20.1 Variation and inheritance Flashcards
What’s a genotype
An organisms genetic composition
What’s a phenotype
An organisms characteristics, often visible they occur as a result of its genotype and its environment
What’s an allele
A gene that exists in two or more different forms
What are homologous chromosomes
In diploid cells, chromosomes that occur in pairs
What’s a homozygous chromosomes
If the alleles at a specific locus are the same type of allele
What’s a heterozygous chromosome
If the alleles at a specific locus are different alleles
When’s a recessive allele not expressed in the phenotype
In a heterozygous chromosome as the dominant alleles expressed
When’s an allele codominant
If it’s expressed in the phenotype along with the other allele in a heterozygous chromosome
What is chlorosis
When a plant isn’t producing the normal amount of chlorophyll so they can’t make sufficient food by photosynthesis
As most plants that have chlorosis have the normal genes coding for chlorophyll production what’s the change in phenotype caused by
Environmental factors like lack of light, mineral deficiencies eg iron or virus infection
How’s genetic variation created
By the genes you inherit from your parents the combination is created by by genetic variation in sexual reproduction in meiosis
What’s continuous variation
Variation created by polygenes (many) its cause by genetics and environments a factors eg. Height or skin colour
What’s discontinuous variation
Variation caused by one or two genes its mainly genetics eg blood type
What’s monogenetic inheritance
The inheritance of a single gene
What’s the variation of animals body mass caused by
Genetic and environmental eg diet and exercise and metabolism
