Chapter 12

One evolutionary advantage of sexual over asexual reproduction may be that it produces ________. a. more offspring per individual b. more variation among offspring c. healthier offspring

Alternative forms of the same gene are called ________. a. gametes b. homologous c. alleles d. sister chromatids

Meiosis is a necessary part of sexual reproduction because it ________. a. divides two nuclei into four new nuclei b. reduces the chromosome number c. produces clones that can cross over

Meiosis________. a. occurs only in germ cells of animals b. supports growth and tissue repair in multicelled species c. gives rise to genetic diversity among offspring d. is part of the life cycle of all cells

Sexual reproduction in animals requires ________. a. meiosis b. fertilization c. gametes d. all of the above

Dogs have a diploid chromosome number of \(78 .\) How many chromosomes do their gametes have? a. 39 b. 78 c. 156 d. 234

Crossing over mixes up ________. a. chromosomes b. alleles c. zygotes d. gametes

Crossing over happens during which phase of meiosis? a. prophase I b. prophase II c. anaphase I d. anaphase II

________contributes to variation in traits among the offspring of sexual reproducers. a. Crossing over b. Chromosome segregation c. Fertilization d. all of the above

Which of the following is one of the very important differences between mitosis and meiosis? a. Chromosomes align midway between spindle poles only in meiosis. b. Homologous chromosomes separate only in meiosis. c. DNA is replicated before mitosis only. d. Sister chromatids separate only in meiosis. e. Interphase occurs only in mitosis.

Match each term with its description. ________interphase ________metaphase I ________alleles ________zygotes ________gametes ________males ________prophase I a. different forms of a gene b. useful for varied offspring c. none between meiosis I and meiosis II d. chromosome lineup e. haploid f. form at fertilization g. mash-up time