Biology

• Plants also have organs
• Leaves


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


  The diffusing of water into roots and up the xylem
• 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
• Photosynthesis


  1. Occurs in chlorophyll and chloroplasts

  2. Provides food for the plant

  3. Glucose made is used for respiration, stored as starch or fat, or used to produce cellulose and amino acids
• Photosynthesis is an endothermic reaction
• Factors affecting the rate of photosynthesis

  • Temperature (unless too high causing enzyme denaturing)
  • Light intensity
  • 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 an inverted measuring cylinder and measure the volume of oxygen made over time

  2. Count the bubbles (less accurate)
• Gibberellins


  Plant hormone that causes seed germination, promotes flowering, and increases fruit size
• Ethene


  Plant hormone that induces fruit ripening
• Auxins


  Plant hormone that controls shoot and root growth, destroyed by sunlight
• Phototropism


  Auxins gather on the shaded side of a shoot, causing more growth and elongation of cells on that side, making the shoot bend towards the light
• Geotropism


  Auxins gather on the bottom of a root, causing the top side to grow more quickly and the root to grow downwards
• Investigating geotropism


  Put seeds on damp cotton wool in a Petri dish, stand it on its side, leave for a few days, then turn 90 degrees and observe the roots bending
• Homeostasis


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


  The body's control of internal temperature through mechanisms like sweating and vasodilation/vasoconstriction
• Endocrine system


  A system of glands that produce hormones that travel to effectors via the blood
• Pituitary gland


  The 'master gland' that produces hormones in response to stimuli and travels to other glands
• Pancreas


  Produces insulin to regulate blood glucose levels
• Thyroid


  Controls growth, heart muscle, and digestive function
• Adrenal glands


  Produce adrenaline
• Ovaries and testes


  Release eggs or produce sperm
• Type 1 diabetes


  Pancreas can't produce enough insulin
• Type 2 diabetes


  Cells no longer absorb glucose properly
• Water and nitrogen balance

  Kidneys filter blood and regulate water and urea levels
• Anti-diuretic hormone (ADH)


  Produced in the pituitary gland, causes kidneys to reabsorb more water
• Menstrual cycle


  1. FSH causes egg maturation and estrogen production

  2. LH causes egg release

  3. Progesterone maintains uterus lining
• Contraception methods


  • Pills that inhibit FSH
  • Progesterone injections
  • Implants
  • Condoms
  • IUDs
  • Tubal ligation
• In vitro fertilization (IVF)

  Eggs harvested and fertilized in lab, then implanted in uterus
• Circulatory system


  Double circulatory system, blood enters heart twice per cycle
• Heart structure


  • Right atrium receives deoxygenated blood
  • Right ventricle pumps blood to lungs
  • Left atrium receives oxygenated blood
  • Left ventricle pumps blood to body
• Double circulatory system


  Blood enters the heart twice every time it's pumped around the body
• Blood flow through the heart

  1. Deoxygenated blood from the body enters the right atrium

  2. Valve between right atrium and right ventricle stops backflow

  3. Heart muscles contract, blood goes through pulmonary artery to lungs

  4. Oxygenated blood returns to left atrium, then left ventricle

  5. Blood pumped out to body through aorta