Chapter 23, Problem 17MC

Which of the following is not associated with sperm production? a. daughter cells identical to the parent cell b. variety in resulting cells c. chromosome number halved in resulting cells d. four daughter cells arising from one parent cell e. 23 chromosomes in the human sperm

A testcross is a way to determine ________. a. phenotype b. genotype c. dominance

Hermaphroditism (a) is a form of asexual reproduction (b) occurs when an unfertilized egg develops into an adult animal (c) is a form of sexual reproduction in which an animal produces both eggs and sperm (d) typically involves self-fertilization (e) typically requires only a male animal

External fertilization occurs in which type of environment? aquatic forested savanna steppe

The genotype XXY corresponds to Klinefelter syndrome Turner syndrome Triplo-X Jacob syndrome

Cleavage produces daughter cells called ________. trophoblasts blastocysts morulae blastomeres

Birth Defects and Multiple Births A woman who carries multiple offspring at the same time increases the risk of some birth defects. FIGURE 42.18 shows the results of Yiwei Tang's study of birth defects reported in Florida from 1W6 to 2000. Tang compared the incidence of various defects among single and multiple births. She calculated the relative risk for each type of defect based on type of birth, and corrected for other differences that might increase risk such as maternal age, income, race, and medical care during pregnancy. A relative risk of less than 1 means that multiple births pose less risk of that defect occurring. A relative risk greater than 1 means multiples are more likely to have a defect. FIGURE 42.18 Prevalence, per 10,000 live births, of various types of birth defects among multiple aria single births. Relative risk for each defect is given after researches adjusted for the motor's age, race, previous adverse pregnancy experience, education, Medicaid participation during pregnancy, as well as the infant's sex and number of siblings. 4. Does a multiple pregnancy increase the relative risk of chromosomal defects in offspring?

If an embryo splits at the two-cell stage, each of the resulting identical twins will have its own placenta. If such a split occurs near the time of implantation, the identical twins may shale a placenta. By contrast, fraternal twins never share placenta. Explain this difference between the two types of twins.

Would ISCI be an option? Why or why not? Jan, a 32-year-old woman, and her husband, Darryl, have been married for 7 years. They have attempted to have a baby on several occasions. Five years ago, they had a first-trimester miscarriage, followed by an ectopic pregnancy later the same year. Jan continued to see her OB/GYN physician for infertility problems but was very dissatisfied with the response. After four miscarriages, she went to see a fertility specialist, who diagnosed her with severe endometriosis and polycystic ovarian disease (detected by hormone studies). The infertility physician explained that these two conditions were hampering her ability to become pregnant and thus making her infertile. She referred Jan to a genetic counselor. At the appointment, the counselor explained to Jan that one form of endometriosis (MIM 131200) can be a genetic disorder, and that polycystic ovarian disease can also be a genetic disorder (MIM 184700) and is one of the most common reproductive disorders among women. The counselor recommended that a detailed family history of both Jan and Darryl would help establish whether Jans problems have a genetic component and whether any of her potential daughters would be at risk for one or both of these disorders. In the meantime, Jan is taking hormones, and she and Darryl are considering alternative modes of reproduction. Using the information in Figure 16.4, explain the reproductive options that are open to Jan and Darryl.