The biological approach

• The biological approach assumes that all human behaviour has a biological origin. This insists that to comprehend human behaviour fully, it is necessary to understand biological structure and processes such as genes, the nervous system and neurochemistry
• Genes - passed on from one generation to the next. They carry information in the form of DNA, which carry instructions for characteristics, such as eye colour, intelligence.
• Genotype - a person's genetic makeup, which is fixed from birth.
• Phenotype - the expression of a person's genes which is physically visible. This is introduced through both genetic inheritance and interaction with the environment.
• Some psychological characteristics such as intelligence or psychological illness can be inherited in a similar way to physical characteristics. Research in this area has used monozygotic ( MZ ) twins ( identical twins ) as they share 100 % of their DNA, whereas dizygotic ( DZ ) twins ( non identical ) who share 50 % of their DNA
• Monozygotic ( MZ ) twins are identical and share 100 % of their DNA
• Dizygotic ( DZ ) twins are non-identical and share 50 % of their DNA
• Recent research has found that monozygotic twins have an increased concordance rate for developing schizophrenia compared to dizygotic twins.
• McMuffin et al ( 1996 ) found that if one identical twin has depression, there is 46 % chance that the other twin will also have depression. This suggests that there is a genetic component to illnesses like schizophrenia and depression.
• Concordance rates - degree of genetic similarity for a particular trait.
• Localisation of function - The theory that specific parts of the brain are responsible for specific functions
• Twin studies are often used to determine whether or not something has a genetic basis. When comparing monozygotic twins to dizygotic twins, if a higher concordance rate is found for MZ twins, it can be assumed that there is a genetic basis for that behaviour.
• Phenotypes refer to the observable characteristics of an individual, which is a consequence of interactions between the genetic makeup and environment of a person
• The genotype is a collection of inherited genetic material that is passed from generation to generation
• The theory of natural selection, proposed by Darwin, states that any genetic material aiding a person's survival is passed on to their offspring which means that only individuals with those alleles will survive.
• Neuroanatomy - concerned with the structure and working of the brain and the nervous system

  The structure of the nervous system is though to be involved in psychology
• Neurochemistry has a role in determining behaviour. Signals sent between neurones by chemicals are neurotransmitters. Imbalances in the number of neurotransmitters are associated with atypical behaviour, e.g. too little serotonin is associated with depression and too much dopamine has been associated with schizophrenia.
• Biological approach AO3. There are methodological issues with related research. Twin studies are often used to determine the biological basis for a behaviour, however it is difficult to separate the effects of nurture from nature as twins often experience similar environments. This means that determining the cause of their behaviour can be very hard. This lowers internal validity of these studies.
• Biological approach AO3. The biological approach assumes causality when there may only be correlation. For example, low levels of serotonin have been found in patients with depression, however there are individuals with low levels of serotonin that do not have depression, indicating that there is only correlation, not cause. This casts doubt on the biological explanation.
• Biological approach AO3. Biologists assume that all behaviours are determined by biology but this ignores other factors such as social learning or culture. Therefore, some psychologists argue that the biological approach does not take into account enough variables and therefore cannot explain human behaviour fully.
• Biological approach AO3. A benefit of the biological approach is that related research uses a scientific method. This means that any theories developed from these studies are based on reliable data and are more likely to be valid. This makes the approach more applicable to real life.
• Biological approach AO3. The biological approach has had real life benefits. Using this approach, drug treatments have been developed, for example antipsychotics for patients with schizophrenia. This means that development of the biological approach has been useful for individuals