AP Psychology/Biological Bases of Behavior

Introduces behaviors and mental processes from a biological perspective and explore the effects of the interaction between human biology and our environment.[1]

Objectives and SkillsEdit

Topics may include:[2]

  • The interaction of inherited traits, environment, and evolution in shaping behavior
  • Structures and functions of biological systems, including the endocrine system and nervous system
  • Brain function, neural firing, and the influence of medication
  • The study of the brain and research techniques for studying its structure and function
  • States of consciousness, including sleeping and dreaming
  • Addiction and drug dependence

Study NotesEdit

  • Phrenology - Different brain areas accounted for a specific character and personality traits (proposed by Franz Joseph Gall). You're the way you are because of the bumps on your head.
  • Reuptake - Neurotransmitters in the synapse are reabsorbed into the sending neurons through the process of reuptake.


Acetylcholine (ACL)
  • Excitatory/Inhibitory
  • Functions: Learning, memory.
  • Problems: ACL deteriorates → causes Alzheimer [forgets stuff]
  • Excitatory
  • Functions: Pleasure, movement.
  • Problems: Not Enough → Parkinson's Disease (trembling, affects movement); Too much → Schizophrenia (two minds) (hereditary)
Norepinephrine (NE)
  • Excitatory/Inhibitory
  • Functions: Mood, alertness.
  • Problems: Not Enough → Depression.
Serotonin (5-HT)
  • Excitatory/Inhibitory
  • Functions: Mood, appetite, sleep.
  • Problems: Not Enough → Depression; Too much → Anxiety/No Dreams
  • Examples: Zoloft, Lexapro, Prozae (inhibit serotonin reuptake inhibitors [SSRI]).
  • Inhibitory
  • Functions: Sleep, inhibits movement/effection axons, calming
  • Problems: Helps to calm anxiety; Not Enough → Seizures, tremors, insomnia
  • Excitatory
  • Functions: Memory, learning, synaptic plasticity (flexible)
  • Problems: Too much → Overstimulate the brain, causing migraines or seizures.
  • Functions: Inhibit neural regulators, pain-relief, treats pain.
  • Examples: Heroin, morphine, opium

  • Lock and Key Mechanism: Neurotransmitters bind to the receptors of the receiving neuron in a key-lock mechanism.
  • Agonists: Similar to neurotransmitters and bind to its receptor sites to mimic its effects.
  • Antagonists: Bind to receptors, but they BLOCK A neurotransmitter's function.

Nervous SystemEdit

See pic.

Endocrine SystemEdit

See pic.



  • Lesion - Tissue Destruction
  • Autopsy - Postmortem Examination

Imaging TechniquesEdit



  • Behaviour Geneticists - Study our differences and weigh the relative effects of heredity and environment. Testing statements like, "you don't curse as much in school compared to a party".

You have 46 chromosomes, half and half from your mom and dad. You will either be XX (a girl) or XY (a boy). From biggest to smallest, you go from chromosomes [contain DNA], DNA [made up of genes], genes [contain code for a certain protein, determines individual biological development], and proteins.

Transmission of Hereditary CharacteristicsEdit

  • Turner Syndrome - Only occurs in girls---the girl lacks ovaries, pubertal development (like breast enlargement) and has a webbed neck. The chromosome is only "X" rather than "XX". Lack of cognitive development.
  • Klinefelter's Syndrome - The chromosome is "XXY" rather than "XY". Male secondary sex characteristics don't develop. Breasts form.
  • Down Syndrome - Presence of 3 copies of chromosome-21. Mentally retarded and similar faces.
  • Tay-Sachs syndrome - Loss of nervous function and death in the baby.
  • Albinism - Failure to store pigment (skin color), abnormal nerve pathway to the brain, inability to see depth/3-dimensionality with both eyes.
  • PKU - Brain damage, survive only with a special diet (low amounts of phenylalanine) within 30 days of birth. Lack of an enzyme to process amino acids which can build up the poison.
  • Huntington's Disease - Example of a dominant gene (expressed) defect that causes degeneration of the nervous system.
  • Colour blindness - Recessive genes for color blindness are located on the X-chromosome -- therefore, males show color blindness more often from females.
  • Alzheimer - Attributed to a gene on the 21st chromosome (some cases).
  • Genome - Complete instructions for making an organism, containing all genetic material in that organism's chromosomes.

Twin BiologyEdit

  • Identical Twin - Monozygotic (same-sex only)
  • Fraternal Twin - Dizygotic (same/opposite sex)
Twins and ProceduresEdit

Behaviour geneticists effects of shaped and unique environments on total or partial genetic makeup.

Separated twins (identical twins) are crazily similar. Differences between fraternal twins are greater than identical twins. Adopted children are more like their biological parents rather than their adoptive parents.

  • Temperament - Person's stable emotional reactivity and intensity (emotional excitability).
  • Molecular Genetics - Subfield of behaviour genetics that seeks to identify specific genes that are influencing behaviour.
  • Heritability - Refers to the extent to which the differences among people are attributable to genes.

Twin studies are conducted by behaviour geneticists in order to differentiate the influences of genes and shared/unshared environment. Genes can influence traits which affect responses and the environment can affect gene activity.

Heritability and differences in the environment [in regards to behaviour] are inversely related. In one environment, a gene will be expressed but in another environment, it may be dormant.

Epigenetics - Study of influences on gene expression that occur without a DNA change (are certain genetics turned off/on?).