Chapter 8 Bio Quiz

Crossing over is an important process in genetic recombination. It involves the exchange of genetic material between homologous chromosomes during meiosis. This exchange results in the creation of new combinations of genes, increasing genetic diversity. Therefore, crossing over plays a crucial role in the generation of genetic variation and is essential for the evolution of species.

Sister chromatids carry the same genetic information because they are two identical copies of a single chromosome that are produced during DNA replication. They are held together by a structure called the centromere and are separated during cell division.

The most significant difference between mitosis and meiosis is that in meiosis, homologous pairs of chromosomes are split up. This is a crucial step in meiosis that ensures genetic diversity in offspring. In mitosis, chromosomes are duplicated, but they do not undergo the same splitting process as in meiosis. This difference is important because it allows for the formation of gametes with unique combinations of genetic material during meiosis.

During anaphase of mitosis, the chromosomes are already replicated and are being separated into two daughter cells. This process does not involve any exchange or rearrangement of genetic material, therefore it does not lead to genetic variability.

The number of chromosomes in an organism's cells is typically halved during the process of meiosis, which occurs during the formation of eggs and sperm. Therefore, if a toad skin cell has 22 chromosomes, a toad egg would contain half of that number, which is 11 chromosomes.

During telophase 2 of meiosis, the chromosomes have already separated and are now in separate cells. Each of these cells will have half the amount of DNA as the original cell. Therefore, the quantity of DNA in one of the grasshopper cells produced by telophase 2 of meiosis would be 50 units.

During sexual reproduction, the sperm and egg cells combine to form a new individual. In most organisms, including grasshoppers, the sperm and egg cells each contain half the number of chromosomes as the other cells in the body. Since the intestinal cell in the grasshopper contains 24 chromosomes, the sperm cell would contain half that number, which is 12 chromosomes.

Meiosis is the process in which cells undergo two divisions to produce gametes (sperm and eggs). During meiosis, the number of chromosomes in the cells is halved, resulting in haploid cells with half the number of chromosomes as the parent cell. This reduction in chromosome number is important for sexual reproduction, as it ensures that when the gametes combine during fertilization, the resulting offspring will have the correct number of chromosomes. Therefore, the answer "halves the number of chromosomes in cells" accurately describes the process of meiosis.

Somatic cells in humans are diploid, meaning they have two sets of chromosomes (one set from each parent). On the other hand, gametes (such as sperm and egg cells) are haploid, meaning they have only one set of chromosomes. Therefore, the correct answer is "somatic cells...gametes".

Mitosis is the process of cell division that results in the formation of two identical daughter cells. It is responsible for various functions in humans, such as repair of wounds, growth, replacement of lost or damaged cells, and multiplication of somatic cells. However, the production of gametes from diploid cells is not a function of mitosis. Gametes, which are sperm and egg cells, are produced through a different process called meiosis, which involves two rounds of cell division to reduce the number of chromosomes in the resulting cells.

In prophase of mitosis, the nuclear membrane breaks down and the miotic spindle begins to form. This is the opposite of what happens in telophase, where the miotic spindle breaks down and nuclear membranes form.

Muscle cells, also known as muscle fibers, are specialized cells that make up muscle tissue. Unlike other types of cells, such as skin cells, cancer cells, cells from an embryo, and intestinal lining cells, muscle cells have a unique characteristic of being multinucleated. This means that they have multiple nuclei within a single cell, which is a result of the fusion of multiple myoblasts during development. Due to this multinucleated nature, muscle cells do not undergo typical cell division, known as mitosis, making it unlikely to see them dividing.

The statement "Bacteria have to duplicate their DNA before dividing; human cells do not" is not a difference between fission of a bacterium and human cell division. Both bacteria and human cells need to duplicate their DNA before dividing. This is a crucial step in the process of cell division to ensure that each daughter cell receives a complete set of genetic information.

Miotic cell division in animals is responsible for asexual reproduction, growth, repair of damaged organs, and cell replacement. However, the production of gametes is not a function of miotic cell division. Gametes, which are reproductive cells, are produced through a different process called meiosis. Meiosis involves two rounds of cell division and results in the formation of haploid cells with half the number of chromosomes. Therefore, the production of gametes is not a function of miotic cell division.

The correct answer is G1- immediately follows cell division. The cell cycle consists of several phases, including G1, S, G2, and M. G1 is the first gap phase, which occurs immediately after cell division. During this phase, the cell grows in size and prepares for DNA replication in the S phase. Therefore, G1 immediately follows cell division.

Deletion is the most drastic chromosomal alteration because it involves the loss of a segment of the chromosome. This loss can result in the deletion of important genes or regulatory elements, leading to significant changes in the genetic information. In contrast, inversion, duplication, and translocation may cause disruptions or rearrangements of genetic material, but they do not involve the loss of genetic information like deletion does. Therefore, deletion has the most severe consequences among the given options.

The correct answer is cytokinesis. Cytokinesis is the process in which the cytoplasm of a cell is divided into two daughter cells during cell division. Microfilaments play a crucial role in the formation of the contractile ring, which constricts and separates the two daughter cells. Therefore, if the chemical interferes with the activity of microfilaments, it will likely disrupt cytokinesis the most.

When cells undergo mitosis repeatedly without undergoing cytokinesis, it results in the formation of large cells containing many nuclei. This is because mitosis is the process of cell division that results in the formation of two daughter cells, while cytokinesis is the process of dividing the cytoplasm and forming separate cell membranes. Without cytokinesis, the cells continue to replicate their DNA and divide their nuclei through mitosis, but the cytoplasm remains undivided, leading to the formation of cells with multiple nuclei.

During the G1 phase of the cell cycle, cells undergo growth and prepare for DNA replication. At this checkpoint, cells receive signals from the environment to determine if they are ready to proceed with division. If the proper signal is received, the cells will continue into the S phase to replicate their DNA. Therefore, the correct answer is G1.

An inversion is a chromosomal abnormality that occurs when a fragment of a chromosome breaks off and reattaches to the original chromosome, but in the reverse direction. This results in a rearrangement of genetic material within the chromosome.

During the G2 phase of the cell cycle, the cell undergoes DNA replication, resulting in the doubling of the amount of DNA. Therefore, if the grasshopper cells contained 200 units of DNA during the G2 phase, each daughter cell formed during telophase of mitosis would contain half of that amount, which is 100 units.

The correct answer is "carry information for the same characteristics at corresponding locations." This is because homologous chromosomes contain genes that code for the same traits or characteristics, and these genes are located at corresponding positions on each chromosome. Therefore, the chromosomes carry information for the same characteristics at corresponding locations.

Cytochalisin B disrupts microfilament formation, which is essential for the process of cleavage. Cleavage is the division of a cell into two daughter cells during cell division. Microfilaments play a crucial role in the formation of the contractile ring, which constricts the cell membrane during cleavage. Therefore, if Cytochalisin B interferes with microfilament formation, it would hinder the process of cleavage.

The picture shows 7 chromosomes, each consisting of 2 chromatids. This indicates that the cell is in the prophase 2 of meiosis. In prophase 2 of meiosis, the chromosomes have already replicated and consist of two sister chromatids. The chromosomes are also condensed and visible under a microscope.

A fruit fly somatic cell contains 8 chromosomes. During meiosis, the chromosomes undergo recombination and independent assortment, resulting in different combinations of chromosomes in the gametes. Each chromosome can independently assort, so the total number of possible combinations is 2^8, which equals 256. However, since the question asks for the number of different combinations, we divide this number by 2 to account for the fact that each combination can be produced in two different ways (e.g., AB and BA). Therefore, the correct answer is 256/2 = 128.

Meiosis is the process by which cells divide and produce eggs or sperm. It is known that meiosis takes longer in the ovary compared to the testes. This increased duration provides more opportunities for errors to occur during the division process, such as the incorrect separation of chromosomes. As a result, geneticists suspect that the extra chromosome seen in Down syndrome usually comes from the egg rather than the sperm.

The correct answer is that extra copies of the chromosomes are probably fatal. This means that individuals with an extra chromosome 3 or chromosome 16 are less likely to survive, resulting in fewer individuals with these extra chromosomes compared to individuals with an extra chromosome 21. This could be due to the fact that having extra copies of certain genes on chromosome 21 may be less detrimental to survival compared to having extra copies of genes on chromosomes 3 or 16.

During interphase, chromosomes are in the form of long thin strands called chromatin. This is because the DNA has not yet condensed and replicated to form distinct chromosomes. Therefore, it is difficult to observe individual chromosomes during this phase.

During prophase 1 of meiosis, the chromosomes replicate to form sister chromatids, resulting in 200 chromosomes, each consisting of 2 chromatids. However, during meiosis, there are two rounds of cell division. At telophase 2 of meiosis, the sister chromatids separate, resulting in four cells with half the number of chromosomes as the original cell. Therefore, each of the four cells would have 100 chromosomes, each consisting of 1 chromatid.

During the S phase of the cell cycle, DNA replication occurs. Sister chromatids are produced during this phase, where each replicated chromosome consists of two identical chromatids held together by a centromere. These sister chromatids are then separated during the first meiotic division, ensuring that each resulting daughter cell receives one copy of each chromosome. Therefore, the correct answer is that sister chromatids are produced during the S phase between cell divisions.

A karyotype is a visual representation of an individual's chromosomes, arranged in pairs according to size and shape. It is used to identify abnormalities in the number or structure of chromosomes. In a karyotype, part of a chromosome turned around would not be easily identifiable as it would not change the overall number or size of chromosomes. Therefore, it is least likely to be shown in a karyotype.

During prophase 2 of meiosis, the sister chromatids separate and move towards opposite poles of the cell. This results in the formation of haploid cells with half the number of chromosomes as the parent cell. Since the picture showed 19 chromosomes, each consisting of two sister chromatids, it suggests that the cell is undergoing meiosis and has not yet completed the second round of division. Therefore, the picture could have been taken during prophase 2 of meiosis.

During the M phase of the cell cycle, the cell undergoes mitosis, which is the process of cell division. In mitosis, the DNA replicates and then separates into two identical sets, one for each new cell. Therefore, the quantity of DNA in a cell doubles during the M phase of the cell cycle.