chapter 13 study guide

A human cell containing 22 autosomes and a Y chromosome is (A) a sperm. (B) an egg. (C) a zygote. (D) a somatic cell of a male.

(A) a sperm. as it contains 23 chromosomes in total, including the Y chromosome, it would be a male's sex chromosome.

Spores and gametes are different in that... (A) gametes can fuse to form a zygote, but spores can develop into independent organisms without first forming a zygote (B) gametes are derived directly from sporophytes to form gametophytes (C) gametes never resemble spores morphologically (D) only the formation of gametes contributes to genetic variation (E) gametes are always haploid whereas spores are diploid

(A) gametes can fuse to form a zygote, but spores can develop into independent organisms without first forming a zygote spores can become multicellular haploid organisms (in plants)

The zipper-like complex that forms in meiosis occurs during __________ and is called the __________. (A) prophase I; synaptonemal complex (B) metaphase II; meiotic complex (C) prophase II; meiotic complex (D) metaphase I; synaptonemal complex (E) prophase I; centromeric complex

(A) prophase I; synaptonemal complex the synaptonemal "binds" the two homologs together, allowing crossing over to occur.

Meiosis II is similar to mitosis in that (A) sister chromatids separate during anaphase. (B) DNA replicates before the division. (C) the daughter cells are diploid. (D) homologous chromosomes synapse.

(A) sister chromatids separate during anaphase. sister chromatids are involved in both meiosis II and mitosis, instead of homologous pairs.

What is the function of meiosis? (A) to make cells with a haploid (half that of the parents) number of chromosomes (B) to make exact copies of the parent cell (C) to make one cell with twice the number of chromosomes as the parent pairs (D) to make four cells with the same chromosome number as the parent (E) to make diploid spores

(A) to make cells with a haploid (half that of the parents) number of chromosomes daughter cells (produced by meiosis) have half the number of chromosomes that their parent cells have

In a diploid set of chromosomes, one member of each pair of homologous chromosomes is derived from the father (paternal), and the other comes from the mother (maternal). If 2n = 6, what is the probability that a particular gamete will contain only paternal chromosomes? (A) 1/4 (B) 1/8 (C) 1/16 (D) 1/32

(B) 1/8 the chance of any one paternal chromosome ending up in a particular gamete is 1/2, so the chance that all three would be of paternal origin would be (1/2)^n, where n = 3

Ignoring crossover, how many kinds of gametes can be produced by an organism with a diploid number of 8? (A) 2 (B) 16 (C) 8 (D) 4 (E) 32

(B) 16 since the organism with a diploid number of 8 (2n=8), the haploid number would be 4 (n=4). through the equation 2^4, the possible number of combinations of chromosomes would therefore be 16. each pair of homolog. chromosomes may orient with either its maternal/paternal chromosome (independently). 2^(n) = possible number of combinations of chromosomes

In a diploid cell containing 10 chromosome, meiosis results in the formation of daughter cells containing ______ chromosomes. (A) 0 (B) 5 (C) 10 (D) 20 (E) 40

(B) 5 Haploid sex cells contain half as many chromosomes as diploid somatic cells.

The two homologs of a pair move toward opposite poles of dividing cell during (A) mitosis. (B) meiosis I. (C) meiosis II. (D) fertilization.

(B) meiosis I it involves homologous pairs, which are in meiosis I.

Which life cycle stage is found in plants but not animals? (A) gamete (B) multicellular haploid (C) unicellular diploid (D) zygote (E) multicellular diploid

(B) multicellular haploid plants go through an alternation of generations life cycle, where they have multicellular haploid and diploid cells. for animals, the only multicellular cell is diploid. gametes are unicellular haploid cells.

Although __________ is nearly universal among animals, bdelloid rotifers __________. (A) sexual reproduction ... reproduce asexually and achieve genetic diversity by mutations alone (B) sexual reproduction ... reproduce asexually but can increase genetic variation present in a population by means of the uptake of DNA from other rotifers (C) asexual reproduction ... have achieved great diversity by using sexual reproduction (D) sexual reproduction ... reproduce asexually because they inhabit very stable environments and the production of gametes would be an inefficient use of energy

(B) sexual reproduction ... reproduce asexually but can increase genetic variation present in a population by means of the uptake of DNA from other rotifers characteristic of the bdelloid rotifers (who haven't had sex in 40 million+ years!)

An organism has a haploid chromosome number n = 4. How many tetrads will form during meiosis? (A) 2 (B) 3 (C) 4 (D) 8 (E) 16

(C) 4 tetrads consists of two chromosomes (4 chromatids). since the organism has n=4 (2n=8), there will be 4 tetrads (16 chromosomes). because of the synapsis of homologous chromosomes, the number of tetrads in meiosis I will be the same as the haploid number of chromosomes.

Regarding the role of cohesin protein in maintaining cohesion between sister chromatids, which of the following statements is false? (A) During meiosis I, cohesion holds sister chromatids together along their lengths as chiasmata form between homologs and during meiosis II, cohesion holds sister chromatids together along their lengths as the second meiotic spindle forms (B) None of the listed responses is false. (C) During meiosis II, cohesion holds sister chromatids together along their lengths as the second meiotic spindle forms. (D) During meiosis I, cohesion holds sister chromatids together along their lengths as chiasmata form between homologs. (E) During meiosis I, cohesion holds sister chromatids together along their lengths as chiasmata form between homologs and cleavage of cohesins between sister chromatid arms at anaphase I allows homologs to separate. )F) Cleavage of cohesins between sister chromatid arms at anaphase I allows homologs to separate.

(C) During meiosis II, cohesion holds sister chromatids together along their lengths as the second meiotic spindle forms. Cohesion holds sister chromatids together along their lengths as the FIRST meiotic spindle forms.

Unless the chromosomes were stained to show band patterns, a karyotype would be least likely to show which of the following? (A) The attachment of a large part of a chromosome to another chromosome. (B) A large part of a chromosome duplicated. (C) Part of a chromosome turned around. (D) An extra chromosome. (E) A missing chromosome.

(C) part of a chromosome turned around. if the chromosomes were not stained, you would not be able to see the INVERSIONS (where part of a chromosome is turned around, affects neither the number of chromosomes nor the length of a chromosome, and is generally difficult to detect without staining to show chromosomal bands).

If we continue to follow the cell lineage from question 4, then the DNA content of a single cell at metaphase of meiosis II will be (A) 0.25x. (B) 0.5x. (C) x. (D) 2x.

(C) x. at the end of meiosis I, the DNA content will be x. since it does not replicate its DNA again, it will remain the same in meiosis II (which is x).

If the DNA content of a diploid cell in the G1 phase of the cell cycle is x, then the DNA content of the same cell at metaphase of meiosis I will be (A) 0.25x. (B) 0.5x. (C) x. (D) 2x.

(D) 2x. at the end of interphase, the DNA content doubles (2x). on the metaphase plate, it will remain as 2x until it divides.

A life cycle in which the only multicellular form is haploid is most typical of __________. (A) protists (B) plants (C) fish (D) fungi (E) primates

(D) fungi although both protists and fungi are mostly haploid, fungi are the multicellular organisms (while protists are unicellular).

The sexual cycle of the diploid, multicellular algal genus Fucus involves _______. (A) mitosis only. (B) both mitosis and meiosis but not fertilization. (C) only meiosis and fertilization. (D) mitosis, meiosis, and fertilization. (E) both mitosis and fertilization but not meiosis.

(D) mitosis, meiosis, and fertilization. Every multicellular organism undergoes mitosis, and all diploid sexually reproducing organism undergoes meiosis/fertilization (goes together!).

Which of the following is part of the life cycle called alternation of generations? (A) spores (B) multicellular diploid stage (sporophyte) (C) zygote (D) multicellular haploid stage (gametophyte) (E) All of the listed responses are correct.

(E) All of the listed responses are correct.

Sister chromatids differ from nonsister chromatids in that sister chromatids __________. (A) are part of only the maternal set (B) are part of nonhomologous chromosomal sets (C) always come from nonsister chromatids (D) are never found in the paternal set (E) are products of the S phase of the cell cycle and are two copies of one chromosome

(E) are products of the S phase of the cell cycle and are two copies of one chromosome sister chromatids are "related", while nonsister chromatids are from different chromosomes.