biology paper 1

• Microscopes


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


  Image size / Object size
• Cell types


  • Eukaryotic cells (have nucleus)
  • Prokaryotic cells (no nucleus)
• Eukaryotic cells


  • DNA is found in the nucleus
  • Examples: plant and animal cells
• Prokaryotic cells


  • DNA is found in a ring called a plasmid
  • No nucleus
• Cell structures


  • Cell membrane
  • Cell wall (in plant cells and bacteria)
  • Cytoplasm
  • Mitochondria
  • Ribosomes
  • Chloroplasts (in plant cells)
• Diploid cells


  Cells with 23 pairs of chromosomes
• Haploid cells


  Cells with 23 single chromosomes
• Mitosis


  1. Genetic material duplicated

  2. Nucleus breaks down

  3. Chromosomes pulled to opposite sides

  4. New nuclei form in each new cell
• Cell specialisation


  • Cells specialize to fulfill different functions e.g. nerve, muscle, root hair
• Stem cells


  Unspecialized cells that can develop into different cell types
• Diffusion


  Movement of molecules/particles from high to low concentration, down concentration gradient, no energy required
• Osmosis


  Diffusion of water across a semi-permeable membrane
• Osmosis practical


  Cut potato cylinders, weigh, place in sugar solutions, reweigh, calculate % change in mass, plot graph to find no change concentration
• 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 that are specific to certain substrates, work on a lock and key principle
• Enzyme activity practical


  Mix amylase and starch, test for starch every 10 seconds using iodine, plot time taken for starch to be broken down against temperature or pH, find optimum
• Food tests


  • Iodine for starch - turns blue/black if present
  • Benedict's solution for sugars - turns red if present, orange/yellow if less present
  • Biuret's reagent for proteins - turns purple if present
  • Ethanol for lipids - turns cloudy if present
• Respiratory system structures


  • Trachea
  • Bronchi
  • Bronchioles
  • Alveoli
• Alveoli


  • Lumpy to increase surface area for gas exchange
• Circulatory system components


  • Heart
  • Blood vessels (arteries, veins, capillaries)
  • Blood (red blood cells, white blood cells, platelets)
• 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
• Coronary arteries


  Supply blood to heart muscle
• Cardiovascular disease


  Non-communicable disease caused by factors within the body, e.g. coronary heart disease
• 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
• Faulty heart valves


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


  Carries plasma, red blood cells, white blood cells (combat infections), and platelets (clot wounds)
• Cardiovascular disease (CVD)


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

  • Cardiovascular disease
  • Autoimmune conditions
  • Cancer
• Communicable disease


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


  Anything that increases the risk of cancer
• Benign cancer


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


  Cancerous cells spread through the body, much worse
• Leaves


  Where photosynthesis takes place, producing food for the plant
• Transpiration


  The diffusing of water out of leaves, allowing water and minerals to be drawn up from the roots
• Xylem


  Long continuous tubes that water rises up, unidirectional