59) Labor progresses through the following three stages: A) dilation, expansion, and pushing stages. B) duration, expansion, and placental stages. C) dilation, effacing, and placental stages. D) dilation, expulsion, and placental stages. Answer: D 60) The first stage of labor is: A) dilation. B) effacement. C) expulsion. D) propulsion. Answer: A 61) Joanne is ready to give birth. How much should her cervix be dilated? A) 2 mm B) 4 cm C) 10 cm D) 20 cm Answer: C 62) What major event occurs during the first stage of labor? A) The placenta is delivered. B) The newborn is delivered. C) The cervix thins and dilates. D) The fetal head crowns. Answer: C 63) During which stage of labor does the fetal head crown? A) placental B) expulsion C) dilation D) effacement Answer: B 64) What is the afterbirth? A) amniotic fluids B) urine C) meconium, bile, and other wastes D) placenta and attached fetal extraembryonic membranes Answer: D 65) The best fetal position for birth is the: A) buttocks-first position. B) vertex position. C) nonvertex position. D) breech position. Answer: B 66) What is the neonatal period? A) the first four weeks of life B) the first four months of life C) the first six months of life D) the first year of life Answer: A 67) The Apgar score is assigned for several criteria measured at birth. What is NOT measured? A) grimace B) defecation C) respiratory level D) muscle activity Answer: B 68) After birth, the mother may lose excess fluids from the uterus as: A) lactation. B) colostrum. C) lochia. D) meconium. Answer: C 69) Which hormones stimulate the growth of alveoli in the mother's mammary gland? A) oxytocin and progesterone B) estrogen and progesterone C) estrogen and prolactin D) prolactin and cortisol Answer: C 70) Which antibodies are found in colostrum? A) IgG B) IgM C) IgA D) IgD Answer: C 71) If two alleles code for the same trait (such as blond hair), they are said to be: A) autologous. B) homozygous. C) heterozygous. D) homologous. Answer: B 72) April has an abundance of freckles, a physical expression of her genes known as the: A) homologous. B) genotype. C) alleles. D) phenotype. Answer: D 73) Predict the possibility of an offspring with a widow's peak, a dominant inherited trait affecting the hairline, when both parents are heterozygous for the trait. A) 0% of the offspring will have a widow's peak. B) 25% of the offspring will have a widow's peak. C) 75% of the offspring will have a widow's peak. D) 100% of the offspring will have a widow's peak. Answer: C 74) Which of the following is an inherited trait influenced by multiple alleles? A) color blindness B) sickle cell anemia C) ABO blood types D) skin color Answer: C 75) Predict the possible blood types, or phenotypes, of offspring in which the father has blood type O and the mother has blood type AB. A) The possible blood types of the offspring are phenotypes A or B only. B) The possible blood types of the offspring are phenotypes A, B, AB, or O. C) The possible blood types of the offspring are phenotypes AB or O only. D) The possible blood types of the offspring are phenotypes A or O only. Answer: A 76) In the case of blood types, both alleles A and B may be expressed as the phenotype. This exemplifies: A) codominance. B) incomplete dominance. C) polygenic inheritance. D) sex-linked inheritance. Answer: A 77) In order for a male to inherit a sex-linked (X-linked) disorder, he must receive the allele from: A) his mother only. B) his father only. C) either his mother or father. D) both his mother and father. Answer: A 78) Inherited traits controlled by two or more genes are called: A) incomplete dominance. B) polygenic inheritance. C) codominance. D) multiple alleles. Answer: B 79) When environmental factors influence gene expression, this is referred to as: A) polygenic inheritance. B) multifactorial inheritance. C) codominance. D) multiple alleles. Answer: B 80) The embryonic period of prenatal development occurs from week 3 until week 8. Answer: TRUE 81) Sperm entry into the secondary oocyte triggers the acrosomal reaction. Answer: FALSE 82) The four extraembryonic membranes that arise from the bilaminar embryonic disc are the chorion, amnion, allantois, and yolk sac. Answer: TRUE 83) The pre-embryonic period starts with a process called gastrulation. Answer: FALSE 84) The three germ layers are the endoderm, mesoderm, and ectoderm. Answer: TRUE 85) The fetal period extends from the beginning of week 4 until the end of week 8. Answer: FALSE 86) The placenta, a temporary organ that is shed after the infant is born, is the site of exchange of oxygen, nutrients, and waste between the mother and fetus. Answer: TRUE 87) During month 4 of prenatal development, the fetus turns upside down in the vertex position. Answer: FALSE 88) The ductus arteriosus is a fetal vascular shunt that allows blood to flow from the pulmonary trunk directly into the aorta. Answer: TRUE 89) Melanocyte-stimulating hormone (MSH) is needed for the maturation of the fetal lungs and the production of surfactant. Answer: FALSE 90) A pregnant woman typically needs about 300 extra calories each day to support both herself and the fetus. Answer: TRUE 91) Dilation is the longest of the three stages of labor. Answer: TRUE 92) Fetal heart rate and respiratory rate are both lower than those of adults. Answer: FALSE 93) Breast milk also acts as a mild laxative and helps cleanse meconium, a tarry, green fecal material made up of bile and other wastes that is first excreted by the newborn. Answer: TRUE 94) A female will express the trait for an X-linked disorder only if she is homozygous for the recessive allele. Answer: TRUE Match the following to the appropriate germ layer. A) ectoderm B) mesoderm C) endoderm 95) This germ layer forms the gonads, kidneys, and spleen of the developing embryo. 96) The majority of the liver, the gallbladder, and pancreas are formed by this germ layer. 97) This germ layer forms the majority of the nervous system and sense organs. 98) The thyroid gland, parathyroid glands, and the thymus are formed by this germ layer. 99) The pigment cells of the skin, cells of the adrenal medulla, and connective tissue cells are formed by this germ layer. 100) This germ layer forms most of the cardiovascular system. Answers: 95) B 96) C 97) A 98) C 99) A 100) B Match the following terms related to heredity. A) genotype B) allele C) heterozygous D) phenotype E) homozygous 101) The physical manifestation of a gene as a trait 102) The makeup of a gene 103) The two alleles that code for a trait are different 104) The two alleles that code for a trait are the same 105) Variants of a gene Answers: 101) D 102) A 103) C 104) E 105) B 106) Explain how the gestation period differs from the prenatal period. Answer: The growing offspring is generally referred to as the conceptus and develops during the gestation period of pregnancy, which extends from the mother's last menstrual period until birth, which is approximately 280 days, or 40 weeks. The gestation period is longer than the prenatal period because it includes the 2 weeks after the mother's last menstrual cycle–a date that women can usually recall. The prenatal period is what people usually refer to as pregnancy and includes the approximately 38 weeks of development inside the mother's womb. 107) List the periods of prenatal development. Answer: The periods of the prenatal development are the pre-embryonic period, the embryonic period, and the fetal period. 108) Is a single sperm cell capable of fertilizing a secondary oocyte alone? Explain. Answer: Numerous sperm cells are needed to release enough hyaluronidase and acrosin during the acrosomal reaction to break through the corona radiata and zona pellucida of a secondary oocyte. Thus, a single sperm cell is not capable of fertilizing an oocyte alone. 109) Explain the role of the chorion in formation of the embryonic part of the placenta. Answer: The chorion encloses all the other membranes and the embryo. As the chorion develops, it forms outgrowths called the chorionic villi, which are initially found around the entire surface of the chorion. However, as the pregnancy progresses, chorionic villi grow only in the direction of the stratum functionalis layer of the endometrium and do not continue to surround the other membranes and the embryo. By late week four of development, the chorionic villi are blended with the stratum functionalis layer and begin to form the principal embryonic part of the placenta. 110) A pregnant woman developed a condition of low amniotic fluid called oligohydramnios. Predict the impact on her developing embryo. Answer: Without sufficient amniotic fluid, the embryo may not be adequately protected from trauma and from drying out. Amniotic fluid is necessary to maintain a constant temperature, to allow freedom of movement, which is important for muscle development, and prevents body parts from adhering to each other. 111) Explain gastrulation and summarize the germ layers produced during this process. Answer: Gastrulation is the rearrangement and migration of the cells of the bilaminar embryonic disc to form the trilaminar embryonic disc. This is the stage at which the three germ layers develop. The first cells that migrate in this way become the inner germ layer, or endoderm, which replaces the hypoblast. The next cells that migrate to a position between the epiblast and endoderm, and this becomes the middle layer, the mesoderm. The remaining cells of the epiblast form the outer layer, the ectoderm. 112) Discuss the two types of embryonic folding. What is accomplished by each type of folding? Answer: The first type of folding, cephalocaudal, occurs in the head and tail regions of the embryo. Cephalocaudal folding creates the future head and buttocks regions of the embryo. The second type of folding, transverse, or lateral, folding, occurs when the left and right sides of the embryo curve and fold toward the midline. As the sides move closer together, the yolk sac is pinched off, leaving only a small area of the endoderm called the vitelline duct. Transverse folding creates the future trunk region and almost immediately forms the primitive gut, which later becomes the digestive tract inside the abdominal cavity. 113) Explain how the processes of gastrulation and organogenesis are related. Answer: Gastrulation is the rearrangement and migration of the cells of the bilaminar embryonic disc to form the trilaminar embryonic disc. Trilaminar means, "having three layers," so this is the stage at which the three germ layers develop. The three germ layers will become all of the major organ systems in the process of organogenesis by the end of week 8. In the process of organogenesis, the three primary germ layers differentiate into organs and organ systems. 114) Describe what is housed within the umbilical cord. Answer: The umbilical cord connects the center of the placenta to the fetus' umbilicus (bellybutton). The cord normally contains two umbilical arteries that carry deoxygenated fetal blood away from the fetal heart to the placenta, and one umbilical vein that carries oxygen and nutrients toward the fetal heart. The umbilical cord also contains a soft connective tissue with a jelly-like consistency, called Wharton's jelly, which insulates and protects the umbilical arteries and vein; its external surface is covered by the amniotic membrane. 115) What are the maternal and fetal contributions to the placenta? Answer: The fetal portion of the placenta is formed by the chorionic villi, and the maternal portion of the placenta is formed by the decidua basalis of the endometrium of the uterus. 116) Determine when the fetal lungs begin producing surfactant and explain why it is important. Answer: The fetal lungs begin producing surfactant during month 6 of prenatal development. Without surfactant, alveoli collapse during exhalation and are difficult to re-inflate due to alveolar surface tension. Infants born before 24 weeks develop infant respiratory distress syndrome (IRDS) because surfactant is not produced in the alveoli until this time. 117) Discuss the effects of prolactin and oxytocin on a female during pregnancy. Answer: Prolactin secreted from the anterior pituitary stimulates milk production by the mammary glands. Oxytocin from the fetal and maternal hypothalamus is secreted during the second and third trimesters and peaks during labor to stimulate uterine contractions and allow milk release from the mammary glands. 118) Discuss morning sickness and hyperemesis gravidarum. Answer: Morning sickness is accompanied by nausea and sometimes vomiting (that do not necessarily occur only in the morning). These symptoms are thought to be related to elevated hCG, estrogen, and progesterone levels, but no definitive cause has been identified. Some women suffer from an extreme form of morning sickness called hyperemesis gravidarum. This results in excessive vomiting leading to dehydration, electrolyte imbalances, and weight loss in the mother. Severe cases require hospitalization and administration of fluids intravenously. 119) Explain why Braxton-Hicks contractions are known as false labor. Answer: Braxton-Hicks contractions are known as false labor because they do not result in the three stages of labor (dilation, expulsion, and placental stages). True labor results in uterine contractions that increase in intensity and regularity and cause changes in the cervix. 120) Mrs. Laurenz learned during her appointment that she would be scheduled for a C-section. She is in her 36th week of pregnancy. Explain to her what happens during a C-section. Answer: A caesarean section, or C-section, may be performed in order to remove the fetus and placenta. A C-section is a surgical procedure in which an incision is made through the abdominal and uterine walls 121) Explain the role of oxytocin in lactation. Answer: Oxytocin is responsible for the actual ejection of milk from the alveoli of the mammary glands during lactation, a process called the let-down reflex. Let-down occurs when oxytocin binds to myoepithelial cells surrounding the glands and causes them to contract and eject the milk. During nursing, oxytocin also stimulates the recently emptied uterus to contract, which helps return it to pre-pregnancy size. 122) Explain codominance using the ABO blood groups as an example. Answer: ABO blood types exhibit the phenomenon of codominance, meaning that some alleles are equally dominant and are therefore equally expressed. IA and IB are codominant alleles, while i is recessive. Someone who is IA IB genotype expresses both A and B antigens on the surface of their red blood cells and thus has blood type, or phenotype, AB. 123) Explain how polygenic inheritance differs from multiple alleles. Answer: Most inherited traits, such as skin color and height, are controlled by the combined effects of two or more genes, a condition called polygenic inheritance. Many human traits, such as the ABO blood types, involve the interaction of multiple alleles for one gene. 124) Chorionic villus sampling (CVS) may be performed early in pregnancy to find certain problems with the fetus. Determine and describe the extraembryonic membrane that is being sampled. Answer: The chorion, an extraembryonic membrane, forms outgrowths called chorionic villi— the membrane being sampled. As the pregnancy progresses, chorionic villi grow only in the direction of the stratum functionalis layer of the endometrium. By late week four of development, the chorionic villi are blended with the stratum functionalis layer and begin to form the principal embryonic part of the placenta. Since this layer is created from the embryonic cells, those cells can be used to determine genetic abnormalities that will also be present in the embryo/fetus. 125) Anencephaly, a fatal condition, results from the failure of the anterior end of the neural tube to close properly, causing failure of the forebrain to develop. Determine and discuss the germ layer involved in this defect. Answer: Failure of the forebrain to develop results in a fatal condition known as anencephaly. Cells of the ectoderm thicken and form the neural plate, which folds inward and deepens. The edges fuse to form a neural tube, which will pinch off from the ectodermal germ layer. The anterior end of the neural tube will become the brain, and the remainder will become the spinal cord. By the end of the fourth week, the anterior end of the neural tube should develop into three enlarged areas called the primary brain vesicles: the forebrain, midbrain, and hindbrain. 126) Discuss the function of ductus venosus in a fetus. Answer: The umbilical vein delivers oxygenated blood to the fetus. Blood that enters the fetus from the umbilical vein travels to the liver first. However, the immature liver cannot perform many of its filtering or storage functions (a job done by the maternal liver), so complete perfusion is not necessary before birth. Therefore, most blood from the umbilical vein bypasses the liver via the ductus venosus, which connects to the inferior vena cava and then flows to the right atrium of the heart. 127) An old saying goes, "For every child, a tooth is lost." This saying suggests that a mother may lose a tooth for each child she births. Predict the hormone responsible for this potential pregnancy issue. Answer: Parathyroid hormone, secreted by the parathyroid glands, helps to maintain a high concentration of maternal blood calcium ions because fetal demand for calcium ions is high to support bone development. Parathyroid hormone may pull calcium from maternal bones and teeth for deposit into the blood, thus causing the loss of one or more teeth. 128) Explain what is meant when a pregnant woman says her "water has broken." Discuss the stage of labor during which this event occurs. Answer: At some point during the dilation stage, the amnion ruptures and releases the amniotic fluid, which is the event known as the "water breaking" or "rupture of membranes." If the amnion does not rupture on its own by the end of this stage, it may need to be ruptured manually. Additionally, the cervix thins and dilates as the fetus' head is forced against the cervix. Toward the end of the dilation stage, the fetus' head enters the true pelvis and the fetus rotates so that its head can pass through the pelvic outlet. 129) Predict the possible genotypes of offspring of a couple who both are heterozygous for free earlobes. The trait for free earlobes are carried on the dominant allele while the trait for attached earlobes is carried on the recessive allele. Answer: The dominant allele, E, is for the free earlobe trait. The recessive allele, e, is for the attached earlobe trait. Both parents are heterozygous for free earlobes; thus, the genotype for each parent is Ee. The possible genotypes of their offspring are EE (1/4, or 25%), Ee (2/4, or 50%), and ee (1/4, or 25%).