Our genes are inherited from our parents, and the different combinations of these genes make us unique. Genetic inheritance controls the characteristics of all living things.
Why does a dominant allele create a higher probability of an offspring affected by a disease, such as cystic fibrosis?
Only one dominant parental allele is needed to produce a 50% chance of an individual being affected by a particular genetic condition
The parents always pass on these alleles
Dominant alleles are more common than recessive alleles
Why is fertilisation a random process?
This process is random because a few sperm and eggs are released at a specific time
It is always known which sperm and egg will fuse during fertilisation
It is not known which sperm and egg fuse during fertilisation
Why is probability used to predict the outcome of fertilisation?
Scientists like using probability, because it is a difficult calculation
The four different allele combinations can only be predicted
Maths makes the outcome more likely
What phenotype is produced from an XY genotype?
Why does cystic fibrosis need two alleles to cause the disease?
It is a recessive disorder - you need two recessive alleles to cause the condition
The alleles are dominant and you need two of them
You need a dominant and a recessive allele to cause the condition
What is an example of a dominant genetic disorder?
Why are genetic tests never 100% reliable?
False positives and false negatives can be detected
The tests aren't carried out carefully
The technology isn't good enough
What type of trees can be used to examine close genetic relationships?
Which of these are the correct human gametes?
Pollen and sperm
Sperm and ova
Pollen and ova
What is a gene?
A complete copy of an organism's DNA
A small section of the DNA in a chromosome that codes for a protein
An x-shaped section of DNA