paper 2

• Leaves


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


  Leaves the plant through leaves, allowing transpiration to take place
• Roots


  Where water and mineral ions enter the plant
• Meristem


  Where new cells are made
• Xylem


  Long continuous tubes which water rises up, unidirectional
• Phloem


  Conveyor belts of cells that transport sugars, food and sap up and down the plant, bidirectional
• Factors that increase the rate of transpiration

  • Increasing temperature
  • Decreasing humidity
  • Increasing air movement
• Cross-section of a leaf

  • Waterproof waxy cuticle
  • Upper epidermis
  • Palisade mesophyll layer
  • Spongy mesophyll layer
  • Vascular bundle
  • Lower epidermis with stomata
• Stomata


  Holes in the lower epidermis of a leaf, controlled by guard cells to regulate gas exchange
• Photosynthesis


  1. Occurs in chlorophyll and chloroplasts

  2. Requires light energy (endothermic reaction)

  3. Produces glucose used for respiration, storage or synthesis
• Factors that increase the rate of photosynthesis

  • Higher temperature (up to enzyme denaturing point)
  • Increasing light intensity
  • Increasing CO2 concentration
• Limiting factor


  The variable that is preventing the rate from increasing further, even if other factors are increased
• Measuring the rate of photosynthesis

  1. Submerge pondweed in inverted measuring cylinder, measure oxygen volume or count bubbles

  2. Vary light intensity as independent variable
• Plant hormones


  • Gibberellins (seed germination, flowering, fruit size)
  • Ethene (fruit ripening)
  • Auxins (shoot and root growth)
• Phototropism


  Shoots bend towards light, roots grow downwards (geotropism)
• Homeostasis


  Organism's ability to regulate internal conditions even when external conditions change
• Thermoregulation


  Body's control of internal temperature through sweating, vasodilation, vasoconstriction, shivering
• Endocrine system


  System of glands that produce hormones, slower than nervous system
• Pituitary gland


  Main/master gland that produces hormones in response to stimuli
• Pancreas


  Produces insulin to regulate blood glucose, and glucagon to increase blood glucose
• Type 1 diabetes


  Pancreas cannot produce enough insulin
• Type 2 diabetes


  Cells do not absorb glucose properly
• Water and nitrogen balance

  Kidneys filter blood, reabsorb useful substances, produce urine to maintain balance
• Negative feedback


  Body responds to return conditions to normal
• Menstrual cycle


  1. FSH causes egg maturation and estrogen production

  2. LH causes egg release

  3. Progesterone maintains uterus lining
• Infertility


  Treated with injections or IVF
• Circulatory system


  Double circulatory system, deoxygenated blood enters right side of heart, oxygenated blood leaves left side
• The heart has thicker walls on the left side
• The heart is at the center of the circulatory or circulatory system, the transport system of your body
• Blood circulation


  1. Deoxygenated blood from the body enters the right side of the heart through the vena cava

  2. Blood goes through the pulmonary artery to the lungs to be oxygenated

  3. Oxygenated blood returns to the heart through the pulmonary vein

  4. Blood goes from the left ventricle out to the body through the aorta
• Heart


  • Left ventricle has thicker walls to pump blood to the whole body, right ventricle only pumps to the lungs
  • Cells near the right atrium create electrical pulses that cause the heart to beat
• Arteries carry oxygenated blood (except the pulmonary artery), veins carry deoxygenated blood
• Blood vessels


  • Arteries have thicker walls and a thinner lumen to withstand higher pressure, veins have thinner walls and valves to stop backflow due to lower pressure
  • Arteries get smaller and become capillaries with one cell thick walls to allow faster diffusion
• The heart needs its own supply of oxygen and blood, delivered by the coronary artery
• Blockage of the coronary arteries can cause a heart attack, known as coronary heart disease (CHD)
• Stents


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


  Drugs that reduce cholesterol and fatty deposits in blood vessels
• Faulty heart valves can result in backflow, and can be replaced with artificial ones
• Blood also carries white blood cells to combat infections and platelets to clot wounds
• Breathing


  1. Air moves down the trachea into the bronchi, bronchioles and alveoli

  2. Oxygen diffuses from the alveoli into the blood vessels

  3. Carbon dioxide diffuses from the blood into the alveoli and is exhaled