phenotypic variation Flashcards
what is a phenotype?
an observable characteristic
what is phenotypic variation
differences between observable characteristics of a group of organisms
what is interspecific variation?
- differences between different species due to different genes
- code for different proteins so look and function differently
- not affected by environment
what is intraspecific variation?
- differences between organisms of the same species
- same genes, different alleles
- subtle differences
- polygenic traits are affected by the environment
- monogenic less likely
what is a gene?
section of DNA that codes for a particular protein
what is meant by monogenic
product of a single gene
what is meant by polygenic
product of multiple genes
what is a homologous pair?
a pair of chromosomes carrying the same genes with different alleles
what is an allele
different versions of a gene with a slightly different base sequence - slightly different proteins are produced
what is genetic variation
variation caused by differences in DNA base sequences
- different hair / eye colour
what is environmental variation
variation caused by the environment in which the organism lives
what is a chromosome
a long section of DNA made up of many genes
what is a genotype
combination of alleles an organism has
describe environmental modification of a genetic trait
- phenotypes of genetic traits are often modified by the environment
- traits are usually polygenic
- eg. weight
what is chlorosis
where leaves turn pale / yellow as plant is not producing chlorophyll
what happens to photosynthesis when a plant goes into chlorosis
photosynthesis cannot occur
how do variations arise
mutations of genetic code
what causes chlorosis
changes in phenotype due to environmental factors
what 3 environmental factors cause chlorosis
- lack of light
- mineral deficiencies
- virus infections
what is etiolation
the process in which plants grow long, pale and unhealthy due to lack of light
why does etiolation occur?
low levels of light
which phenotypic characteristics are affected by what we eat?
body mass
what genetic and environmental factors influence weight?
how does our diet affect our genes?
