B17 - Variation and Selection Flashcards
What is variation? [2]
differences between individuals of the same species
What is the biological name for humans? [1]
homo sapiens
What two ways do humans get differences from? [2]
- environment
- genes
What are examples of environmental differences? [5]
- dyed hair
- piercings
- accent
- scars
- fashion sense
What are examples of genetic differences? [5]
- eye colour
- natural hair colour
- nose shape
- blood group
- tongue rolling
What is continuous variation? [3]
- results in a range of phenotypes between a minimum and maximum
- quantitative
- histogram
What is discontinuous variation? [4]
- results in a limited number of phenotypes with no intermediates
- characteristic falls into a distinct group
- qualitative
- bar chart
What are examples of continuous variation? [4]
- height
- arm span
- head circumference
- leaf surface area
What are examples of discontinuous variation? [4]
- eye colour
- tongue rolling
- skin colour
- left or right handed
What is the cause and genetic control of continuous variation? [2]
- genetic & environmental
- multiple genes
What is the cause and genetic control of discontinuous variation? [2]
- genetic
- one (or few) genes
What is a mutation? [1]
a change in the base sequence of DNA
How are new alleles formed? [3]
- mutations
- they cause a change in the sequence of DNA bases
- this results in different proteins being coded for
How are mutations formed? [1]
mistakes happen when DNA is being copied
How are mutations increased? [2]
- ethanol
- xrays
What is a genetic variant? [2]
- different version of a gene (allele) caused by mutations
What is genetic variation? [1]
differences in genotype
What is phenotypic variation? [1]
differences in phenotype
What is the formula for pecentage change? [2]
(new - old / old) x 100
What is selective breeding? [4]
- when humans artificially select
- the plants or animal that are going to breed
- so that the frequency of alleles for desired characteristics
- increases in a population.
What are desired characteristics in animals? [4]
- docile (peaceful)
- more muscle (meat)
- produce more milk
- more wool
What are desired characteristics in plants? [2]
- increased yield
- disease resistant
What are the 5 stages in selective breeding? [5]
- decide most important characteristic and select parents with the highest levels of this characteristic
- breed these individuals
- select the best offspring
- breed again
- repeat process over many generations and eventually all will have that characteristic
What does selective breeding mean? [1]
you’re choosing which alleles are passed on
What are the problems with selective breeding? [2]
- increased risk of genetic disease
- reduction in variation
What is natural selection? [1]
how organisms adapt from one generation to another
What is the cause of genetic variation? [1]
mutations
What are the steps for natural selection? [5]
- any population has genetic mutations
- all organisms overproduce when good conditions (to ensure survival of species)
- competition for resources - leads to struggle for survival
- those who do survive will reproduce
- their alleles for characteristics will be passed onto their offspring and more common in the population
How do bacteria become resistant to antibiotics? [1]
natural selection
