Genetics Quiz Chapter 2
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Questions and Answers

What is the basic unit of inheritance passed from parents to offspring?

  • Chromosome
  • Nucleotide
  • DNA
  • Gene (correct)

    • Which of the following is NOT a base found in DNA?

  • Adenine
  • Cytosine
  • Uracil (correct)
  • Guanine

    • What is the shape of a DNA molecule?

  • Linear
  • Circular
  • Single helix
  • Double helix (correct)

    • What are the two components that make up the backbone of a DNA molecule?

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

    Which of the following scientists is considered the "Father of Genetics"?

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

    What is the significance of Chargaff's rule in DNA structure?

    <p>It states that the amount of adenine always equals thymine, and guanine equals cytosine. (A)</p> Signup and view all the answers

    What is the approximate number of protein-coding genes in the human genome?

    <p>20,000 (B)</p> Signup and view all the answers

    Which of the following is NOT a characteristic typically observed in humans and used for inheritance studies?

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

    What is the genotype of a rabbit that is heterozygous for fur color and homozygous dominant for ear length?

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

    When a heterozygous pea plant for both traits is crossed with another heterozygous pea plant, what is the probability of obtaining round seeds?

    <p>3/4 (C)</p> Signup and view all the answers

    In the cross between a homozygous recessive rabbit for fur color and a heterozygous rabbit for ear length, what trait cannot be determined?

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

    Which alleles represent the dominant traits in pea plants according to Mendelian inheritance?

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

    What field can genetics be applied to for improving food security?

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

    What is the significance of the Law of Dominance in Mendelian genetics?

    <p>A dominant allele is always expressed over a recessive allele. (A)</p> Signup and view all the answers

    According to the Law of Segregation, what happens to alleles during gamete formation?

    <p>One allele from each pair is passed to each gamete. (B)</p> Signup and view all the answers

    What does the Law of Independent Assortment imply?

    <p>Alleles of different traits segregate independently during gamete formation. (C)</p> Signup and view all the answers

    What is the genotype of a heterozygous tall pea plant?

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

    In a monohybrid cross, what does a Punnett square represent?

    <p>Possible gene combinations of the offspring. (A)</p> Signup and view all the answers

    If a homozygous black-haired father (AA) and a heterozygous black-haired mother (Aa) have children, which phenotype will be the least likely among the offspring?

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

    Which of the following correctly identifies the genotypic ratio from a monohybrid cross involving two heterozygous parents?

    <p>1 YY : 2 Yy : 1 yy (A)</p> Signup and view all the answers

    In a case where a mother has genotype Bb for eye color and a father has genotype bb, what are the possible genotypes for their child?

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

    What phenotype ratio can be expected from a monohybrid cross between two heterozygous yellow (Yy) flower plants?

    <p>3 yellow : 1 green (C)</p> Signup and view all the answers

    When performing a dihybrid cross, what is the first step?

    <p>Identify the genotypes of the parents (C)</p> Signup and view all the answers

    How are dominant and recessive alleles represented in a Punnett square?

    <p>Dominant alleles with capital letters and recessive with lowercase letters. (D)</p> Signup and view all the answers

    What is the phenotypic ratio expected when crossing a heterozygous tall plant with a short plant?

    <p>1:1 (A)</p> Signup and view all the answers

    Which of the following traits is considered dominant in the described mouse traits?

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

    What does a homozygous genotype imply about the alleles present?

    <p>The organism has two identical alleles for a trait. (B)</p> Signup and view all the answers

    Which of the following describes a dihybrid cross?

    <p>A cross that examines two traits simultaneously. (D)</p> Signup and view all the answers

    In the context of fur color in rabbits, which genotype will produce white-furred offspring?

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

    What would be the result if a homozygous running mouse is crossed with a heterozygous running mouse?

    <p>100% running mice (C)</p> Signup and view all the answers

    If a child has a genotype of dd for hair color, what must one parent’s genotype be?

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

    Which step follows after determining the possible gamete combinations in a dihybrid cross?

    <p>Pair the gametes inside the boxes (D)</p> Signup and view all the answers

    Flashcards

    Heterozygous

    An organism with two different alleles for a trait (e.g., Rr).

    Homozygous

    An organism with two identical alleles for a trait (e.g., RR or rr).

    Mendelian inheritance

    The patterns of inheritance first described by Gregor Mendel, explaining how traits are passed from parents to offspring.

    Probability of offspring traits

    The likelihood that specific traits will be expressed in the offspring based on parental genotypes.

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    Dominant and recessive alleles

    Dominant alleles mask the expression of recessive alleles in offspring. Dominant traits are expressed (R, Y), recessive traits are not (r, y).

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    Law of Dominance

    States that some alleles are dominant and expressed over others.

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    Law of Segregation

    Each individual has two alleles for each trait, and they separate during gamete formation.

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    Law of Independent Assortment

    Alleles segregate independently during gamete formation, not influencing each other.

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    Monohybrid Cross

    A genetic cross that considers one trait and its alleles.

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    Punnett Square

    A grid used to predict offspring genotypes from parental alleles.

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    Genotypic Ratio (GR)

    The ratio of different genotypes resulting from a cross.

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    Phenotypic Ratio (PR)

    The ratio of different traits/appearances in the offspring.

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    Homozygous Allele

    An allele pair that consists of two identical alleles.

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    Heterozygous Allele

    An allele pair that consists of one dominant and one recessive allele.

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    Dihybrid Experiment

    An experiment studying the inheritance of two different traits.

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    Dominant allele

    An allele that expresses its trait even in the presence of a recessive allele.

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    Recessive allele

    An allele that only expresses its trait when two copies are present.

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    Genotypic ratio

    The ratio of different genotypes produced in a genetic cross.

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    Phenotypic ratio

    The ratio of different phenotypes produced from a genetic cross.

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    Dihybrid cross

    A genetic cross that examines two traits controlled by two genes.

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    Gamete combinations

    The possible combinations of alleles from parents during meiosis.

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    Trait inheritance

    The process by which traits are passed from parents to offspring.

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    Genetics

    The scientific study of genes and heredity, including variations in DNA that affect traits.

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    Gene

    Units of heredity made of DNA that determine specific traits passed from parents to offspring.

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    DNA

    Molecule containing the genetic information for the development and function of living things.

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    Base pairs

    Pairs of chemical bases in DNA: adenine (A) with thymine (T) and guanine (G) with cytosine (C).

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    Nucleotide

    The building block of DNA, consisting of a base, sugar, and phosphate.

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    Double helix

    The structure formed by two strands of nucleotides twisted around each other in DNA.

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    Mendelian Laws of Inheritance

    Principles formulated by Gregor Mendel that describe how traits are inherited through generations.

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    Erwin Chargaff

    A biochemist known for Chargaff's rules regarding the base pairing ratios in DNA.

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    Study Notes

    Introduction to Genetics

    • Genetics is the scientific study of genes and heredity, exploring how DNA variations influence traits passed down.
    • It's a branch of biology, focusing on the DNA of organisms, its expression as genes, and inheritance patterns.

    Learning Targets

    • Students will understand Mendelian Laws of Inheritance.
    • The process of predicting offspring genotypes and phenotypes will be demonstrated.

    Preliminary Activity

    • Students should check with their seatmates on traits, for example, tongue rolling ability, earlobe attachment, hair line type, and dimples presence.

    Traits

    • Ability to roll tongue
    • Attached or detached earlobes
    • Straight hair line or widow’s peak
    • Dimples or no dimples

    What is Genetics?

    • Genetics examines how variations in DNA sequence lead to specific traits.
    • These passed-down traits are often the result of DNA sequence variations.

    Vocabulary

    • The slides show examples of relevant vocabulary words related to genetics.

    Genetics

    • Genetics is the study of genes and how they play a role in heredity.

    Genes

    • Genes are units of heredity, composed of DNA molecules that pass traits from parents to offspring.
    • The human genome comprises approximately 20,000 protein-coding genes.

    Gene

    • A gene is the fundamental unit of inheritance.
    • It is passed from parents to offspring, carrying instructions for physical and biological traits.
    • Genes, part of the genome, encode the information necessary for protein synthesis.
    • Genes are made up of DNA.

    DNA

    • DNA is primarily located in the cell nucleus.
    • DNA serves as a code composed of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T).
    • Complementary base pairing links A to T, and C to G. Each base is attached to a sugar molecule.
    • DNA's structure is a double helix made up of paired nucleotides.

    DNA

    • DNA's structure consists of an alternating sugar-phosphate backbone.
    • Erwin Chargaff's findings in biochemistry show that adenine percentage equals thymine, and guanine equals cytosine.

    DNA (continued)

    • A nucleotide is a combined structure of a base, sugar, and phosphate.
    • Nucleotides form paired strands creating a double helix.

    Important Terms to Remember

    • Allele: An alternative form of a gene.
    • Dominant trait: A trait always expressed if present.
    • F₁ generation: The first generation of offspring.
    • F₂ generation: The second generation of offspring arising from interbreeding F₁ individuals.
    • Gamete: A reproductive cell.
    • Genotype: The genetic makeup of an individual.
    • Heterozygous: Having different alleles for a given trait.
    • Homozygous: Having identical alleles for a given trait.
    • Phenotype: The observable characteristics of an individual.
    • Punnett square: A diagram used to predict the outcome of a genetic cross.
    • Recessive trait: A trait masked by a dominant trait.

    Brief History of Genetics

    • Gregor Mendel's experiments with peas over eight years (1856-1863) laid the foundation for genetics.
    • He documented 10,000 pea plants, tracking generational traits.

    Gregor Mendel

    • Born in 1822 in Czechoslovakia, Mendel later became a monk.
    • His studies encompassed biology and statistics.
    • Mendel studied at the University of Vienna.

    Mendel Continued

    • Mendel's experiments involved approximately 28,000 pea plants.

    Why Peas?

    • Peas were chosen for Mendel's experiments due to their ease of growth.
    • Observable traits made identification simple.
    • A large sample size permitted comprehensive analysis.

    Characteristics of Garden Peas Studied by Mendel

    • Traits like seed color, seed shape, seed coat color, flower position, stem length, pod color, and pod shape were studied.

    Gregor Johann Mendel

    • Mendel's work formulated the laws of inheritance, including the Law of Dominance, Segregation, and Independent Assortment.

    Law of Dominance

    • A trait is considered dominant if its expression overrides another (recessive) allele.
    • A dominant trait always manifests even if a recessive one is present.
    • An organism expressing a dominant trait is always visible.
    • Conversely, a recessive allele is only expressed if the dominant one isn't present.

    Law of Segregation

    • Each individual has a pair of alleles for each trait that separates during gamete formation.
    • Each gamete receives just one allele from each trait.
    • Allele allocation from parents to offspring is random.
    • Separation of alleles occurs during gamete formation.

    Law of Independent Assortment

    • Alleles for different traits segregate independently during gamete formation.
    • The inheritance of a trait isn't influenced by others.

    Law of Independent Assortment

    • Traits, such as freckles and curly hair, are inherited independently, not connected.

    Law of Dominance

    • Dominance signifies an allele's capacity to express itself in the presence of another allele for the same trait.
    • Some alleles are dominant, prevailing over others that are recessive.

    Law of Dominance (continued)

    • An organism with a dominant allele for a specific trait always expresses that trait.

    Law of Dominance (continued)

    • Recessive traits express themselves only in the absence of a dominant allele.

    Mendelian Laws Through Punnett Square

    • A Punnett Square illustrates possible gene combinations in offspring.
    • Dominant alleles are denoted by capital letters, while recessive ones are lowercase.

    Monohybrid Cross

    • A monohybrid cross examines the inheritance of a single trait.
    • Each square represents a 25% chance for a specific genotype and phenotype of an offspring.

    Example

    • The allele for yellow flowers is dominant over the allele for green flowers.

    Example (continued)

    • Both parents in the example have heterozygous alleles for yellow flowers.

    Example (continued)

    • Ratios of genotypes and phenotypes in offspring will be identified, such as 1:2:1 for genotypes (YY, Yy, yy) and 3:1 for phenotypes (yellow, green).

    Sample Problem

    • A problem, likely involving pea plants or mice, is presented for determining genotypic and phenotypic ratios via Punnett Squares.

    Dihybrid Cross

    • A dihybrid cross investigates the inheritance of two traits.
    • It analyzes how parents with contrasting traits influence their offspring's genotypes and phenotypes.
    • An example would be observing traits like black hair vs blonde hair and blue eyes vs brown eyes.

    Steps in Doing a Dihybrid Cross

    • Identify the genotypes of the parents in a dihybrid cross.
    • Determine possible gamete combinations from each parent for each trait.
    • Create a Punnett Square to visualize possible combinations for the trait in the offspring.
    • Determine genotypes and phenotypes of potential offspring.
    • Calculate genotypic and phenotypic ratios for offspring.

    Sample Problem (1)

    • Scenarios on parentage disputes, examining if the child in question can be truly attributed to a declared father.

    Sample Problem (2)

    • Another case, focused on a child with a specific trait, determines if the child is biologically related to a declared parent.

    Sample Problem (3)

    • A problem involving mice and their color/running traits will determine the genotypic and phenotypic ratios based on their traits.

    Sample Problem (4)

    • A problem involving rabbits discusses their fur color and ear length characteristics, analyzing the likelihood of offspring inheriting these attributes.

    Sample Problem (5)

    • A pea plant example highlights the inheritance of seed traits, identifying offspring probabilities given particular parental traits.

    Let's Apply It!

    • This section demonstrates the application of Mendelian Laws across various fields relevant to genetics.

    Instructions

    • Guidance for tasks likely involving partner work, research, and infographic creation.

    Mendelian Laws on Real-life / Social Context

    • Different areas of application for Mendelian laws, such as healthcare, agricultural practices, and conservation biology.

    Resource Page

    • Examples include images or illustrations of a variety of situations and concepts related to the subject matter.

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    Lesson 2 Genetics PDF

    Description

    Test your understanding of fundamental genetics concepts in this quiz. Answer questions about inheritance, DNA structure, and key figures in genetics. This quiz will challenge your knowledge and deepen your understanding of genetic principles.

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