Variation and Inheritance Flashcards
(11 cards)
State the meaning of the term ‘discrete variation’.
Discrete variation is caused by inheritance due to a single gene.
What causes continuous variation?
Continuous variation is caused by polygenic inheritance.
Why are phenotypic ratios not always achieved?
Phenotypic ratios are not always achieved because fertilisation is a random process,
and the ratio is also dependent on the sample size- if its too small.
State the definition of a gene.
a section of dna that codes for a protein which controls a particular characteristic
What is the meaning of the term ‘allele’?
different forms of the same gene.
What is the definition of a phenotype?
Phenotype is a ‘physical’ description of a characteristic,
What is the definition of the genotype?
Genotype is a description of the genes using letters to represent the alleles.
What is meant by the term dominant allele
some alleles are dominant over other alleles. You only need to inherit one copy of a dominant allele to express the characteristic
What is meant by a recessive alleles
Recessive alleles are often masked by dominant alleles, and you must inherit 2 copies to express this characteristic
.
What is meant by the term ‘homozygous’.
If you inherit 2 of the same alleles,
What is meant by the term ‘heterozygous’.
If you inherit 2 different alleles
