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

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

Meiosis __________. a. occurs in all eukaryotes 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. germ cells d. all of the above

Meiosis ______________ the parental chromosome number. a. doubles b. halves c. maintains d. mixes up

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

Which of the following cells can undergo meiosis? a. the diploid body cells of an animal b. cells set aside for reproduction in eukaryotes c. haploid gametes d. all of the above

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

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 pair up only in meiosis. c. DNA is replicated only in mitosis. d. Sister chromatids separate only in meiosis. e. Interphase occurs only in mitosis.

Match each term with the best 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

_________ contributes to variation in traits among the offspring of sexual reproducers. a. Crossing over b. Random attachment of chromosomes to spindle poles c. Fertilization d. both a and b e. all are factors