Genetics Quiz: Inheritance and Traits
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Questions and Answers

What is the term for different forms of the same gene?

  • Phenotype
  • Alleles (correct)
  • Locus
  • Genotype

What did Mendel's experiments with pea plants demonstrate about inheritance?

  • There are physical units of inheritance that maintain their identity. (correct)
  • Inheritance is determined by the environment only.
  • Traits are only passed down through the maternal line.
  • Traits blend together in offspring.

Which of the following describes a polygenic trait?

  • A trait determined by a single gene.
  • A trait that has a continuous range of variation. (correct)
  • A trait that exhibits only two possible phenotypes.
  • A trait determined by one gene and that is discrete.

What is the term for a specific combination of alleles?

<p>Genotype (C)</p> Signup and view all the answers

Which of the following best describes a locus?

<p>The physical location of a gene (C)</p> Signup and view all the answers

How many pairs of chromosomes does a typical human cell contain?

<p>23 pairs (D)</p> Signup and view all the answers

What is the process of cell division specific to germ cells called?

<p>Meiosis (D)</p> Signup and view all the answers

What is the primary function of genes mentioned in this content?

<p>To code for at least 100,000 proteins (C)</p> Signup and view all the answers

What is the primary function of regulatory genes?

<p>To control the expression of other genes (D)</p> Signup and view all the answers

Which of these is not a component of the DNA backbone?

<p>Adenine (B)</p> Signup and view all the answers

What is the ultimate source of all new genetic variation?

<p>Mutation (A)</p> Signup and view all the answers

What does gel electrophoresis primarily detect?

<p>Differences in the amino acid sequences of proteins. (C)</p> Signup and view all the answers

What did scientists initially believe about most mutations in a species?

<p>They were predominantly deleterious (A)</p> Signup and view all the answers

What does the high polymorphism in protein-producing loci suggest?

<p>Different forms of the protein have similar efficiency, and neutral mutations might be present (A)</p> Signup and view all the answers

Which of the following is a potential consequence of neutral mutations?

<p>Increased significance of random genetic drift (C)</p> Signup and view all the answers

What farming techniques are associated with cassava and yam cultivation?

<p>Iron tools, slash and burn, and abandoned fields (D)</p> Signup and view all the answers

A person with the AA genotype for hemoglobin will express:

<p>Normal hemoglobin production (C)</p> Signup and view all the answers

What role does Plasmodium falciparum play in the etiology of sickle cell anemia?

<p>It is a parasite that uses both humans and mosquitoes to complete its life cycle, which triggers red blood cell damage. (A)</p> Signup and view all the answers

In which part of the human does Plasmodium falciparum reproduce?

<p>First in the liver, then in red blood cells (C)</p> Signup and view all the answers

What is the primary geographical region associated with sickle cell anemia?

<p>West Africa (C)</p> Signup and view all the answers

What is the effect of low oxygen pressure on Hemoglobin in individuals with sickle cell anemia?

<p>Decreased ability to load oxygen and decreased lifespan. (B)</p> Signup and view all the answers

Which genetic concept best describes the relationship between the A and s alleles at a locus?

<p>Codominance (A)</p> Signup and view all the answers

What is characteristic of a disruptive selection pattern?

<p>Both homozygotes are fitter than the heterozygotes. (A)</p> Signup and view all the answers

What is the primary effect of gene flow on the genetic makeup of breeding populations?

<p>It increases genetic diversity within a breeding population and decreases genetic difference between breeding populations. (A)</p> Signup and view all the answers

Which condition is necessary for natural selection to occur?

<p>A stress resulting in differential mortality between groups of individuals. (C)</p> Signup and view all the answers

In the context of the medium ground finches studied by the Grants, what was the key factor leading to increased beak size in the 1977 drought?

<p>The finches with larger beaks that were better able to eat larger seeds had higher survival rates during the drought. (D)</p> Signup and view all the answers

What does it mean when a trait is described as polygenic?

<p>The trait is controlled by multiple genes, resulting in a continuous range of phenotypes. (B)</p> Signup and view all the answers

How did the frequency of the black peppered moth change in England during the Industrial Revolution?

<p>The black moths increased to more than 98% due to their increased survival rate. (D)</p> Signup and view all the answers

What is a key characteristic of stabilizing selection?

<p>It favors individuals with average phenotypic traits, increasing the prevalence of the current average. (B)</p> Signup and view all the answers

In the context of sickle cell anemia, what does balanced polymorphism mean?

<p>The heterozygote genotype is better adapted than either homozygote under specific conditions. (D)</p> Signup and view all the answers

How did the shift from hunter-gatherer lifestyles to sedentary horticulture contribute to the spread of malaria and the S allele?

<p>Sedentary horticulture practices led to increases in land use and water storage that created breeding grounds for mosquitos and increased malaria prevalence, indirectly causing an increase of the S allele. (A)</p> Signup and view all the answers

What effect did the shift in rainfall patterns have on the average body size of the medium ground finch after the drought of 1977, according to the study?

<p>A gradual decrease in average body size until 1983, as smaller birds had better access to seeds. (B)</p> Signup and view all the answers

How does directional selection affect the distribution of a polygenic trait?

<p>It shifts the population toward one extreme of the phenotypic range over time. (A)</p> Signup and view all the answers

What is a defining characteristic of a monogenic trait?

<p>It is controlled by one gene, resulting in two or more distinct phenotypes. (C)</p> Signup and view all the answers

What was the impact of the Clean Air Act on the peppered moth population?

<p>It reversed the pattern, causing the light-colored moths to become more prevalent again. (D)</p> Signup and view all the answers

What is the defining feature of a virgin population in the context of a virus?

<p>The population has never before been exposed to the virus. (B)</p> Signup and view all the answers

What is the relationship between seed size and plant location described in the text?

<p>Plants producing large seeds tend to live in low-lying areas where there is greater access to ground water, and plants producing small seeds tend to live in high-lying areas. (A)</p> Signup and view all the answers

What can be inferred about the virulence of a virus when rabbits possessing neutral mutations are more likely to survive?

<p>The virus has become less virulent. (B)</p> Signup and view all the answers

Flashcards

Blending theory of inheritance

The idea that offspring inherit traits from both parents, without traits blending together.

Genes

Physical units of inheritance that determine traits, passed from parents to offspring.

Allele

A version of a gene, responsible for different variations of a trait.

Homozygote

An individual with two identical alleles for a specific trait.

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Heterozygote

An individual with two different alleles for a specific trait.

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Genotype

The genetic makeup of an organism, representing the specific alleles it possesses.

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Phenotype

The observable characteristics of an organism resulting from the interaction of its genotype with the environment.

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Monogenic Trait

A trait influenced by a single gene. These traits often show distinct categories, like eye color.

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Codon

A sequence of three DNA bases that codes for a specific amino acid.

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Mutation

The process of changing the sequence of DNA bases, ultimately leading to new genetic variations.

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Neutral Mutation

A mutation that neither benefits nor harms an organism's survival.

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Evolution

The theory that changes in the frequency of alleles within a breeding population over generations drive evolution.

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Ultimate Source of Genetic Variation

The source of all new genetic variations, often occurring randomly during DNA replication.

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Deleterious Mutation

A change in DNA sequence that reduces an organism's chance of survival.

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Meiosis

The process of cell division that produces gametes (sperm and egg cells) and ensures genetic diversity.

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Forces of Evolution

Factors that influence the frequency of alleles in a population, driving evolution.

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Malaria

An infectious disease caused by the parasite Plasmodium falciparium, which is transmitted through the bite of an infected Anopheles mosquito.

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Sickle Cell Anemia (SCA)

A form of anemia caused by a genetic mutation in the hemoglobin gene, leading to abnormal red blood cells that can't effectively carry oxygen.

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Codominance

A genetic inheritance pattern where both alleles of a gene are expressed in the phenotype.

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Disruptive Selection

Natural selection where individuals with extreme traits have a higher survival and reproduction rate than those with intermediate traits.

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Sickle Cell Trait

A condition where an individual carries one normal allele (A) and one sickle cell allele (S) for the hemoglobin gene.

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Point Mutation

A genetic mutation that changes a single base pair in the DNA sequence, potentially affecting protein function.

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Adaptation

The process of natural selection where organisms with traits better suited to their environment have higher chances of survival and reproduction.

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Gene flow

The movement of individuals from one breeding population to another, where mate exchange occurs, resulting in changes in genetic variation.

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Natural selection

A process where individuals with traits better suited to their environment are more likely to survive and reproduce, passing these favorable traits to their offspring.

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Stabilizing selection

A type of natural selection where the average trait becomes more common in a population. Individuals with traits closer to the average have higher survival rates.

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Directional selection

Natural selection where an extreme trait becomes more common in a population, often due to environmental change. This shifts the average trait in a particular direction.

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Monogenic trait (discrete phenotype)

A situation where a single gene influences a specific trait, resulting in distinct categories for the trait.

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Balanced polymorphism

A type of natural selection where an individual with two different versions of a gene (heterozygous) has a higher survival rate than individuals with two copies of the same version (homozygous).

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Polygenic trait (continuous phenotype)

A trait that is influenced by multiple genes, resulting in a continuous range of variations for the trait.

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Virgin population

A population that has not been exposed to a particular virus.

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Resistant population

A population that has evolved in response to a specific disease or environmental pressure, resulting in increased resistance to the disease.

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Viral attenuation

The natural process where less virulent strains of a virus are more likely to survive in a population, leading to a decrease in the severity of the disease.

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Study Notes

Mendelian Genetics

  • Gregor Mendel (1822-1884) experimented with pea plants, observing discrete traits that didn't blend.
  • Mendel's experiments used 28,000 plants and 400,000 seeds.
  • Inheritance involves physical units of inheritance (genes) that are passed from parents to offspring without blending.

Inheritance Patterns

  • Dominance/Recessiveness (Codominance): Different forms of a gene (alleles) exist.
  • Locus: Physical location of genes on a chromosome.
  • Alleles: Different versions of the same gene.
  • Homozygous: Two identical alleles.
  • Heterozygous: Two different alleles.
  • Genotype: Specific combination of alleles.
  • Phenotype: Observable traits resulting from the genotype.
  • Monogenic traits: Determined by one gene (discrete).
  • Polygenic traits: Determined by multiple genes (continuous).
  • Polymorphism: Existence of two or more alleles at a locus leading to multiple genotypes.

Chromosomes and DNA

  • Chromosomes are containers of DNA.
  • Humans have 23 pairs of chromosomes (46 total).
  • Each chromosome contains one DNA molecule.

DNA Structure

  • DNA is a double helix with a sugar-phosphate backbone and base pairs (adenine-thymine, guanine-cytosine).

Genes

  • Humans have approximately 21,000 genes.
  • Genes produce proteins, essential for life processes.
  • Some DNA, initially called "junk DNA," now understood to regulate genes. Non-coding RNA is found in this non-protein-coding region.
  • Epigenetics describes changes in DNA structure without altering the underlying base sequence. Changes such as methylation and response to environmental stressors can impact gene expression.
  • Exons (coding regions) and introns (non-coding regions) are parts of a gene.
  • Multiple operating genes exist in organisms; they can be combined in numerous ways.

Meiosis and Mitosis

  • Meiosis is a type of cell division in germ cells (sperm and egg).
  • Mitosis occurs in all other cells.
  • Meiosis creates gametes (egg and sperm) that carry half the number of chromosomes as the parent cell.

Evolution and Variation

  • Ultimate source of new genetic variation is alteration in DNA bases.
  • Mutations are random and rare.
  • Natural selection favors the survival and reproduction of individuals with beneficial traits.
  • Gene flow involves the movement of individuals and alleles between populations.
  • Drift, (random change in allele frequencies) is important part of evolutionary force when populations are small.

Directional Selection

  • Individuals best adapted to environmental pressures are more likely to survive and reproduce, passing on their genes.
  • Traits (e.g., beak size) can vary considerably within a species.

Monogenic and polygenic traits

  • Monogenic: controlled by a single gene.
  • Polygenic: controlled by multiple genes.
  • Stablizing selection: the average values for a trait result in better adaptation.

Balanced Polymorphism

  • The frequency of both alleles (versions of a gene) remains relatively constant over time due to advantageous heterozygotes.
  • Examples include the sickle cell allele in malaria-prone regions.

Population Genes and Evolution

  • Microevolution: observable changes in allele frequencies within a population over time.
  • Macroevolution: large-scale changes in species over vast periods, not typically observable.
  • Hardy-Weinberg principle: describes allele and genotype frequencies within a population if no outside forces affect them.
  • Breeding populations are the primary units of evolution.

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Description

Test your knowledge on key concepts in genetics, including gene variations, inheritance patterns, and chromosomal structures. This quiz covers Mendelian genetics, polygenic traits, and contemporary understandings of mutations and genetic variation. Perfect for students studying genetics or those interested in the science of heredity.

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