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AP Bio Exam: Unit 5
AP Exam
| Question | Answer |
|---|---|
| What is meiosis? | A type of cell division that produces haploid gametes from a diploid cell, reducing chromosome number by half. |
| How do the parent cells compare to the daughter cells in meiosis? | Parent is diploid (2n); four daughter cells are haploid (n) and genetically unique. |
| What is the function of meiosis? | Produces gametes (sperm/egg) for sexual reproduction, ensuring genetic diversity. |
| How is the chromosome number reduced through the process of meiosis from one generation to the next? | Homologous chromosomes separate in Meiosis I, reducing the diploid set to haploid. |
| What are the FOUR phases of meiosis I? | Prophase I, Metaphase I, Anaphase I, Telophase I. |
| Describe each of the phases of meiosis I? | Prophase I: Crossing over; Metaphase I: Homologs align; Anaphase I: Homologs separate; Telophase I: Two nuclei form. |
| What is the role of meiosis I? | Separates homologous chromosome pairs to reduce chromosome number by half. |
| What is the ploidy of the daughter cells after meiosis I? | Haploid (n), though chromosomes consist of two sister chromatids. |
| What are the FOUR phases of meiosis II? | Prophase II, Metaphase II, Anaphase II, Telophase II. |
| Describe each of the phases of meiosis II? | Prophase II: Chromosomes condense; Metaphase II: Chromosomes align; Anaphase II: Chromatids separate; Telophase II: Nuclei reform. |
| What is the role of meiosis II? | Separates sister chromatids, similar to mitosis, resulting in four unique haploid cells. |
| What is the ploidy of the daughter cells after meiosis II? | Haploid (n) with single chromatid chromosomes. |
| Identify three differences between meiosis I and meiosis II? | Meiosis I separates homologs; Meiosis II separates chromatids. Meiosis I is reductional; II is equational. |
| Identify what part of meiosis results in the reduction of chromosome number. | Anaphase I, when homologous chromosomes are pulled to opposite poles. |
| Compare and contrast Mitosis and Meiosis in parent cell ploidy, phases involved, rounds of DNA replication + nuclear division, number of daughter cells, daughter cell ploidy, independent assortment and what phase, and crossing over and what phase | Mitosis: 2n parent, 1 round, 2n daughters, no crossing over. Meiosis: 2n parent, 2 rounds, n daughters, crossing over in Prophase I, independent assortment in Metaphase I. |
| Describe the daughter cells resulting from mitosis. | Two genetically identical diploid daughter cells. |
| Describe the daughter cells resulting from meiosis. | Four genetically unique haploid daughter cells. |
| Identify three similarities between mitosis and meiosis. | Both involve DNA replication, spindle formation, and cytokinesis. |
| Identify three differences between mitosis and meiosis. | Mitosis produces 2 cells; Meiosis produces 4. Mitosis is for growth; Meiosis is for reproduction. Meiosis has crossing over. |
| How does meiosis generate genetic diversity? | Through crossing over, independent assortment, and random fertilization. |
| Describe the material separated during meiosis I vs meiosis II. | Meiosis I separates homologous chromosomes; Meiosis II separates sister chromatids. |
| How does the segregation of this material affect the ploidy of the daughter cells? | Separating homologs reduces ploidy from 2n to n; separating chromatids maintains n. |
| Describe the process that allows for homologous chromosomes to segregate during meiosis I. | Homologous pairs align at the metaphase plate and attach to spindle fibers from opposite poles. |
| Describe the process that allows for sister chromatids to segregate during meiosis II. | Sister chromatids align individually and kinetochores attach to spindle fibers from opposite poles. |
| How do daughter cells receive both maternal and paternal chromosomes? | Independent assortment randomly distributes maternal and paternal homologs into gametes. |
| What process occurs during meiosis I that causes daughter cells to be haploid? | Separation of homologous chromosome pairs reduces the chromosome number by half. |
| What is nondisjunction? | Error in cell division where homologs or chromatids fail to separate properly. |
| Describe how the resulting daughter cells differ depending on whether this occurs in meiosis I or meiosis II. | Meiosis I: Two cells lack a chromosome, two have an extra. Meiosis II: Two normal, two abnormal (nul/trisomic). |
| What checkpoint fails leading to nondisjunction? | The spindle assembly checkpoint fails to detect improper attachment. |
| What is crossing over? | Exchange of genetic material between non-sister chromatids of homologous chromosomes. |
| How does crossing over increase genetic diversity? | Creates new combinations of alleles on chromosomes, increasing variation in gametes. |
| TRUE OR FALSE: Crossing over occurs during mitosis AND meiosis. | False; crossing over typically occurs only during Prophase I of meiosis. |
| TRUE OR FALSE: Crossing over in meiosis increases genetic diversity vs mitosis has no affect of genetic diversity. | True; crossing over creates recombinant chromosomes, while mitosis produces clones. |
| How does segregation lead to genetic variation? | Random separation of maternal and paternal homologs creates unique allele combinations. |
| What is independent assortment? | Random orientation of homologous chromosome pairs during metaphase I. |
| How does independent assortment increase genetic diversity? | Generates 2^n possible combinations of chromosomes in gametes. |
| What is random fertilization? | Random fusion of sperm and egg gametes during reproduction. |
| How does random fertilization increase genetic diversity? | Combines two unique genetic profiles, multiplying variation in offspring. |
| Identify Mendel’s laws. | Law of Segregation and Law of Independent Assortment. |
| Describe the law of segregation. | Allele pairs separate during gamete formation, so gametes receive only one allele. |
| Describe the law of independent assortment. | Genes for different traits assort independently during gamete formation. |
| What is the function of fertilization? | Fuses haploid gametes to form a diploid zygote, restoring chromosome number. |
| How does the ploidy of the gametes compare to the zygote? | Gametes are haploid (n); zygote is diploid (2n). |
| What is the difference in ploidy significant? | Maintains constant chromosome number across generations. |
| What is a monohybrid cross? | A cross between individuals heterozygous for a single trait. |
| What is the expected genotypic ratio of a monohybrid cross based on Mendel’s laws? | 1:2:1 (Homozygous Dominant : Heterozygous : Homozygous Recessive). |
| What is the expected phenotypic ratio of a monohybrid cross based on Mendel’s laws? | 3:1 (Dominant phenotype : Recessive phenotype). |
| What is a dihybrid cross? | A cross between individuals heterozygous for two different traits. |
| What is the expected genotypic ratio of a dihybrid cross based on Mendel’s laws? | 1:2:1:2:4:2:1:2:1 (various combinations of two alleles). |
| What is the expected phenotypic ratio of a dihybrid cross based on Mendel’s laws? | 9:3:3:1 (Both Dominant : Dom/Rec : Rec/Dom : Both Recessive). |
| What are the parent’s genotype if the F1 ratio is 1:1? | One parent is heterozygous (Aa) and the other is homozygous recessive (aa). |
| What is complete dominance? | Phenotype of the heterozygote is identical to the homozygous dominant. |
| What is a test cross? | Crossing an individual with unknown genotype with a homozygous recessive individual. |
| Describe the difference between a homozygous or heterozygous individual. | Homozygous has two identical alleles; Heterozygous has two different alleles. |
| Describe the difference in an autosomal inheritance vs a linked trait inheritance. | Autosomal traits assort independently; Linked traits are on same chromosome and tend to inherit together. |
| What does it mean if an allele is dominant? | It masks the expression of a recessive allele in the heterozygote. |
| What does it mean if an allele is recessive? | It is only expressed phenotypically when two copies are present. |
| How could a homozygous dominant and heterozygous individual have the same phenotype? | The dominant allele masks the recessive allele in both cases. |
| How do you determine if a trait is dominant or recessive? | If two parents with a trait have offspring without it, the trait is likely recessive. |
| What would you look for in a pedigree to identify if the trait is dominant or recessive? | Dominant: Appears every generation. Recessive: Can skip generations. |
| What would you look for in a pedigree to identify if the trait is autosomal or sex linked? | Sex-linked affects mostly males; Autosomal affects both sexes equally. |
| What are linked traits? | Genes located close together on the same chromosome that tend to be inherited together. |
| How are the predicted ratios different in linked genes? | Deviate from Mendelian ratios because they do not assort independently. |
| How would this be observed in a pedigree? | Traits appear together more often than expected by chance. |
| How do you calculate map units of two genes? | Map units equal the recombination frequency percentage between the genes. |
| Determine the map units between A, B, and C based on the following information: A– B: 13.2%, B – C= 6.4%, A– C= 18.5% | A-B is 13.2 mu; B-C is 6.4 mu; A-C is 18.5 mu. |
| Determine the map units between body color and wing shape based on the following information: Gray Body/Normal Wings = 1239, Black Body/Vestigial Wings = 1295 Gray Body/Vestigial Wings= 156, Black Body/Normal Wings=149 | Total = 2839. Recombinants = 305. RF = 305/2839 = 10.7%. Distance is 10.7 map units. |
| If the recombination frequency is 15%, how far apart are the two genes? | 15 map units. |
| What is codominance? | Both alleles in the heterozygote are fully and distinctly expressed. |
| What is the expected genotypic ratio of this cross? | 1:2:1. |
| What is the expected phenotypic ratio of this cross? | 1:2:1 (Red : Spotted : White). |
| What is incomplete dominance? | Heterozygote phenotype is intermediate between the two homozygous phenotypes. |
| What is the expected genotypic ratio of this cross? | 1:2:1. |
| What is the expected phenotypic ratio of this cross? | 1:2:1 (Red : Pink : White). |
| What are sex-linked traits? | Traits determined by genes located on the sex chromosomes. |
| TRUE OR FALSE: Sex-linked traits only affect the X chromosome. | False; Y-linked traits exist but are rare. Most are X-linked. |
| TRUE OR FALSE: Sex-linked traits affect males more frequently than females. | True; males have only one X, so recessive alleles are always expressed. |
| If a male is affected with a sex-linked trait with unaffected parents, what are the genotypes of the parents? | Mother is carrier (X^A X^a); Father is normal (X^A Y). |
| What type of sex-linked cross would result in 2 normal females, 1 normal male, and 1 affected male? | Carrier female (X^A X^a) crossed with normal male (X^A Y). |
| If given a pedigree, how would you determine if the trait is sex linked? | Look for a pattern where mostly males are affected or passed from mother to son. |
| What is pleiotropy? | One gene influences multiple, seemingly unrelated phenotypic traits. |
| Provide ONE example of pleiotropy. | Sickle cell anemia affects hemoglobin and malaria resistance. |
| What organelles contain DNA? | Mitochondria and chloroplasts. |
| How does this support the endosymbiotic theory? | Suggests these organelles evolved from free-living prokaryotes. |
| If a trait is mitochondrially linked, what is the mode of inheritance? | Maternal inheritance, as mitochondria are passed through the egg. |
| If an animal or plant has a mitochondrial linked trait, which gamete is responsible for this inheritance? | The egg (female gamete). |
| If a trait is found on the DNA in a chloroplast, what is the mode of inheritance? | Maternal inheritance in plants. |
| If a plant has a chloroplast linked trait, which gamete is responsible for this inheritance? | The egg (female gamete). |
| What would you look for in a pedigree to identify if the trait is due to nonnuclear inheritance? | Trait passed only from mothers to all offspring. |
| What is phenotype plasticity? | Ability of a single genotype to produce different phenotypes in response to environmental conditions. |
| Identify two examples of phenotype plasticity. | Tanning in response to UV light; Temperature-dependent sex determination in reptiles. |
| What is the evolutionary significance of phenotype plasticity? | Allows organisms to adjust to changing environments without genetic change. |
| How do environmental factors affect gene expression? | External signals (like temperature or diet) can trigger regulatory proteins that turn genes on or off. |
Created by:
chianti
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