Chapter 12

The main evolutionary advantage of sexual over asexual reproduction is 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 c. germ cells b. fertilization d. all of the above

Meiosis_____the parental chromosome number. a. doubles c. maintains b. halves d. mixes up

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

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

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

________ contributes to variation in traits among the offspring of sexual reproducers. a. Crossing over c. Fertilization b. Random attachment d. both a and \(b\) \(\begin{array}{ll}\text { of chromosomes } & \text { e. all are factors }\end{array}\) to spindle poles

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.