Approaches – exam questions

Explain why John’s genotype will not reveal whether he will suffermfrom Alzheimer’s disease?

• The genetic test reveals the genotype not the phenotype

• Johns genotype will only reveal his set of genes (not their interaction with the environment

• A genetic test will only reveal if he is predisposed to suffering with Alzheimer’s disease but will not reveal if he will suffer from the disease

• Environmental factors may contribute to the disorder

The genotype for tooth decay will be the exact same for all the twin pairs as they are MZ/identical twins (which means they share 100% of the same DNA). So for each pair their teeth will be expected to decay in exactly the same way.

The fact that some twin pairs have different decay to each other (52) indicate their phenotype differ and something other than jeans affected their tooth decay e.g how much sweets they eat.

• Holly and Rita have identical genotypes as they are MZ twins

• They have the predisposition to develop the same personalities unless other factors intervene

• For them to have developed different personalities overtime, this must have been influenced by being in different environments

• Their personalities (phenotypes) are different presumably because Rita was encouraged to be more sociable and lively, Holly was not

Make assumptions about mental processes that cannot be directly observed/going beyond research evidence