Bio 148 Exam 3 Questions With ELABORATED 100% Correct COMPLETE SOLUTIONS Guaranteed Pass!! Current Update!!

Bio 148 Exam 3 Questions With ELABORATED 100% Correct COMPLETE SOLUTIONS Guaranteed Pass!! Current Update!! Where are nonsister chromosomes only found - Answer- between homologous chromosomes An organism is 2n=16. During Metaphase I of meiosis, cells will have ______ chromosomes and ___________ DNA molecules present in the cell. - Answer- 16; 32. During metaphase I cells are still diploid. However, the chromosomes are in their replicated form, which means they are each composed of 2 DNA molecules. So you would have 16 chromosomes multiplied by 2 DNA molecules a piece, giving you 32. An organism is 2n=16. During Metaphase II of meiosis, cells will have _____________ chromosomes and ___________ DNA molecules present in the cell. - Answer- 8; 16. During metaphase II the cell is haploid. However, the chromosomes are still in their replicated form, which means they are each composed of 2 DNA molecules. So you would have 8 chromosomes (the haploid number) multiplied by 2 DNA molecules apiece, giving you 16. Homologous chromosomes - Answer- contain the same gene order but not necessarily the same alleles because you inherit one from mom and one from dad, which makes them not genetically identical. The only time we see these paired is during meiosis Rules for what chromosomes look like in the zygote immediately following fusion of these two haploid cells during fertilization Egg cells- T, D Sperm cells- t, D - Answer- T,t,D,D 1. You would never see a replicated chromosome after fertilization and 2. You would never see replicated chromosomes that have chromatids with different genes together. You discover a population of insects in which the maternally inherited (inherited from mom) chromosomes line up on the same side of the metaphase plate during meiosis I. Will the gametes produced by these insects all be identical? - Answer- No. Even if the maternal chromosomes all line up the same side, you would still be able to get two different types of gametes, meaning they won't all be identical. A cell has completed meiosis I and is just beginning meiosis II. How does this cell differ from the cell that began meiosis? - Answer- It has half the number of chromosomes and half the amount of DNA. By the end of meiosis I, a cell is haploid, meaning that it will have half the number and chromosomes—which in turn means it can only have half the amount of DNA What is true of a species that has a chromosome number of 2n=16? - Answer- A gamete from this species has 8 chromosomes. What occurs during metaphase I of meiosis? - Answer- Homologous chromosome pairs line up at the metaphase plate. Only during metaphase I do we see homologous chromosomes paired at the metaphase plate. During which stage would you NOT observe a chromosome containing two sister chromatids? - Answer- After completion of meiosis II. You will see replicated chromosomes from Prophase I through Metaphase II. During Anaphase II is when the sister chromatids are finally separated. An insect species has 42 chromosomes in a normal body cell. At the end of Meiosis I, each cell has _____ chromosomes. After meiosis II and cytokinesis, each cell has ____ chromosomes. - Answer- 21, 21. Remember that by the end of meiosis I, all cells are haploid. So, you would observe the haploid number for both the end of meiosis I and meiosis II. An individual has the genotype TtDd . Explain how the chromosomes would appear in a gamete produced by this individual if the T and d chromosomes align on opposite sides of the metaphase plate during meiosis I? **Assume there is no crossing over** - Answer- If T and d line up on opposite sides of the metaphase plate, that means that the T alleles will end up with the D alleles in the same cells at the end and the t alleles and d alleles will end up in the same cells at the end. -T-D- What does this photo show? - Answer- anaphase I; segregation. Mendel's law of segregation states that alleles are separated during the process of gamete formation. This separation of alleles takes place during anaphase I. Sickle cell anemia is caused by a missense mutation in the β-globin gene. The normal allele of the β-globin gene is located near the left end of chromosome 2. If someone has one normal allele and one mutant allele, where are they located? - Answer- One is located on the left end of one chromosome 2, the other is on left end of the homologous chromosome. Remember that you get one allele for each gene on the chromosomes you inherit from mom and the other allele for each gene on the chromosomes you inherit from dad. So, one each pair of alleles will be found on homologous chromosomes. During interphase before meiosis begins, a mutation arises during DNA replication resulting in a new allele for one of the genes on ONE sister chromatid of one chromosome. When this cell completes meiosis, how many gametes will contain this new allele? - Answer- 1. The new allele is only on one chromatid. After meiosis one, the chromosome containing the allele will only be in one of the two cells. Then during anaphase II, the chromatid with the new allele would be separated from its sister chromatid and only be found in one cell. In certain plants, tall is dominant to short. If a heterozygous plant is crossed with a homozygous tall plant, what is the probability that the offspring will be tall? - Answer- 1. When crossing a heterozygote with a homozygous tall plant, every offspring will possess at least one dominant allele, making it a probability of 1 that they will all be tall A pure-breeding black, curly haired dog is crossed to a pure-breeding brown, straight haired dog. The F1 offspring are black, straight haired dogs. What happens as the F1 cross - Answer- Crossing the F1 to each other should produce a 9:3:3:1 phenotypic ratio in the F2 generation. We can determine that black and straight hair are dominant because that is what is observed in the F1 after crossing the two pure breeding lines. If pure breeding lines are homozygous for the traits they possess. A pure-breeding black, curly haired dog is crossed to a pure-breeding brown, straight haired dog. The F1 offspring are black, straight haired dogs. You cross a black, straight haired F1 dog back to the brown, straight haired parent. What is the probability that offspring will have brown, curly hair? - Answer- 0. Since you are crossing a dog that is heterozygous for straight hair (which is the dominant trait) and homozygous for straight hair (dominant trait), there is no way to produce an offspring with the curly haired phenotype present, regardless of what color fur it has. In general, asexual reproduction results in the production of more offspring per individual than does sexual reproduction. Despite this, sexual reproduction is a major form of reproduction in eukaryotes. What is the probable explanation for the prevalence of sexual reproduction? - Answer- Sexual reproduction mixes up alleles contributing to variation in a species. Remember that the major advantage of sexual reproduction is the allelic variation it produce, which allows some individuals to survive when deleterious alleles are present of when the environment changes.