Heredity and Evolution Quiz
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Questions and Answers

What is the term for differences in characters among individuals of the same species?

  • Inheritance
  • Reproduction
  • Variation (correct)
  • Heredity

    • All variations produced during reproduction have equal chances of survival.

    False (B)

    What is the branch of biology that studies heredity and variations?

    Genetics

    During sexual reproduction, variations can result from __________ during meiosis.

    <p>crossing over</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Heredity = The process by which characters pass from one generation to the next Variation = Differences in characters among individuals of the same species Genetics = The branch of biology that deals with heredity and variations Asexual reproduction = Reproduction that does not involve the fusion of gametes</p> Signup and view all the answers

    Which of the following does NOT contribute to variations in living organisms?

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

    Human beings can inherit characteristics directly as exact copies from their parents.

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

    Give an example of a variation found among human beings.

    <p>Free earlobe and attached earlobe</p> Signup and view all the answers

    What is the primary focus of the branch of biology called Genetics?

    <p>Study of heredity and variation (B)</p> Signup and view all the answers

    Gregory Mendel used corn plants for his experiments on inheritance.

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

    What are the terms used to describe individuals with two similar factors for a trait?

    <p>Homozygous</p> Signup and view all the answers

    Mendel's first generation of offspring is referred to as the ______.

    <p>F1</p> Signup and view all the answers

    Match the following terms related to Mendel's experiments with their definitions:

    <p>Trait = Specific characteristic of an organism Phenotype = External appearance of an individual Genotype = Genetic makeup of an individual Selfing = Crossing of two organisms of the same kind</p> Signup and view all the answers

    How many contrasting traits did Mendel specifically study in pea plants?

    <p>7 (C)</p> Signup and view all the answers

    The principle of paired factors states that each characteristic is controlled by a single factor.

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

    What does it mean for an individual to be heterozygous?

    <p>An individual has two dissimilar factors for a trait.</p> Signup and view all the answers

    What term is used to describe the trait that expresses itself in the presence of two dissimilar factors?

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

    The recessive gene is represented by a capital letter.

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

    What does the Principle of Segregation state?

    <p>Factors are separated during gamete formation.</p> Signup and view all the answers

    In a Monohybrid cross, Mendel observed a phenotypic ratio of ____ in the F2 generation.

    <p>3:1</p> Signup and view all the answers

    What is formed when a male gamete fuses with a female gamete during fertilization?

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

    Which type of cross involves two traits?

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

    Humans possess 23 pairs of chromosomes, with all of them involved in sex determination.

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

    In a Dihybrid cross, all F1 offspring display both dominant traits.

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

    How many genes are estimated to be present in human beings?

    <p>30000 – 40000</p> Signup and view all the answers

    The chromosomes concerned with sex determination are called ______.

    <p>Allosomes</p> Signup and view all the answers

    What did Mendel mean by 'factors' in his experiments?

    <p>Hereditary units that determine characteristics.</p> Signup and view all the answers

    Which pair of chromosomes represents a male in human beings?

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

    A recessive factor can control the synthesis of a fully functional structural protein or enzyme.

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

    If a gene for an enzyme is altered to be less efficient, the amount of hormone produced will be ______.

    <p>less</p> Signup and view all the answers

    Flashcards

    Heredity

    The passing of traits from parents to offspring.

    Genetics

    The study of heredity and variations in organisms.

    Variations

    Differences in characteristics among individuals of the same species.

    Useful Variations

    Variations that are beneficial to an organism's survival.

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    Harmful Variations

    Variations that are harmful to an organism's survival.

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    Reproduction

    The process of creating new offspring.

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    Errors in DNA Copying

    Changes in DNA that create variations.

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    Random Fertilization

    The combination of genes from two parents during sexual reproduction.

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    Trait

    The specific characteristic of an organism, like tallness or dwarfism.

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    Genotype

    The combination of genes that an individual carries for a particular trait.

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    Phenotype

    The physical appearance of an organism based on its genotype.

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    F1 generation

    The offspring resulting from the first cross of two parent organisms.

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    F2 generation

    The offspring resulting from the self-pollination or cross-pollination of the F1 generation.

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    Principle of paired factors

    The pairing of factors (genes) that determines a specific trait.

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    Homozygous

    An individual with two identical factors for a specific trait.

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    Heterozygous

    An individual with two different factors for a specific trait.

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    Principle of Dominance

    When a combination of two different factors for a trait exists in an organism, only one factor, called the dominant factor, is expressed. The other unexpressed factor is called the recessive factor.

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    Principle of Segregation (Law of Purity of Gametes)

    During the formation of sex cells (gametes), the two factors responsible for a trait separate, with each gamete receiving only one factor for that trait. This means gametes are pure for their character.

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    Monohybrid Cross

    A cross between two individuals differing in one characteristic, such as height, seed color, or flower color.

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    Principle of Independent Assortment

    When more than one trait is considered in a cross, the factors for each trait assort independently of each other during gamete formation.

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    Dihybrid Cross

    A cross between two individuals differing in two characteristics, such as seed shape and seed color.

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    Factors (Genes)

    Units that carry genetic information from parents to offspring. They are responsible for controlling specific traits.

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    Gene

    A segment of DNA on a chromosome that holds the instructions for making a specific protein.

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    Alleles

    A pair of genes (one from each parent) that determine a specific trait.

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    Dominant Gene

    The gene that masks the effect of its recessive counterpart.

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    Recessive Gene

    The gene whose effect is hidden by its dominant counterpart.

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    Fertilization

    The union of a male gamete (sperm) and a female gamete (egg) to form a single cell with a complete set of chromosomes.

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    Zygote

    The first cell formed after fertilization, containing a full set of chromosomes from both parents.

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    Sex Chromosomes

    Chromosomes that determine an individual's sex (male or female).

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    Study Notes

    Heredity and Evolution

    • Living organisms produce offspring similar to their parents, but not exact copies.
    • Variations arise from changes in DNA or sexual reproduction.
    • Errors in DNA copying and random fertilization contribute to variation.
    • Sexual reproduction results in more variations compared to asexual reproduction.
    • Variations are less noticeable in asexually reproduced plants, such as sugarcane.
    • Humans have more distinct variations due to sexual reproduction.
    • Inheritance is the process where characteristics are passed from one generation to the next.
    • Heredity is the inheritance of characteristics from parents to offspring.
    • Variations are differences among individuals within a species.
    • Genetics is the branch of biology studying heredity and variations.

    Accumulation of Variations During Reproduction

    • Inheritance provides a common basic body design and slight variations.
    • Offspring inherit parental characteristics but are not exact copies.
    • Variation exists among individuals of a species in some traits.
    • Variations, particularly beneficial ones, are selected by nature.

    Earlobes as an Example of Variation

    • Earlobes are either free-hanging (free earlobes) or attached to the head (attached earlobes).
    • These variations exist in the human population.

    Heredity

    • Gregor Mendel was the first to systematically study inheritance.
    • He experimented with pea plants, focusing on seven contrasting traits.

    Mendel's Seven Traits in Pea Plants

    • Pea shape (round or wrinkled)
    • Pea color (green or yellow)
    • Pod shape (constricted or inflated)
    • Pod color (green or yellow)
    • Flower color (purple or white)
    • Plant size (tall or dwarf)
    • Position of flowers (axial or terminal)

    Genetical Terms

    • Trait: A specific characteristic of an organism (e.g., tallness, color).
    • Phenotype: The observable traits of an organism.
    • Genotype: The genetic makeup of an organism.
    • F1 generation: First generation of offspring from a cross.
    • F2 generation: Second generation of offspring from a cross.
    • Selfing: Crossing of two organisms of the same kind.
    • Homozygous: Having two similar factors for a trait (e.g., TT for tall).
    • Heterozygous: Having two dissimilar factors for a trait (e.g., Tt for tall).

    Principles of Inheritance

    • Principle of paired factors: Each trait is controlled by a pair of factors (now called genes).
    • Principle of dominance: In heterozygous individuals, one factor (dominant) expresses itself while the other (recessive) does not.
    • Principle of segregation: Each gamete receives only one factor of each pair during gamete formation.
    • Principle of independent assortment: Factors for different traits segregate independently during gamete formation.

    Dihybrid Cross

    • A cross involving two traits.
    • Mendel's dihybrid crosses showed that traits can be inherited independently.

    How Traits are Expressed

    • Inheritance of traits occurs through hereditary units (genes).
    • Genes are a pair of factors that work in pairs.
    • Each parent has a pair of genes for each trait.

    Mechanism of Heredity

    • Genes are segments of DNA located on chromosomes.
    • DNA carries the information for making proteins.
    • Dominant genes code for fully functional proteins or enzymes.
    • Recessive genes code for partially functional or defective proteins or enzymes.

    Sex Determination

    • Sex in humans is determined genetically by chromosomes.
    • Human cells have 46 chromosomes (23 pairs).
    • 22 pairs are autosomes, while one pair (23rd) are sex chromosomes.
    • Females have XX chromosomes.
    • Males have XY chromosomes.
    • The sex of the offspring is determined by the male gamete (sperm).

    Sex Determination in Other Animals

    • In some animals, the sex is determined by environmental factors, like temperature during incubation.

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    Heredity and Evolution (PDF)

    Description

    Test your knowledge on the concepts of heredity and evolution, including the processes of DNA variations and sexual reproduction. This quiz covers fundamental principles of genetics and how traits are passed from parents to offspring. Understand the significance of variations in living organisms and their impact on evolution.

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