Genetics Population And Ecosystems Flashcards
What is the genotype?
The genetic constitution of an organism.
What is the phenotype?
The expression of the genetic constitution and its interaction with the environment.
What is an allele?
One of a number of alternative forms of a gene.
What does a locus represent?
The location of a gene on a chromosome.
What does ‘diploid’ mean?
Cells with nuclei containing two sets of chromosomes.
What does ‘haploid’ mean?
Cells with a single copy of each chromosome, e.g., gametes.
What is a dominant allele?
An allele that is always expressed in the phenotype.
What is a recessive allele?
An allele expressed in the phenotype only when both alleles are recessive.
What does codominance mean?
When both alleles are expressed in the phenotype.
What does homozygous mean?
Having identical alleles for a particular gene.
What does heterozygous mean?
Having different alleles for a particular gene.
What is the principle of the Hardy-Weinberg equation?
It predicts allele frequencies in a population will remain constant if certain conditions are met.
What is a monohybrid cross?
A genetic cross involving one gene.
What is a dihybrid cross?
A genetic cross involving two genes.
What is autosomal linkage?
Two genes located on the same chromosome, reducing their likelihood of being separated during crossing over.
What is sex linkage?
A gene’s locus being on a sex chromosome, often the X chromosome.
What is epistasis?
When one gene affects the expression of another gene at a different locus.
How can the chi-squared test be used in inheritance?
To compare observed and expected phenotypic ratios.
What is the gene pool?
The total number of all alleles in a population.
What is genetic drift?
Random changes in allele frequency, particularly impactful in small populations.
What is natural selection?
The process where alleles providing selective advantages increase in frequency within a population.
What are the conditions required for Hardy-Weinberg equilibrium?
Random mating, no natural selection, large population size, no mutations, and no migration.
What is allopatric speciation?
The formation of a new species due to geographical isolation followed by reproductive isolation.
What is sympatric speciation?
The formation of a new species within the same geographical area due to reproductive isolation.
What is a carrying capacity?
The maximum population size of a species an ecosystem can support, determined by biotic and abiotic factors.
What is the difference between intraspecific and interspecific competition?
Intraspecific competition occurs within a species, while interspecific competition occurs between different species.
What is primary succession?
The colonization of bare ground by pioneer species leading to a climax community.
What is secondary succession?
The recolonization of a damaged ecosystem where soil is already present.
Why is genetic diversity important?
It allows populations to adapt and survive changes in environmental pressures.
What is the significance of a large gene pool?
It indicates high genetic diversity, providing stability and adaptability to the population.”Question
What is a phenotype influenced by?
The genotype and interaction with the environment.
What does ‘multiple alleles’ mean?
More than two alleles exist for a gene, though only two are present in a diploid organism.
What is the expected phenotypic ratio in a monohybrid cross between two heterozygous organisms?
3:1 (dominant:recessive).
What is the expected phenotypic ratio in a dihybrid cross between two heterozygous organisms?
9:3:3:1 (unless linked genes or epistasis).
How does codominance affect the phenotype?
Both alleles are expressed, resulting in a phenotype that shows characteristics of both alleles.
What are the three alleles in human blood groups?
IA, IB, IO.
Which blood group alleles are codominant?
IA and IB.
What is the genotype of a person with blood group AB?
IAIB.
What does the Hardy-Weinberg equation calculate?
The allele frequency or number of carriers in a population.
What is the equation for Hardy-Weinberg equilibrium?
p² + 2pq + q² = 1, where p and q are allele frequencies.
What is the definition of genetic drift?
Random changes in allele frequency, particularly significant in small populations.
What are two types of genetic drift?
Founder effect and genetic bottleneck.
What is the founder effect?
When a small number of individuals start a new population, leading to reduced genetic diversity.
What is a genetic bottleneck?
A sharp reduction in population size due to events like disasters, reducing genetic diversity.
Why are small populations more affected by genetic drift?
Rare alleles are more likely to be lost by chance.
What is the difference between allopatric and sympatric speciation?
Allopatric involves geographical isolation; sympatric occurs without geographical barriers.
What causes sympatric speciation?
Reproductive isolation due to factors like mutations or behavioral changes.
What is stabilizing selection?
A type of natural selection that favors the average phenotype, reducing variation.
What is directional selection?
A type of natural selection that favors one extreme phenotype, shifting the population mean.
What is disruptive selection?
A type of natural selection favoring both extreme phenotypes over the average, potentially leading to speciation.
What are abiotic factors?
Non-living factors like temperature, light intensity, and pH that influence ecosystems.
What are biotic factors?
Living factors like competition, predation, and disease that influence ecosystems.
What is a niche?
The role of a species within its ecosystem, including its interactions and use of resources.
What does the mark-release-recapture method estimate?
The population size of motile species.
What are key assumptions in the mark-release-recapture method?
No immigration/emigration, marks do not affect survival, and enough time is allowed for mixing.
What is primary succession?
The colonization of bare ground by pioneer species leading to soil formation and biodiversity increase.
What is secondary succession?
Recolonization of a disturbed ecosystem, starting with soil and resulting in a climax community.
What is a climax community?
The final, stable community in an ecosystem, characterized by high biodiversity and complex food webs.
What is the purpose of the chi-squared test in genetics?
To determine if observed phenotypic ratios differ significantly from expected ratios.
How is the null hypothesis used in chi-squared tests?
It states there is no significant difference between observed and expected frequencies.
What is epistasis?
When one gene masks or modifies the expression of another gene.
What is autosomal linkage?
When two genes are located on the same chromosome and tend to be inherited together.
Why does autosomal linkage affect phenotypic ratios?
Linked genes reduce the chance of recombination, altering expected ratios.
What is sex linkage?
A gene located on a sex chromosome, usually the X chromosome.
Why do males often exhibit recessive sex-linked traits?
Males have only one X chromosome, so recessive alleles on it are expressed.
What is the definition of a gene pool?
The total collection of alleles in a population.
How do selection pressures affect allele frequencies?
They favor certain alleles, increasing their frequency while reducing others.
What is conservation?
The active management of ecosystems to maintain biodiversity and prevent species extinction.
Why is managing succession important for conservation?
To maintain habitats for species that may be outcompeted in a climax community.
What factors can change carrying capacity in an ecosystem?
Abiotic factors like temperature and biotic factors like new predators or diseases.”Question
What is the definition of a species?
A group of organisms that can interbreed to produce fertile offspring.
What is a population?
A group of organisms of the same species occupying a specific area at the same time.
What is a community?
Populations of different species living in the same area.
What is an ecosystem?
A community and the non-living components of its environment.
What is a habitat?
A specific part of an ecosystem where a population lives.
What does primary succession start with?
Bare ground or surfaces like rock, sand, or water.
What do pioneer species do in succession?
They colonize hostile environments, improve soil quality, and make the environment less hostile for other species.
What characterizes the climax community in succession?
Stable populations, high biodiversity, and complex interactions.
What is the effect of interspecific competition?
It reduces resource availability between different species.
What is the effect of intraspecific competition?
It regulates population size within a species by competition for resources.
How can quadrats be used to estimate population size?
By dividing the area into sections, randomly sampling, and calculating averages.
What are examples of abiotic factors affecting ecosystems?
Light intensity, temperature, pH, and water availability.
What are examples of biotic factors affecting ecosystems?
Predators, competition, disease, and availability of mates.
What is the formula for estimating population size using mark-release-recapture?
Population size = (number in first sample × number in second sample) / number of marked individuals recaptured.
What are assumptions of the Hardy-Weinberg principle?
Random mating, no selection, large population, no mutation, no migration.
What is genetic variation caused by?
Mutations, meiosis (crossing over and independent segregation), and random fertilization.
How does the bottleneck effect reduce genetic diversity?
A significant population reduction causes loss of alleles by chance.
What is directional selection?
A form of natural selection favoring one extreme phenotype, shifting allele frequencies.
What is disruptive selection?
A form of natural selection favoring extreme phenotypes over intermediate ones, potentially leading to speciation.
What does ‘null hypothesis’ state in chi-squared tests?
There is no significant difference between observed and expected results.
What is the role of degrees of freedom in chi-squared tests?
It determines the critical value, calculated as the number of phenotypes minus one.
What is the critical value in chi-squared tests for p < 0.05?
7.815 when degrees of freedom is 3.
What does a significant chi-squared result indicate?
The null hypothesis is rejected; observed differences are not due to chance.
What is the role of random sampling in population studies?
It removes bias and ensures representative data.
Why is a large sample size important in biological studies?
It increases reliability and reduces the impact of anomalies.
What is the role of conservation in managing ecosystems?
To maintain biodiversity and prevent extinction by managing succession and human impact.
What is the founder effect?
When a new population is started by a few individuals, leading to reduced genetic diversity.
What is the importance of genetic diversity in populations?
It allows adaptation to environmental changes and survival under selection pressures.
What is an example of stabilizing selection?
Human birth weight, where average weights have higher survival rates.
How do you calculate percentage change in biology experiments?
Percentage change = (change / original value) × 100.
What is the purpose of controls in experiments?
To ensure that only the independent variable affects the results.
What is epistasis, and how does it influence phenotypes?
Interaction between genes where one gene masks or modifies another’s expression.
How does crossing over during meiosis affect inheritance?
It increases genetic variation by exchanging DNA between homologous chromosomes.
What is the phenotype ratio for a dihybrid cross of heterozygous parents?
9:3:3:1, unless linked genes or epistasis are involved.
What is the effect of linked genes on inheritance ratios?
They are inherited together more often, altering expected phenotypic ratios.
What is the interaction of abiotic and biotic factors in niches?
Species adapt their roles based on resource use, predation, and competition.
What are examples of human activities that affect carrying capacity?
Deforestation, pollution, introduction of invasive species, and overhunting.
Why do species in the same habitat occupy different niches?
To reduce competition by specializing in different resources or times.
What is a correlation coefficient used for in biology?
To measure the strength and direction of a relationship between two variables.
How is the p-value interpreted in statistical tests?
A p-value < 0.05 indicates results are statistically significant.
