upgrade
← back to ap psychology

ap psychology unit 1 study guides

biological bases of behavior

1.1

Interaction of Heredity and Environment

1.2

Overview of the Nervous System

1.3

The Neuron and Neural Firing

1.4

The Brain

1.5

Sleep

1.6

Sensation

unit 1 review

The biological bases of behavior unit explores how the brain and nervous system shape our actions and mental processes. It covers brain structure, neuron communication, and the role of neurotransmitters and hormones in regulating behavior and mood. This unit delves into the central and peripheral nervous systems, brain disorders, and real-world applications. Understanding these biological foundations is crucial for treating mental illnesses, developing medications, and improving learning and memory in everyday life.

What's This Unit All About?

  • Explores the biological underpinnings of behavior and mental processes
  • Focuses on the structure and function of the brain and nervous system
  • Examines how neurons communicate with each other to transmit information
  • Investigates the role of neurotransmitters in regulating behavior and mood
  • Discusses the influence of hormones on behavior and psychological processes
  • Covers the central and peripheral nervous systems and their respective functions
  • Delves into various brain disorders and their effects on behavior and cognition
  • Highlights real-life applications of understanding the biological bases of behavior (treating mental illnesses, developing medications, improving learning and memory)

Key Brain Parts and What They Do

  • Cerebral cortex: responsible for higher-order cognitive functions (thinking, reasoning, decision-making)
    • Divided into four lobes: frontal, parietal, temporal, and occipital
    • Each lobe specializes in processing specific types of information (visual, auditory, sensory, motor)
  • Limbic system: involved in emotional processing, memory formation, and motivation
    • Includes the amygdala, which plays a crucial role in fear and emotional responses
    • Hippocampus is essential for forming new memories and spatial navigation
  • Hypothalamus: regulates basic biological needs and drives (hunger, thirst, sleep, sexual behavior)
    • Controls the release of hormones from the pituitary gland
  • Brainstem: connects the brain to the spinal cord and regulates vital functions (breathing, heart rate, blood pressure)
  • Cerebellum: coordinates fine motor movements, balance, and posture
  • Basal ganglia: involved in motor control, learning, and decision-making
  • Thalamus: relays sensory and motor information between the brain and body

Neurons: The Brain's Building Blocks

  • Neurons are specialized cells that transmit electrical and chemical signals throughout the nervous system
  • Consist of three main parts: dendrites, cell body (soma), and axon
    • Dendrites receive incoming signals from other neurons
    • Cell body contains the nucleus and other organelles necessary for cellular functions
    • Axon is a long, thin fiber that carries electrical signals away from the cell body
  • Neurons are surrounded by a fatty substance called myelin, which insulates the axon and speeds up signal transmission
  • There are three main types of neurons: sensory neurons, motor neurons, and interneurons
    • Sensory neurons detect stimuli from the environment and send signals to the central nervous system
    • Motor neurons carry signals from the central nervous system to muscles and glands
    • Interneurons connect sensory and motor neurons and process information within the central nervous system
  • Neurons do not divide or regenerate once they are damaged or lost, making brain injuries and neurodegenerative diseases particularly devastating

How Neurons Talk to Each Other

  • Neurons communicate with each other through electrical and chemical signals
  • Electrical signals, called action potentials, travel along the axon of a neuron
    • Action potentials are generated when the neuron's membrane potential reaches a certain threshold
    • The action potential is an all-or-none response, meaning it either occurs at full strength or not at all
  • Chemical signals, called neurotransmitters, are released from the axon terminals of one neuron and bind to receptors on the dendrites of another neuron
    • Neurotransmitters can have either excitatory or inhibitory effects on the receiving neuron
    • Common neurotransmitters include dopamine, serotonin, norepinephrine, and GABA
  • The junction between two neurons where neurotransmitters are released is called a synapse
    • Synaptic transmission can be modulated by various factors (neurotransmitter availability, receptor sensitivity, reuptake mechanisms)
  • Long-term potentiation (LTP) and long-term depression (LTD) are processes that strengthen or weaken synaptic connections, respectively, and are thought to underlie learning and memory

The Nervous System: Central vs. Peripheral

  • The nervous system is divided into two main parts: the central nervous system (CNS) and the peripheral nervous system (PNS)
  • The CNS consists of the brain and spinal cord and is responsible for processing information and generating responses
    • The brain is the control center of the nervous system and is involved in higher-order cognitive functions, emotion, and behavior
    • The spinal cord relays sensory and motor information between the brain and the rest of the body
  • The PNS consists of all the nerves and ganglia outside the brain and spinal cord
    • Divided into the somatic nervous system and the autonomic nervous system
    • The somatic nervous system controls voluntary movements and receives sensory input from the environment
    • The autonomic nervous system regulates involuntary functions (heart rate, digestion, respiration) and is further divided into the sympathetic and parasympathetic nervous systems
      • The sympathetic nervous system activates the "fight or flight" response during stress or emergencies
      • The parasympathetic nervous system promotes "rest and digest" functions and helps maintain homeostasis

Hormones and Behavior

  • Hormones are chemical messengers released by endocrine glands that travel through the bloodstream and affect target cells throughout the body
  • Hormones play a crucial role in regulating behavior, mood, and various physiological processes
    • Examples include cortisol (stress response), testosterone (aggression, sexual behavior), and oxytocin (social bonding, maternal behavior)
  • The hypothalamus-pituitary-adrenal (HPA) axis is a key system that regulates the body's response to stress
    • The hypothalamus releases corticotropin-releasing hormone (CRH), which stimulates the pituitary gland to secrete adrenocorticotropic hormone (ACTH)
    • ACTH then stimulates the adrenal glands to release cortisol, which helps the body cope with stress
  • Hormonal imbalances can lead to various behavioral and psychological disorders (depression, anxiety, mood swings)
  • Sex hormones, such as estrogen and testosterone, play a significant role in sexual differentiation and the development of gender-specific behaviors
  • Hormones interact with neurotransmitters and other signaling molecules to modulate brain function and behavior

When Things Go Wrong: Brain Disorders

  • Brain disorders can arise from a variety of factors, including genetic predisposition, environmental influences, and injury or illness
  • Neurodegenerative diseases, such as Alzheimer's and Parkinson's, involve the progressive loss of neurons in specific brain regions
    • Alzheimer's disease is characterized by memory loss, cognitive decline, and changes in behavior and personality
    • Parkinson's disease affects motor function, causing tremors, rigidity, and difficulty with movement
  • Mental illnesses, such as depression, anxiety disorders, and schizophrenia, are associated with imbalances in neurotransmitter systems and abnormalities in brain structure and function
    • Depression is linked to reduced levels of serotonin and norepinephrine in the brain
    • Schizophrenia involves disruptions in dopamine signaling and abnormal brain development
  • Substance use disorders, such as addiction to drugs or alcohol, involve changes in the brain's reward system and can lead to compulsive drug-seeking behavior
  • Traumatic brain injuries (TBIs) can result in a range of cognitive, emotional, and behavioral deficits, depending on the location and severity of the injury
  • Understanding the biological basis of brain disorders is crucial for developing effective treatments and interventions

Real-Life Applications

  • Knowledge of the biological bases of behavior has led to the development of various pharmacological treatments for mental illnesses (antidepressants, antipsychotics, anxiolytics)
    • These medications work by modulating neurotransmitter systems in the brain to alleviate symptoms and improve functioning
  • Cognitive-behavioral therapy (CBT) is a psychotherapeutic approach that aims to modify maladaptive thoughts and behaviors by targeting the underlying neural circuits involved in emotional processing and decision-making
  • Neurofeedback is a technique that uses real-time monitoring of brain activity to help individuals learn to regulate their own brain function and improve symptoms of various disorders (ADHD, anxiety, depression)
  • Understanding the role of the brain in learning and memory has informed educational practices and the development of strategies to enhance academic performance (spaced repetition, retrieval practice, elaborative encoding)
  • Research on the biological basis of addiction has led to the development of medications and behavioral interventions to help individuals overcome substance use disorders (methadone, buprenorphine, contingency management)
  • Advances in neuroimaging techniques (fMRI, PET, EEG) have allowed researchers to study the living brain and gain insights into the neural basis of behavior, cognition, and mental disorders
  • Knowledge of the biological factors underlying aggression and violence has informed the development of prevention and intervention strategies to reduce antisocial behavior and promote prosocial behavior

Frequently Asked Questions

What is Unit 1 of AP Psych about?

Unit 1 is Biological Bases of Behavior — it digs into how heredity and environment interact, the nervous system (CNS/PNS), neuron structure and neural firing, brain structures and plasticity, sleep and circadian rhythms, and sensation (vision, hearing, chemical senses, touch, pain, vestibular/kinesthetic). This unit is worth about 15–25% of the exam and emphasizes functions (how systems affect behavior), research methods, data interpretation, and applying concepts to explain behavior. Key skills include linking neurotransmitters and hormones to behavior, explaining neural transmission and drug effects, and using brain–behavior knowledge to interpret case scenarios. Check out the unit overview and resources (https://library.fiveable.me/ap-psych-revised/unit-1). For extra practice, Fiveable’s 1000+ practice questions are here (https://library.fiveable.me/practice/psych-revised).

What topics are covered in AP Psych Unit 1 (Biological Bases of Behavior)?

You’ll cover six main topic areas; the full unit guide is at (https://library.fiveable.me/ap-psych-revised/unit-1). 1. Interaction of Heredity and Environment — nature vs. nurture, twin and adoption studies, evolutionary perspective. 2. Overview of the Nervous System — CNS vs. PNS, autonomic vs. somatic, sympathetic/parasympathetic. 3. The Neuron and Neural Firing — neuron types, action potential, major neurotransmitters, hormones, psychoactive drugs. 4. The Brain — structures, lobes, split-brain, plasticity, research methods. 5. Sleep — circadian rhythms, sleep stages, REM, sleep disorders. 6. Sensation — thresholds, vision, hearing, chemical senses, touch, pain, vestibular/kinesthetic. The unit weighs about 15–25% of the exam and usually takes ~17–23 class periods; the Fiveable unit page has study guides and practice.

How much of the AP Psych exam is Unit 1?

Expect Unit 1 (Biological Bases of Behavior) to count for roughly 15%–25% of the AP Psychology exam — that’s the College Board’s weighting (see the unit study guide at https://library.fiveable.me/ap-psych-revised/unit-1). That range reflects content emphasis across multiple-choice and free-response topics rather than a fixed number of raw points. Also remember the exam score includes Section II free-response questions, so weightings describe how much of the course content appears on the test. Per the CED, plan about 17–23 class periods on this unit. Focus your study on neurons, the nervous system, brain structures, sensation, sleep, and heredity × environment interactions.

What's the hardest part of AP Psych Unit 1?

Many students say the neuron/neural-firing material and mapping brain structures to functions are the toughest parts. Those topics demand both vocabulary (action potential, refractory period) and step-by-step reasoning about processes and localization. The heredity vs. environment section can also be tricky because it blends biology with conceptual thinking about nature vs. nurture. These sections are heavy on terms, diagrams, and cause–effect chains, so spaced practice, drawing neurons and brain regions from memory, and teaching concepts aloud help a lot. For a focused review, see the Unit 1 guide (https://library.fiveable.me/ap-psych-revised/unit-1) and practice questions (https://library.fiveable.me/practice/psych-revised) — Fiveable’s cheatsheets and cram videos speed up memorization.

How should I study for AP Psych Unit 1 (best resources and strategies)?

Study Unit 1 by focusing on neurons, nervous-system organization, major brain structures, sleep stages, sensation, and heredity vs. environment. Start with a quick read of the Fiveable unit guide (https://library.fiveable.me/ap-psych-revised/unit-1). Then make a one-page concept map linking brain areas to functions and neurotransmitters to their effects. Use active recall and spaced practice: try daily 15–20 minute sessions for two weeks, then taper to weekly reviews. Do targeted practice questions on neural firing, localization, and sleep to find weak spots, and write 1–2 short FRQ-style explanations to practice applying ideas. Label diagrams from memory and use real-world examples. Finish with mixed, timed practice; Fiveable’s 1000+ practice questions and cram resources are at (https://library.fiveable.me/practice/psych-revised).

Where can I find AP Psych Unit 1 PDF notes or review sheets?

Try Fiveable’s Unit 1 page (https://library.fiveable.me/ap-psych-revised/unit-1). That page has a focused study guide for Unit 1: Biological Bases of Behavior (topics 1.1–1.6) and covers key concepts like heredity vs. environment, neurons and neural firing, the nervous system, the brain, sleep, and sensation. For extra practice and quick review, Fiveable also offers cheatsheets, cram videos, and 1000+ practice questions at https://library.fiveable.me/practice/psych-revised. If you need a downloadable PDF, the unit study guide includes printable resources and concise review sheets that are great for last-minute review or consolidating notes. Students sometimes share community-made PDFs on forums, but the Fiveable unit link is the official, centralized resource to start with.

Are there reliable AP Psych Unit 1 practice tests or Quizlet sets for 2025?

Yes — there are Quizlet sets at https://quizlet.com/13270887/ap-psychology-unit-1-flash-cards/ for AP Psych Unit 1, but quality varies and many were made for pre-2025 exams. For deeper practice beyond flashcards, Fiveable’s Unit 1 study guide at https://library.fiveable.me/ap-psych-revised/unit-1 and the practice bank at https://library.fiveable.me/practice/psych-revised are more reliable and updated. Keep in mind the 2025 AP Psych exam format changed, so older free practice tests may not match new item types or weighting. If you use Quizlet, pick sets made or updated in 2024–2025 and cross-check terms against the CED topics (Biological Bases: heredity & environment, nervous system, neurons, brain, sleep, sensation). Fiveable’s cheatsheets and cram videos help with quick review too.

Is Unit 0 going to affect AP Psych Unit 1 content on the exam?

Nope — Unit 0 (usually course intro and skills) won’t change the Unit 1 content that’s tested. Unit 1 (Biological Bases of Behavior) is listed on the CED and carries about 15–25% of the exam. Unit 0 typically covers course logistics, science practices, or basic study skills and isn’t a separate College Board content unit you’ll be tested on. Focus your study time on Unit 1 topics from the CED — neurons and neural transmission, brain structures, sleep, and sensation — since those show up on multiple-choice and FRQ tasks. For a quick, reliable review that lines up with the CED, see Fiveable’s Unit 1 study guide (https://library.fiveable.me/ap-psych-revised/unit-1).