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AP Psych



Unit 2

2.0 Unit 2 Overview: Biological Bases of Behavior

3 min readfebruary 18, 2021


Megan Revello


Dalia Savy

From the College Board

👀 Develop your Understanding of this Unit

According to the College Board, "The structures of human biological systems and their functions⚙️ influence our behavior and mental processes. Some psychologists study behaviors and mental processes from a biological perspective🌱. This includes an examination of the influence that the interaction between human biology and our environment has on behavior and mental processes. This is a recurring topic throughout the course that will be used to explain many psychological phenomena🧠.
The biological perspective also provides insight into the causes of and treatments for psychological disorders💊. There is a complex interaction between a person’s biology and their behavior and mental processes. Heredity and environment🌲 play a role, as do variations in a person’s consciousness💭."

🔎 Guiding Questions

  1. How can biology influence our behavior and mental processes?
  2. What happens when a particular neurotransmitter is absent from the body?
  3. How do biological and environmental factors interact to influence our behaviors and mental proccesses?

🤔Contextualizing the Unit

Unit 2 focuses on studying the physical (biological) bases for behavior and what can alter it. In this unit we study the brain🧠, body systems, genetics🧬, consciousness, sleep, and drugs. All of these influence our behavior and mental processes (which are exactly what psychology is).
This unit comprises 8 - 10% of the AP Exam for Psychology.

Key Facts

🤓Psychologists to Know

  • Charles Darwin (1896)-- Darwin is known for his principle of natural selection and his other contributions to evolution. He established the idea that all species of life come from the same ancestor.
  • Paul Broca (1861)-- Paul Broca discovered the Broca's area in the brain, which is associated with language and speaking.
  • Carl Wernicke (1874)-- Wernicke studied nerve disease and parts of the brain. He discovered Wernicke's area which is essential in understanding language and speech.
  • Roger Sperry (1950s)-- Roger Sperry was one of the few key neuropsychologists to claim that we have two brain hemispheres and each has its own specialized functions. He studied split-brain patients and conducted experiments to learn more about each half of the brain. He actually won a Nobel Prize for his research.
  • Michael Gazzaniga (1979)-- Gazzaniga helped with the understanding of lateralization. He also worked with split-brain patients to advance his research and began to understand how the two hemispheres of the brain work together.
  • William James (1890)-- James coined the term "stream of consciousness." He is considered the Father of American Psychology.
  • Sigmund Freud (1897)-- Freud is the father of psychoanalysis and studied many areas of psychology through his psychoanalytic perspective. For this unit in particular, he came up with three levels of consciousness: the conscious, preconscious, and the unconscious.


ChromosomesEpigeneticsNatural SelectionMutations
GenesEnvironmentEndocrine SystemHormones
Nervous SystemNervesDendritesNeurons
AxonsAction PotentialAll-or-none ResponseSynapse
DepressantsStimulantsHallucinogensPsychoactive Drug
BrainstemSplit BrainConsciousnessLimbic System
Circadian RhythmREM sleepLatent ContentManifest Content

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