Bio. chapter 11

Describe what happens to the tetrads after they form. Describe what happens to the tetrads after they form. A. Prophase I of meiosis forms the tetrads. They line up at the midway point between the two poles of the cell to form the metaphase plate. There is equal chance of a microtubule fiber to encounter a maternally or a paternally inherited chromosome. Orientation of each tetrad is independent of the orientation of other tetrads. B. Prophase II of meiosis forms the tetrads. They line up at the midway point between the two poles of the cell to form the metaphase plate. There is equal chance of microtubule fiber to encounter maternally or paternally inherited chromosome. Orientation of each tetrad is independent of the orientation of other tetrads. C. Prophase I of mitosis forms the tetrads. They line up at the midway between the two poles of the cell to form the metaphase plate. There is equal chance of a microtubule fiber to encounter a maternally or a paternally inherited chromosome. Orientation of each tetrad is independent of the orientation of other tetrads. D. Prophase I of meiosis forms the tetrads. They line up at the midway between the two poles of the cell to form the metaphase plate. There is a chance of microtubule fiber to encounter maternally inherited chromosome. Orientation of each tetrad is independent of the orientation of other tetrads.

A. Prophase I of meiosis forms the tetrads. They line up at the midway point between the two poles of the cell to form the metaphase plate. There is equal chance of a microtubule fiber to encounter a maternally or a paternally inherited chromosome. Orientation of each tetrad is independent of the orientation of other tetrads.

Single-celled organisms, like amoebas, reproduce by mitosis. Explain how the genetic makeup of these organisms differs from organisms that undergo meiosis.

Organisms producing through mitosis create genetically identical offspring as only a single parent copies its entire genetic material to the offspring. In meiosis, two parents produces gametes and the offspring have only half the number of chromosomes of each parent and hence genetic variation is introduced

Compare the three main types of life cycles in multicellular organisms as described below. Determine which comparison is accurate and which also gives an appropriate example of an organism that employs each type. a. In a diploid-dominant life cycle, the diploid multicellular stage is present, as in humans. Haploid-dominant life cycles have a multicellular haploid stage, as in fungi. In alternation of generations, both haploid-dominant and diploid-dominant stages are multicellular and the stages alternate, as in plants. b. In a diploid-dominant life cycle, the unicellular stage is present, as in humans. Haploid-dominant life cycles have a multicellular haploid stage, as in fungi. In alternation of generations, both haploid-dominant and diploid-dominant stages are multicellular and the stages alternate, as in plants. c. In a diploid-dominant life cycle, a haploid multicellular stage is present, as in humans. Haploid-dominant life cycles have a multicellular haploid stage, as in fungi. In alternation of generations, both haploid-dominant and diploid-dominant stages are multicellular and the stages alternate, as in plants. d. In a diploid-dominant life cycle, a multicellular diploid stage is present, as in algae. In a haploid-dominant life cycle, a multicellular haploid stage is present, as in plants. In alternation of generations, both haploid-dominant and diploid-dominant stages are multicellular and the stages alternate, as in humans.

a. In a diploid-dominant life cycle, the diploid multicellular stage is present, as in humans. Haploid-dominant life cycles have a multicellular haploid stage, as in fungi. In alternation of generations, both haploid-dominant and diploid-dominant stages are multicellular and the stages alternate, as in plants.

Which of the following distinguishes metaphase I from metaphase II? a. Metaphase I occurs when homologous chromosome pairs align on the metaphase plate. Metaphase II has sister chromatids of chromosomes aligned at the metaphase plate. b. Metaphase I occurs when chromosomes appear in homologous pairs at the metaphase plate. Metaphase II has single sister chromatids of chromosomes on the spindle. c. Metaphase I occurs when chromosomes separate the homologous pairs on the spindle. Metaphase II has a single line of chromosomes on the plate. d. Metaphase I occurs when chromosomes appear in homologous pairs on the spindle. During metaphase II, the chromosomes line up in a double line across the spindle

a. Metaphase I occurs when homologous chromosome pairs align on the metaphase plate. Metaphase II has sister chromatids of chromosomes aligned at the metaphase plate.

Which statement is true about the alternation of generations life cycle? a. The diploid plant is called a sporophyte and haploid plants are called gametophytes. b. Gametophytes produce gametes through the process of meiosis. c. Fertilization between the gametes of a gametophyte produce haploid zygotes. d. Sporophyte cells undergo mitosis to produce haploid spores.

a. The diploid plant is called a sporophyte and haploid plants are called gametophytes.

Describe what happens to the number of chromosomes in each of the two divisions of meiosis. a. The number of chromosomes is halved in the first division of meiosis. In the second division, the number of chromosomes remains the same. bThe number of chromosomes is doubled in the first division of meiosis. In the second division, the number of chromosomes is halved. cThe number of chromosomes is halved in the first division of meiosis. In the second division, the number of chromosomes doubles. dThe number of chromosomes remains the same in the first division of meiosis. In the second division, the number of chromosomes is halved.

a. The number of chromosomes is halved in the first division of meiosis. In the second division, the number of chromosomes remains the same.

In prophase I, the homologous chromosomes are paired up and linked together. Which explanation best describes the structures and mechanisms responsible for this action? a. The synaptonemal complex is a protein lattice that binds chromosomes together across their length and maintains their tight alignment. bTetrads act as a sort of "glue" that prevents the chromosomes from separating along their length and maintains chromosome alignment. cThe centromere consists of cohesin proteins that bind paired chromosomes at their tips. dCohesin proteins make up the synaptonemal complex that binds chromosomes together at their centromeres.

a. The synaptonemal complex is a protein lattice that binds chromosomes together across their length and maintains their tight alignment.

Explain how a boy could have his mother's nose and his father's ears. a. independent assortment of chromosomes b. the movement of homologous pairs during meiosis c. by receiving his father's Y chromosome d. inheritance of intact chromosomes from parents

a. independent assortment of chromosomes

Which one of the three types of life cycles of sexually reproducing organisms does not have a multicellular haploid stage? a alternation of generations b diploid-dominant c haploid-dominant d They all have a multicellular haploid stage in their life cycles.

b diploid-dominant

A comparison of haploid-dominant life cycles and alternation of generation life cycles reveals that they share some similarities yet also display differences. Which of the following processes or structures is found in haploid-dominant life cycles but not alternation of generation life cycles? a. meiosis b. (+) and (−) mating types c. spores d. a free-living haploid stage

b. (+) and (−) mating types -During sexual reproduction in haploid-dominant organisms, specialized haploid cells from two individuals, designated the (+) and (−) mating types, join to form a diploid zygote.

If a chemical reaction could occur without an enzyme, provide the reasoning to explain why it is important to have an enzyme to catalyze that reaction. a. Enzymes are important because they ensure that only the desired products are produced by the reaction. b. Enzymes are important because they ensure that the reaction products are obtained consistently with time. c. Enzymes are important because they ensure that energy remains conserved and no loss of energy occurs. d. Enzymes are important because they do not alter the concentration of the reaction products.

b. Enzymes are important because they ensure that the reaction products are obtained consistently with time. -Enzymes provide the products consistently with life. The products are needed for an organism's growth and maintenance, thus they should be available in timely manner.

The Red Queen hypothesis seeks to explain coevolution between competing species. Comparing the following scenarios, which provides the best support for the Red Queen hypothesis? aAn asexually reproducing plant rapidly populates a hillside left barren by a fire. b. Individuals of a snail population that reproduce asexually die out after a parasite invades its territory. cA widely dispersed population of ruffed grouse disappears because individuals have difficulty finding mates. dA sexually reproducing species of gophers goes extinct after a new predator is introduced.

b. Individuals of a snail population that reproduce asexually die out after a parasite invades its territory.

Chemotherapy drugs such as vincristine and colchicines disrupt mitosis by binding to tubulin (the subunit of microtubules) and interfering with microtubule assembly and disassembly. Exactly what mitotic structure do these drugs target, and what effect would that have on cell division? a. The drugs bind tubulin and inhibit the formation of the metaphase plate. This can arrest the cell cycle. b. The drugs bind the tubulin, which leads to an error in the chromosome separation. This could lead to apoptosis. c. The drugs bind the tubulin, thereby inhibiting their division in S-phase. This inhibits cell division. d. The drugs bind the spindle fiber and hinder the separation of chromatins. This promotes the division spontaneously.

b. The drugs bind the tubulin, which leads to an error in the chromosome separation. This could lead to apoptosis.

Diploid-dominant and haploid-dominant are two of three main types of sexual reproduction in multicellular organisms. Analyze the statements below, then identify which best explains a similarity between these categories of life cycles. aIn both types, adult organisms grow from multicellular diploid zygotes. bBoth types perform meiosis by the reduction division of germ cells. c. Both types produce diploid zygotes from haploid cells. dBoth types produce haploid spores from diploid cells.

c. Both types produce diploid zygotes from haploid cells.

Which of the following events occurs in both mitosis and meiosis I? a. Homologous chromosomes pair together. b. Crossover occurs between chromosomes. c. Chromosomes line up at the metaphase plate. d. Sister chromatids remain attached during anaphase.

c. Chromosomes line up at the metaphase plate.

Why is it necessary that meiosis occurs in sexually reproducing organisms? ato maintain the viability of the gametes bto ensure that genetic variation is reduced c. to maintain a constant chromosome number in each generation dto ensure evolutionary success

c. to maintain a constant chromosome number in each generation

There are three sources of genetic variation in sexual reproduction. Determine which of the following statements accurately describes which of these are considered random and which are not. a. Crossing over is considered random; egg and sperm fertilization and tetrad alignment on the meiotic spindle are not. b. Tetrad alignment on the spindle and crossing over are considered random; egg and sperm fertilization is not. c. Egg and sperm fertilization and tetrad alignment on the spindle are considered random; crossing over is not. d. All three sources of genetic variation are considered random.

d. All three sources of genetic variation are considered random.

How do telophase I and telophase II differ during meiosis in animal cells? aCells remain diploid at the end of telophase I, but are haploid at the end of telophase II. bDaughter cells form a cell plate to divide during telophase I, but divide by cytokinesis during telophase II. cCells enter interphase after telophase I, but not after telophase II. d. Chromosomes can remain condensed at the end of telophase I, but decondense after telophase II.

d. Chromosomes can remain condensed at the end of telophase I, but decondense after telophase II.

What is the function of recombination nodules in meiosis? a. Recombination nodules organize the spindle. b. Recombination nodules guide the chromosomes along the spindle during anaphase. c. Recombination nodules function with the kinetochore to facilitate microtubule binding. d. Recombination nodules mark the points of chiasmata and mediate the crossover process.

d. Recombination nodules mark the points of chiasmata and mediate the crossover process

Which of the following statements is not true in relation to crossing over? a. Chiasmata are formed. b. Non-sister chromatids exchange genetic material. c. Recombination nodules mediate cross over events. d. Spindle microtubules guide the movement of chromosomal material.

d. Spindle microtubules guide the movement of chromosomal material.

Cells enter meiosis after going through an S-phase of their life cycle, so the chromosomes within the cells have been duplicated. In order to produce reproductive cells or gametes, however, the number of chromosomes in cells needs to be cut in half. Select the explanation that provides the correct reasoning for how meiosis accomplishes this goal. aMeiosis produces haploid cells because only half of the DNA is replicated in the S-phase preceding meiosis I. bMeiosis reduces the chromosome number in the first division and then restores the number in the second division through recombination. cThe chromosome number is halved during the interphase between meiosis I and meiosis II, when two haploid cells form. d. The chromosome number is halved during meiosis I when the homologous chromosomes separate, but the sister chromatids remain connected.

d. The chromosome number is halved during meiosis I when the homologous chromosomes separate, but the sister chromatids remain connected.

The alignment of chromosomes during prophase I facilitates the crossing over of chromosomal material. Provide the appropriate explanation for how this occurs. aThe homologous chromosomes cross over at recombination nodules, where the chromatids physically overlap. bThe chiasmata holds the homologous chromosomes closely together at specific points along their lengths. cThe synaptonemal complex forms bridges between the paired homologous chromosomes at points where crossing over occurs. d. The homologous chromosomes are tightly paired along their entire lengths, forming a synapsis.

d. The homologous chromosomes are tightly paired along their entire lengths, forming a synapsis.

Enzyme-linked receptors a. cell-surface receptor that activates membrane-bound G-proteins to transmit a signal from the receptor to nearby membrane components b. (also, intracellular receptor) receptor protein that is located in the cytosol of a cell and binds to ligands that pass through the plasma membrane c. cell-surface receptor that forms a plasma membrane channel, which opens when a ligand binds to the extracellular domain (ligand-gated channels) d. cell-surface receptor with intracellular domains that are associated with membrane-bound enzymes

d. cell-surface receptor with intracellular domains that are associated with membrane-bound enzymes

Which three processes lead to variation among offspring that have the same two parents? agenetic recombination, fertilization, meiosis bcrossing over, random chromosome assortment, genetic recombination cmeiosis, crossing over, genetic recombination d. fertilization, crossing over, random chromosome assortment

d. fertilization, crossing over, random chromosome assortment

How are spores produced in alternation of generation life cycles? a by gametophytes b by germ cells c through mitosis d through meiosis

d. through meiosis

cytochrome complex

group of reversibly oxidizable and reducible proteins that forms part of the electron transport chain between photosystem II and photosystem I

septum

structure formed in a bacterial cell as a precursor to the separation of the cell into two daughter cells.