Variation & Inheritance Flashcards
What is discrete variation?
Discrete variation is caused by inheritance due to a single gene. It is non measurable and falls into distinct groups
Give 3 examples of discrete variation
-Blood group
-Flower colour
-Tongue roll (y/n)
What is continuous variation?
Continuous variation is caused by polygenic inheritance (characteristics affected by more than one gene). Is is measurable and ranges between a minimum and maximum
Give 3 examples of continuous variation
-Shoe size
-skin colour
-Height
How does sexual reproduction maintain variation?
The offspring inherit one set of chromosomes from each parent
What is a gene?
A small section of DNA that codes for a protein which controls a particular characteristic
What is an allele?
Different forms (versions) of the same gene
Ex/ Gene = eye colour Allele = blue/green etc
What is meant by the term ‘phenotype’?
Phenotype is a physical description of a characteristic
Ex/ blue eyes or brown eyes
What is meant by the term ‘genotype’
Genotype is a description of the genes using letters to represent the alleles
What is meant by the term dominant?
Some alleles are dominant over others. You only need to inherit one copy of a dominant allele to express the characteristic. Dominant alleles are always represented by a capital letter
What is meant by the term recessive?
Recessive alleles are often masked by the dominant allele and you have to inherit 2 copies to express this characteristic. These alleles are represented by using the lower case letter at the beginning of the dominant characteristic
What is meant by the term ‘homozygous’?
If you inherit 2 of the same alleles, you are homozygous for a characteristic
What is meant by the term ‘heterozygous’?
If you inherit 2 different alleles e.g. 1 dominant and 1 recessive then you are said to be heterozygous for a characteristic
