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• Microscopes


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


  Have a nucleus containing DNA
• Subcellular structures


  • Cell membrane
  • Cell wall
  • Cytoplasm
  • Mitochondria
  • Ribosomes
  • Chloroplasts
  • Vacuole
• Haploid cells


  Have 23 chromosomes (not in pairs)
• Mitosis


  1. Genetic material duplicated

  2. Nucleus breaks down

  3. Chromosomes pulled to opposite sides

  4. New nuclei form
• Specialised cell types


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


  Unspecialised cells that can differentiate
• Diffusion


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


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

  1. Cut potato cylinders

  2. Weigh and place in sugar solutions

  3. Reweigh after a day

  4. Calculate percentage change in mass

  5. Plot against sugar concentration to find no change point
• Active transport


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


  • Acid in stomach
  • Bile and enzymes in small intestine
  • Emulsification of fats
• 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 taken for starch to be broken down against temperature or pH

  4. Find optimum temperature or pH
• Food tests


  • Iodine for starch
  • Benedict's solution for sugars
  • Biuret's reagent for proteins
  • Ethanol for lipids
• Respiration


  Provides energy for cells, different from breathing
• Gas exchange


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

  2. Oxygen diffuses into blood, carbon dioxide diffuses out
• Circulatory system components


  • Heart
  • Arteries
  • Veins
  • Capillaries
• Blood flow through heart

  1. Deoxygenated blood enters right atrium

  2. Passes through right ventricle to lungs

  3. Oxygenated blood enters left atrium

  4. Passes through left ventricle to body
• Arteries vs Veins


  Arteries carry oxygenated blood, have thicker walls

  Veins carry deoxygenated blood, have valves
• Coronary arteries supply heart muscle with oxygen
• Cardiovascular disease


  Non-communicable disease caused by internal factors
• Other non-communicable diseases include autoimmune conditions and cancer
• Coronary artery


  Delivers blood to the heart muscle to supply oxygen
• Stents


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


  Drugs that reduce cholesterol and fatty deposits
• Blood components


  • Plasma
  • Red blood cells
  • White blood cells (combat infections)
  • Platelets (clot wounds)
• Cardiovascular disease (CVD)


  Non-communicable disease caused by factors within the body, e.g. obesity, diet, smoking
• Communicable disease


  Caused by a pathogen (virus, bacteria, fungus, or parasite) that enters the body
• Carcinogen


  Anything that increases the risk of cancer, e.g. ionizing radiation
• Benign cancer


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


  Cancerous cells spread through the body, much worse
• Plant organs


  • Leaves (photosynthesis)
  • Roots (water and mineral absorption)
  • Meristem (new cell production)
• Phloem


  Conveyor belts of cells that transport sugars, food, and sap up and down the plant
• Transpiration

  The evaporation of water from leaves
• Factors increasing transpiration rate


  • Higher temperature
  • Lower humidity
  • Increased air movement
• Chlorosis


  Yellowing of leaves due to magnesium deficiency
• Leaf structure

  • Waxy cuticle
  • Upper epidermis
  • Palisade mesophyll
  • Spongy mesophyll
  • Vascular bundle
  • Lower epidermis with stomata
• Guard cells


  Control the size of stomata to regulate gas exchange
• Communicable disease


  Caused by pathogens (viruses, bacteria, fungi, or protists)