variation and inheritance Flashcards
what’s the definition of variation
the differences between members of the same species
why does variation occur in species
due to sexual reproduction with in a species, as it allows genes from different parents to combine
what’s the definition of continuous variation
a factor that has a range of values between maximum and minimum
what’s the definition of discreet variation
the characteristics that can be separated into distinct groups
3 examples of discrete variation
can/can’t roll tongue
blood type
eye colour
3 examples of continuous variation
hieght
weight
shoe size
name the two types of inheritance shown by characteristics in organisms
single gene and polygenic
which from of variation is controlled by many genes (polygenic)
continuous
which form of variation is controlled by a single gene
discrete
number of genes involved in
1. single gene
2.polygenic
1.1 (single)
2. 2+ (many/several)
what’s a definition and example of alleles
different form of a gene for a characteristics
eye colour & blood type
what’s a definition and example of genotype
this is the set of genes that an organism posses
BB Bb
what’s a definition and example of phenotype
physical appearance of a characteristics
hair colour - blond & brown
what’s a definition and example of dominant genes
when one alleles mask or hide the others presence
brown eyes
what’s a definition and example of recessive genes
the masked or hidden alleles
blue eyes
what’s a definition and example of true breeding
organisms that is homozygous and can only pass on one type of allele for a particular characteristic
BB or bb
what’s a definition and example of homozygous
when there are 2 alleles the same
bb
what does polygenic mean
a characteristic controlled by many genes
what’s a definition and example of heterozygous
when both alleles are different
Bb
what are different forms of a gene
known as
alleles
explain the meaning of the term phenotype
physical characteristics
give three examples of the phenotypes that exists for hair colour in humans
brown, blond and black
explain the meaning of the term monohybrid cross
a cross involving the inheritance of one only characteristic
give a definition of a carrier
when someone has a dominant/recessive genotype for a gene
why do some people undergo genetic counselling
when someone may carry an inheritance disorder they may go to get it checked before having a child
define the term haploid and give one example
a cell with one set of chromosomes
sex cells
what does p stand for
the first set of parents crossed
what does F1 stand for
the first filial generation of offspring
what does F2 stand for
the second filial generation of offspring
what is an allele
different versions of the same gene
what is the weaker allele known as
recessive allele
describe why the predicted phenotype ratio off offspring may be different from the observed ratio
because fertilisation is a random process
