Biology Chapter: Variation and Inheritance
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Questions and Answers

What are homologous chromosomes?

  • Chromosomes from different species
  • Matching pairs of chromosomes from both parents (correct)
  • Chromosomes that have mutated due to environmental factors
  • Unpaired chromosomes in human cells

    • How many pairs of homologous chromosomes are present in human body cells?

  • 22
  • 23 (correct)
  • 46
  • 44

    • Which component of the cell contains the genetic information in the form of chromosomes?

  • Nucleus (correct)
  • Cytoplasm
  • Ribosome
  • Mitochondria

    • From which parent do you inherit the ovum, and how many chromosomes does it contain?

    <p>Mother; 23 chromosomes</p> Signup and view all the answers

    What process makes chromosomes most visible?

    <p>Cell division</p> Signup and view all the answers

    What is the organization of genetic information from larger to smaller components?

    <p>Cell → Nucleus → Chromosome → DNA → Gene</p> Signup and view all the answers

    Which of the following represents a type of variation in genetics?

    <p>Both environmental and genetic variation</p> Signup and view all the answers

    How many total chromosomes are present in human body cells, excluding sex cells?

    <p>46</p> Signup and view all the answers

    What defines a species?

    <p>A group of organisms that can reproduce and produce offspring capable of reproduction.</p> Signup and view all the answers

    Which of the following is an example of environmental variation?

    <p>Dietary habits</p> Signup and view all the answers

    Which pair correctly distinguishes continuous variation from discontinuous variation?

    <p>Height is continuous, blood group is discontinuous.</p> Signup and view all the answers

    Which of the following traits exhibits discontinuous variation?

    <p>Number of fingers</p> Signup and view all the answers

    What is the distinction between inherited and environmental characteristics?

    <p>Inherited characteristics are passed from parents, while environmental characteristics arise from external factors.</p> Signup and view all the answers

    Which trait can be considered a form of continuous variation?

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

    Which of the following traits is NOT a discontinuous variation?

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

    Which statement correctly describes a characteristic of heterochromia?

    <p>It's a result of genetic variation.</p> Signup and view all the answers

    What are the two types of sex chromosomes present in human beings?

    <p>X and Y chromosomes</p> Signup and view all the answers

    How many chromosomes does a human cell typically have?

    <p>46 chromosomes</p> Signup and view all the answers

    From whom does a baby boy inherit his Y chromosome?

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

    What is the process called through which sex cells are produced?

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

    How are chromosomes organized in a karyotype?

    <p>By size and structure</p> Signup and view all the answers

    Which chromosome pair determines the sex of an individual?

    <p>Last pair</p> Signup and view all the answers

    What is a chromosomal disorder?

    <p>A change in chromosome number or structure</p> Signup and view all the answers

    What is the total number of chromosomes contributed by a sperm and an egg together?

    <p>46 chromosomes</p> Signup and view all the answers

    What is Klinefelter Syndrome characterized by?

    <p>An extra X chromosome in males</p> Signup and view all the answers

    What do chromosomes primarily contain?

    <p>Genetic information and proteins</p> Signup and view all the answers

    How many chromosomes are present in most human cells?

    <p>46</p> Signup and view all the answers

    What process forms sex cells from diploid cells?

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

    What is the karyotype of a normal female?

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

    What is the chromosomal composition of an individual with Down syndrome?

    <p>47 chromosomes</p> Signup and view all the answers

    Why are mules considered infertile?

    <p>Their chromosomes do not match up during meiosis</p> Signup and view all the answers

    Which of the following best defines a karyotype?

    <p>A complete set of chromosomes in an organism</p> Signup and view all the answers

    What is the genotype of an individual who expresses the recessive phenotype for blue eye color?

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

    What is the purpose of a Punnett square?

    <p>To show the possible combinations of genes from parents</p> Signup and view all the answers

    If a mother is a carrier for cystic fibrosis (X'X) and the father is normal (XY), what is the likelihood of having a child with cystic fibrosis?

    <p>25%</p> Signup and view all the answers

    How many copies of a recessive allele are required to express a recessive trait?

    <p>Two copies</p> Signup and view all the answers

    Which genotype will result in brown eye color?

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

    What is the phenotype for an individual with the genotype 'BB'?

    <p>Brown eyes</p> Signup and view all the answers

    Why are calico cats predominantly female?

    <p>Males cannot express the trait because they have one X chromosome</p> Signup and view all the answers

    Which of the following statements is true about dominant and recessive alleles?

    <p>Dominant alleles will express a trait even with one copy</p> Signup and view all the answers

    Study Notes

    Species

    • A group of organisms that can reproduce with one another to produce offspring that can also reproduce.

    Variation

    • Definition: Differences between individuals of the same species.
    • Inherited Variation: Passed on from parents.
    • Environmental Variation: Influenced by surroundings.
    • Continuous Variation: Features with a complete range of measurements.
      • Examples: Height, weight, wingspan, milk yield in cows
    • Discontinuous Variation: Features that cannot be measured across a complete range.
      • Examples: Eye color, male or female, blood group

    Inherited vs. Environmental Variation

    • Inherited: Characteristics passed from parents.
    • Environmental: Characteristics not inherited.
    • Many characteristics are a combination of both.

    Discontinuous Variation

    • Examples:
      • Color blindness
      • Wet or Dry earwax
      • Number of fingers

    Continuous Variation Examples

    • Height
    • Weight

    Our Inheritance

    • Heterochromia: Difference in melanin distribution

    Genes and Chromosomes

    • Genes: Units of heredity that determine traits.
    • Chromosomes: Long strands of genetic information located in the nuclei of cells.
      • Made of DNA wrapped around proteins.

    Genes and Chromosomes: Where do your Genes come from?

    • We inherit half of our chromosomes from our mother and half from our father.

    Level of Organization in Gene

    • Cell
    • Nucleus
    • Chromosome
    • DNA
    • Gene

    Homologous Chromosomes

    • Matching pairs of chromosomes.
    • One chromosome from each parent.

    Human Chromosomes

    • Human body cells (except sex cells) have 46 chromosomes.
    • There are 23 pairs of homologous chromosomes.

    X and Y Chromosomes

    • X Chromosome: Females have two X chromosomes.
    • Y Chromosome: Males have one X chromosome and one Y chromosome.
    • A baby boy inherits his Y chromosome from his father.

    Chromosomal Disorder

    • A change in the number or structure of chromosomes.
    • Examples:
      • Down Syndrome: Extra copy of chromosome 21.
      • Turner Syndrome: One of the X chromosomes is missing or partially missing. Affects only females.
      • Klinefelter Syndrome: Male born with an extra X chromosome.

    Summary (Genes)

    • Different variations between humans are due to genes (alleles).
    • Long strands inside the nucleus are called chromosomes.
    • DNA and proteins make up chromosomes.
    • Humans have 46 chromosomes in most cells.
    • Sex cells have 23 chromosomes.
    • The cell division process to form sex cells is different from other cells: Meiosis and mitosis.
    • Chromosomes are chemically stained and categorized digitally from large to small, forming a Karyotype.

    Short Summary

    • Karyotype: A diagram of a complete set of chromosomes.
    • Chromosome: Long strands of genetic information located in the nuclei of cells.
    • A person with Down Syndrome has 47 chromosomes.

    Why are mules infertile?

    • Mules are hybrids resulting from a cross between a horse (64 chromosomes) and a donkey (62 chromosomes). They inherit an uneven number of chromosomes, making them infertile.

    Recessive vs Dominant

    • Recessive Allele: Only shows if an individual has two copies of it.
      • Example: Blue eye color.
    • Dominant Allele: Always shows, even with one copy.
      • Example: Brown eye color.

    Punnett Square

    • A diagram showing the possible combinations of genes, based on the genes of parents.
    • Used to predict the outcome of a particular cross or breeding experiment.

    Calico Cats

    • Mostly female because the gene for coat color is located on the X chromosome.
    • Males only have one X chromosome, so they can't be calico.

    Preimplantation genetic screening (PGS)

    • A technique used to test embryos for genetic disorders before implantation.

    Cystic Fibrosis

    • A genetic disorder caused by a recessive allele.
    • Affects mostly the lungs, but also the pancreas, liver, kidneys, and intestine.
    • If both parents are carriers of the recessive allele, their children have:
      • 25% chance of having cystic fibrosis.
      • 50% chance of being a healthy carrier.

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    Y8 Genetics PDF

    Description

    This quiz explores the concepts of variation within species, focusing on inherited versus environmental traits. It delves into continuous and discontinuous variation with relevant examples, enhancing your understanding of biological inheritance. Test your knowledge on how these variations affect organisms and populations.

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