Phenotypic Variation
Genetic Factors
Physical, chemical and biological agents, known as mutagens, increase rate of mutation
Chromosome mutations may occur in meiosis:
o Indel Mutations (deletion/insertion)
o Point Mutations (base pair changed)
o Inversion (180° rotation)
o Translocation (section moves to another chromosome)
o Duplication (section is duplicated)
Genetic variation can occur during sexual reproduction
o Allele shuffling during crossing over in prophase I
o Independent assortment of chromosomes during metaphase/anaphase I and II
o Random fusion of gametes produces genetic variation between offspring
Environmental Factors
Injuries can affect phenotype such as scars
Habits learned from social groups e.g. regional dialects
Access to resources is a main environmental factor
o Genetics determine potential growth while food and nutrients determine how
much growth is actually achieved
o Chlorotic plants have the gene for making chlorophyll but don’t produce any and
end up yellow or yellow-white due to a lack of light or nutrients
Genetic Factors
Physical, chemical and biological agents, known as mutagens, increase rate of mutation
Chromosome mutations may occur in meiosis:
o Indel Mutations (deletion/insertion)
o Point Mutations (base pair changed)
o Inversion (180° rotation)
o Translocation (section moves to another chromosome)
o Duplication (section is duplicated)
Genetic variation can occur during sexual reproduction
o Allele shuffling during crossing over in prophase I
o Independent assortment of chromosomes during metaphase/anaphase I and II
o Random fusion of gametes produces genetic variation between offspring
Environmental Factors
Injuries can affect phenotype such as scars
Habits learned from social groups e.g. regional dialects
Access to resources is a main environmental factor
o Genetics determine potential growth while food and nutrients determine how
much growth is actually achieved
o Chlorotic plants have the gene for making chlorophyll but don’t produce any and
end up yellow or yellow-white due to a lack of light or nutrients
