What is the difference between the sympathetic and parasympathetic nervous systems?

The sympathetic nervous system prepares the body for 'fight or flight' by increasing heart rate, dilating pupils, and inhibiting digestion. The parasympathetic nervous system returns the body to 'rest and digest' by slowing heart rate, constricting pupils, and stimulating digestion. They work antagonistically to maintain homeostasis.

How do neurotransmitters affect behaviour?

Neurotransmitters are chemical messengers that transmit signals across synapses. For example, serotonin regulates mood and sleep; low levels are linked to depression. Dopamine is involved in reward and movement; excess is associated with schizophrenia. Imbalances can lead to psychological disorders, which is why many drugs target neurotransmitter systems.

What is the role of the amygdala in aggression?

The amygdala is a brain region involved in processing emotions, especially fear and aggression. Research shows that stimulating the amygdala can trigger aggressive responses, while damage reduces aggression. For example, Raine et al. (1997) found reduced activity in the prefrontal cortex (which inhibits the amygdala) in violent offenders, suggesting a neural basis for aggression.

How do twin studies help separate genetic and environmental influences?

Twin studies compare concordance rates (the likelihood both twins share a trait) between monozygotic (identical) and dizygotic (fraternal) twins. If MZ twins show higher concordance than DZ twins, it suggests a genetic component. For example, studies on schizophrenia show ~50% concordance in MZ twins vs. ~15% in DZ twins, indicating a strong genetic influence.

What is the difference between a hormone and a neurotransmitter?

Neurotransmitters are released from neurons into synapses and act locally on adjacent neurons. Hormones are secreted by endocrine glands into the bloodstream and affect distant target cells. For example, adrenaline acts as both a neurotransmitter (in the nervous system) and a hormone (from the adrenal glands). Hormones generally have slower, longer-lasting effects.

Can the brain change after damage?

Yes, the brain exhibits neuroplasticity, meaning it can reorganise by forming new connections. After injury, other areas may take over lost functions, especially in younger individuals. For example, stroke patients can regain speech through rehabilitation that encourages neural rewiring. However, plasticity decreases with age, and recovery is often incomplete.

Topic 3: Biological psychology

EDEXCEL

A-Level

Biological psychology focuses on the mechanisms within the body and how they affect human behaviour, with a specific emphasis on aggression. It explores the central nervous system, neurotransmitters, brain structure, evolution, and hormones as explanations for behaviour, while considering individual differences and developmental factors.

Objectives

Exam Tips

Pitfalls

Key Terms

Mark Points

Topic Overview

Biological psychology explores the physiological and genetic underpinnings of behaviour, cognition, and emotion. In the Edexcel A-Level Psychology specification, this topic covers key areas such as the structure and function of the nervous system, synaptic transmission, the influence of hormones and pheromones, and the role of genes and evolution in behaviour. You will examine how biological factors like brain structures (e.g., the amygdala, hippocampus) and neurotransmitters (e.g., serotonin, dopamine) relate to behaviours such as aggression, stress, and memory. Understanding these mechanisms is crucial for linking psychology to biology and for evaluating biological explanations of behaviour.

This topic is central to the course because it provides a scientific foundation for many psychological theories. For example, you'll learn how the fight-or-flight response involves the sympathetic nervous system and how chronic stress can lead to illness via the HPA axis. You'll also explore the nature-nurture debate through twin and adoption studies, and consider the ethical implications of biological treatments like drugs. Mastering biological psychology will help you critically evaluate research methods such as brain scans (fMRI, EEG) and understand how biological approaches complement cognitive, social, and learning perspectives.

Biological psychology fits into the wider subject by offering a reductionist view that can be contrasted with holistic approaches. It also links to topics like psychopathology (e.g., the dopamine hypothesis of schizophrenia), forensic psychology (e.g., the role of the prefrontal cortex in criminal behaviour), and health psychology (e.g., stress and the immune system). By the end of this topic, you should be able to explain behaviour using biological concepts, evaluate strengths and limitations of biological explanations, and apply your knowledge to real-world issues like addiction or mental health.

Key Concepts

Core ideas you must understand for this topic

→The nervous system: central (brain and spinal cord) and peripheral (somatic and autonomic) divisions; the autonomic nervous system's sympathetic and parasympathetic branches.
→Synaptic transmission: how neurotransmitters (e.g., acetylcholine, dopamine) cross the synapse, bind to receptors, and are broken down or reabsorbed; the role of excitatory and inhibitory postsynaptic potentials.
→Hormones and pheromones: the endocrine system's glands (e.g., pituitary, adrenal) and hormones (e.g., cortisol, adrenaline); how pheromones may influence behaviour (e.g., McClintock effect).
→Genes and evolution: the role of heritability, twin studies, and adoption studies in separating genetic from environmental influences; evolutionary explanations like natural selection and sexual selection.
→Localisation of function: specific brain areas (e.g., Broca's area for speech production, motor cortex for movement) and the concept of plasticity (the brain's ability to reorganise itself).

What You Need to Demonstrate

Key skills and knowledge for this topic

Structure and role of the neuron, neurotransmitters, and synaptic transmission
Effect of recreational drugs on CNS transmission
Brain structure and functioning (e.g., pre-frontal cortex) as an explanation for aggression
Role of evolution and natural selection in human behaviour/aggression
Biological explanation of aggression vs. Freud's psychodynamic explanation (id, ego, superego, unconscious, catharsis)
Role of hormones (e.g., testosterone) in aggression
Correlational research methods (co-variables, scatter diagrams, cause and effect issues)
Brain-scanning techniques (CAT, PET, fMRI)

Marking Points

Key points examiners look for in your answers

Structure and role of the neuron, neurotransmitters, and synaptic transmission
Effect of recreational drugs on CNS transmission
Brain structure and functioning (e.g., pre-frontal cortex) as an explanation for aggression
Role of evolution and natural selection in human behaviour/aggression
Biological explanation of aggression vs. Freud's psychodynamic explanation (id, ego, superego, unconscious, catharsis)
Role of hormones (e.g., testosterone) in aggression
Correlational research methods (co-variables, scatter diagrams, cause and effect issues)
Brain-scanning techniques (CAT, PET, fMRI)
Twin and adoption studies
Raine et al. (1997) classic study
Contemporary studies: Li et al. (2013), Brendgen et al. (2005), Van den Oever et al. (2008)

Examiner Tips

Expert advice for maximising your marks

💡Ensure you can apply inferential statistical tests (Spearman's rho) to correlational data
💡Be prepared to discuss issues and debates (e.g., ethics, reductionism, nature-nurture) specifically within the context of biological psychology
💡Practice evaluating the validity and reliability of brain-scanning techniques
💡Ensure you can link biological theories to the specific contemporary studies listed in the specification
💡Be ready to discuss the implications of biological findings for society (e.g., social control, drug therapy)
💡When evaluating biological explanations, always consider both strengths (e.g., scientific credibility, practical applications) and limitations (e.g., reductionism, determinism). Use specific studies (e.g., Raine et al. on brain abnormalities in murderers) to support your points.
💡For essay questions, structure your answer with clear paragraphs: define key terms, describe the biological mechanism, provide evidence (studies), and then evaluate. Use phrases like 'However, a limitation is...' to show critical thinking.
💡Remember to link biological concepts to the question's context. For example, if asked about stress, discuss the HPA axis and cortisol, but also mention individual differences (e.g., genetic vulnerability) and ethical issues (e.g., using drugs to manage stress).

Common Mistakes

Pitfalls to avoid in your exam answers

Confusing correlation with causation in correlational research
Failing to address the specific requirements of the practical investigation (e.g., Spearman's rho, descriptive statistics)
Over-simplifying biological explanations (reductionism)
Inadequate evaluation of brain-scanning techniques
Misunderstanding the distinction between biological and psychodynamic explanations for aggression
Misconception: The brain works as one unified whole with no specialised areas. Correction: While the brain is interconnected, many functions are localised (e.g., language in Broca's and Wernicke's areas). However, localisation is not absolute; complex functions involve distributed networks.
Misconception: Neurotransmitters are either 'good' or 'bad'. Correction: Neurotransmitters like serotonin and dopamine have multiple roles; imbalances can contribute to disorders, but they are not inherently positive or negative. For example, dopamine is involved in reward but also in schizophrenia.
Misconception: Genes determine behaviour completely. Correction: Most behaviours are influenced by a combination of genes and environment (epigenetics). Twin studies show that even highly heritable traits like intelligence have environmental influences.

Frequently Asked Questions

Common questions students ask about this topic

Before You Start

Prior knowledge that will help with this topic

•Basic knowledge of the nervous system and neurons from GCSE Biology or Psychology.
•Understanding of the scientific method and research methods (e.g., experiments, correlations) as covered in the Research Methods topic.
•Familiarity with the nature-nurture debate and reductionism vs. holism, which are recurring themes in psychology.

Likely Command Words

How questions on this topic are typically asked

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Discuss

Evaluate

Explain

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Practice questions tailored to this topic

Topic 3: Biological psychology

Topic Overview

Key Concepts

What You Need to Demonstrate

Marking Points

Examiner Tips

Common Mistakes

Frequently Asked Questions

Before You Start

Likely Command Words

Ready to test yourself?

Related Topics in EDEXCEL A-Level Psychology

E2E stub topic

Topic 1: Social psychology

Topic 2: Cognitive psychology

Topic 4: Learning theories

How to Revise Topic 3: Biological psychology — Edexcel A-Level Psychology

Examiner Tips for Topic 3: Biological psychology

Common Mistakes in Topic 3: Biological psychology

Key Marking Points

Topic 3: Biological psychology

Topic Overview

Key Concepts

What You Need to Demonstrate

Marking Points

Examiner Tips

Common Mistakes

Frequently Asked Questions

What is the difference between the sympathetic and parasympathetic nervous systems?

How do neurotransmitters affect behaviour?

What is the role of the amygdala in aggression?

How do twin studies help separate genetic and environmental influences?

What is the difference between a hormone and a neurotransmitter?

Can the brain change after damage?

Before You Start

Likely Command Words

Ready to test yourself?

Related Topics in EDEXCEL A-Level Psychology

E2E stub topic

Topic 1: Social psychology

Topic 2: Cognitive psychology

Topic 4: Learning theories