BIOL 471 Ch. 7 (Practice questions with complete answers)

Unisexual correct answers Referring to an individual containing only male or only female reproductive organs. Animals can be referred to as gonochoric, while plants are dioecious. Bisexual correct answers Individuals containing both male and female reproductive organs. Plants of this nature are referred to as monoecious, while males are referred to as hermaphrodites. Intersex correct answers Individuals of an intermediate sexual condition, most of whom are sterile. Chlamydomonas correct answers The green alga, which spend most of their life in a haploid phase, asexually reproducing daughter cells by mitotic division. -(1) Under unfavorable nutrient conditions such as nitrogen depletion, certain daughter cells function as gametes and joining together in fertilization. -(2) Following fertilization, a diploid zygote undergoes meiosis to form vegetative colonies with a better chance of surviving the unfavorable environment. Isogametes correct answers Gametes that are not morphologically distinguishable from one another, such as in Chlamydomonas. -(1) May differ biochemically, e.g. mt⁺ must mate with mt⁻ Zea mays correct answers This monoecious plant is a diploid sporophyte that bears stamens and pistils that give rise to microspores and megaspores. -(1) Stamen: an adult sporophyte, produces haploid microspores, which grow through mitosis to form dicellular microgametophytes also known as pollen. -(2) Pistil: an adult sporophyte, produces haploid megaspores, which grow through mitosis to have a total of 8 haploid nuclei. -(3) The pollen double fertilizes the megagametophyte, creating a diploid zygote and a triploid endosperm. -(4) Ultimately the maturing kernel consists of an outer fruit stemming from the diploid sporophyte, an layer consisting of a 1n gametophyte covering, a 3n endosperm, and a 2n zygote. C elegans correct answers This animal is a very popular organism that expresses a hermaphroditic and a male sex. -(1) Hermaphrodites, with an XX genotype, have both eggs and sperm, and fertilize their own eggs in sexual reproduction. -(2) Individuals with XO genotypes have only sperm and also the ability to transfer that sperm to other organisms, thus allowing it to sexually reproduce with other organisms. Protenor mode of sex determination correct answers The model of sex determination in which the presence or absence of the X chromosome provides sex determination, and depends on the random distribution of the X chromosome into one-half of the male gametes during segregation. -(1) Fertilization by X-bearing sperm results in female offspring,