Mitosis and Meiosis Quiz
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Questions and Answers

What defines the genotype of an organism?

  • The observable traits influenced by environmental factors
  • The dominant phenotype expressed by the organism
  • The physical appearance as a result of inheritable traits
  • The combination of alleles present for a characteristic (correct)

    • Which statement best describes the concept of true breeding?

  • Parents are homozygous and pass the same alleles to offspring (correct)
  • Parents are heterozygous for all traits
  • Offspring inherit only recessive traits from their parents
  • Offspring show a mix of traits from both parents

    • In Mendel's F1 generation experiment, what was the phenotype observed?

  • Only some offspring had purple flowers
  • All offspring had white flowers
  • A mixture of purple and white flowers
  • All offspring had purple flowers (correct)

    • Which of the following best describes the law of segregation?

    <p>Only one allele of each trait is passed to offspring from each parent</p> Signup and view all the answers

    How can dihybrid crosses be best characterized?

    <p>They identify inheritance patterns for two traits on non-homologous chromosomes</p> Signup and view all the answers

    What type of selection favors individuals at both extremes of the phenotypic range?

    <p>Disruptive selection</p> Signup and view all the answers

    Which species concept focuses on the ecological niche of a species?

    <p>Ecological species concept</p> Signup and view all the answers

    What mechanism prevents fertilization from occurring due to different breeding times?

    <p>Temporal isolation</p> Signup and view all the answers

    Which of the following is a postzygotic barrier?

    <p>Reduced hybrid viability</p> Signup and view all the answers

    Allopatric speciation occurs when populations are separated by what?

    <p>Geographic barriers</p> Signup and view all the answers

    Which reproductive barrier prevents different species from attempting to mate?

    <p>Habitat isolation</p> Signup and view all the answers

    Which of the following describes stabilizing selection?

    <p>Favors intermediate variants</p> Signup and view all the answers

    What type of isolation involves differences in mating behavior?

    <p>Behavioral isolation</p> Signup and view all the answers

    What term describes the two identical chromatids held together by a centromere?

    <p>Sister chromatids</p> Signup and view all the answers

    During which phase do centrosomes duplicate?

    <p>G2 phase</p> Signup and view all the answers

    What is the primary purpose of microtubules during metaphase?

    <p>To align chromosomes along the metaphase plate</p> Signup and view all the answers

    At the end of which phase do sister chromatids separate?

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

    Which event occurs during telophase?

    <p>The nuclear membrane forms around the chromosomes</p> Signup and view all the answers

    What occurs during cytokinesis?

    <p>The cytoplasm divides into two new daughter cells</p> Signup and view all the answers

    Which statement about G0 phase is true?

    <p>Cells do not participate in the cell cycle actively</p> Signup and view all the answers

    What distinguishes sister chromatids from regular chromosomes?

    <p>Sister chromatids are duplicated forms of a chromosome</p> Signup and view all the answers

    What is the term for the genetic makeup variations, represented as different forms of a gene?

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

    Which of the following correctly describes a haploid cell?

    <p>Contains one set of chromosomes</p> Signup and view all the answers

    How many total chromosomes are present in a diploid cell?

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

    What is the main purpose of DNA replication during the S phase of interphase?

    <p>To duplicate the DNA molecule</p> Signup and view all the answers

    Which phase of the cell cycle is primarily responsible for extensive synthesis of new organelles?

    <p>G1 phase</p> Signup and view all the answers

    In plant cells, what structure forms during cytokinesis to separate daughter cells?

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

    What distinguishes the sex chromosomes in humans?

    <p>They are involved in determining an individual's sex</p> Signup and view all the answers

    What is a key characteristic of semiconservative DNA replication?

    <p>One strand is from the original duplex and one is newly synthesized</p> Signup and view all the answers

    What must occur for a population to be considered at genetic equilibrium?

    <p>Random mating and no migration</p> Signup and view all the answers

    Which process introduces genetic variation into a population?

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

    What is the effect of assortative mating on a population's genetic structure?

    <p>Increases the proportion of homozygous individuals</p> Signup and view all the answers

    Which statement best describes genetic drift?

    <p>It can lead to a loss of genetic variation within populations</p> Signup and view all the answers

    What does gene flow primarily result from?

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

    What is a consequence of the bottleneck effect in genetic drift?

    <p>Decrease in population size and genetic variation</p> Signup and view all the answers

    Which of the following statements is true regarding natural selection?

    <p>It leads to certain alleles being passed to the next generation at higher rates</p> Signup and view all the answers

    Which factor does NOT contribute to microevolution?

    <p>Genetic equilibrium</p> Signup and view all the answers

    What is a significant piece of evidence for endosymbiosis regarding mitochondria and chloroplasts?

    <p>They have their own circular DNA, like prokaryotes.</p> Signup and view all the answers

    Which of the following contributed to the founding principles of evolution prior to Darwin?

    <p>Lamarck proposed the idea of inheritance of acquired traits.</p> Signup and view all the answers

    What role does natural selection play in evolution?

    <p>It acts on heritable traits and influences survival and reproduction.</p> Signup and view all the answers

    What did Charles Lyell contribute to the understanding of geological changes?

    <p>He introduced the principle of uniformitarianism.</p> Signup and view all the answers

    What defines a population in the context of evolution?

    <p>The smallest group that can undergo evolutionary changes.</p> Signup and view all the answers

    What was one of Aristotle's contributions to the understanding of species?

    <p>He suggested that species are fixed and unchanging.</p> Signup and view all the answers

    Which statement describes the relationship between mitochondrial chloroplasts and prokaryotes?

    <p>They reproduce through binary fission, like prokaryotes.</p> Signup and view all the answers

    What are adaptations defined as in the context of evolution?

    <p>Inherited characteristics enhancing survival and reproduction in specific environments.</p> Signup and view all the answers

    Study Notes

    Mitosis and Meiosis

    • Mitosis is cell division that results in two identical daughter cells.
    • It's used for tissue renewal, growth and development, and asexual reproduction.
    • Cells in interphase (not dividing) have chromatin (euchromatin and heterochromatin) in long, thin fibres.
    • Chromatin condenses to form chromosomes when a cell is ready to divide.
    • A human cell has 46 chromosomes (23 pairs), homologous chromosomes having the same gene at the same loci but different alleles.
    • A haploid cell has one set of 23 chromosomes (in sperm or egg).
    • A diploid cell has two sets of 46 chromosomes.
    • Autosomes are chromosomes 1-22, all homologous.
    • Sex chromosomes are the 23rd pair (XX in females-homologous; XY in males—not homologous).
    • Cell division in plants differs from animal cells in that they do not have centrioles. Instead, a cell plate forms in the centre of the cell.

    Cell Cycle

    • Interphase is the period when a cell is not dividing.
      • G1 phase: Growth, synthesizing new organelles
      • S phase: DNA replication (the cell makes a copy of each chromosome thus creates sister chromatids).
      • G2 phase: Second growth phase, cell increases in size, prepares for mitosis.
    • During S phase, each chromosome consists of two identical sister chromatids.
    • Sister chromatids are joined by a centromere.

    Mitosis Stages

    • Prophase: Chromatin condenses, nucleus remains intact but the nucleolus disappears, duplicated centrosomes separate and move to opposite poles, microtubule fibres extending between centrosomes form the mitotic spindle.
    • Prometaphase: Nuclear membrane breaks down. Centrosomes at opposite ends of the cell. Some microtubules attach to kinetochores (structures on the centromere).
    • Metaphase: Chromosomes align along the middle of the cell (metaphase plate). Sister chromatids are attached to microtubules coming from opposite poles.
    • Anaphase: Centromeres break, sister chromatids separate, and the chromosomes are pulled to opposite poles of the cells by microtubules.
    • Telophase: One copy of each chromosome is present at the opposite ends of the cell. Chromatin fibers start to loosen and become less coiled. Spindle fibers disappear. Nuclear membrane forms around chromosomes.
    • Cytokinesis: Cytoplasm divides into two new daughter cells. Cell pinches in the middle (cleavage furrow in animal cells) or a cell plate forms in plant cells.

    Meiosis

    • Meiosis is cell division in sexually reproducing organisms, that produces cells with half the number of chromosomes as the parent cell for sexual reproduction in humans (sperm and eggs).
    • Produces four genetically different haploid daughter cells.
    • Has two rounds of division (meiosis I and meiosis II).
    • In meiosis I, homologous chromosomes pair up and exchange genetic material in a process called crossing over.
    • Homologous chromosome pairs separate at the end of Meiosis I.
    • In meiosis II, sister chromatids separate.
    • Meiosis increases genetic variation in offspring.

    Genetic Variation

    • Mutations are the original source of genetic variation.
    • Reshuffling of alleles during sexual reproduction creates new combinations.
    • Crossing over in meiosis increases variation.
    • Independent assortment of chromosomes during meiosis affects variation.
    • Random fertilization of gametes (sperm and egg) further increases variability.

    Mendelian Genetics

    • Genotype: Combination of alleles for a characteristic.
    • Phenotype: Appearance of a characteristic
    • Characters: Observable heritable feature.
    • Traits: Variant of a character.
    • Gene locus: Specific location of a gene on a chromosome.
    • Inheritance: Transmission of traits from one generation to the next.
    • Mendel's experiments: Show that traits are inherited in a distinct manner (law of segregation and independent assortment).
    • Monohybrid cross: Observing the inheritance of a single trait.
    • Dihybrid cross: Observing the inheritance of two traits.
    • Law of segregation: Each individual has two alleles for each characteristic. During gamete formation, the alleles separate, so that each gamete receives only one allele for each characteristic.
    • Law of independent assortment: Alleles of different genes separate independently during gamete formation.
    • Dominant/recessive alleles: One allele can mask the expression of another

    Speciation

    • Species: Group of organisms that can interbreed and produce fertile offspring in nature
    • Reproductive barriers: Prevent interbreeding between species.

    • Prezygotic barriers: Prevent fertilization

    • Postzygotic barriers: Prevent the resulting zygote from developing into a viable, fertile adult

    • Allopatric speciation; populations geographically separated from one another.
    • Sympatric speciation; populations in the same geographic area.

    Phylogenetic History

    • Phylogeny: The evolutionary history of a species or group of related species.
    • Can represent relationships in a branching tree or diagram called a phylogenetic tree (cladogram)/phylogenetic tree.
    • Similar characteristics (homologous) or traits are derived from a common ancestor.
    • Similar adaptations (analogous) reflect adaptation to a similar environment.

    Early Life on Earth

    • Conditions on Earth early in its history allowed production of organic molecules from inorganic molecules, which may have occurred via extraterrestrial origin, abiotic synthesis, and Abiogenesis.
    • The first cells were prokaryotes that dominated life until eukaryotes arose.
    • Eukaryotes likely arose through endosymbiosis, in which one prokaryotic cell engulfed another.

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    Description

    Test your understanding of mitosis and meiosis with this quiz. Learn about the stages of cell division, the differences between haploid and diploid cells, and the formations of chromosomes. Perfect for students studying biology or related fields.

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