea

  2. Into bronchi and bronchioles

  3. Diffuses into alveoli

  4. Oxygen binds to haemoglobin in red blood cells

  5. Carbon dioxide diffuses into alveoli and is exhaled
• Circulatory system

  Double circulatory system, deoxygenated blood enters right side of heart, oxygenated blood leaves left side
• Heart structure

  Right atrium and ventricle, left atrium and ventricle, valves to prevent backflow, pacemaker cells
• Blood vessels


  Arteries carry oxygenated blood away from heart, veins carry deoxygenated blood towards heart, capillaries allow diffusion
• Coronary arteries


  Supply heart muscle with oxygen and nutrients
• Cardiovascular disease


  Non-communicable disease caused by factors within the body, e.g. atherosclerosis, heart valve problems
• Communicable diseases are caused by pathogens that can be transmitted between individuals
• Coronary artery


  Delivers blood to the heart muscle to supply oxygen
• Coronary heart disease (CHD)


  Occurs when coronary arteries are blocked by fatty deposits, causing a heart attack
• Stents


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

  Drugs that reduce cholesterol, which in turn reduces fatty deposits
• Faulty heart valves

  Result in backflow, can be replaced with artificial ones
• Blood

  Carries plasma, red blood cells, white blood cells, and platelets
• White blood cells

  Combat infections
• Platelets


  Clump together to clot wounds and stop bleeding
• Cardiovascular disease (CVD)


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


  Caused by a pathogen that enters the body, can be viral, bacterial, or fungal
• Type 2 diabetes


  Can be caused by obesity and too much sugar
• Carcinogen


  Anything that increases the risk of cancer
• Benign cancer


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