Genetics: Punnett Squares & Inheritance Laws
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Questions and Answers

What is the term for a trait that is expressed only when two identical alleles are present?

  • Recessive trait (correct)
  • Dominant trait
  • Sex-linked trait
  • Codominant trait

    • In a scenario where both alleles for a gene are fully expressed in the phenotype, what is this inheritance pattern called?

  • Polygenic inheritance
  • Codominance (correct)
  • Incomplete dominance
  • Multiple alleles

    • Which of the following best describes the concept of a 'genotype'?

  • The change in frequency of an existing gene variant due to random chance.
  • The physical appearance or observable traits of an organism.
  • The movement of genes into or out of a population.
  • The specific combination of alleles an organism carries. (correct)

    • What does the Law of Segregation explain with regard to alleles?

    <p>Each individual has two alleles for each trait, which separate during gamete formation. (B)</p> Signup and view all the answers

    What is the term for the event where a section of a chromosome breaks off, flips, and reattaches in reverse order?

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

    Which of the following best describes ‘genetic drift’?

    <p>A change in the frequency of a gene due to random chance. (C)</p> Signup and view all the answers

    Which of the following chromosomal mutations leads to a section of one chromosome attaching to a completely different one?

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

    Which condition is a result of having an extra copy of chromosome 21?

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

    What does Chargaff's first rule state about DNA?

    <p>The amounts of thymine and adenine are identical. (D)</p> Signup and view all the answers

    Which scientist provided direct evidence of the helical structure of DNA?

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

    What is the role of mRNA in protein synthesis?

    <p>To deliver a copy of the DNA code to a ribosome (D)</p> Signup and view all the answers

    Where is transfer RNA (tRNA) located within the cell?

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

    Which type of mutation involves the substitution of a purine for a pyrimidine?

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

    What is the effect of a missense mutation on a protein?

    <p>It results in a change to a different amino acid. (D)</p> Signup and view all the answers

    What is the consequence of a nonsense mutation?

    <p>Premature termination of protein synthesis (C)</p> Signup and view all the answers

    What is the effect of a neutral mutation on a protein?

    <p>There is no effect on the protein’s function. (C)</p> Signup and view all the answers

    What effect does a frameshift mutation typically have on protein function?

    <p>It often results in a nonfunctional protein. (A)</p> Signup and view all the answers

    Which technique is used to separate DNA fragments based on their size?

    <p>Agarose Gel Electrophoresis (B)</p> Signup and view all the answers

    How do epigenetic changes influence gene expression?

    <p>Through mechanisms that do not change the DNA sequence. (A)</p> Signup and view all the answers

    What is a primary use of the polymerase chain reaction (PCR)?

    <p>To amplify specific DNA sequences. (C)</p> Signup and view all the answers

    What type of technology can be used to increase crop yield and food security?

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

    Which of the following is an application of synthetic biology?

    <p>Biodegradable Plastics Development (D)</p> Signup and view all the answers

    What is a potential application of 3D bioprinting?

    <p>Generating tissue-like structures for research. (D)</p> Signup and view all the answers

    What does personalized medicine consider when tailoring therapeutic approaches?

    <p>The genetic makeup and environment of the patient. (C)</p> Signup and view all the answers

    What is the main difference between genetic testing and genetic screening?

    <p>Genetic testing is for individuals while screening is for populations. (A)</p> Signup and view all the answers

    What is a key feature of gene therapy?

    <p>It modifies genes to treat or cure diseases. (D)</p> Signup and view all the answers

    What significant contribution did the Human Genome Project make to science?

    <p>It identified all human gene sequences and their functions. (D)</p> Signup and view all the answers

    In which phase of meiosis do homologous chromosomes align at the equatorial plate?

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

    Bioremediation involves which of the following?

    <p>The use of living organisms to remove contaminants. (B)</p> Signup and view all the answers

    Which of the following methods is NOT a use of recombinant DNA technology?

    <p>Development of biofuels (D)</p> Signup and view all the answers

    How many non-identical haploid daughter cells are produced at the end of meiosis?

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

    What is a characteristic of biofuels compared to fossil fuels?

    <p>They are considered more sustainable. (A)</p> Signup and view all the answers

    Study Notes

    Punnett Squares and Pedigrees

    • Punnett squares visually represent possible genotypes of offspring from parents with known genotypes.
    • Pedigrees show inheritance patterns across generations, depicting affected and unaffected individuals with possible carriers.

    Gregor Mendel's Laws of Inheritance

    • Mendel's experiments with pea plants led to the fundamental laws of inheritance.
    • Dominant traits appear more frequently than recessive traits.
    • Recessive traits are expressed only when both alleles of the gene are recessive.
    • Sex-linked traits are controlled by genes located on sex chromosomes (X or Y).
    • Codominance occurs when both alleles are fully expressed in heterozygotes.
    • Incomplete dominance occurs when both alleles are partially expressed.
    • Multiple alleles means more than one allele.
    • Polygenic inheritance results when numerous genes influence a single trait. A range of variations can occur.
    • Heterozygous means two different alleles.
    • Homozygous means two of the same alleles.
    • Phenotype is observable traits.
    • Genotype is the genetic composition of traits.

    Chromosomes and Meiosis

    • Law of segregation: alleles separate during gamete formation.
    • Law of independent assortment: genes for different traits assort independently.
    • Law of dominance: one trait will dominate another unless both factors are recessive.
    • Mitosis: cell division producing two identical daughter cells.
    • Mutations involve changes in DNA sequence. Examples include duplication, deletion, inversion, and translocation.
    • Nondisjunction: homologous chromosomes do not separate during meiosis, leading to abnormal chromosome numbers.

    DNA Structure and Function

    • Chargaff's rules: amount of adenine equals thymine and guanine equals cytosine.
    • DNA is a double-helix polymer with two strands.
    • Franklin and Wilkins provided evidence for the helical structure.
    • Watson and Crick deduced the arrangement of bases within the DNA double helix.

    RNA and Protein Synthesis

    • mRNA carries the genetic instructions from DNA to ribosomes for protein synthesis.
    • tRNA transfers amino acids to the ribosome during translation.
    • rRNA is a major component of ribosomes, the protein synthesis sites.

    Point Mutations

    • Base pair substitutions: a single nucleotide is exchanged. This can further be categorized into transitions, transversions, insertions, and deletions.
    • Insertion/deletions (indels): addition or removal of nucleotides. This significantly affects the reading frame.
    • Missense mutation: causes an amino acid change in the protein which may or may not affect the function.
    • Nonsense mutation: changes a codon to a stop codon, often leading to a nonfunctional protein.
    • Neutral mutation: changes an amino acid but does not affect a protein function.

    Biotechnology, DNA Fingerprinting and Gene Therapy

    • Biotechnology involves using living organisms to create products.
    • DNA fingerprinting analyses DNA sequences to identify individuals.
    • Gene therapy aims to modify genes to treat or cure diseases
    • Genetic cloning, genetic engineering, gene therapy, assisted reproduction, and synthetic biology.

    Epigenetics

    • Changes in gene expression without altering the underlying DNA sequence.
    • Behaviors and environment affect gene expression.

    Meiosis

    • Meiosis results in four genetically different haploid cells from one diploid cell.
    • Meiosis is important to sexual reproduction.
    • Meiosis I encompasses the separation of homologous chromosomes.
    • Meiosis II separates sister chromatids and forms haploid daughter cells.

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    Genetics PDF - Biology Past Paper

    Description

    Explore the fundamental concepts of Punnett squares and Pedigrees in genetics, which illustrate potential genotypes and inheritance patterns. Understand Gregor Mendel's vital contributions to our knowledge of dominant and recessive traits, codominance, and polygenic inheritance. Test your understanding of these key aspects of genetic theory.

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