Chapter 6 Learning Curve + Chapter 6 quizzes – Flashcards
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_________ marks the break in the cell cycle between the end of mitosis and beginning of the synthesis stage. A. Gap 1 B. cytokinesis C. DNA synthesis phase D. Gap 2 E. None of the above.
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A. Gap 1
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Programmed cell death, or __________, takes place particularly in parts of the body where the cells are likely to accumulate significant genetic damage over time and are therefore at high risk of becoming cancerous.
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Apoptosis
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In multicellular organisms, cells that undergo mitotic division but not meiotic division are called _____ cells. A. Germ B. Somatic C. Interphase D. Skin E. Somosis
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B. Somatic
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In some species, sex is determined by environmental, rather than genetic, factors. This is true of: A. Turtles. B. Bees. C. Birds. D. Humans. E. Kangaroos.
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A. Turtles
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Nondisjunction: A. occurs during mitosis but not meiosis. B. is the cause of sex determination in birds and mammals. C. is the unequal division of the genetic material during cell division. D. is the division of cytoplasmic constituents. E. occurs only in prophase I of meiosis.
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C. is the unequal division of the genetic material during cell division.
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The linear strands of DNA in eukaryotes are efficiently packed within the nucleus of the cell. The packing of DNA strands are mediated by proteins called: A. nucleosomes. B. barr bodies. C. histones. D. topoisomerases. E. DNA polymerases.
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C. Histones
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Using a light microscope, it is easiest to see chromosomes: A. in the mitochondria because they are circular. B. during interphase when they are concentrated in the nucleus. C. during mitosis and meiosis because the condensed chromosomes are thicker and therefore more prominent. D. during interphase because they are uncoiled and have a more linear structure. E. during asexual reproduction.
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C. during mitosis and meiosis because the condensed chromosomes are thicker and therefore more prominent.
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Chromosomes on which recombination takes place: A. have a mixtures of maternal and paternal chromosomes. B. are created during meiosis. C. contain more dominant genes than recessive. D. usually result in aborted fetuses. E. Both the first and second choices are correct.
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E. Both the first and second choices are correct. Correct. Recombination (crossing over) produces a mixture of maternal and paternal genes on each chromatid and this only occurs meiosis.
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http://www.macmillanhighered.com/externalcontent/learningcurve.bfwpub.com/question_pics/x_and_y_chromosomes.gif Which of the following is TRUE about sex determination in humans? A. An X chromosome is smaller than a Y chromosome. B. Without a Y chromosome, a fertilized egg usually dies. C. The father's sperm determines the gender of a baby. D. In the absence of a Y chromosome, the fetal gonads develop into ovaries, not testes. E.One would expect babies to have two Y chromosomes about half the time.
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C. The father's sperm determines the gender of a baby.
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Which of the following combinations of sex chromosomes is never seen in human being? A. XXY B. XXX C. YYY D. X_ (also written as XO) E. XYY
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C. YYY Each egg always gets at least one X chromosome. Therefore, it is impossible to have a YYY individual.
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After replication, the region of contact between sister chromatids, which occurs near the center of the two chromosome strands is called the _____________.
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Centromere
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Cancer cells differ from normal cells in two important aspects. They are: A. the ability to metastasize and retention of contact inhibition. B. loss of contact inhibition and the halting of all cell division. C. apoptosis and contact inhibition. D. a halting of all cell division and the ability to metastasize. E. indefinite cell division and the loss of contact inhibition.
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E. indefinite cell division and the loss of contact inhibition. Cancer cells can divide indefinitely and spread to remote locations from an originating tumor as a result of their loss of contact inhibition.
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The human genome comprises: A. 46 pairs of chromosomes. B. 48 chromosomes. C. 46 chromosomes. D. an X and a Y chromosome. E. 23 chromosomes.
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46 chromosomes. The human genome has 46 chromosomes total.
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Which of the following is NOT a method of sex determination that occurs in nature? A. In bees, the eggs that the queen allows to be fertilized become females and the eggs she doesn't fertilize become males. B. In birds, the female is the heterogametic (ZW) sex and the male is the homogametic (ZZ) sex. C. In sea turtles, eggs laid in hot sand become females and eggs laid in cooler sand become males. D. In humans, the male is the heterogametic (XY) sex and the female is the homogametic (XX) sex. E. All of the above are naturally occurring examples of sex determination.
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All of the above are naturally occurring examples of sex determination. All of the above are actually methods of sex determination in nature.
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Which of the following statements about nondisjunction is true? A. Trisomy occurs in chromosomes 1, 13, 15, 18, 21, and 22. B. Nondisjunction can occur when sister chromatids fail to separate during meiosis I or when homologues fail to separate during meiosis II. C. Some chromosomes are more likely to fail to separate during cell divisions, which is why trisomy 21 is more common than others. D. The survival rate of developing embryos with trisomy is related to the sizes of chromosomes. E. The gametes of a male at age 80 will have as many errors as the gametes of a female half that age.
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D. The survival rate of developing embryos with trisomy is related to the sizes of chromosomes. A karyotype reveals that chromosome are numbered in order of size. Larger chromosomes have more genes, which makes them less likely to survive to birth.
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Binary fission is to asexual reproduction as __________ is to __________. A. dividing into two; genetically different offspring B. meiosis; mitosis C. dividing into four; genetically different offspring D. dividing into two; genetically identical offspring E. mitosis; meiosis
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D. dividing into two; genetically identical offspring Binary fission results in two genetically identical cells. Because they do not have nuclei, they do not divide by mitosis. Cells that divide by asexual reproduction result in two cells that are genetically identical.
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Mitosis results in: A. daughter cells with the same number of chromosomes but different combinations of alleles. B. daughter cells with the same number and composition of chromosomes. C. daughter cells with twice as much genetic material and a unique collection of alleles. D. gametes. E. eight daughter cells.
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B. daughter cells with the same number and composition of chromosomes. Daughter cells are genetically identical to the parent cell.
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What is the definition of "female"? A. producing the larger, less motile gamete B. producing the smaller, less motile gamete C. producing the female reproductive system D. producing the smaller, more motile gamete E. producing more gametes
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A. producing the larger, less motile gamete The slight variation in meiosis in the production of female gametes results in the production of a larger, less motile gamete because of unequal cytoplasmic division.
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Which of the following conditions is the result of too few sex chromosomes? A. Turner syndrome B. Down syndrome C. Klinefelter syndrome D. "Metafemales" E. "Super Males"
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A. Turner syndrome
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Telomeres have been directly linked to aging in humans. If scientists were able to develop treatments that could reverse the shortening of telomeres, would they be able to reverse the aging of humans? A. No, organisms that have lost normal telomere function are sterile. B. No, cells that have lost normal telomere function are cancerous. C. Yes, scientists have succeeded in creating immortal rats through telomere treatments. D. Yes, this is the subject of intense research. E. No, aging in humans has more to do with gene mutation than telomeres.
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B. No, cells that have lost normal telomere function are cancerous. Cells that acquire the ability to rebuild telomeres can continuously divide.
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During which phase of the cell cycle do the chromosomes align in one plane at the center of the cell? A. G2 B.. Interphase C. Metaphase D. Prophase E. Anaphase
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C. Metaphase Metaphase is when the duplicated, condensed chromosomes are aligned in the center of the cell.
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Which of the following is NOT a disadvantage of sexual reproduction? A. The transfer of genetic information from generation to generation is not as efficient as it is during asexual reproduction. B. Sexual reproduction breaks down genotypes that are well-adapted for a stable environment. C. It takes time and energy to find a mating partner. D. Variability among offspring enables parents to produce a range of offspring, any one of which may be suitable to changes in the environment. E. Organisms can expose themselves to danger during the mating process.
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D. Variability among offspring enables parents to produce a range of offspring, any one of which may be suitable to changes in the environment. A major advantage of sexual reproduction is that it increases variability in a population. Asexual reproduction, in contrast, does not increase genetic variation in a population, which may in turn limit its ability to adapt to changes in the environment.
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A part of the cytoskeleton of a cell, formed in prophase (in mitosis) or in prophase I (in meiosis), from which extend fibers that organize and separate the sister chromatids is called the ________.
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The Spindle The spindle can be thought of as a group of parallel threads stretching across the cell between its two ends, or poles.
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During which stage of the mitotic cell cycle do the chromosomes decondense back to strands of chromatin and each set of separated genetic material becomes enclosed in a nuclear envelope to form two daughter nuclei? A. Gap-1 B. S-phase C. anaphase D. metaphase E. telophase
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E. telophase In telophase the already separated chromosomes are beginning to decondense, the nuclear envelope reforms and the cell begins to pinch into two cells.
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Without histones, eukaryotic DNA most likely would be: A. attached to a large number of stick proteins. B. much longer than it is. C. found in a greater number of chromosomes. D. circular, as it is in prokaryotes. E. much more tightly coiled.
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B. much longer than it is. Histones are used to package DNA, so they take up less space.
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http://www.macmillanhighered.com/externalcontent/learningcurve.bfwpub.com/question_pics/phelan3e_ch6_mitosispromet.jpg The image above shows the events that occur as a cell moves between which two phases of the mitotic cell cycle? A. prophase to metaphase B. telophase to cytokinesis C. metaphase to anaphase D. anaphase to interphase E. interphase to prophase
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prophase to metaphase A. The first cell in the image shows already duplicated, condensed chromosomes indicating prophase and the second cell in the image shows the duplicated, condensed chromosomes aligned in the center of the cell indicating metaphase.
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http://www.macmillanhighered.com/externalcontent/learningcurve.bfwpub.com/question_pics/prophase.gif Which of the following does NOT occur during Prophase I of meiosis? A. Chromosomes begin to condense. B. Homologous pairs of chromosomes separate and move toward the poles. C. A protein structure called a synaptonemal complex forms between the homologues. D. Spindle is formed. E. Crossing over between tetrads occurs.
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B. Homologous pairs of chromosomes separate and move toward the poles. This step does not occur in prophase, but takes place during anaphase and telophase.
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Healthy individuals may have just one sex chromosome, as long as it is an X chromosome. Why can't a person survive with a Y chromosome and no X chromosome? A. The Y chromosome has a full complement of genetic material, much of which is vital to life; the X chromosome is missing the vast majority of these genes. B. A person with just an X chromosome would be a female, while a person with just a Y chromosome would not have a sexual identity. C. The X chromosome has a full complement of genetic material, much of which is vital to life; the Y chromosome is missing the vast majority of these genes. D. The X chromosome is capable of duplicating itself, so that the affected individual will eventually have two X chromosomes; the Y chromosome is incapable of duplicating itself. E. The statement above is incorrect; it is possible to survive with just a Y chromosome, it's just very rare.
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C. The X chromosome has a full complement of genetic material, much of which is vital to life; the Y chromosome is missing the vast majority of these genes. The X chromosome carries many essential genes whereas the Y chromosome does not.
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If DNA replication occurs by unwinding and rebuilding, then: A. the two resulting DNA molecules are an unpredictable mixture of old and newly synthesized DNA. B. the two resulting DNA molecules each contain one original strand and one new strand. C. the two resulting DNA molecules are completely composed of newly synthesized strands. D. both the first and second choices are true. E. None of the above is true about DNA replication.
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C. the two resulting DNA molecules each contain one original strand and one new strand.
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http://www.macmillanhighered.com/externalcontent/learningcurve.bfwpub.com/question_pics/mitosis.gif Which of the following places the events of mitosis into the CORRECT order? A. Chromosomes line up in the middle of the cell, cytokinesis occurs, sister chromatids separate, chromosomes wind up B. Chromosomes wind up, chromosomes line up in the middle of the cell, sister chromatids separate, cytokinesis occurs C. Sister chromatids separate, chromosomes wind up, cytokinesis occurs, chromosomes line up in the middle of the cell D. Chromosomes wind up, sister chromatids separate, chromosomes line up in the middle of the cell, cytokinesis occurs E. Cytokinesis occurs, chromosomes wind up, chromosomes line up in the middle of the cell, sister chromatids separate
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B. Chromosomes wind up, chromosomes line up in the middle of the cell, sister chromatids separate, cytokinesis occurs Cells undergoing mitosis must replicate their chromosomes, and they condense during interphase. Chromosomes migrate to and line up along the center, called the equator. The sister chromatids separate and move to the poles of each daughter cell, the nuclear envelope forms around each set of chromosome of daughter cells. Finally, and occurring simultaneously with latter parts of mitosis, cytoplasm divides up among the two daughter cells during cytokinesis.
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Which of the following does NOT contribute to variability of the offspring in sexual reproduction? A. The swapping of genetic information between homologues during meiosis B. Crossing over in prophase I of meiosis C. Combining genes from two unrelated parents during fertilization D. The different ways homologous can separate in metaphase I E. A brother and a sister producing children together
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E. A brother and a sister producing children together This difference would not directly result in variation.
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Which of the following is TRUE about prokaryotic reproduction? A. Four cells are produced from a single parent cell. B. Mitosis is used. C. It is a form of sexual reproduction. D. The chromosomes wind up into tight packages before cellular division. E. A single circular DNA helix is replicated into two identical circular DNA helices.
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E. A single circular DNA helix is replicated into two identical circular DNA helices. Prokaryotic cells do not have nuclei. Binary fission results in two genetically identical cells.
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All of the following are cells that undergo mitosis, EXCEPT: A. skin cells. B. yeast. C. stomach cells. D. muscle cells. E. sperm cells.
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E. sperm cells.
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Which of the following is TRUE about meiosis in men and women? A. The egg is motile, while the sperm is not. B. In egg production, the division of cells in meiosis produces cells of equal size. C. Women make sperm, while men make eggs. D. Sperm production results in four cells from one starting cell; for eggs, only one egg results from one starting cell. E. Sperm are larger in size than eggs.
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D. Sperm production results in four cells from one starting cell; for eggs, only one egg results from one starting cell.
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Which of the following explains the fact that the Y chromosome carries nonessential information? A. A man who inherits two or three Y chromosomes as a result of an error in meiosis is fully normal. B. Sperm contribute no genetic information to the egg in fertilization. C. Eggs that are not fertilized can still develop into normal human being. D. Women don't have a Y chromosome and are not genetically disadvantaged. E. Males are not needed in sexually reproducing species.
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D. Women don't have a Y chromosome and are not genetically disadvantaged. Females have two copies of the X chromosomes and no Y chromosomes. The genetic information included in the Y chromosomes contributes to male sexual characteristics.
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Which of the following is NOT true about the human karyotype? A. It can reveal whether non-disjunction occurred in an egg or sperm. B. It can be made from placental tissue. C. It can be made from cells gathered by amniocentesis. D. It reveals the gender of the individual. E.It can be used to diagnose genetic diseases like cystic fibrosis.
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E. It can be used to diagnose genetic diseases like cystic fibrosis. Many genetic diseases, like cystic fibrosis, are due to mutations in a particular gene which cannot be detected in a karyotype. A karyotype can only detect changes in chromosome number or structure.
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Which of the following statements about tumors is FALSE? A. Cancer cells from malignant tumors can travel to other parts of the body in a process call metastasis. B. Tumors are caused by excessive cell growth and division. C. They contain cells with abnormally high contact inhibition. D. Malignant tumors shed cancer cells that can spread to other parts of the body. E. Benign tumors pose less of a health risk than do malignant tumors.
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C. They contain cells with abnormally high contact inhibition. This is the false statement. In fact, cancer cells have an abnormally LOW level of contact inhibition.
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The spindle begins to assemble at which phase of the mitotic cell cycle?
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Prophase
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Which of the following statements about telomeres is FALSE? http://www.macmillanhighered.com/externalcontent/learningcurve.bfwpub.com/question_pics/telomere.gif A. They function like a counter, keeping track of how many times a cell has divided. B. They contain no critical genes. C. They function like a protective cap on chromosomes. D. They are slightly shorter in prokaryotic cells than in eukaryotic cells. E. At birth, they are long enough to permit approximately 80-90 cell divisions in most cells.
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D. They are slightly shorter in prokaryotic cells than in eukaryotic cells. Prokaryotes don't have telomeres, so this statement is false.
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If a cell containing 10 chromosomes divides by mitosis, how many daughter cells will be produced? A. 20 B. 5 C. 2 D. 10 E. 15
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C. 2 At the end of mitosis there will be 2 identical daughter cells produced.
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How does crossing over introduce variation in meiosis? A. It increases the amount of DNA in the nucleus. B. It causes homologous chromosomes to be grouped differently. C. It positions alleles next to each other that previously were not together. D. It causes eggs and sperm to unite in different ways. E. It causes all the homologous chromosomes to find new partners.
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C. It positions alleles next to each other that previously were not together. Crossing over produces a mixture of maternal and paternal alleles on each chromatid.
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Joseph went to a copy center and used a copy machine to make a duplicate set of 46 pages. Joseph then stapled every copied sheet to its original. This is similar to how a cell replicates its chromosomes in mitosis. For what reason would a cell do something similar during mitosis? A.to keep the cell from making too many copies of a particular chromosome B.to allow the cell to move onward into Gap 1 phase C.to keep the copies and originals organized for later separation D.to keep the cell from dividing too early E.to introduce helpful mutations that make mitosis more successful
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c. to keep the copies and originals organized for later separation During the DNA duplication subphase of interphase, the cell produces sister chromatids that are exact duplicates of each chromosome. Therefore, each set of homologous chromosomes is made up of duplicated sister chromatids that will separate during mitosis.
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Bacteria reproduce asexually, whereas most plants and animals reproduce sexually. Which is the better method? A.Neither method is better—each is effective in different environments for different kinds of organisms. B.Asexual reproduction, because there are more bacteria than plants and animals. C.Sexual reproduction, because there are more plants and animals than bacteria. D.Asexual reproduction, because binary fission is more efficient. E.Sexual reproduction, insures more offspring.
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A.Neither method is better—each is effective in different environments for different kinds of organisms. There are advantages and disadvantages to both sexual and asexual reproduction. Asexual reproduction, while fast and efficient, produces no genetic variety to enable adaptation. Sexual reproduction produces genetic diversity, however it is risky and requires more time and energy.
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The rate at which mitosis occurs varies dramatically for different types of cells. The most rapid cell division occurs: A. on the skin. B. in the blood and the cells lining the various tissues of organs. C. in the gametes. D. in the blood and the heart. E. in the liver and the brain.
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B. in the blood and the cells lining the various tissues of organs. Red blood cells made in the bone marrow are short lived cells as are the cells lining the intestine.
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If a cell containing 8 chromosomes divides by mitosis, how many chromosomes will be in each daughter cell? A. 2 B. 4 C. 26 D. 16 E. 8
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E. 8 There will be 8 chromosomes in each daughter cell after a cell with 8 chromosomes undergoes mitosis. The outcome of mitosis and cytokinesis is two, genetically identical cells.
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Which is NOT true about a pair of homologous chromosomes? A. Both chromosomes are the same length. B. Both chromosomes have centromeres in the same location. C. One homologue is of paternal origin, while the other is of maternal origin. D. One of the two homologous chromosomes is produced by the cell during DNA synthesis phase. E. Both chromosomes carry information about the same genetic characteristics.
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D. One of the two homologous chromosomes is produced by the cell during DNA synthesis phase. This is an incorrect statement. During the DNA synthesis phase, sister chromatids are produced, which are exact copies of each other
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Which of the following is the direct product of DNA replication? A. The two strands in a DNA helix B. The lining up of chromosomes in mitosis metaphase C. Cytokinesis D. The production of two spindle fibers E. Two sister chromatids
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E. Two sister chromatids Sister chromatids produced during mitosis are exact copies of each other and will separate during mitosis.
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The float in a toilet tank stops the filling of the tank when the water reaches a certain level. If this float is damaged so that it sinks instead, the water would overflow the tank after a flush. This scenario is similar to which of the following cellular concepts? A.the lengthening of telomeres B.increase in cell suicides C.loss of contact inhibition D.failure of cancer cells to metastasize E.loss of the ability to perform mitosis
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C.loss of contact inhibition If cells no longer have contact inhibition, they will continue to migrate regardless of their contact will other cells of their own type and may move to other remote locations of an organism.
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Which of the following is the BEST definition of a homologous chromosome? http://www.macmillanhighered.com/externalcontent/learningcurve.bfwpub.com/question_pics/homologous_pair.gif A.the type of chromosome found in prokaryotes B.one of two identical chromosomes held together by a centromere C.the central area that joins two chromatids D. one of two chromosomes of the same length and type inherited from a father or mother E.a chromosome that has undergone crossing over
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D. one of two chromosomes of the same length and type inherited from a father or mother In diploid organisms, such as humans, cells carry pairs of chromosomes. One of each chromosome is from a different biological parent. Having pairs of chromosomes lessens the chances that an undesirable allele will be expressed.
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Which of the following is NOT a known mechanism of sex determination? A. Females develop from diploid (fertilized) eggs, while males develop from haploid (unfertilized) eggs. B. Males develop from eggs with no chromosomes, females from diploid eggs. C. Eggs that are kept hot during incubation become females; otherwise, the egg is male. D. Females have two different chromosomes (WZ), while males have two of the same chromosome (ZZ). E. An individual is both male and female at the same time, having gonads for each sex.
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B. Males develop from eggs with no chromosomes, females from diploid eggs. Since chromosomes are made up of genes, they must be present in a cell at some point in their existence.
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How many sex chromosomes does the normal human female inherit from her mother? A. 23 B. 2 pairs C. 46 D. 2 E. 1
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E. 1 A normal human female will inherit one of the two sex chromosomes from her mother.
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The human genome comprises: A. 46 chromosomes. B. an X and a Y chromosome. C. 46 pairs of chromosomes. D. 48 chromosomes. E. 23 chromosomes.
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A. 46 chromosomes.
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Which of the following statements about telomeres is FALSE? A.They function like a protective cap on chromosomes. B.They contain no critical genes. C.They are slightly shorter in prokaryotic cells than in eukaryotic cells. D.They function like a counter, keeping track of how many times a cell has divided. E.At birth, they are long enough to permit approximately 80-90 cell divisions in most cells.
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C.They are slightly shorter in prokaryotic cells than in eukaryotic cells. Prokaryotes don't have telomeres, so this statement is false.
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Gap 1, S phase (DNA synthesis), and Gap 2 of the cell cycle are collectively called: A. prophase. B. mitosis. C. cytokinesis. D. M phase. E. interphase.
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E. interphase.
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Odometer is to an old, rusty car as __________ is to _________. A. DNA replication, cell division B. circular chromosome, linear chromosome C. asexual reproduction, sexual reproduction D. telomere, a cell after 50 cell divisions E. binary fission, mitosis
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D. telomere, a cell after 50 cell divisions
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DNA replication is facilitated by the fact that the base on one strand of the double helix (T, for example) always has the same partner (A, in this case) on the other strand. This feature of DNA is called: A. cytokinesis. B. complementarity. C. duplication. D. translation. E. transcription.
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B. complementarity.
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If a cell containing 20 chromosomes divides by mitosis, a total of how many daughter cells will be produced? A. 1 B. 2 C. 4 D. 20 E. 40
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B. 2
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The stage of the cell cycle where the chromosomes are aligned along the equator in single file is called: A. Gap-1. B. metaphase. C. S-phase. D. anaphase. E. telophase.
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B. metaphase.
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The image above shows the events that occur as a cell moves between which two phases of the mitotic cell cycle? http://www.macmillanhighered.com/externalcontent/digitalfirst.bfwpub.com/phelan_check_your_knowledge/asset/mitosis_pm.png A. interphase to prophase B. anaphase to interphase C. prophase to metaphase D. metaphase to anaphase E. telophase to cytokinesis
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C. prophase to metaphase
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Unrestrained cell growth and division that causes serious health problems is called: A. diabetes. B. cytokinesis. C. cancer. D. metaphase. E. mitosis.
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C. cancer.
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Which process is necessary to prevent the doubling of genome size during sexual reproduction? A. metastasis B. contact inhibition C. meiosis D. apoptosis E. mitosis
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C. meiosis Meiosis: a type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell, as in the production of gametes and plant spores. Mitosis: a type of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus, typical of ordinary tissue growth.
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Sex cells having the ___________ number of chromosomes are called ____________. A. haploid; zygotes B. diploid; somatic cells C. diploid; sperm D. diploid; gametes E. haploid; gametes
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E. haploid; gametes
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Which of the following is TRUE about meiosis in men and women? A. Sperm are larger in size than eggs. B. Women make sperm while men make eggs. C. In egg production, the division of cells in meiosis produces cells of equal size. D. The egg is motile while the sperm is not. E. Sperm production results in 4 cells from one starting cell; for eggs, only one egg results from one starting cell.
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E. Sperm production results in 4 cells from one starting cell; for eggs, only one egg results from one starting cell.
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Of all the varying types of sex-chromosomal abnormalities, one possibility—that of an individual having one Y but no X—has never been reported. Which of the following statements is the most likely reason that medical researchers have yet to report a person having the karyotype of one Y but no X? A. People are probably born with this karyotype; however, since the phenotypic abnormalities caused by it are so slight, the individuals live out their lives normally and are unaware of it. B. There does not exist a meiotic event that could produce an oocyte that does not have a X chromosome. C. The X chromosome contains genes that are unrelated to sex determination and are necessary for life. D. Our current technology for karyotyping would not reveal such an abnormality. E. The Y chromosome needs the X chromosome to be present in the cell in order for its genes to be expressed.
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C. The X chromosome contains genes that are unrelated to sex determination and are necessary for life.
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Which of the following statements is NOT correct of human sex chromosomes? A. On average, half a man's sperm carry an X chromosome and half carry a Y. B. All diploid cells have both an X and a Y chromosome. C. All diploid cells have at least one X chromosome. D. Gametes produced by females have an X chromosome, but not a Y. E. X and Y chromosomes differ in structure.
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B. All diploid cells have both an X and a Y chromosome.
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What type of chromosomal abnormality leads to the phenotype known as Down syndrome? A. trisomy 21 B. monosomy 21 C. trisomy 22 D. monosomy 22 E. disomy 21
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A. trisomy 21
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A karyotype: A. can be used to diagnose Down syndrome in humans. B. reveals the autosomes but not the sex chromosomes. C. can be used to determine the sex of a fetus in humans. D. can be produced only from cells in telophase of mitosis. E. Both the first and third choices are correct.
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E. Both the first and third choices are correct.
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A man having the "super male" genotype, meaning he has one extra Y-chromosome (XYY) marries a woman who is "meta female," having an extra X-chromosome (XXX). All of the following are possible genotypes of their children, EXCEPT: A. XX. B. XYY. C. YY. D. XY. E. XXY.
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C. YY.
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"Metafemales" are: A. females with an XX genotype. B. females with an XXX genotype. C. males with an XX genotype. D. females with an XY genotype. E. females with an XXY genotype.
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B. females with an XXX genotype.
