biology paper 2

• Homeostasis


  An organism's ability to regulate internal conditions even when external conditions change
• Importance of homeostasis


  • Allows crucial chemical reactions involving enzymes to happen at an Optimum rate
  • Regulates blood glucose concentration, temperature, and water levels
• Nervous system regulation of homeostasis

  1. Receptor detects stimulus

  2. Electrical signal travels to spine through sensory and relay neurons

  3. Signal travels across synapse by neurotransmitter

  4. Signal goes to brain for conscious decision

  5. Signal goes back to effector (muscle) via relay and motor neurons
• Reflex


  Signal bypasses the brain and goes straight through the spine to the effector
• Effectors


  Glands that produce specific chemicals the body needs
• Investigating reaction time


  1. Hold ruler between finger and thumb, drop without warning

  2. Measure distance fallen before caught

  3. Repeat multiple times, take mean average
• Thermoregulation


  1. Brain senses blood temperature

  2. Sends nervous and hormonal signals to effectors (sweat glands, blood vessels)

  3. To increase or decrease heat loss
• 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
• Insulin


  Hormone produced by the pancreas that causes glucose to move from blood into cells
• Glucagon


  Hormone produced by the pancreas that causes the liver and muscles to turn glycogen back into glucose
• Type 1 diabetes


  Pancreas can't produce enough insulin
• Type 2 diabetes


  Cells no longer absorb glucose properly
• Dialysis


  Process that does the job of the kidneys when they aren't working properly
• 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
  • Diaphragms
  • IUDs
  • Tubal ligation
• IVF


  In vitro fertilization - eggs harvested and fertilized in lab, then implanted
• Adrenaline


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


  Hormone secreted by the thyroid that controls metabolic rate
• Negative feedback in thyroid regulation

  1. Hypothalamus releases TRH

  2. Pituitary releases TSH

  3. Thyroid releases more thyroxin
• Meiosis


  Process that produces gametes (sex cells)
• Mitosis


  Process of cell division that produces genetically identical daughter cells
• Genome


  All the genetic material in an organism
• Gene


  Section of DNA that codes for a specific protein
• Genotype


  Genetic code stored in DNA
• Phenotype


  How the genetic code is expressed in an organism's characteristics
• Parasite


  Can reproduce on its own without a parent
• DNA


  A two-stranded polymer in a double helix shape
• Gene


  A section of DNA that codes for a specific protein
• The Human Genome Project completed its initial goal in 2003 when scientists mapped out what every gene is responsible for coding
• Genotype


  The code stored in your DNA specifically
• Phenotype


  How the genotype is expressed in your characteristics and physiology
• Allele


  Different versions of the same gene
• Dominant allele


  Results in a characteristic being expressed even if there is another recessive allele present
• Recessive allele


  Only expressed when there is no dominant allele present
• Homozygous


  Having only one type of allele
• Heterozygous


  Having two different types of alleles
• Predicting phenotype using a Punnett square

  1. Combine parental alleles

  2. Determine probability of offspring phenotypes
• Polydactyly (extra fingers/toes) is caused by a dominant allele, cystic fibrosis is caused by a recessive allele
• Chromosomes


  Contain human DNA, 23 pairs, one pair determines sex