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A-Level · Psychology

PSY.APP6 The Biological Approach: Genes, Neurochemistry and Evolutionary Explanations

AQA 7182 · Calculators not allowed · about 60 minutes

Total Marks

Name: _______________________________ Date: ____ / ____ / ______

Answer ALL questions. Show all your working.

In the context of the biological approach to behaviour, define the assumption that behaviour has a physiological basis in the body and brain. Name the assumption and explain briefly what it means for behaviour.

Definition of the biological approach assumption that behaviour has a physiological basis

(Total for Question 1 is 2 marks)

Refer to the structure of a typical neuron. Outline three main parts of a neuron and give a brief function for each part, suitable for A level study.

Neuron structure parts and functions

(Total for Question 2 is 3 marks)

Explain the role of the myelin sheath and nodes of Ranvier in neural transmission, at a level suitable for A level specification.

Function of myelin sheath and nodes of Ranvier in neural transmission

(Total for Question 3 is 3 marks)

Define synaptic transmission in the biological approach and give the basic sequence of events that occurs at a chemical synapse.

Definition and basic sequence of synaptic transmission

(Total for Question 4 is 2 marks)

Outline how the neurotransmitter serotonin is thought to influence behaviour in the biological approach. Include one clear example of a behaviour or condition linked to serotonin.

Role of serotonin in behaviour

(Total for Question 5 is 3 marks)

Define the terms genotype and phenotype in the context of genetic explanations of behaviour, and give one brief example of each in relation to a behavioural trait.

Definition and example of genotype and phenotype

(Total for Question 6 is 2 marks)

Outline briefly how twin and adoption studies are used to estimate heritability of behavioural traits. Your answer should explain the logical comparison used in each type of study.

Use of twin and adoption studies to estimate heritability

(Total for Question 7 is 3 marks)

Outline the role of the neurotransmitter dopamine in behaviour and give one example of a behaviour or condition linked to dopamine in the biological approach.

Role of dopamine in behaviour

(Total for Question 8 is 4 marks)

Explain how an evolutionary explanation using natural selection could account for a behaviour such as human food preference for energy-dense foods. Refer to survival and reproductive advantages in your answer.

Explain how evolutionary natural selection accounts for preference for energy-dense foods

(Total for Question 9 is 6 marks)

Define natural selection in the context of evolutionary explanations of behaviour, and give one brief example of a behaviour (other than food preference) that could be explained by natural selection.

Definition of natural selection and example behaviour

(Total for Question 10 is 4 marks)

Explain the process of neurotransmitter action at the synapse in more detail. Your answer should include vesicle release, diffusion, receptor binding, and either reuptake or enzymatic breakdown as ways the signal is terminated.

Detailed explanation of neurotransmitter action and termination at a chemical synapse

(Total for Question 11 is 6 marks)

Evaluate the biological approach to explaining behaviour. In your answer, outline key strengths such as the use of scientific methods and real-world applications, and key limitations such as biological determinism and difficulties separating nature and nurture. Use evidence and consider implications. Write a coherent evaluative response.

Evaluate strengths and limitations of the biological approach

(Total for Question 12 is 12 marks)

Mark scheme · PSY.APP6 The Biological Approach: Genes, Neurochemistry and Evolutionary Explanations

Question 1

B1 names the assumption, e.g. behaviour has a physiological or biological basis oe
B1 explains that behaviour is influenced by biological processes such as genes, neurotransmitters or brain structures rather than only by environment oe
Answer: The biological approach assumes behaviour has a physiological basis: behaviour is influenced by biological processes such as genes, neurotransmitters and brain structures rather than only by environmental learning.

Question 2

B1 identifies and states function of one part, e.g. dendrites receive signals from other neurons oe
B1 identifies and states function of a second part, e.g. cell body / soma contains nucleus and integrates incoming signals oe
B1 identifies and states function of a third part, e.g. axon/axon terminal conducts impulses away from the cell body and transmits to the next neuron oe
Answer: Dendrites receive incoming signals; the cell body or soma contains the nucleus and integrates inputs; the axon conducts impulses away from the cell body and axon terminals release neurotransmitter to the next neuron.

Question 3

M1 identifies the myelin sheath as an insulating layer around some axons oe
A1 explains that myelin increases conduction speed by allowing electrical impulses to jump between nodes of Ranvier, called saltatory conduction oe
A1 explains that nodes of Ranvier are gaps in the myelin where action potentials are regenerated, enabling faster transmission along the axon oe
Answer: The myelin sheath insulates parts of the axon and enables faster transmission by causing action potentials to jump from one node of Ranvier to the next, while nodes of Ranvier are gaps where the impulse is regenerated.

Question 4

B1 defines synaptic transmission as the process by which a signal is passed from one neuron to another across a synapse oe
B1 states sequence: action potential arrives, neurotransmitter released from presynaptic vesicles, diffuses across cleft, binds to postsynaptic receptors oe
Answer: Synaptic transmission is the process where an electrical impulse triggers release of neurotransmitter from the presynaptic neuron; the chemical crosses the synaptic cleft and binds to receptors on the postsynaptic neuron, causing a response.

Question 5

M1 states that serotonin is a neurotransmitter involved in mood regulation oe
A1 links low serotonin function to behaviours/conditions such as low mood or depression oe
A1 gives an example, e.g. selective serotonin reuptake inhibitors increase serotonin at synapses and are used to treat depression oe
Answer: Serotonin is a neurotransmitter involved in regulating mood. Low serotonin activity is associated with low mood and depression; for example, antidepressant drugs such as SSRIs act to increase serotonin levels at synapses to reduce depressive symptoms.

Question 6

B1 defines genotype as the genetic makeup or alleles an individual possesses oe
B1 defines phenotype as the observable characteristics or traits resulting from genes interacting with environment, and gives an example oe
Answer: Genotype is an individual's genetic makeup, the alleles they carry. Phenotype is the observable characteristics produced by genes interacting with the environment, for example genetic tendency for high activity level (genotype) may result in an outgoing behaviour (phenotype) depending on upbringing.

Question 7

M1 for twin studies: compares concordance rates for a trait between monozygotic (MZ) twins and dizygotic (DZ) twins oe
A1 explains that higher concordance in MZ than DZ suggests genetic influence because MZ share 100% genes while DZ share about 50% oe
A1 for adoption studies: compares similarity between adopted child and biological parents versus adopted child and adoptive parents, to separate genetic and environmental influences oe
Answer: Twin studies compare concordance rates for a trait between monozygotic twins, who share 100% of genes, and dizygotic twins, who share about 50% of genes; higher concordance in MZ twins suggests genetic influence. Adoption studies compare similarity between an adopted child and their biological parents versus their adoptive parents to separate genetic from environmental contributions.

Question 8

M1 states that dopamine is a neurotransmitter associated with reward, motivation and motor control oe
A1 links high or dysregulated dopamine to behaviours such as addictive behaviour or schizophrenia symptoms oe
A1 provides an example, e.g. excess dopamine activity in some brain pathways is associated with positive symptoms of schizophrenia oe
A1 or alternative example: dopamine-related reward pathways are implicated in addictive behaviours oe
Answer: Dopamine is involved in reward, motivation and motor control. Dysregulated dopamine function is linked to behaviours and conditions such as addiction, where reward pathways are overactive, and to schizophrenia, where excess dopamine activity in certain pathways is associated with positive symptoms.

Question 9

M1 identifies that behaviours that aided survival and reproduction tend to become more common via natural selection oe
A1 applies this to energy-dense food preference: such preference would promote survival during food scarcity by providing calories oe
A1 explains survival advantage: individuals preferring energy-dense foods would be more likely to survive famines and support offspring oe
A1 explains reproductive advantage: better nutrition increases chances of reaching reproductive age and successful offspring rearing oe
A1 mentions that advantageous behavioural tendencies are passed on genetically or via interactions with environment, increasing population frequency over generations oe
A1 may acknowledge modern mismatch: in current obesogenic environments the same preference can be maladaptive, showing how environment interacts with evolved tendencies oe
Answer: Natural selection favours behaviours that improved survival and reproduction. A preference for energy-dense foods would have helped ancestors survive periods of scarcity by encouraging calorie intake, improving chances of surviving to reproductive age and caring for offspring. Over generations, genes associated with such preferences would become more common. In modern environments with abundant high-calorie food the same evolved preference can become maladaptive, showing an interaction with current environment.

Question 10

M1 defines natural selection as the process by which heritable traits that increase survival and reproductive success become more common in a population over generations oe
A1 states that this operates through differential survival and reproduction of individuals with advantageous traits oe
A1 gives a clear behavioural example, e.g. fear of snakes aiding survival by avoiding danger oe
A1 links example to survival or reproduction in a sentence oe
Answer: Natural selection is the process where heritable traits that improve survival and reproductive success become more common across generations because individuals with those traits leave more offspring. For example, a fear of snakes could have aided survival by reducing dangerous encounters, increasing the chance of living to reproduce.

Question 11

M1 states that an action potential arriving at the presynaptic terminal causes calcium ion influx and triggers vesicle fusion oe
A1 explains that neurotransmitter is released from synaptic vesicles into the synaptic cleft by exocytosis oe
A1 explains that neurotransmitter diffuses across the cleft and binds to specific receptors on the postsynaptic membrane causing excitatory or inhibitory post-synaptic potentials oe
M1 states that termination of the signal occurs by reuptake into the presynaptic neuron or enzymatic breakdown in the cleft oe
A1 explains reuptake mechanism, e.g. transporter proteins return neurotransmitter to presynaptic neuron for recycling oe
A1 or explains enzymatic breakdown, e.g. enzymes in the synaptic cleft break down neurotransmitter into inactive components, preventing continuous stimulation oe
Answer: When an action potential reaches the presynaptic terminal it causes calcium ions to enter, triggering synaptic vesicles to fuse with the membrane and release neurotransmitter into the synaptic cleft. The neurotransmitter diffuses across, binds to specific receptors on the postsynaptic membrane and elicits excitatory or inhibitory effects. The signal is then terminated either by reuptake via transporter proteins into the presynaptic neuron for recycling, or by enzymatic breakdown in the cleft which renders the neurotransmitter inactive.

Question 12

Level 4 (10-12): Knowledge of the biological approach is accurate and detailed. Evaluation is thorough and well balanced, addressing strengths and limitations with developed reasoning and relevant evidence. Discussion is applied and coherent, showing understanding of implications. Specialist terminology is used effectively.
Level 3 (7-9): Knowledge is clear and mostly accurate. Evaluation considers strengths and limitations with some development and supporting examples. Argument is generally coherent with appropriate terminology.
Level 2 (4-6): Knowledge is present but limited in depth. Evaluation is basic or one-sided, with limited development or examples. Response may lack clarity in places and use limited specialist terms.
Level 1 (1-3): Very limited knowledge and evaluation. Points are brief, undeveloped or largely descriptive. Little specialist vocabulary is used and argument lacks organisation.
Level 0 (0): No creditable content.
Indicative content:
- AO1 strengths: the biological approach uses objective scientific methods such as brain imaging, PET and fMRI, biochemical analysis and genetic studies, producing reliable, quantifiable data.
- AO1 strengths: twin and adoption studies provide systematic approaches to estimate genetic influences, and pharmacological research links neurotransmitters to behaviour providing mechanistic explanations and treatments.
- AO1 applications: findings have led to real-world applications such as drug treatments for mental disorders, and biological markers that inform interventions.
- AO3 limitations: biological determinism claims behaviour is governed by biology which can underplay the role of choice and social factors; this raises ethical implications about responsibility and stigma.
- AO3 limitations: difficulty separating nature and nurture, since biological research such as twin studies can be confounded by shared environment and gene-environment interaction, complicating simple genetic explanations.
- AO3 limitations: reductionism, explaining complex behaviours in terms of genes or neurotransmitters can ignore psychological and social levels of explanation, limiting understanding and treatment approaches.
- AO3 methodological critique: some biological measures such as brain scans show correlation not causation; small or unrepresentative samples in genetic studies can limit generalisability.
- AO3 strengths: scientific rigour enables replication and cumulative knowledge, and biological explanations have predictive power and clear practical outcomes, such as development of SSRIs for depression.
- AO3 balanced conclusion: the biological approach contributes important, testable explanations and effective interventions, but must be integrated with psychological and social perspectives to avoid deterministic or reductionist conclusions and to acknowledge complexity.

The Biological Approach: Genes, Neurochemistry and Evolutionary Explanations - Worksheets, Questions and Revision