Section 7

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  • Created by: aarafa11
  • Created on: 11-12-18 15:52
Define species
A group of similar organisms that can breed and produce a fertile offspring
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Define population
A group of individuals, of the same species that occupy the same habitat and can potentially interbreed
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Define gene pool
• All the alleles in all individuals •In a population • At the same time
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Define allele frequency
• The number of times • An allele occurs • In a gene pool
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What does Hardy-Weinberg predict
The proportion of recessive and dominant allele of any gene in a population. It should remain the same in every generation
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Condition for Hardy-Weinberg
1) No mutation 2) Population is isolated 3) No selection 4) Population is large 5) Mating is random
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What causes variation
• Environment factors • Genetic factors • COMBINATIONJ OF BOTH
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Explain crossing over
•Prophase 1 •Homologous pairs of chromosomes pair up. •The chromatids twist around each other • Genetic information is exchanged • Produces a new combination of allele
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How does asexual organism increase genetic variation
by muation
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Define selection pressure
• The ENVIRONMENTAL factors that limit the population of species
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What does selection pressure determine
The frequency of allele in a gene pool
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Factors of evolution that effect natural selection
1. Over production of offspring 2. Genetic variety 3. Variety of phenotype that selection operates against
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Why does natural selection effect over production of offspring
•High population •Increase intraspecific competition •For the limited resources •Individual will die as they can’t survive
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How does natural selection effect over production of offspring
•Mutation help it be better adapted •Will survive better •Pass advantageous allele to offspring •Increase allele frequency
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Define ecosystem
•Is a system made up of a community •And all the non-living factors of its environment
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Define habitat
•Where all the organisms usually live •It is characterised by the physical condition •And the type organisms present
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Define Ecological niche
•organisms role/position in an ecosystem •terms of its interaction •With abiotic and biotic factors
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Where does competitive exclusion principle take place
inter specific competition
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What is competitive exclusion principle
•Where 2 species •Are competing •For limited recourse •Will eventually eliminate the other species
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Define Genotype
genetic constitution of an organism
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Define phenotype
observable or biochemical characteristic of an organism
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Define Gene
the sequence of nucleotide that codes for particular polypeptide
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Define allele
different versions of a gene
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Define co-dominant
2 alleles both contribute to the phenotype
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Define multiple allele
Gene has more than 2 allelic forms
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What is mono-hybrid inheritance
Inheritance of a single gene
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What is pure breeding
•Breeding repeatedly an organism with the same homologous allele •For the offspring to have the same characteristic
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What is F1 generation
TH offspring of two different pure breds
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What is the ratio for monohybrid inheritence
3:1
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What is the basic law of genetics
In diploid organism= characteristic are determined by allele that occur in pairs. Only 1 of each pair can be presented in single gamete
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Define Dihybrid cross
cross involving two genes that control two different characteristics
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Why does a characteristic only need one chromosome for it to be expressed
The other chromosome doesnt have an allele so it wont express a phenotype
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Why is the expected ration in sex-linkage different to the observed
•Fertilisation is random •Not a large population •Fusion of gamete is random
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What is autosomal linkage
situation where 2 or more genes are carried on the same autosome
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What is autosome
The remaining 22 chromosome that isn't the sex chromosome
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What is epistatis
When the allele of one gene affects or masks the expression of another in they phenotype
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The affect of breeder only breeding a dominant allele on the frequency of heterozygous phenotype
Increase in homozygous dominant and a decrease in homozygous recessive
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Effects the characteristic of population by stabalisng selection
PRESERVES the AVERAGE phenotype. Selection against extreme phenotype
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When does stabilizing selection occur
• environmental condition s is constant • over long period of time
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Effects the characteristic of population by directional selection
• changes the phonotype • favouring phenotype in one direction • selection for 1 extreme phenotype
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Effects the characteristic of population by distruptive selection
• favours individual with extreme
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Why is disruptive selection so important
Brings out evolutionary changes
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When does disruptive selection take place
When abiotic factors are in more than 2 forms
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How are new species formed
• there is a geographical isolation • mutation will occur • for better adaptations • from selection pressure • the advantageous will be passed to offspring • this will increase allele frequency
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What is adaptive radiation
•Combination of allele produced •Subject to selection pressure •Lead to population • Adapting to environment
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Where does genetic drift take place
In a small population
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What are the types of speciation
Allopatric and sypatric
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Define Speciation
is the evolution of new species from existing ones
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What is allopatric speciation
Where 2 population become geographically separated. DIFFERENT COUNTRIES
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What is sympatric speciation
Population in the same area leading to them becoming reproductively separated
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Name given to the stable final stage of any succession
climax community
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Other cards in this set

Card 2

Front

Define population

Back

A group of individuals, of the same species that occupy the same habitat and can potentially interbreed

Card 3

Front

Define gene pool

Back

Preview of the front of card 3

Card 4

Front

Define allele frequency

Back

Preview of the front of card 4

Card 5

Front

What does Hardy-Weinberg predict

Back

Preview of the front of card 5
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