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Questions and Answers
Which of the following best describes the function of a codon?
Which of the following best describes the function of a codon?
What are the primary components of the DNA backbone?
What are the primary components of the DNA backbone?
What is the ultimate source of all new genetic variation?
What is the ultimate source of all new genetic variation?
What is the primary function of regulatory genes, such as enhancers and silencers?
What is the primary function of regulatory genes, such as enhancers and silencers?
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What was the primary conclusion of Mendel's pea breeding experiments regarding inheritance?
What was the primary conclusion of Mendel's pea breeding experiments regarding inheritance?
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What does the term 'polymorphic' refer to, in the context of genetics?
What does the term 'polymorphic' refer to, in the context of genetics?
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Which of the following best describes a 'locus' in the context of genetics?
Which of the following best describes a 'locus' in the context of genetics?
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What is the difference between a monogenic and a polygenic trait?
What is the difference between a monogenic and a polygenic trait?
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Which of the following is true about neutral mutations?
Which of the following is true about neutral mutations?
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What is the term for the existence of two or more alleles at a locus?
What is the term for the existence of two or more alleles at a locus?
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What is the role of gel electrophoresis in genetic studies?
What is the role of gel electrophoresis in genetic studies?
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According to the evolutionary model discussed, what is the significance of neutral mutations?
According to the evolutionary model discussed, what is the significance of neutral mutations?
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How many total chromosomes are typically found in a human cell?
How many total chromosomes are typically found in a human cell?
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What is the primary function of the 2-3% of DNA that is directly and consistently involved in protein production?
What is the primary function of the 2-3% of DNA that is directly and consistently involved in protein production?
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Which agricultural practice is NOT explicitly mentioned in the context?
Which agricultural practice is NOT explicitly mentioned in the context?
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What genotype results in the production of normal hemoglobin?
What genotype results in the production of normal hemoglobin?
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What are epigenetic changes, in genetic terms?
What are epigenetic changes, in genetic terms?
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Which of the following processes produces gametes through cell division?
Which of the following processes produces gametes through cell division?
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In the life cycle of Plasmodium falciparum, what is the immediate stage following the parasite entering the bloodstream of a human?
In the life cycle of Plasmodium falciparum, what is the immediate stage following the parasite entering the bloodstream of a human?
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What is the primary geographical region where sickle cell anemia is most commonly found?
What is the primary geographical region where sickle cell anemia is most commonly found?
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What effect does low oxygen pressure have on hemoglobin and red blood cells, as detailed in the content?
What effect does low oxygen pressure have on hemoglobin and red blood cells, as detailed in the content?
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How does the genetic mutation causing sickle cell anemia affect the hemoglobin protein?
How does the genetic mutation causing sickle cell anemia affect the hemoglobin protein?
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What genetic inheritance pattern is exhibited by the sickle cell trait (AS), according to the text?
What genetic inheritance pattern is exhibited by the sickle cell trait (AS), according to the text?
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What is a characteristic of a disruptive selection?
What is a characteristic of a disruptive selection?
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What is the primary effect of gene flow on genetic variation within a breeding population?
What is the primary effect of gene flow on genetic variation within a breeding population?
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What is a critical requirement for natural selection to occur?
What is a critical requirement for natural selection to occur?
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In the context of the medium ground finches studied by the Grants, what environmental change led to an increase in average beak size?
In the context of the medium ground finches studied by the Grants, what environmental change led to an increase in average beak size?
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What characteristic of the peppered moth makes it a classic example of directional selection?
What characteristic of the peppered moth makes it a classic example of directional selection?
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What does 'balanced polymorphism' mean with regard to genetics, specifically referring to stabilizing selection?
What does 'balanced polymorphism' mean with regard to genetics, specifically referring to stabilizing selection?
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Why is the S allele for sickle cell anemia maintained at higher levels in some African populations?
Why is the S allele for sickle cell anemia maintained at higher levels in some African populations?
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How does the change from hunter-gatherer lifestyle to Bantu horticulture influence the frequency of malaria and thus the S allele?
How does the change from hunter-gatherer lifestyle to Bantu horticulture influence the frequency of malaria and thus the S allele?
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What is a direct result of directional selection on a polygenic trait?
What is a direct result of directional selection on a polygenic trait?
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In the example of the rabbits and the virus, what was a critical factor in the rabbit’s survival and the virus's decreased virulence?
In the example of the rabbits and the virus, what was a critical factor in the rabbit’s survival and the virus's decreased virulence?
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Which of the following scenarios best exemplifies stabilizing selection on a polygenic trait?
Which of the following scenarios best exemplifies stabilizing selection on a polygenic trait?
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What is the relationship between seed size and plant location within the Galapagos environment mentioned in the content?
What is the relationship between seed size and plant location within the Galapagos environment mentioned in the content?
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How did the return to normal rainfall levels following the 1977 drought affect the average body size of the medium ground finches?
How did the return to normal rainfall levels following the 1977 drought affect the average body size of the medium ground finches?
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What immediate impact did the El Nino event have on the finch population?
What immediate impact did the El Nino event have on the finch population?
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What observation about the change of the peppered moth population after the Clean Air Act was implemented best demonstrates the effects of natural selection?
What observation about the change of the peppered moth population after the Clean Air Act was implemented best demonstrates the effects of natural selection?
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In the context of stabilizing selection, if heterozygotes are better adapted, what happens to the prevalence of different alleles in a population?
In the context of stabilizing selection, if heterozygotes are better adapted, what happens to the prevalence of different alleles in a population?
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Study Notes
Mendel's Experiments
- Gregor Mendel (1822-1884) conducted breeding experiments on pea plants.
- He studied 7 different discreet combinations of traits.
- Mendel used 28,000 plants and 400,000 seeds.
- He found that traits were not blended, but instead inherited as discrete units (genes).
Inheritance Principles
- There's no blending of traits during inheritance.
- Physical units of inheritance (genes) maintain their identity when passed from parents to offspring.
- Dominance, recessiveness, and codominance are important concepts in understanding trait inheritance.
- Locus: physical location of a gene.
- Allele: different forms of a gene at a specific locus.
- Homozygote: A pair of the same allele.
- Heterozygote: A pair of different alleles.
- Genotype: Specific combination of alleles.
- Phenotype: Morphological (appearance) result of the genotype.
- Monogenic traits are determined by one gene.
- Polygenic traits are influenced by multiple genes.
- Polymorphism—the existence of two or more alleles at a locus, leading to two or more genotypes at that locus.
Chromosomes and DNA
- Chromosomes are containers of DNA.
- Humans have 23 pairs of chromosomes (46 total) in each cell.
- Each chromosome has one strand from each parent.
DNA Structure and Function
- DNA produces at least 100,000 proteins. -2-3% of DNA is directly involved in protein production; the rest is involved in regulating gene expression.
- Noncoding RNA plays an important role in regulating genes.
- Epigenetics: Changes in DNA structure without changing the DNA sequence itself; this may be significant in response to environmental stressors.
- Exons (coding) vs introns (non-coding), with some introns being regulatory genes playing a significant function in controlling complex traits.
- Homeoboxes—Hox genes—are involved in developmental processes.
Evolution
- Evolution refers to changes in allele frequencies in a population over multiple generations.
- Mutation is the ultimate source of new genetic variation.
- Spontaneous mutations and mutagens can lead to new genetic variations.
- Natural selection is a force of evolution.
- Gene flow: the exchange of individuals between populations can increase genetic variation within populations, but decrease the genetic differences between them.
Natural Selection and Adaptation
- Individuals with traits better suited for their environment are more likely to survive and reproduce.
- Environmental pressures (e.g., changes in rainfall, food availability) influence the selective pressures that drive adaptation.
- Polygenic traits (continous)—like body size—may show a pattern of adaptations over many generations, with larger or smaller forms being more useful in different environmental scenarios.
Monogenic vs. Polygenic Traits
- Monogenic: Traits controlled by one gene.
- Polygenic: Traits controlled by multiple genes (e.g., body size). -Stabilizing selection: favours average traits; -Directional selection: favours extreme traits; such as in response to environmental changes.
Sickle Cell Anemia
- Sickle cell anemia is a genetic disease.
- It has a high frequency in some populations due to a balanced polymorphism— an allele that is maintained in a population because it confers a survival advantage in certain environments, even if it might be harmful in other environments.
Microevolution and Population Genetics
- Microevolution describes changes in allele frequencies within populations over relatively short timeframes.
- Population genetics studies the genetic makeup of populations, including the concepts of allele frequency, gene pool, and Hardy-Weinberg equilibrium.
- Macroevolution describes changes over long timeframes; changes that are too large or gradual to be readily observed.
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Description
Explore the revolutionary work of Gregor Mendel and his experiments with pea plants. This quiz covers Mendel's findings on genetic inheritance, including key concepts such as genes, alleles, and the principles of dominance and recessiveness. Test your knowledge of how traits are passed from parents to offspring and the terminology associated with genetics.
