section 2: patterns of inheritance - topic 1: types and causes of variation Flashcards
what are the 3 types of variation?
continuous.
discontinuous.
phenotypic.
what is continuous variation?
when the individuals in a population vary within a range.
^ there are no distinct categories.
examples of continuous variation.
height.
waist circumference.
fur length.
what kind of data is continuous?
quantitative.
what is quantitative data?
data that has values that can be measured with a number.
(numerical data)
what is discontinuous variation?
when there are 2 or more distinct categories - each individual falls into only 1 of these categories (there are no intermediates).
examples of discontinuous variation.
blood group.
violet flower colour.
tongue-rolling ability.
what kind of data is discontinuous?
qualitative.
what is qualitative data?
data that doesn’t contain any numbers.
(non-numerical data)
what is phenotypic variation?
the variation in an organisms phenotype.
what is a phenotype?
the characteristics an organism displays.
what is phenotypic variation influenced by?
genotype.
the environment.
genotype & the environment.
what make up a genotype?
the genes and alleles an organism has.
how does meiosis lead to genetic variation?
- meiosis makes gametes with a unique assortment of alleles through crossing-over and the independent assortment of chromosomes.
- the random fusion of gametes during fertilisation also increases genetic variation in the offspring.
differences in genotype result in phenotypic variation.
example of a genotype affecting phenotypic variation.
human blood group.
- there are 3 different blood group alleles, which result in 4 different blood groups.
what does it mean when characteristics are polygenic?
inherited characteristics that show continuous variation are usually influenced by many genes.
are characteristics that are polygenic more likely to show continuous or discontinuous variation?
continuous.
example of a polygenic characteristic.
human skin colour - it comes in loads of different shades.
what does it mean when characteristics are monogenic?
inherited characteristics that show discontinuous variation are usually influenced by only one gene.
are characteristics that are monogenic more likely to show continuous or discontinuous variation?
discontinuous.
example of a monogenic characteristic.
violet flower colour.
- either coloured or white.
- controlled by 1 gene.
what differences in the environment can affect phenotypic variation?
climate.
food.
lifestyle.
examples of phenotypic variation caused by the environment.
etiolation.
chlorosis.
what is etiolation?
this is when plants grow abnormally long and spindly because they’re not getting enough light.
