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 a gene?
section of DNA that codes for a particular protein
describe continuous variation
- takes any value on a scale
- caused by mostly genes with many alleles
- eg height
- polygenic
- histogram
describe discontinuous variation
- variation that fits into distinct categories
- caused by genes with few/no alleles and the environment
- eg blood group
- monogenic
- bar chart
what is a homologous pair?
a pair of chromosomes carrying the same genes but different alleles
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 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 gene?
a section of DNA that codes for a particular polypeptide
what is the genotype?
combination of alleles an organism has
what is the phenotype?
observable characteristics resulting from the genotype
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?
a condition where a plant doesn’t produce enough chlorophyll so leaves appear yellow
what is chlorosis caused by?
the environment
why does chlorosis occur?
- lack of light
- magnesium deficiency
- virus infection
what is etiolation?
plants grown in the dark will be yellow and grow long and spindly
why does etiolation occur?
they grow as long as possible to try and reach a light source
which phenotypic characteristics are affected by what we eat?
height and weight
what genetic and environmental factors influence weight?
- exercise
- presence of disease
how does our diet affect our genes?
- obesity genes are triggered
- eating unhealthily from a young age can trigger the genes and make it harder to lose weight
what is epigenetics?
- changes in gene expression that do not involve DNA sequence changes
- environment and individual lifestyle interact with the genome to influence epigenetic change
state the difference between a homozygous and heterozygous genotype (1)
homozygous = same alleles of same gene
heterozygous = different alleles of same gene
explain the difference between the phenotype and genotype of an oak tree (2)
phenotype = physical appearance eg height
genotype = allele that determines the characteristic
state and explain the difference between continous and discontinuous variation (6)
- continuous = variation that takes any value on a scale
- eg height between 1-200cm
- influenced by environment and genetics
- discontinuous = variation that fits into distinct categories which you do or do not have
- eg eye colour blue/green
- mainly only influenced by genetics
what graph would display data that is controlled by one or two genes and is influenced only by genes? (1)
bar chart
- only genetic = discontinuous
- few genes = monogenic
state 3 phenotypic characteristics that show discontinuous variation (3)
- eye colour
- hair colour
- blood group
state 3 phenotypic characteristics that show continuous variation (3)
- height
- weight
- hand span
