B17 - variation & selection Flashcards
types of variation
-continuous - has a spread
-discontinuous - boolean
causes of discontinuous variation
-controlled by 1 pair of genes
causes of continuous variation
-controlled by more than 1 pair of genes
-environment
examples of continuous variation
-height
-skin colour
examples of discontinuous variation
-blood groups
-attached or detached earlobes
-tongue rolling
-eye colour
description of continuous variation
-range of phenotypes btw 2 extremes *
-no distinct categories
-many intermediates
(use of frequency histogram without gaps)
description of discontinuous variation
-limited no. of phenotypes
-with no intermediates *
(uses a bar chart with gaps)
inherited features example
-eye colour
-tongue rolling
environmental features
-muscles
-scars
inherited features affected by environment
-skin colour
which graph is used for which variation
continuous - frequency histogram with no gaps - has line of normal distribution
discontinuous - bar chart with gaps
define variation
differences btw individuals of the same species
causes of variation & examples
-genes - eye colour, blood type, tongue rolling
-environment - sun burnt, scars, accent
define mutation & example
-a genetic change to the DNA in a gene or chromo.
-cystic fibrosus, Albinism, hemophilia
-same genes, diff alleles
result of mutation
-new alleles are formed because mutation changes the sequence of DNA bases which result in diff. protein being coded for
define artificial selection
-choosing particular organisms with desired characteristics to breed tgt & continuing this process over many generations
process of artificial selection
-select organism with desirable features
-cross them with each other to make the next gen.
-select offspring with desirable characteristics and cross them
-continue this over many generations
-desirable features become more & more common until all offspring has the features
reasons for artificial selection for corn
-larger cob
-larger kernel (seed)
-juicier kernel
-resistant to diseases
reasons for artificial selection for pigs
-larger
-non hair
-no tusks
-resistant to diseases
stages for natural selection
-genetic variation
-overproduction
-struggle for existence
-survival of the fittest
-advantageous characteristics passed on to offspring
define natural selection
process where individuals with advantageous features are more likely to survive, reproduce, and pass their alleles to the next gen.
stages for natural selection in cactus
-cactis with either long or short rooted alleles
-in wet season, more offspring produced than environment can support
-competition of water in dry season
-only long rooted survive because they can access deeper water. Short rooted die
-long rooted reproduce and pass their alleles, more long rooted alleles in population
explain how population of antibiotic-resistant bacteria develop
-this is an example of natural selection
-some bacteria are mutated so there is variation
-normal bacteria die when exposed to antibiotics but mutated bacteria survive, reproduce and pass on their alleles .
-this happens over many gen. until antibiotic resistant bacteria are common in the population
what is antibiotic bacteria have
resistantance, not immunity
difference btw natural & artificial selection: agent of selection
-natural - nature
-artificial - man
difference btw natural & artificial selection: species chance for survival
-natural - High: adapted to survive in environment
-artificial - Low: chosen to benefit man/ more likely inbred
difference btw natural & artificial selection: speed of change
-natural - slower
-artificial - faster
difference btw natural & artificial selection: examples
-natural - cactus root length, giraffe neck length
-artificial - dairy cows, domesticated dogs, modern corn
how to measure effectiveness of antibiotic on bacteria
measure diameter of circle
factors that cause mutation
-radiation causes
-chemical causes
-natural causes
note: all genetic variation are mutations
how are new alleles created
mutation which rarely happen
how to find % change
diff/ org x 100%
how does a flower develop bigger leaf size over time
-This is an example of natural selection
-There was a mutation which cause leaf sizes to increase
-plants with smaller leaf sizes could trap less sunlight and photosynthesize less than plants with bigger leaf sizes so they died and couldn’t pass their alleles
-Plants with larger leaf sizes survived and passed on their alleles.
-This happens over multiple gen. until big leaf sizes as common in the population
2 useful characteristics of saddleback pigs from wild pigs
-no tusk
-larger animal
