Karteikarten
Patterns of Inheritance
Karten in diesem Stapel (40)
- 1Name three factors that may cause genetic variation within phenotypes-Physical mutations (i.e mutagens)
-Chromosomal mutations
-Sexual reproduction - 2How does sexual reproduction cause phenotypic variation?-Random assortment of alleles during metaphase 1/2
-Random crossover and recombination
-Random gametes fusing together - 3Define monogenic charateristics-These are traits that are dictated by one gene with different alleles
- 4Define dihybrid in terms of inheritance-This is when characteristics are determined by two different genes
- 5Define codominance-This is when each allele in a heterozygotic phenotype is expressed, maybe no to the same extent, but they are still expressed
- 6What does the terms multiple alleles actually mean?-This means that there are three or more alleles for a characteristic in one gene pool. e.g eye colour: green, blue, brown
- 7What is the difference between linked and unlinked?-Linked is when the different alleles involved are on the same chromosome, they are physically with each other
-Unlinked is when the different alleles are separate from one another, meaning that the possible phenotypes are more - 8What would the phenotypic ratio be when two heterozygote parents breed? (Use the letters A and B)-The ratio should be 9:3:3:1
- 9Tell me what the phenotypic percentage would be when the dihybrid linked genotypes of both parents are heterozygous75% of one and 25% of the other
- 10Define polygeneticWhen traits are determined by more than one gene/ more than one gene contributes to the gene
- 11Calculate the phenotypic ratio for a height, when Homozygous dominant breeds with a homozygous recessive Let dominant= 10 cm taller Let recessive= 5cm taller (Hint: height is a polygenetic feature)100% will increase height by 30cm
- 12Why may people be getting taller?-Improved diet; more protein to grow
-Improved healthcare; less energy needed to fight disease
-Taller men are more attractive; more likely to reproduce and pass on genes
-Improved clothes; less energy used for heat more on growing - 13"Explain how theinheritance of flower colour in snap dragons is an example of codominance*
- 14Link blood groups with codominanceA and B are codominant. This means that they are just as dominant as each other
-AA= group A
-BB= group B
-AB= group AB
-OO= group O
-AO= group A
-BO= group B - 15What am I describing? "This is all the different alleles in one breeding population at any one time"The definition of a gene pool
- 16What am I describing? "The number of times a specific allele occurs in a population"The definition of allelic frequency
- 17TOP TIP!That whole section on the isolating populations and that jazz in Mr. O'Dwyers side is talking about what things can change the number of times a specific allele can show up in a population....yeah this one is quite a dry tip, sorry!
- 18TOP TIP!Remember that selection and environmental factors do NOT affect how likely a mutant allele will pop up, but the FREQUENCY of that allele showing up, once its already there
- 19Using sickle cell anaemia, discuss how environmental factors can affect allelic frequcies-So sickle cell anaemie (SCA) is a codominant trait so if you have two, you have a severe SCA if just one allele you have lesser symptoms
-Those with SCA are resistant to malaria, so much so that in areas of malaria, SCA sufferers are favoured, but only those with one because those with two have such bad anaemia that it outweighs the resistance.
-Normal people are selected elsewhere but at a disadvantage in high malaria areas - 20Explain why the homo recessive genotype in malarial countries hasn't been wiped out yet, if its such a downerWell because heterozygous is the most dominant type and it has one recessive, if two heteros have a child, it is 25% likely to suck up both the recessive alelles
- 21Define "Speciation"Speciation is the process whereby one species is formed from an already existing one
- 22What am I describing? -A group of individuals with similar ancestry and so therefore have similar genes and are able to freely breed to produce fertile offspringOne of the many definitions of a species
- 23What am I describing? -This chooses which traits are successful enough to be transmitted from generation to generationSelective pressures
- 24I don't get, explain stabilising selective pressures to meOkay so the majority of this population is white right?
What if there was this disease (God forbid) That took out anyone with melanin
-This means the already majority would become even more of a majority
-This stabilises the allelic frequency of the white gene because their more likely to pass on their white genes to future gens without competition from POCs - 25State two simple ways in which speciation can occur1) You could form like some kind of mutant hybrid thing that runs off and starts its new species
2) Isolation between two demes could start the spiral of speciation - 26Can you remember what adaptive radiation is for me? Hint: It is something to do with isolating mechanismsAdaptive radiation is when two isolated demes become adapted to their own environmental selective pressure
-This then changes the allelic frequencies and then the phenotypic ratios so they may end up having different features from one another - 27Distinguish between allopatric and sympatric speciationAllopatric is when two demes become separated via physical barriers e.g oceans but symparic is where they occupy the same land but differences in lifstyle may prevent gene flow between deme
- 28What are the two ways that two demes living on the same land can't even reproduce together?Pre-zygotic; they may occur same land, but they can't actually have sex; maybe different sleep schedules or different sized penises...
Post-zygotic; the offspring is formed but it might not survive and continue the empire.... - 29State 2 examples of pre-zygotic mechanisms in sympatric speciation1) Temporal; different times of breeding
2) Ecological; they may sty within different habitats and never meet
3) Behavioural; courtship and "specific dances" *eyeroll* - 30State 2 examples of post-zygotic mechanisms in sympatric speciation1) Hybrid sterility
2) Hybrid inviability
3) Hybrid breakdown; when first generation is fertile but the second is not
(Kinda is what it says on the tin) - 31Give one example of post mating but prezygotic sympatric isolation mechanismsThe gametes may not meet, maybe because of differences in biochemistry
- 32How may populations be affected by different factors?You can have:
Directional effect; when a change in environment causes a shift toward one end of characteristic intensity
Stabilising effect; when no change in environment causes the average to continously increase in allele frequency (cos trait isnt adv or dis so not selected against) - 33What is the founder affect?This is when a sub group of a larger population start up a new population
-This causes the gene pool to be relatively small, which increases chances of recessive/ genetic diseases - 34TEveryone seems to think that natural selection is the only driving force of evolution, but they always forget genetic drift...
- 35TOP TIPNatural selection is only to do with survival
- 36Discuss genetic driftThis is a force of evolution that is not to do with survival
-Eveything revolves around chance; it is just by chance that some groups have alleles passed on more....nothing more, nothing less - 37How does genetic bottleneck relate to anything?This is when allele frequencies changed due to natural disasters e.g flood
1. Even allele frequency of A and B
2. Flood comes and by chance, takes out more A than B
3. B is now more common so more alleles are passed to next generation - 38TOP TIPEvolution is a change in allele frequency
- 39Compare and contrast artificial selection and natual selectionSimilarities; -Both cause change in allele frequency over time
-Both based on random mutations
Differences;
-AS has an agenda, NS is unpredictable
-NS increases adaptation of the species
-AS the pressure is humans , NS it's the environment - 40What are the two main driving forces of evolution?-Natural selection
-Genetic drift
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- GCSE Biology Karteikarten am Patterns of Inheritance, erstellt von Sparkle Shine am 30/11/2017.
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