Specific details

Cards (28)

  • Epidermal tissues
    Covered with a waxy cuticle which helps to reduce water loss by evaporation
  • The upper epidermis
    Is transparent so that light can pass through it to the palisade layer
  • Spongy mesophyll
    Contains big air spaces to allow gases to diffuse in and out of the cells
  • Xylem and phloem

    They transport things like water, mineral ions and food around the plant
  • Meristem tissue 

    This is found at the growing tips of shoots and roots and is able to differentiate into lots of different types of plant cell, allowing the plant to grow
  • Palisade mesophyll

    This is the part of the leaf where most photosynthesis happens
  • Xylem:
    • Made of dead cells joined end to end with no end walls between them and a hole down the middle
    • They are strengthened with a material called lignin
    • Carry water and mineral ions
    • The movement of water from the roots through the xylem and out of the leaves is called the transpiration stream
  • Phloem:
    • Made of columns of elongated living cells with small pores in the end walls to allow cell sap to flow through
    • They transport food substances (mainly dissolved sugars) made in the leaves to the rest of the plant for immediate use or for storage
    • The transport is bidirectional
    • This process is called translocation
  • Transpiration
    caused by the evaporation and diffusion of water from a plant's surface
  • Arteries
    The heart pumps the blood out at high pressure so the artery walls are strong and elastic
    The walls are thick compared to the size of the hole down the middle(lumen)
    They contain thick layers of muscle to make them strong and elastic fibres to allow them to stretch and spring back
  • Veins
    Capillaries eventually join up to make veins
    The blood is at low pressure in the veins so the walls don't need to be as thick as artery walls
    They have a larger lumen than arteries to help the blood flow despite the lower pressure
    Have valves to prevent back flow of blood
  • Capillaries
    Arteries branch into capillaries
    Capillaries are too small to see
    Carry blood really close to every cell in the body to exchange substances with them
    They have permeable walls so substances can diffuse in and out
    Walls are one cell thick
    Take waste away like co2 and water
  • How a heart uses its chambers

    Blood flows into the 2 atria from the vena cava and the pulmonary vein .
    The atria contract, pushing the blood into ventricles
    The ventricles contract forcing the blood into the pulmonary artery and the aorta out of the heart
    The blood then flows to organs via arteries and returns through veins
    The atria fill again and the cycle starts again
  • Coronary heart disease
    When the coronary arteries that supply blood to the muscle of the heart get blocked up by layers of fatty material building up
    This causes the arteries to become narrow, so blood flow is restricted and there's a lack of oxygen to the heart muscle, this can result in a heart attack
  • Stents
    tubes that are inserted inside arteries. They keep them open making sure blood can pass through to the heart muscles, keeps the heart beating
    Lowers the risk of a heart attack happening and recovery time is quick
    There are risks during the operation, as well as picking up infections or even blood clots developing called thombosis
  • Statins
    Having too much LDL(bad cholesterol) can cause health problems.
    Too much (LDL) can cause fatty deposits to form inside the arteries which can lead to coronary heart disease
    Statins are a drug that can reduce the amount of bad cholesterol present in the bloodstream. This slows down the rate of fatty deposits forming
  • Advantages of statins

    Statins can reduce the risk of strokes, coronary heart disease and heart attacks
    Increase levels of HDL which can help remove LDL
    Statins may also help prevent other diseases
  • Disadvantages of statins

    Are a drug that must. be taken long term and regularly. There is a risk of. forgetting to take the drug
    Can cause negative side effects
    The effect of statins is not instant. It takes time to kick in
  • The role of bile in emulsification

    Bile emulsifies fat
    It creates a larger surface of fat for the lipase
    Lipase can break down fat quicker
  • Food tests --> Starch
    Add iodine solution to the sample
    Mix the contents
    If the sample contains starch the colour of the solution will change from orange to blue-black
  • Food tests --> Protein
    Add Biuret's solution to the sample
    Mix the contents
    If the sample contains protein the solution will change from blue to lilac
  • Food Tests --> Sugars
    Add some Benedict's solution to the test tube (about 10 drops)
    Place the test tube in the water bath using a test tube holder and leave it there for 5 mins
    If the sample contains less sugar it will go from blue to green
    medium sugar: blue to yellow
    high sugar: blue to brick red
  • Testing drugs 6 marker:
    1. Preclinical trials of the drug on animals to test toxicity
    2. Clinical trials on healthy volunteers and patients at low doses
    3. Monitors side effects
    4. Then trials done to check dose
    5. Double-blind trials and use of placebo which doesn't contain drug
    6. Random allocation of patients to groups
    7. So no-one knows who has placebo
    8. Peer-review of data to prevent false claims
  • Differences in anaerobic respiration
    Yeast produces ethanol
    Muscles produce lactic acid
    Both release small amounts of energy quickly
    Yeast produces CO2 muscles don't
  • HCG hormone 6 marker
    (as) urine passes through reaction zone
    HCG hormone binds to the mobile HCG antibody (in the reaction zone) (passes up the stick) HCG hormone binds to the immobilised HCG antibodies in the results zone
    (the other) antibodies which do not attach to HCG
    bind to antibodies in control zone
    blue dye appears in both control and results zones (to show positive result)
  • Mechanical valves:
    • More long-lasting
    • More durable
    • No ethical issues
    • Expensive
    • readily available
    • anti-clotting medicine required
    • risk of blood clotting
    • Risk of heart attack
  • Biological valves;
    • Potential immune response
    • Higher death rate after put in place
    • Ethical issues as a pig's valve is used
    • Readily available
    • Potential need of immunosuppressants
    • More likely needing replacing and future operations
  • Cell cycle

    Stage 1: The nucleus divides and replicates genetic information and the sub-cellular structures replicate
    Stage 2: One set of chromosomes is pulled to each end of the cell
    Stage 3: The cytoplasm and cell membrane replicate