Topic 7 - inheritance population evolution and ecosystems Flashcards
What is the genotype?
The genetic constitution of an organism
What is the phenotype?
The expression of the genes and its interaction with the environment
What is homozygous?
A pair of homologous chromosomes carrying the same alleles for a single gene.
What is heterozygous?
A pair of homologous chromosomes carrying two different alleles for a single gene.
What is a recessive allele?
An allele only expressed if no dominant allele is present.
What is the dominant allele?
An allele that will always be expressed in the phenotype.
What is meant by codominant?
Both alleles are equally dominant and expressed in the phenotype
What is meant by multiple alleles?
More than two alleles for a single gene
What is sex linkage?
A gene whose locus is on the X chromosome.
What is autosomal linkage?
Genes that are located on the same chromosome
What is epistasis?
When one gene modifies or masks the expression of a different gene at the different locus.
What is meant by monohybrid?
Genetic inheritance cross of a characteristic determined by one gene.
What is meant by dihybrid?
Genetic inheritance cross for a characteristic determined by two genes.
The type of inheritance is monohybrid what is the genetic diagram coding?
Single letter capital or lowercase for dominant or recessive.
The type of inheritance is codominant what is the genetic diagram coding?
Gene*allele
Multiple alleles is the title inheritance. What is the genetic diagram coding?
Gene*allele
Sex linkage is the type of inheritance. What is the genetic diagram coding?
Chromosome*allele
The type of inheritance is autosomal linkage. What is the genetic diagram coding?
Example: Aa Bb
Epistasis is the type of inheritance. What is the genetic diagram coding?
Example: EE Bb
Monohybrid inheritance: cystic fibrosis is caused by a recessive allele. If two carriers reproduce what is the probability they will have a child with cystic fibrosis? What is the probability they will have a girl with cystic fibrosis? (Parental genotypes = Ff x Ff
Punnet square of parental genotypes: creates FF, Ff, Ff, ff.
25% probability that the child will have cystic fibrosis.
50% (chance of having a girl) x 25% (probability of having cystic fibrosis) = 12.5%.
Codominant inheritance: cows can be red, white or roan in colour; red and white are both dominant. If two roan cows reproduce what is the probability they will produce red offspring?
Parental genotypes = CRCW(roan) x CRCW(roan)
Punnet Square = CRCW (roan), CRCR (red), CWCW (white), CRCW (roan)
25% probability of getting a red cow.
Multiple alleles: parents with blood group AB and blood group O reproduce. IA and IB codominant and IO is recessive. What is the probability they will have an offspring with a blood group A?
Parental genotypes = IAIB x IOI*O
Create the punnet square = IBIO (blood group B), IAIO (blood group A), IAIO (blood group A), IBIO (blood group B).
50% chance of the offspring having blood group A.
Sex linkage = colour blindness is caused by recessive allele found on the X chromosome. If a non-colourblind male we produces with a female carrier of the allele, what is the probability their children will be colourblind?
Workout parental genotypes = XRXr and XrY.
Do the punnet square = XRXr (normal vision), XRXRXR (normal vision), XrY (colour blind), X*RY (normal vision).
The probability of the child having colour blindness is 25% .
Epistasis:
Gene 1: controls whether pigment will be expressed.
Allele E: dominant and codes for pigment production
Allele e: recessive and codes for no pigment production.
Gene 2: controls which pigment is expressed (if pigment is being expressed)
Allele B: dominant and codes for black fur
Allele b: recessive and codes for brown fur
Parental genotypes = Ee Bb x Ee E Bb
Parental phenotypes: both black ( EB Eb eB eb x EB Eb eB eb).
Do a punnet square and work out all the possible combinations: EEBB (black), EEBb(black), EeBB(black), EeBb(black), EEBb(black), EeBB(black), EeBb(black), EeBb(black), EeBb(black), Eebb(brown), Eebb(brown), Eebb(brown), eeBB(yellow), eeBb(yellow), eeBb(yellow), eebb(yellow), The ratios of the genotype should be 9:3:3:1.
What are dihybrid crosses?
A genetic cross where the inheritance of two genes is considered at the same time.
In genetic cross exam questions what features do you have to have to get all the marks?
- Parental phenotype.
- Parental genotype.
- Possible gametes
- Offspring genotype.
- Offspring phenotype.
- Proportion of each phenotype.
Question about peas:
Round and yellow traits are dominant
And
Wrinkled and green traits are recessive
The parental genotypes are : (both heterozygous) RrYy and RrYy
What are the possible gametes.
Possible gametes: RY, Ry, rY, ry and RY, Ry, rY, ry
What is crossing over in miosis?
Crossing over results in new combinations of alleles in the gametes.
This means the predicted gambit in your punnet square may differ.
What is a gene pool?
All the alleles of all the genes within a population at one time.
What is a population?
All the individuals of one species in one area at one time that can interbreed to make fertile offspring.
What is allele frequency?
The proportion of an allele within the gene pool
What is the hardy Weinberg equation and what does the different things mean?
P + q = 1
P2 + 2pq + q2 = 1
P = the frequency of the dominant allele
Q = the frequency of the recessive allele
P2 = the frequency of the homozygous dominant genotype
2pq = the frequency of the heterozygous genotype
Q2 = the frequency of the homozygous recessive genotype.
What is meant by variation?
– Individuals within a population of a species may show a wide range of variation in the phenotype.
– This is due to genetic and environmental factors.
What are the sources of genetic variation?
– Mutation is the primary source.
– However random fertilisation of gambit during meiosis introduces genetic variation.
What things drive natural selection?
Predation, disease and competition for the means of survival results in differential survival and reproduction.
What will happen to phenotypes providing selective advantages?
They’re likely to produce more offspring and passed on their favourable alleles to the next generation. The effect of this differential reproductive success on the allele frequencies within energy pool.
What is disruptive selection?
When individuals which contain alleles coding for extreme traits are more likely to survive and pass on their alleles. As a result, the allele frequency changes and more individuals possess the allele for the extreme trait and the Midling trait allele becomes less frequent continued disruptive selection can immediately lead to speciation.
What is speciation?
Speciation is the process that results in the creation of a new species.
This occurs when one original population of the same species becomes reproductively isolated this isolation means that there are now two populations of the same species, but they cannot breathe together.
What can isolation of species cause?
It can result in the accumulation of differences in their gene pool to the extent that two populations would be unable to interbreed to make fertile offspring, and are therefore classed as two different species.
What are the two different ways that populations can become reproductively isolated?
Geographically isolated: Allopatric
Changes in reproductive mechanisms: sympatric
What is Allopatric speciation?
- Populations can become separated geographically leading to reproductive isolation.
– Within all populations there is genetic variation due to random mutations.
– A population could become geographically isolated overtime by new mountain ranges or new bodies of water separating land masses. This separates the original population into two which are now unable to reproduce due to the geographical barrier.
What is sympatric speciation?
– Populations can become reproductively isolated due to differences in their behaviour.
– Individuals of the same species may not be separated by geographical barriers but are unable to reproduce.
– This could be because a random mutation within the population could impact reproductive behaviour, for example it may cause individuals to perform a different courtship ritual or for individuals to be fair at different times of the year.
– Due to this these individuals would not reproduce together and there will be no gene flow between the two groups within the populations.
– Overtime these reproductively isolated populations will accumulate different mutations to the extent that their DNA is so different they cannot indeed to create offspring. They are therefore classified as two different species.
What is genetic drift?
– This is the change in the allele frequency within a population between generations.
– There will always be genetic drift from one generation to the next but continual substantial genetic drift results in evolution.
– The smaller population is the bigger. The impact frequency changes have proportionally and this is why evolution of often occurs more rapidly in smaller populations.
What is a population?
A group of organisms of the same species living in the same area at the same time and can interbreed to make fertile offspring.
What is a habitat?
Part of an ecosystem, in which particular organisms live.
What is a community?
All the populations of different species are in the same area at the same time.
What is an ecosystem?
A community and the nonliving components of an environment, the biotic and abiotic factors. Ecosystems can range in size from the very small to the very large.
What is a niche?
An organisms role within an ecosystem, including its position in the food web and habitat each species occupies its own leash governed by adaptation to both abiotic and biotic conditions.
What is carrying capacity?
The maximum population size an ecosystem can support.
What are abiotic factors?
The nonliving conditions of an ecosystem.
What are biotic factors?
The living components of an ecosystem
What are the abiotic factors of an ecosystem?
They will affect the size of the different populations.
These factors can range from temperature, oxygen and carbon dioxide concentration, light intensity, pH, and soil conditions.
Plants and animals are adapted to abiotic factors within their system.
These adaptations developed through the process of natural selection over many generations.
The less harsh the abiotic factors such as plenty of water and light the large large of the range of species and the large of the population sizes.
What is inter-specific competition?
When members of different species are in competition for the same resource that is in limited supply. This could be competition for a habitat food or water. The individual better adapted to the environment is more likely to succeed in this competition.
What is intra specific competition?
When members of the same species are in competition for resources and a maid competition for a main links to the courtship rituals individuals that are fitter with more energy to perform a more impressive courtship ritual or may have fur or feathers in a better condition to attract a female.
What is the predator prey relationship?
The interaction between predators and prey in a food web.
The predator prey graph always follows the same dynamic.
The size of the predator and prey population both fluctuate.
What ever happens to the prey happens to the predators afterwards (delayed).
Why do we sample?
- Sampling is more time efficient and if implemented correctly, it can be more accurate.
- Samples must accurately represent the population. This is insured by:
Random sampling in uniform areas to eliminate bias.
Line transects to examine a change over distance.
Large number of samples.
What type of sampling method should you use if you have slow moving or non-motile organisms such as plants?
Sample using a quadrat.
It is uniformly ditrsibuted use random sampling.
If it is uneven distribution use a line transect.
Would you sample motile organisms?
Sample using the mark–release–capture method.
How would you randomly sample organisms?
- Lie to tape measures at a white angle to create a gridded area.
- Use a random number generator to generate two coordinates.
- Place the quadrat and collect the data.
- Repeat loads more.
What is a belt transact?
The quadrat is placed at every position along the tape measure.
What is an interrupted belt transect?
The quadrat is placed at uniform intervals along the tape measure
How would you do a line transact?
- Place the tape measure at a right angle to the shoreline.
- Place the quadrat every 5 m/every position.
- Collect the data.
- Repeat by placing another 30 transacts along the beach at right angles to the shoreline.
How would you do the mark release recapture method?
- An initial sample of the population is captured.
- These individuals are then marked and the number caught is recorded. (The mark must be whether resistant).
- These marked individuals are released and are left for a period of time to allow them to randomly disperse throughout the habitat.
- Then a second sample is captured.
- The total number captured in the second sample and the number recaptured with the markings is recorded.
- The size of the population is estimated on the principle that the proportion marked in the second sample is equal to the portion of marked individuals in the population as a whole.
What is the mark release recapture calculation?
Estimated total population = number of organisms initially caught x number of organisms in the second sample / number of marked organisms recaptured.
What must be the considerations for marking animals in the mark release recapture method?
Ethical issues mean that it cannot be toxic must not increase chances of predation and must not reduce chances of reproduction.
What are the assumptions of the mark release recapture method?
- The population size is constant, so there is no birth no death and no migration.
- The animals always redistribute evenly they may all huddle their food in reality.
What is primary succession?
Primary succession starts with a pioneer species colonising bear rock or sand.
– Pioneer species are adapted to survive in harsh abiotic factors and through their death and decomposition change the abiotic factors to become less harsh and thin layers of soil and humus.
– Smaller plants can now survive and further increase the depth and nutrient content of soil. The patting continues and the abiotic factors get less harsh and larger plants can now survive the environment further.
Each species may change the environment in such a way that it becomes less suitable for the previous species therefore each existing species is out competed by a new species colonising.
– Changes that organisms produce in their abiotic environment can result in a less hostile environment and increase by diversity. The final stage in succession is known as the climax community and this is dominated by trees.
What is secondary succession?
The succession is distributed and plants are destroyed.
Succession starts again, but the soil is already created so it does not start from the bear rock stage.
The species richness and number of organisms increases a.k.a. the biodiversity.
As succession occurs larger plants, species and animals start to colonise the area.
What is conservation of habitats?
– Destruction of habitats is usually due to human activity resulting in a loss of food space and can lead to extinction to conserve habitats. Succession is often managed.
– Maintaining earlier stages in succession and preventing a climax community. A greater variety of habitats are conserved and therefore a greater range of species.
– Human behaviour needs to be monitored because of scarcity of natural resources.
