Worksheet: Exam 4 Review Supplemental Instruction

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1 Worksheet: Exam 4 Review Supplemental Instruction Leader: Matt Course: Biol 211 (1) Instructor: Biederman Date: 10/26/16 Iowa State University 1.) If a species has a 2n number of chromosomes = 16 then which of the following is true? A) The species is diploid with 32 chromosomes per cell B) A gamete from this species contains 4 chromosomes C) Each cell has 8 homologous pairs D) The species has 16 sets of chromosomes per cell E) None of the above Follow up: What is a homologous pair? Only in meiosis. One from dad, one from mom. Same genes, different alleles. 2.) Which of the following occurs in meiosis but not mitosis? A) chromosome replication B) synapsis of chromosomes C) production of daughter cells D) alignment of chromosomes at the center of cell E) condensation of chromatin 3.) A human cell containing 22 autosomes and a Y chromosome is a A) egg B) zygote C) sperm D) a male somatic cell E) a female somatic cell 4.) Which of the following happens at the conclusion of meiosis I? A) homologous chromosomes are separated B) the chromosome number per cell is conserved C) sister chromatids are separated D) four daughter cells are formed E) the sperm cell fertilizes the egg 5.) A cross between a homozygous purple flowered and a homozygous white flowered pea plants results in offspring with purple flowers. This demonstrates A) blending inheritance B) true breeding traits C) dominance of one trait over another D) a di-hybrid cross E) a mistake by Mendel 6.) When you cross an organism that is homozygous recessive for a trait with one that is a heterozygote for the same trait, what is the chance of producing homozygous recessive offspring? A) 0% B) 25% C) 50% D) 75% E) 100% 1060 Hixson-Lied Student Success Center sistaff@iastate.edu

2 7.) The rare llama-rabbit is known to have 2 traits: head shape (H) and tail length (T) that are controlled by un-linked genes. The genotype of a stud-male llama-rabbit is HhTt. Which of the following is a possible genotype found in his gametes? A) HT B) Hh C) HhTt D) Tt E) H 8.) An organism s appearance or observable traits are referred to as its A) genotype B) phenotype C) character D) trait E) dominant allele 9.) Red-green color blindness in humans is a sex-linked recessive trait. A husband and a wife with normal vision have a color-blind son. What are the genotypes of the parents? A) X c X c and X c Y B) X c X c and X C Y C) X C X C and X c Y D) X C X C and X C Y E) X C X c and X C Y

3 The Mitotic Cell Cycle: H Label each letter What is happening to the chromosomes at each step? If letter (I) was added, what might it represent? What letters = Interphase? Mitosis? How would a circular representation of meiosis differ? Compare and Contrast: Mitosis: Meiosis: What stage do they both start out in? Interphase G1 Is binary fission more similar to mitosis or meiosis? What events are unique to this type of cell division? Can produce diploid cells What is the purpose of this type of cell division? Growth and development Tissue renewal/repair Final Product in humans: (Number cells? Ploidy? Relation to original cell?) Two diploid cells, identical to parent cell What events/structures are unique to this type of cell division? Synapsis, prophase 1, homologous pairs stick together, crossing over, tetrad (homologous pair) What is the purpose of this type of cell division? Sexual reproduction Making gametes Final Product in humans: (Number? Ploidy? Relation to original cell?) 4 haploid cells, genetically distinct What human cells does this process produce? How many autosomes/sex chromosomes? 44 autosomes, 2 sex chromosomes Somatic cells What problems can arise? Uncontrolled replication-tumors Is genetic variation introduced? How? Mutation What human cells does this process produce? How many autosomes/ sex chromosomes? 22 autosomes, 1 sex chromosome gametes What problems can arise? Extra or missing chromosomes Trisomy (down syndrome) Is genetic variation introduced? How? Mixing of genetic material from different parent cells (bi parental inheritance), crossing over, mutation For a good animated overview of Mitosis and Meiosis visit: vcell.ndsu.nodak.edu/animations

4 Briefly describe the difference between the following: Genotype vs. Phenotype? Genotype: types of alleles Phenotype: physical characteristics Gene vs. Loci vs. Allele? Gene: DNA that codes for a trait Allele: type of gene Loci: location of gene DNA Dominant allele vs. Recessive allele? Dominant: covers up recessive Recessive: Only shows if only recessive alleles are possessed Homozygous vs. Heterozygous? Homo: Has all either dominant or recessive Hetero: has both dominant and recessive Are the following homozygous or heterozygous? How many gametes could each produce? HH Rr EeGG TtAa RrHHTT Homozygous 1 gamete Hetero Hetero for E Homo for G Hetero for T and A 4 gametes Hetero R, homo H and T Punnett Square practice: 1. Albinism (lack of skin pigmentation) is caused by a recessive autosomal allele. Persons who are heterozygous for albinism are carriers. Persons who are homozygous recessive have the disease. If a person who does not have the disease and is not a carrier marries a carrier for the disease, what is the chance they will have a child with the disease? What is the chance they will have a child who is a carrier? Show the Punnett square to support your answer. What are the parental genotypes: Are they hetero/homozygous? One hetero, one homo dominant How many different gametes can each parent produce: 1 from homozygous, 2 from hetero

5 2. You have a dog that is homozygous recessive at locus (A) and has light fur. She has 8 puppies that all express dark fur color. What is most likely the genotype of the father? Show the Punnett square to support your answer. What are the parental genotypes: Are they hetero/homozygous? homozygous How many different gametes can each parent produce: 1 3. Sex linked: If the mother is a carrier for colorblindness XCB then what ratio of her children will be colorblind? (The father is not colorblind.) XCBX XX XCBY XY 4. Dihybrid Crosses: P: GGDD x ggdd GD Gd gd gd F1: F2 (from F1 self): GGDD GGDd GgDD GD GD GGDd GGdd Ggdd GgDD ggdd ggdd Ggdd ggdd ggdd Polygenic Inheritance What is it? Many genes contributing to one trait Examples? Skin tone Incomplete Dominance blending RR is red, rr is white, Rr is pink Codominance: Equally expressed. Example: RR is red, rr is white, Rr is alternating red and white petals