AP Ch 10 Meiosis Outline Quiz

Crossing-over occurs during prophase I of meiosis. This is the stage where homologous chromosomes pair up and exchange genetic material through a process called crossing-over or recombination. This genetic exchange contributes to genetic diversity by creating new combinations of alleles on the chromosomes. Therefore, prophase I is the correct stage for crossing-over to occur.

This statement is true because during DNA replication, the DNA molecule is duplicated to form two identical copies called sister chromatids. These sister chromatids are held together at a specific region called the centromere. This allows for the accurate distribution of genetic material during cell division. Therefore, if DNA replication has already occurred, the chromosomes will indeed consist of sister chromatids held together at a centromere.

Crossing-over is an important process that occurs during meiosis, specifically during prophase I. During crossing-over, homologous chromosomes exchange genetic material, resulting in the formation of new combinations of alleles. This increases the likelihood that daughter cells will contain different genetic material, leading to genetic diversity. This genetic diversity is crucial for the survival and adaptation of a species as it allows for the emergence of new traits and enhances the ability to respond to changes in the environment.

If a sperm cell contains 8 chromosomes, it comes from an animal that has 16 chromosomes. This is because during sexual reproduction, each parent contributes half of the chromosomes to the offspring. Since the sperm cell is a haploid cell, it only contains half of the genetic material. Therefore, if it has 8 chromosomes, the animal it comes from must have a diploid number of 16 chromosomes.

During anaphase I of meiosis, the homologous chromosomes, which are paired together as bivalents, separate and move towards opposite poles of the cell. This separation is facilitated by the disruption of the association between the members of the bivalent. Therefore, the statement that during anaphase I the association between members of a bivalent is disrupted and they separate is true.

During meiosis I, the cell undergoes DNA replication, resulting in the formation of two identical sister chromatids. However, during meiosis II, there is no further replication of DNA. Instead, the sister chromatids separate, resulting in the formation of four haploid daughter cells. Therefore, the statement that there is no replication of DNA between meiosis I and meiosis II is true.

Synapsis is the process in which duplicated chromosomes align and pair up with their homologues during meiosis. This pairing is crucial for the exchange of genetic material between homologous chromosomes, known as crossing over. Therefore, the statement that synapsis occurs when a duplicated chromosome begins to pair with its homologue is correct.

During metaphase I of meiosis, the homologous chromosomes pair up to form bivalents. These bivalents align themselves along the metaphase plate, which is an imaginary line in the center of the cell. The correct answer, "True," states that the chromosome bivalents are indeed located at the metaphase plate during metaphase I.

During meiosis I, the cell undergoes a reduction division where the number of chromosomes is halved. So, if the cell starts with 12 chromosomes, at the end of meiosis I, each daughter cell will contain 6 chromosomes. Meiosis II is similar to mitosis, where the sister chromatids are separated. Therefore, at the end of meiosis II, each daughter cell will still contain 6 chromosomes.