AP Psychology
2025 College Board Version
Unit Overview
● Unit 1
● Unit 2
● Unit 3
● Unit 4
● Unit 5
,Unit 1: Biological Bases of Behavior
Overview of the lessons:
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
Highlight Key:
Vocabulary
Important
,1.1 Interaction of Heredity and Environment
● Evolution in psychology
○ Animals evolve to survive → developing instincts, behaviors, etc.
○ Charles Darwin inspired psychologists like William James
○ Show how environment may change traits
■ Genes and experience work together to wire brain
■ To contribute to survival fitness
● Nurture
○ Nurture: upbringing, education, and environment
○ Nurture is based on one’s environment and how one is treated when growing up
○ Reciprocal determinism: environment affects person, person (reacting) affects
the environment
○ *Some argue that it has little effect on personality
■ can be proven by cases of separated twins
● Even if twins, given birth by the same parents, are adopted by
different parents and grow up in different families, they may
still have a similar personality
● Confounding factor
○ Adopting parents are usually altruistic → making both
children altruistic and thus seemingly similar
● Heredity
○ Heredity: passing on of physical or mental characteristics from one generation
to another
■ affected by nature
■ each human has 46 chromosomes (23 from mom; 23 from dad)
○ Have much effect on personality and health
■ can be proven by cases of twins
● Identical twins have a high chance of both getting diseases,
divorced, and similar personality tests
■ Personality traits are around 40% heritable
■ Intelligence is 60% heritable
■ Height is 90% heritable
● Genes
○ can be active (expressed) or inactive
■ whether or not a trait shows still depends on the random process of
gene making
■ A fundamental characteristic of genes and gene making
■ Creates variability → serves as a criteria of natural selection in a
macro-view
○ can still be triggered by environmental events
■ Epigenetics: study of changes in gene expression that occur without
altering the underlying DNA sequence
, ■ environmental pressure can change activity of genes → gene gets
turned on or off after long-term pressure/triggers
● Possible changes
○ Body functions e.g. metabolic process
○ Behaviors
○ Traits that can be passed down e.g. disease & obesity
○ Related Vocabulary
■ Polygenetic : relating to or determined by more than one gene
■ Diathesis: a hereditary or constitutional predisposition to a group of
diseases, an allergy, or other disorder
■ Maturationism: educational and psychological theory that sees the child
as a growing organism and believes that the role of education is to
passively support this growth
● growth and development unfolds from within the organism
○ Neuroplasticity : the brain structure changes itself to respond to environment
■ Form new neural connections
■ Can form new connections after one has amputated a body’s structure
● Making the area around the amputated part more sensitive
○ Neurogenesis: the forming of new neurons
■ Originate in deep brain part, migrate to other brain areas and form
connections there
○ Biopsychosocial approach: genes, environment, and our culture all combine to
influence our development
1.2 & 1.3 Overview of the Nervous System & The Neuron and
Neural Firing
The Endocrine system is no longer in the AP Psychology Syllabus, but topics on specific hormones
(adrenaline, leptin, ghrelin, melatonin, and oxytocin) are still taught.
I have included notes on the endocrine system, regardless, as it may be beneficial to understand
the entire system. Feel free to skip the other parts at first and come back for information when
necessary.
● The endocrine system and nervous system communicate with each other all the time
○ Neurotransmitter fits with receptor sites of glands
○ Hormones fits in receptor sites of neurons
Endocrine system
● The system uses hormones to communicate with glands via the bloodstream.
● Steps
1. Hypothalamus (structure in the brain) sends out orders
a. Controls the pituitary gland, which tells other glands what to do and take in
other signals
2025 College Board Version
Unit Overview
● Unit 1
● Unit 2
● Unit 3
● Unit 4
● Unit 5
,Unit 1: Biological Bases of Behavior
Overview of the lessons:
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
Highlight Key:
Vocabulary
Important
,1.1 Interaction of Heredity and Environment
● Evolution in psychology
○ Animals evolve to survive → developing instincts, behaviors, etc.
○ Charles Darwin inspired psychologists like William James
○ Show how environment may change traits
■ Genes and experience work together to wire brain
■ To contribute to survival fitness
● Nurture
○ Nurture: upbringing, education, and environment
○ Nurture is based on one’s environment and how one is treated when growing up
○ Reciprocal determinism: environment affects person, person (reacting) affects
the environment
○ *Some argue that it has little effect on personality
■ can be proven by cases of separated twins
● Even if twins, given birth by the same parents, are adopted by
different parents and grow up in different families, they may
still have a similar personality
● Confounding factor
○ Adopting parents are usually altruistic → making both
children altruistic and thus seemingly similar
● Heredity
○ Heredity: passing on of physical or mental characteristics from one generation
to another
■ affected by nature
■ each human has 46 chromosomes (23 from mom; 23 from dad)
○ Have much effect on personality and health
■ can be proven by cases of twins
● Identical twins have a high chance of both getting diseases,
divorced, and similar personality tests
■ Personality traits are around 40% heritable
■ Intelligence is 60% heritable
■ Height is 90% heritable
● Genes
○ can be active (expressed) or inactive
■ whether or not a trait shows still depends on the random process of
gene making
■ A fundamental characteristic of genes and gene making
■ Creates variability → serves as a criteria of natural selection in a
macro-view
○ can still be triggered by environmental events
■ Epigenetics: study of changes in gene expression that occur without
altering the underlying DNA sequence
, ■ environmental pressure can change activity of genes → gene gets
turned on or off after long-term pressure/triggers
● Possible changes
○ Body functions e.g. metabolic process
○ Behaviors
○ Traits that can be passed down e.g. disease & obesity
○ Related Vocabulary
■ Polygenetic : relating to or determined by more than one gene
■ Diathesis: a hereditary or constitutional predisposition to a group of
diseases, an allergy, or other disorder
■ Maturationism: educational and psychological theory that sees the child
as a growing organism and believes that the role of education is to
passively support this growth
● growth and development unfolds from within the organism
○ Neuroplasticity : the brain structure changes itself to respond to environment
■ Form new neural connections
■ Can form new connections after one has amputated a body’s structure
● Making the area around the amputated part more sensitive
○ Neurogenesis: the forming of new neurons
■ Originate in deep brain part, migrate to other brain areas and form
connections there
○ Biopsychosocial approach: genes, environment, and our culture all combine to
influence our development
1.2 & 1.3 Overview of the Nervous System & The Neuron and
Neural Firing
The Endocrine system is no longer in the AP Psychology Syllabus, but topics on specific hormones
(adrenaline, leptin, ghrelin, melatonin, and oxytocin) are still taught.
I have included notes on the endocrine system, regardless, as it may be beneficial to understand
the entire system. Feel free to skip the other parts at first and come back for information when
necessary.
● The endocrine system and nervous system communicate with each other all the time
○ Neurotransmitter fits with receptor sites of glands
○ Hormones fits in receptor sites of neurons
Endocrine system
● The system uses hormones to communicate with glands via the bloodstream.
● Steps
1. Hypothalamus (structure in the brain) sends out orders
a. Controls the pituitary gland, which tells other glands what to do and take in
other signals
