Biology (9-1) - 0970 CIE

Variation

Gbogbo ọrọ náà

No two individuals of a species are exactly alike, and that variety is the raw material of evolution. Some differences fall into neat, separate categories; others form a smooth range. Understanding which is which, and where new variation comes from, is the bridge between genetics and natural selection.

In this lesson you will define variation, distinguish continuous from discontinuous variation with examples, link each to its causes, investigate both types, and explain mutation as the source of new alleles, including what raises the mutation rate and (for Extended) the other sources of genetic variation in populations.

Ebumnobi

Describe variation as differences between individuals of the same species
State that continuous variation results in a range of phenotypes between two extremes; examples include body length and body mass
State that discontinuous variation results in a limited number of phenotypes with no intermediates; examples include ABO blood groups, seed shape in peas and seed colour in peas
State that discontinuous variation is usually caused by genes only and continuous variation is caused by both genes and the environment
Investigate and describe examples of continuous and discontinuous variation
Describe mutation as genetic change
State that mutation is the way in which new alleles are formed
State that ionising radiation and some chemicals increase the rate of mutation
[Supplement] Describe gene mutation as a random change in the base sequence of DNA
[Supplement] State that mutation, meiosis, random mating and random fertilisation are sources of genetic variation in populations

Akọmọ Ojú-ẹkọ

Variation is what natural selection acts on, so it underpins evolution, selective breeding and the survival of species facing change. Telling continuous from discontinuous variation, and knowing that mutation makes new alleles, are reliably examined and easy marks once the definitions are secure.

Ọ dị na ngwa Green Bridge

Budata ngwa Green Bridge CBT na ekwentị maọbụ kọmputa gị iji nweta akwụkwọ ndụmọdụ zuru oke, ajụjụ mmụta, na ndị ọzọ.

Akwụkwọ ndụmọdụ zuru oke nwere eserese

Onye inyeaka mmụta AI

Mụọ n'ụzọ na-enweghị ịntaneti, oge ọbụla, ebe ọbụla

Budata ngwa ekwentị Budata ngwa kọmputa

Ọ dị na Android, Windows, macOS, na Linux

Ayẹwo Ẹkọ

Ekele diri gi maka imecha ihe karịrị na Variation. Ugbu a na ị na-enyochakwa isi echiche na echiche ndị dị mkpa, ọ bụ oge iji nwalee ihe ị ma. Ngwa a na-enye ụdị ajụjụ ọmụmụ dị iche iche emebere iji kwado nghọta gị wee nyere gị aka ịmata otú ị ghọtara ihe ndị a kụziri.

Ị ga-ahụ ngwakọta nke ụdị ajụjụ dị iche iche, gụnyere ajụjụ chọrọ ịhọrọ otu n’ime ọtụtụ azịza, ajụjụ chọrọ mkpirisi azịza, na ajụjụ ede ede. A na-arụpụta ajụjụ ọ bụla nke ọma iji nwalee akụkụ dị iche iche nke ihe ọmụma gị na nkà nke ịtụgharị uche.

Jiri akụkụ a nke nyocha ka ohere iji kụziere ihe ị matara banyere isiokwu ahụ ma chọpụta ebe ọ bụla ị nwere ike ịchọ ọmụmụ ihe ọzọ. Ekwela ka nsogbu ọ bụla ị na-eche ihu mee ka ị daa mba; kama, lee ha anya dị ka ohere maka ịzụlite onwe gị na imeziwanye.

Variation is best defined as: A. differences between individuals of different species B. differences between individuals of the same species C. the inheritance of alleles D. a change in the environment Answer: B
Which is an example of continuous variation? A. ABO blood group B. tongue rolling C. human height D. seed shape in peas Answer: C
Discontinuous variation is usually caused by: A. the environment only B. genes only C. genes and the environment D. diet only Answer: B
Mutation is best described as: A. the shuffling of existing alleles B. genetic change that forms new alleles C. a type of meiosis D. an environmental effect Answer: B
Which factor increases the rate of mutation? A. a balanced diet B. ionising radiation C. regular exercise D. drinking water Answer: B