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Biology Chapter 8: Mitosis and Meiosis

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Bacteria divide by:
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Binary Fission. Binary fission is the method used by bacteria to divide.
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The first step of bacterial replication is _____.
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DNA Replication. The DNA must be copied in order to proceed.
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What is different concerning the DNA in bacterial cells as opposed to eukaryotic cells?
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The amount of DNA present, whether the DNA is housed in a nucleus or not, and whether the DNA is linear or circular.
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Zookeepers at the Chester Zoo in England reported that, without sexual reproduction, a Komodo dragon laid a clutch of eggs that hatched into healthy young. What evidence confirms this claim?
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DNA testing confirmed that all of the DNA of the Komodo dragon babies was derived from their mother. Normally, an offspring would inherit half their DNA from their mother and half from their father. But, in this case, there was no father.
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Most of an organism’s DNA is carried by its _____.
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Chromosomes. An organism’s chromosomes carry most of its DNA, but some is found on small DNA molecules in mitochondria and chloroplasts.
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Replication of chromosomal DNA occurs __________.
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Chromosomes replicate before cell division. This ensures that genetic material is appropriately distributed to the daughter cells.
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How is sexual reproduction different from asexual reproduction?
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Sexual reproduction requires fertilization of an egg by a sperm. Asexual reproduction does not.
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_____ is a carcinogen that promotes colon cancer.
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Fat. A diet high in fat increases the risk of both colon and breast cancer.
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Nucleoli are present during _____.
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Interphase.
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Cytokinesis often, but not always, accompanies _____.
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Telophase.
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Chromosomes become visible during _____.
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Prophase.
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Centromeres divide and sister chromatids become full-fledged chromosomes during _____.
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Anaphase.
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Spindle fibers attach to kinetochores during _____.
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Prometaphase.
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During prophase a homologous pair of chromosomes consists of _____.
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Two chromosomes and four chromatids.
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During _____ both the contents of the nucleus and the cytoplasm are divided.
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The mitotic phase.
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During _____ the cell grows and replicates both its organelles and its chromosomes.
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Interphase.
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What must happen before a cell can begin mitosis?
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Before mitosis can begin, the chromosomes, or genetic material, must be copied, which occurs during interphase.
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The centrosomes move away from each other and the nuclear envelope breaks up during which phase of mitosis?
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Prophase is the first phase of mitosis, when the centrosomes begin moving toward opposite poles and the nuclear envelope breaks up.
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The chromosomes line up in the center of the cell during which phase of mitosis?
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Metaphase occurs in the middle of mitosis, when the chromosomes line up in the middle of the cell.
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The sister chromatids separate and begin moving toward opposite poles of the cell during which phase of mitosis?
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Sister chromatids separate and start their migration toward opposite poles during anaphase.
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The chromosomes arrive at the poles and nuclear envelopes form during which phase of mitosis?
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Telophase is the final phase of mitosis, when the chromosomes have arrived at the poles and the nuclear envelopes of the two new cells form.
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At the end of the mitotic (M) phase, the cytoplasm divides in a process called _____________.
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Cytokinesis is the division of the cytoplasm that occurs in conjunction with telophase, the last phase in mitosis.
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With the exception of gametes, a human cell contains _____ chromosomes.
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46. Human somatic cells contain 22 pairs of nonsex chromosomes (autosomes) and 2 sex chromosomes.
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The cell cycle is a series of events that occur in which order?
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G1, S, G2, mitosis, cytokinesis. All of the events are listed in the correct order. G1 refers to the gap between cell divisions. S refers to the period of time when cells are synthesizing new DNA. Mitosis happens after DNA synthesis, and cytokinesis (cell division) occurs after all of the newly replicated chromosomes are separated and the cell is ready to divide.
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Which of the following is a function of the cell cycle that involves mitosis in eukaryotes?
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Cell Replacement. Mitosis produces new cells. This results in either growth or replacement of old or damaged cells.
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What is the correct order for the four main stages of mitosis?
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Prophase, metaphase, anaphase, telophase. This is the order of the main four stages of mitosis. “Pro” means first. “Meta” means together. One of the definitions for “ana” is “divided into equal quantities.” “Telo” means last.
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What is the risk that someone in the United States will die of cancer?
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1 in 5. About 1 in 5 people in the United States will die of cancer, but many who get cancer survive.
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Gametes are produced by _____.
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Meiosis. Meiosis produces haploid gametes from a diploid parental cell.
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Normal human gametes carry _____ chromosomes.
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23.
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A diploid organism whose somatic (nonsex) cells each contain 32 chromosomes produces gametes containing _____ chromosomes.
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16. (16 is half of 32.)
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Meiosis I produces _____ cells, each of which is _____.
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Two… Haploid. At the end of meiosis I there are two haploid cells.
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Meiosis II typically produces _____ cells, each of which is _____.
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Four… Haploid. At the end of meiosis II there are typically 4 haploid cells.
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During _____ sister chromatids separate.
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Anaphase II. Anaphase II is essentially the same as mitotic anaphase except that the cell is haploid.
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At the end of _____ and cytokinesis, haploid cells contain chromosomes that each consist of two sister chromatids.
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At the end of telophase I and cytokinesis, there are two haploid cells with chromosomes that consist of two sister chromatids each.
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Synapsis occurs during _____.
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Prophase I. Synapsis, the pairing of homologous chromosomes, occurs during prophase I.
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Homologous chromosomes migrate to opposite poles during _____.
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Anaphase I. During anaphase I sister chromatids remain attached at their centromeres, and homologous chromosomes move to opposite poles.
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During _____ chromosomes align single file along the equator of a haploid cell.
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Metaphase II. Metaphase II is essentially the same as mitotic metaphase except that the cell is haploid.
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At the end of _____ and cytokinesis there are four haploid cells.
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At the end of telophase II and cytokinesis there are four haploid cells.
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During _____ a spindle forms in a haploid cell.
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Prophase II is essentially the same as mitotic prophase except that the cells are haploid.
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Which processes lead to most genetic variation in sexually reproducing organisms?
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Random fertilization, Independent Orientation of Chromosomes in Meiosis, Crossing Over