Psychology A4 - concept two - biological

Question 1

what are genes?

Answer 1

-genes are located on chromosomes
-humans have 46 chromosomes
-each gene is made up of strands of DNA
-genes carry ‘instructions’ relating to the physical and non-physical characteristics of living organisms
-each individual inherits two copies of each gene, one from each parent

Question 2

genotype

Answer 2

-individual’s genetic make-up
-collection of genes you inherit from your parents
-genotype doesn’t determine your physical and non-physical characteristics directly, genes are expressed through an interaction with your ‘environment’
-environment has an influence on the body; what you eat etc.

Question 3

phenotype

Answer 3

-refers to how individual’s genes are expressed in their observable characteristics
-example, hair and eye colour
-phenotype is the result of interaction between genotype and environment influences

Question 4

example: identical twins

Answer 4

-identical twins have different phenotypes but the same genotype
-different phenotypes = result of individual twin experiencing different environmental influences
-example, twins may look physically different because one goes to the gym and the other doesn’t
-distinction between phenotype and genotype suggests that human behaviours are due to an interaction of inherited and environmental factors

Question 5

the SRY gene

Answer 5

-one pair of chromosomes determines sex – XX = female, XY = male
-Y chromosome = a stunted X chromosome, missing some genetic material
-located on Y = gene called sex-determining region Y gene (SRY)
-development before birth, SRY cwitched on other genes causing XY embryo to develop testes
-adult males testes produce sperm, during development it produces sex hormones (testosterone)
-cause embryo to become biologically male
-without SRY other genes remain switched off, embryo develops into female

Question 6

evaluation: practical applications (+)

Answer 6

-practical benefits in distinguishing between genotype and phenotype
-example, depression (phenotype) is result of genetic predisposition (genotype), triggered by environment
-without trigger the individual won’t become depressed even though they have a genotype
-although genes cannot be changed, environment can be, reduces risk of negative outcome

Question 7

evaluation: research support (+)

Answer 7

-evidence of the role of the SRY gene in development
-rarely, process of ‘copying’ SRY gene goes wrong, producing a mutation of the gene
-SRY gene cannot perform its usual function of ‘switching on’ testicular development of XY
-individual = genetically male but develops female-typical reproductive organs
-evidence shows that the usual role of the SRY gene is to initiate male biological sex development in genetically male embryos

Question 8

evaluation: risk of oversimplification (-)

Answer 8

-influence of genes = oversimplified
-example, ‘gene for depression’ – inaccurate view of how genes operate
-genes may increase risk of developing depression but don’t cause it
-human behaviour isn’t caused by a single gene
-many genes make small but important contributions in complex interactions with each other
-oversimplified explanations of how genes work exaggerate role of inheritance and presents misleading view of causes of behaviour