random fertilisation and generic variation Flashcards
what two main ways is phenotypic variation controlled in?
genetic or environmental
what is genetic phenotypic variation?
controlled entirely by genes
what is environmental phenotypic variation?
caused entirely by the environment in which the organism lives
does mitosis or meiosis create genetic variation?
meiosis
the genetic variation in gametes carries what type of alleles?
substantially different alleles
what causes genetic variation between zygotes?
during fertilisation, any male gamete can fuse with any female gamete to form a zygote- this random fusion of gametes at fertilisation creates genetic variation between zygote as each will have a unique combination of alleles
what are some examples of genetic variation in humans?
blood group
eye colour
gender
ability to roll tongue
what are some environmental factors that characteristics of species can be affected by?
climate
diet
accidents
culture
lifestyle
what are some examples of environmental variation?
an accident may lead to scarring on the body
eating too much and not leading an active lifestyle will cause weight gain
bring raised in a certain country will cause you to speak a certain language with a certain accent
what is discontinuous variation usually caused by?
genetic variation alone
why will continuous features often vary?
because of a combination of genetic and environmental causes e.g.
talk parents will pass genes to their children for height
their children have the genetic potential to also be tall
however if their diet is poor then they will not grow very well
therefore the environment also has an impact on their height
genes decide what and what does the surrounding environment affect?
genes decide what characteristics we inherit
the surrounding environment will affect how these inherited characteristics develop
