Chapter 8 stuff. – Flashcards
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The creation of genetically identical offspring by a single parent, without the participation of sperm and egg, is called
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asexual reproduction.
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Which of the following statements regarding sexual and asexual reproduction is true?
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Sexual reproduction is more likely to increase genetic variation than is asexual reproduction.
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Asexual reproduction requires ________ individual(s).
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1
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With the exception of identical twins, siblings who have the same two biological parents are likely to look similar, but not identical, to each other because they have
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a similar but not identical combination of genes.
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Which of the following statements regarding cell division is false?
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Cell division is common in eukaryotes but rare in prokaryotes.
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Which of the following statements regarding prokaryotes is false?
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Prokaryotic chromosomes are more complex than those of eukaryotes.
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Eukaryotic chromosomes differ from prokaryotic chromosomes in that they
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are housed in a membrane-enclosed nucleus.
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Sister chromatids are
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joined together at a centromere.
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Prior to mitosis, each chromosome of a eukaryotic cell consists of a pair of identical structures called
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sister chromatids.
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Eukaryotic cells spend most of their cell cycle in which phase?
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interphase
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Which of the following occurs during interphase?
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cell growth and duplication of the chromosomes
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The genetic material is duplicated during
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the S phase.
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Looking into your microscope, you spot an unusual cell. Instead of the typical rounded cell shape, the cell has a very narrow middle separating two bulging ends. It sort of looks like the number 8! Then you realize that this cell is
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undergoing cytokinesis.
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The phase of mitosis during which the mitotic spindle begins to form is
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prophase
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During which phase of mitosis do the chromosomes line up on a plane equidistant from the two spindle poles?
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metaphase
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At the start of mitotic anaphase,
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the centromeres of each chromosome come apart.
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During which phase of mitosis does the nuclear envelope re-form?
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telophase
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Which of the following is a feature of plant cell division that distinguishes it from animal cell division?
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formation of a cell plate
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Which of the following must occur for a plant or animal to grow and develop normally?
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The organism must be able to control the timing and rate of cell division in different parts of its body.
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When animal cells are grown in a petri dish, they typically stop dividing once they have formed a single, unbroken layer on the bottom of the dish. This arrest of division is an example of
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density-dependent inhibition.
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As a patch of scraped skin heals, the cells fill in the injured area but do not grow beyond that. This is an example of
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density-dependent inhibition.
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Mature human nerve cells and muscle cells
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are permanently in a state of nondivision.
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Which of the following statements regarding the cell-cycle control system is false?
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The cell-cycle control system operates independently of the growth factors.
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You are asked to culture an unidentified sample of animal tissue. You notice that the cells seem to fail to exhibit density-dependent inhibition. The source of this tissue sample is most likely
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a cancer.
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A benign tumor differs from a malignant tumor in that a benign tumor
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does not metastasize.
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Which of the following shows the greatest promise as a cancer chemotherapy agent?
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a drug that prevents mitotic spindle from forming
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Two chromosomes in a nucleus that carry genes controlling the same inHerited characteristics are
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Homologous chromosomes.
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Which of the following statements is false?
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An X chromosome is an autosome.
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During which stage of meiosis do synapsis and crossing over occur?
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prophase I
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Both mitosis and meiosis are preceded by
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interphase
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Independent orientation of chromosomes at metaphase I results in an increase in the number of
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possible combinations of characteristics.
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Karyotyping
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can reveal alterations in chromosome number.
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Which of the following statements regarding Down syndrome is false?
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Down syndrome is least likely to be seen in the infants of mothers over 40.
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Nondisjunction occurs when
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members of a chromosome pair fail to separate.
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Which of the following statements about nondisjunction is false?
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In mammals, extra copies of the Y chromosome are typically inactivated.
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If a chromosome fragment breaks off and then reattaches to the original chromosome, but in the reverse direction, the resulting chromosomal abnormality is called a(n)
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inversion
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According to the graph, at what maternal age does the incidence of Down syndrome begin to increase substantially?
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about 37 or 38
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Cancer is not usually inherited because
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the chromosomal changes in cancer are usually confined to somatic cells.
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Which of the following variations of the sentence "Where is the cat" is most like a chromosomal deletion?
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Where is cat?
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A karyotype is most like
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photographs of every couple at a high school prom.
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If these four cells resulted from cell division of a single cell with diploid chromosome number 2n = 4, what best describes what just occurred?
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nondisjunction
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What type of cell is shown?
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plant cell in telophase
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The process by which the cytoplasm of a eukaryotic cell divides to produce two cells is called
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cytokinesis
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Which of the following features likely accounts for the difference between plant and animal cell cytokinesis?
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Plant cells have cell walls.
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Which of the following is probably the main factor responsible for the phenomenon of density-dependent inhibition?
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physical contact of cell-surface proteins between adjacent cells
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Which of the following statements regarding the function of mitosis is false?
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Mitosis allows organisms to generate genetic diversity.
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Which of the following statements regarding the differences between mitosis and meiosis is false?
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Crossing over is a phenomenon that creates genetic diversity during mitosis.
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Without crossing over
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genetic recombination could not occur.
