Chapter 6 Chromosomes – Flashcards

Which of the following is TRUE about sex determination in humans? A. One would expect babies to have two Y chromosomes about half the time. B. The father's sperm determines the gender of a baby. C. Without a Y chromosome, a fertilized egg usually dies. D. In the absence of a Y chromosome, the fetal gonads develop into testes, not ovaries. E. An X chromosome is smaller than a Y chromosome.

In some species, sex is determined by environmental, rather than genetic, factors. This is true of: A. humans. B. bees. C. kangaroos. D. birds. E. turtles.

Which of the following is NOT a method of sex determination that occurs in nature? A. In sea turtles, eggs laid in hot sand becomes females and eggs laid in cooler sand become males. B. All of the above are naturally occurring examples of sex determination. C. In birds, the female is the heterogametic (ZW) sex and the male is the homogametic (ZZ) sex. D. In humans, the male is the heterogametic (XY) sex and the female is the homogametic (XX) sex. E. In bees, the eggs that the queen allows to be fertilized become females and the eggs she doesn't fertilize become males.

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. The Y chromosome needs the X chromosome to be present in the cell in order for its genes to be expressed. C. There does not exist a meiotic event that could produce an oocyte that does not have a X chromosome. D. Our current technology for karyotyping would not reveal such an abnormality. E. The X chromosome contains genes that are unrelated to sex determination and are necessary for life.

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. Gametes produced by females have an X chromosome, but not a Y. C. All diploid cells have at least one X chromosome. D. All diploid cells have both an X and a Y chromosome. E. X and Y chromosomes differ in structure.

Nondisjunction: A. is the unequal division of the genetic material during cell division. B. is the cause of sex determination in birds and mammals. C. occurs during mitosis but not meiosis. D. occurs only in prophase I of meiosis. E. is the division of cytoplasmic constituents.

What type of chromosomal abnormality leads to the phenotype known as Down syndrome? A. disomy 21 B. trisomy 21 C. monosomy 21 D. trisomy 22 E. monosomy 22

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.

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. XYY. B. XX. C. YY. D. XXY. E. XY.

"Metafemales" are: A. females with an XX genotype. B. females with an XY genotype. C. males with an XX genotype. D. females with an XXX genotype. E. females with an XXY genotype.

1. Eukaryotic cells can divide by: a. replication only. b. mitosis only. c. meiosis only. d. segregation only. e. mitosis and meiosis.

Bacteria divide by a type of ______________________ called ____________________. a. sexual reproduction; binary fission b. asexual reproduction; binary fission c. asexual reproduction; elongation d. sexual reproduction; replication e. asexual reproduction; replication

In DNA replication, when the DNA molecule separates into two strands: a. it is possible to reconstruct perfectly all the information on the missing strand because one strand carries all the information needed to construct its complementary strand. b. the rebuilding process begins, in which an enzyme connects the appropriate complementary base to the exposed base. c. the cell is ready for prophase. d. All of the above are correct. e. Only the first and second choices are correct.

4. During DNA replication, errors occasionally occur when DNA strands are copied. However, there are many cellular mechanisms that help to remove many of these errors. Suppose an organism evolved such that DNA replication was seemingly perfect every time. What consequences might this hold for the organism? a. It would be robust and out-compete other organisms. b. It would be less robust and more susceptible to predation. c. It would evolve slowly and would therefore be more likely to become extinct. d. It would not be prone to dominant genetic disorders. e. It would be more susceptible to recessive genetic disorders

All of the following are cells that undergo mitosis, EXCEPT: a. yeast. b. skin cells. c. sperm cells. d. muscle cells. e. stomach cells.

What is the difference between embryonic development and differentiation? a. Development and differentiation are really two words for the same thing. b. Development involves the formation of three germ layers; differentiation includes the formation of a blastula. c. Development involves meiosis; differentiation involves the creation of the three germ layers. d. Development involves mitosis and embryonic growth; differentiation involves specialization of tissues. e. Development involves the events just before birth; differentiation specifically refers to neurulation.

The rate at which mitosis occurs varies dramatically for different types of cells. The most rapid cell division occurs: a. in the gametes. b. on the skin. c. in the blood and the heart. d. in the blood and the cells lining the various tissues of organs. e. in the liver and the brain.

. two daughter nuclei are formed (telophase) II. centromeres separate (early anaphase) III. cytoplasm is divided (cytokinesis) IV. chromosomes move toward opposite poles (anaphase) V. chromosomes line up in single file (metaphase) Which of the following represents the correct order of events in the mitotic cell cycle listed above? a. III, V, I, IV, II b. V, II, IV, I, III c. V, IV, I, III, II d. IV, I, II, V, III e. V, II, I, IV, III

Side effects of undergoing chemotherapy for cancer treatment include: a. reduction of the rate at which red blood cells are produced, causing fatigue and shortness of breath. b. reduction of the rate at which white blood cells are produced, causing increased susceptibility to infection. c. reduction of the rate at which hair follicle cells divide, causing loss of hair. d. All of the above are correct. e. The first and third choices are correct.

Radiation therapy for cancer works because a cell's DNA is exposed during mitosis and most vulnerable to damage from radiation. Because cancer cells are uncontrollably undergoing mitosis, they die when exposed to the treatment. The common side effects of radiation treatment are hair loss and vomiting. What does this imply? a. Radiation treatment will be ineffective in treating stomach cancer. b. Both skin and stomach cancer will be made worse if treated with radiation. c. Radiation therapy is an ineffective way to treat cancer. d. Both stomach and skin cells are constantly being replaced. e. Radiation treatment will be most effective for the treatment of skin and stomach cancers.

The ability for cancer cells to divide indefinitely is made possible because: a. cancer cells rebuild their telomeres after every cell division. b. cancer cells rebuild their centromeres after every cell division. c. cancer cells break down their centromeres after every cell division. d. cancer cells break down their telomeres after every cell division. e. cancer cells avoid interphase during cell division.

When a male donkey is bred with a female horse, the offspring produced is a mule, which is healthy but sterile. Karyotyping experiments have revealed that horses and donkeys have different numbers of chromosomes, 64 for horses and 62 for donkeys. The mule therefore has 63 chromosomes. Knowing this, what is the best explanation for the inability of mules to produce offspring? a. Proper pairing of homologues is impossible during meiosis I. b. Gametes formed in meiosis II do not contain sex-determining chromosomes. c. Crossing over is not possible between unmatched chromosomes during meiosis II. d. Spindle fibers cannot properly bind to the odd number of chromosomes during meiosis I. e. Chromosomes cannot align on the metaphase plate during meiosis II.

For crossing over to increase genetic variation, it must involve the exchange of material between: a. gametes from the two different sexes. b. non-homologous chromosomes. c. sister chromatids of a single chromosome. d. non-sister chromatids of a homologous pair of chromosomes. e. Crossing over can increase genetic variation in any of the ways mentioned above.

Seventy to ninety percent of the genetic material in a gamete made in your body could be inherited from your mother. How could this be? a. You receive many mitochondria, which have their own genome, from your mother, but not from your father. b. The maternal genes contain more dominant genes so they are expressed at least seventy percent of the time. c. Your maternal genes kill off your paternal genes at a greater rate than your paternal genes kill of your maternal genes. d. The X chromosome is substantially larger than the Y chromosome. e. The above statement is incorrect. Fifty percent of the genetic material in your gametes comes from your father.

Sexual reproduction leads to offspring that are all genetically different from one another and from either parent. What are the three aspects of sexual reproduction that lead to this variation? a. crossing over during the production of gametes; shuffling and reassortment of homologues during mitosis; and combination of alleles from two parents during binary fission. b. crossing over during the production of gametes; shuffling and reassortment of homologues during mitosis; and combination of alleles from two parents at fertilization. c. crossing over during the production of gametes; shuffling and reassortment of homologues during meiosis; and combination of alleles from two parents at fertilization. d. crossing over during the production of zygotes; shuffling and reassortment of homologues during mitosis; and combination of alleles from two parents at fertilization. e. shuffling and reassortment of homologues during mitosis; shuffling and reassortment of homologues during meiosis; and combination of alleles from two parents at fertilization.

Which of the following is NOT a disadvantage of sexual reproduction? a. It takes time and energy to find a mating partner. b. Variability among offspring enables parents to produce a range of offspring, any one of which may be suitable to changes in the environment. c. Organisms can expose themselves to danger during the mating process. d. Sexual reproduction breaks down genotypes that are well adapted for a stable environment. e. The transfer of genetic information from generation to generation is not as efficient as it is during asexual reproduction.

any species of birds, males are XX and females are XZ. With birds like this, who is most likely to display a sex-linked recessive trait? a. males b. females c. Males and females are equally likely to display a sex-linked recessive trait. d. The gender that's incubated at a higher temperature. e. The traits will show up equally in males and females.