Topic 7 Inheritance Flashcards
What is a genotype
The genetic constitution of an organism
What is the phenotype
The expression of the genes and it’s 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 2 different alleles for a single gene
What is a recessive allele
An allele only expressed if no dominant allele is present
What is a dominant allele
An allele that will always be expressed in the phenotype
What does co dominant mean
Both alleles are equally dominant and expressed in the phenotype
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 (not sex chromosome)
What is epistsis
When one gene modified or masks the expression of a different gene at a different locus
What is mono hybrid
Genetic inheritance cross of characteristics determined by one gene
What is dihybrid
Genetic inheritance cross for a characteristic determined by 2 genes
How would you write a sex linkage genetic diagram
Chromosome and then the allele
What type of allele is cystic fibrosis caused by
Recessive
If 2 carriers of CF reproduce what is the probability they have a girl with cystic fibrosis
So the parental genotypes would be Ff and Ff so there would be a 25% chance of child with CF but if it’s a girl there’s 50% chance so you’d do 25% x 50% = 12.5%
What is the ratio of a dihybrid cross with 2 heterozygous parents
9:3:3:1
If autosomal linkage has occurred what is the ratio for dihybrid cross
3:1
What is chi squared
The statistic to investigate differences between frequencies
What is the null hypothesis
There is no significant difference between the expected and observed frequency of …
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 if one species in one area at one time
What is allele frequency
The proportion of an allele within the gene pool
What is the equation for hardy Weinberg
P2 + 2pq + q2 =1
P= dominant allele
q = recessive
2pq = heterozygous
P2 = homozygous dominant
q2 = homozygous recessive
What is the 2nd equation for hardy Weinberg
P+q=1
What are the main sources of genetic variation(3)
Mutations, meiosis and random fertilisation
What is disruptive selection
When individuals contain alleles coding for either extreme trait are more likely to survive and pass on their alleles
What is speciation
A creation of a new species
how does speciation occur
When original propulsion becomes reproductively isolated and cannot breed together
What is allopatric speciation
Geographic isolation
What is sympatric speciation
Changes in the reproductive mechanisms
Explain how sympatric speciation occurs
- Random mutation impacts reproductive behaviour e.g different courtship or different fertility times
- Due to this the individuals will not reproduce so there will be no gene flow between the 2 groups within the population
- Causing reproductive isolation they will accumulate different mutations so they cannot interbreed
What is genetic drift
Change in allele frequency within a population between generations
What is a population
Group of organisms of the same species living in the same habitat
What is a habitat
Part of an ecosystem in which particular organisms live
What is a community
All the populations of different species in the same area at the same time
What is an ecosystem
A community and the non living components of an environment
What is a niche
Organisms role in an ecosystem including their position on the food web and habitat
What is a carrying capacity
The maximum population size an ecosystem can support
Give 3 examples of abiotic factors
Carbon dioxide conc, light intensity and Ph
Give 2 examples of biotic factors
Competition and predication
What is interspecfic competition
Members of different species are in competition for the same recources such as food or water
What is intraspecific competition
Members of the SAME species are in competition e.g a mate
When would you sample using a quadrat
When is it a slow moving organism
What would you use for sampling with motile organisms
Mark - release - recapture
Explain the method of the mark-recapture- release
- Initial sample of population is captured
- Individual are marked harmlessly
- Marked individuals released and left for period of time allowed to randomly disperse
- Second sample captured
- Total number of captured in the second sample and number recaptured with marks recorded
- Size of population is then estimated on principle that proportion marker in second sample = proportion of marked individuals as population as a whole
What is the calculation for the estimated total population
Number of organisms initially caught x number of organisms caught in 2nd sample / number of marked organisms recaptured
What is succession
Change in ecological community over time
What is primary succession
Starts with a pioneer species colonising a bare rock or sand
E.g lichen adapted to survive harsh abiotic factors and from their death the abiotic factors become less harsh and from a thin layer of soil called humus
What is secondary succession
Disrupted and plants are destroyed
