bio paper 2

• Plants also have organs
• 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 on the x-axis that must be the limiting factor before the graph plateaus
• Measuring the rate of photosynthesis

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

  2. Independent variable is light intensity, changed by varying distance from light source
• 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 controlling internal temperature through sweating, vasodilation, vasoconstriction, shivering
• Endocrine system


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


  Produces insulin to regulate blood glucose, produces glucagon when blood glucose is too low
• Type 1 diabetes


  Pancreas can't produce enough insulin
• Type 2 diabetes


  Cells don't absorb glucose properly
• Water and nitrogen balance

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


  Hormone that increases heart and breathing rate in stressful situations
• Thyroxin


  Hormone secreted by thyroid that controls metabolic rate
• Anti-diuretic hormone (ADH)


  Produced in pituitary gland, causes kidneys to reabsorb more water
• Dialysis


  Process that artificially filters blood when kidneys aren't working properly
• Menstrual cycle


  1. FSH causes egg maturation and estrogen production

  2. LH causes egg release

  3. Progesterone maintains uterus lining
• IVF


  In vitro fertilization, eggs harvested and fertilized in lab, embryos inserted into uterus
• Circulatory system


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


  1. Blood enters the heart twice every time it's pumped around the body

  2. Deoxygenated blood from the body enters the right side of the heart through the vena cava into the right atrium

  3. Valve between the right atrium and right ventricle stops backflow

  4. Heart muscles contract, blood goes through the pulmonary artery to the lungs to be oxygenated

  5. Oxygenated blood returns to the heart through the pulmonary vein into the left atrium, then into the left ventricle

  6. Blood pumped out to the body through the aorta
• Heart


  • Left side has thicker walls as the left ventricle has to pump blood to the whole body, while the right ventricle only pumps to the lungs
  • Group of cells near the right atrium create electrical pulses that cause the heart muscles to contract
• If the heart's electrical pulses aren't working properly, an artificial pacemaker can be given to do the same job
• Arteries


  Blood vessels that carry oxygenated blood away from the heart, have thicker walls to withstand higher pressure
• Veins


  Blood vessels that carry deoxygenated blood towards the heart, have thinner walls due to lower blood pressure, have valves to stop backflow
• Blood vessel structure


  1. Arteries split and get smaller until they end up as tiny capillaries with one cell thick walls

  2. Allows faster diffusion of molecules in and out of cells
• The heart needs its own supply of oxygen and blood, delivered by the coronary artery
• If the coronary arteries are blocked by fatty deposits, a heart attack can occur (coronary heart disease)
• Stents


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