mastering biology hw 5- chapter 10 meiosis – Flashcards
Unlock all answers in this set
Unlock answersquestion
What can we observe in order to visualize Mendel's Law of Segregation?
answer
homologous chromosomes separating during meiosis I
Homologous chromosomes each carry an allele for every gene. Those alleles may be the same or different, but they are segregated during meiosis I and distributed to each gamete.
question
Homologous chromosomes move toward opposite poles of a dividing cell during
answer
meiosis I.
question
How many different combinations of maternal and paternal chromosomes can be packaged in gametes made by an organism with a diploid number of 8 (2n = 8)?
answer
16
question
Heritable variation is required for which of the following?
answer
evolution
Variation is the raw material of evolution.
question
Gregor Mendel set up a dihybrid cross with one pea plant from the parental generation (P) producing round yellow peas and the other pea plant producing wrinkled green peas. The F2 generation included 315 plants producing round yellow peas, 108 with round green peas, 101 with wrinkled yellow peas, and 32 with wrinkled green peas. How would these results have differed if pea shape and pea color had been linked genes, located close together on the same chromosome?
answer
The F2 generation would have included a higher percentage of pea plants producing round, yellow peas.
If pea shape and pea color were determined by closely linked genes, they would not show independent assortment. Chromosomes would carry the combination of alleles seen in the P generation: yellow + round or green + wrinkled. Approximately ¾ or 75% of the F2 generation would inherit at least one chromosome carrying the yellow + round alleles. That is higher than Mendel's observed percentage of 315/556 or 56%. Read how linkage affects inheritance.
question
Mendel's second law of independent assortment has its basis in which of the following events of meiosis I?
answer
alignment of tetrads at the equator
question
Select the correct explanation for the fact that a carrier of a recessive genetic disorder does not have the disorder.
answer
In a recessive disorder, only a single functioning allele is necessary to determine a normal phenotype.
question
When a dominant allele coexists with a recessive allele in a heterozygote individual, how do they interact with each other?
answer
An allele is called dominant because it appears in the phenotype of a heterozygote, not because it subdues a recessive allele. Read about dominance.
They do not interact at all.
question
In general, the frequency with which crossing over occurs between two linked genes depends on what?
answer
how far apart they are on the chromosome
The farther apart two genes are, the greater the probability that a crossover will occur between them, and therefore the greater the recombination frequency.
question
During which part of meiosis (meiosis I or meiosis II) do the two alleles of a gene separate? During which phase does the separation occur?
answer
Alleles separate from one another during anaphase of meiosis I, when the homologous pairs of chromosomes separate.
question
What is crossing over?
answer
the exchange of homologous portions of nonsister chromatids
The result is new combinations of genetic material (genetic recombination).
question
Mendel's observation of the segregation of alleles in gamete formation has its basis in which of the following phases of cell division?
answer
anaphase I of meiosis
question
How are sister chromatids and homologous chromosomes different from each other?
answer
Homologous chromosomes contain the same gene loci but may have different alleles of a particular gene. Sister chromatids are identical copies of each other produced during DNA replication.
One homologous chromosome comes from the father, and the other comes from the mother. Sister chromatids are identical copies of each other.
question
What name is given to the most common phenotype in a natural population?
answer
The most common phenotype is the wild type.
question
If the DNA content of a diploid cell in the G1 phase of the cell cycle is x, then the DNA content of the same cell at metaphase of meiosis I would be
answer
2x.
question
This chromosome has two chromatids, joined at the centromere. What process led to the formation of the two chromatids?
answer
The two chromatids were formed by duplication of a chromosome.
question
Which of the following occurs during meiosis but not during mitosis?
answer
Synapsis occurs.
The pairing of homologous chromosomes that only occurs during prophase I of meiosis is called synapsis.
question
If the DNA content of a diploid cell in the G1 phase of the cell cycle is x, then the DNA content of the same cell at metaphase of meiosis II would be
answer
x
