biology paper 2

• 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 hormones that cause seed germination, promote flowering, and increase fruit size
• Ethene


  Plant hormone that induces fruit ripening
• Auxins


  Plant hormones that control 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
• Homeostasis is an organism's ability to regulate internal conditions even when external conditions change
• Thermoregulation


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


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


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


  Produces insulin to regulate blood glucose levels
• Type 1 diabetes


  Pancreas can't produce enough insulin
• Type 2 diabetes


  Cells no longer absorb glucose properly
• Adrenaline


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


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


  Hormone produced in the pituitary gland that causes the kidneys to reabsorb more water
• Dialysis


  Process where blood is sent through a machine to do the job of the kidneys
• 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
• IVF (in vitro fertilization)


  Eggs harvested and fertilized in a lab, then inserted into the uterus
• Circulatory system


  Double circulatory system where blood enters the heart twice per cycle
• Structure of the heart

  • Right atrium
  • Right ventricle
  • Pulmonary artery
  • Pulmonary vein
  • Left atrium
  • Left ventricle
  • Aorta
• The rate of multiple births is very low but there is also the risk that there could be more than one baby born which might not be desirable
• Heart


  At the center of the circulatory or circulatory system, the transport system of the 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 to be oxygenated

  4. Oxygenated blood returns to left atrium, then left ventricle, then out to the body through the aorta