API Ch 29 Human Development & Inheritance Mastering HW, DSM, Study Area
Which of the following statements concerning gastrulation is FALSE? At the primitive streak, migrating cells leave the surface and move between the surface layer and the deep layer. The three germ layers are established during gastrulation. During gastrulation, the deep layer becomes the ectoderm. During gastrulation, cells in specific areas of the surface move toward the primitive streak.
During gastrulation, the deep layer becomes the ectoderm
The most dangerous period in prenatal or postnatal life is the
FIRST trimester
Which of the following hormones is not produced by the placenta?
FSH and LH
Which of the following events is NOT part of oocyte activation?
Fusion of the sperm pronucleus and egg pronucleus
If an individual carries a pair of alleles that are the same, the individual is ________ for the trait.
HOMOZYGOUS (not homologous)
Which of the following statements about amniocentesis is correct? A sample of the placenta is removed for examination. More than 100 disorders can be diagnosed by examining the placental sample. Sampling of the placenta occurs within the first trimester. None of the listed responses is correct.
NONE
The normal male genotype is __________, and the normal female genotype is __________.
XY; XX
Embryogenesis is the process that establishes the foundation for __________.
all the major organ systems
The extraembryonic membrane that begins as an outpocketing of endoderm and whose base gives rise to the urinary bladder is the __________.
allantois
What is the extra-embryonic membrane that gives rise to the urinary bladder?
allantois
A space opens within the inner cell mass that will form the
amniotic cavity
In cases of gestational trophoblastic neoplasia, the trophoblast __________.
divides excessively and spreads to other tissues, behaving much like cancer
Which embryonic germ layer forms the BRAIN and SPINAL CORD?
ectoderm
Which embryonic germ layer forms the linings of the respiratory and digestive TRACTS?
endoderm
Embryologic development __________.
ends two weeks after conception
What event marks the onset of development?
fertilization
Which of the following enzymes are released from the acrosome of sperm?
hyaluronidase and acrosin
The penetration of the endometrium by the blastocyst is referred to as
implantation
Which of the following is NOT a factor that opposes the calming effect of progesterone on uterine smooth muscle (the myometrium) and may lead to the onset of labor? Increasing oxytocin levels Increasing relaxin levels Increasing estrogen levels Prostaglandin production
increasing relaxin levels
Which of the following statements about fertilization is FALSE? Normal fertilization occurs in the body of the uterus. The ovum must provide the nourishment and genetic programming to support embryonic development for nearly a week. Fertilization involves the fusion of two haploid gametes. Of the roughly 200 million spermatozoa introduced into the vagina in a typical ejaculation, fewer than 100 actually reach the ovum.
normal fertilization occurs in the body of the uterus
the site where fertilization normally occurs is in the
outer one third of the uterine tube
stretching of the cervix causes an increase in the blood levels of
oxytocin
what is the hormone that causes milk ejection?
oxytocin (NOT prolactin)
The first meiotic division __________.
reduces the number of chromosomes from 46 to 23
As development proceeds, the differentiation of other embryonic cells is affected by small zygotic cells that __________.
release RNA, polypeptides, and small proteins
Each of the following contributes to the onset of labor contractions EXCEPT __________. rising oxytocin levels rising estrogen levels rising prostaglandin levels rising progesterone levels
rising progesterone levels
Prostaglandins in the endometrium _________________.
stimulate smooth muscle contractions
The umbilical cord, or umbilical stalk, contains __________.
the allantois, blood vessels, and yolk stalk
What is the fate of the cluster of cells in the blastocyst known as the inner cell mass?
the cells will develop into the embryo
Exchange between the embryonic and the maternal circulations occurs by diffusion across the syncytial and cellular trophoblast layers via __________.
the chorionic blood vessels
The formation of extraembryonic membranes occurs in the correct sequential steps, which are __________.
yolk sac, amnion, allantois, chorion
What prevents more than one sperm from fertilizing the secondary oocyte?
zonal inhibition proteins
The development stages that occur during cleavage follow which sequence?
zygote, blastomeres, morula, blastocyst
During gastrulation,
three germ layers are formed
The inner cell mass does NOT form which of the following structures?
trophoblast
Fraternal, or dizygotic, twins result from __________.
two oocytes being ovulated in one cycle
The ________ is formed by the allantois, blood vessels, and yolk sac.
umbilical cord
Fertilization usually occurs in the
uterine tube
The primary nutrient source for early embryonic development that later becomes an important site for blood formation is the
yolk sac
The Extra-embryonic membranes that develop from the endoderm and the mesoderm are the __________.
yolk sac and the amnion
Before gestation, the uterus weighs about __________.
1 OZ
At the end of gestation, the uterus may weigh __________ lb.
14 LB
In general, a male with a sperm count of less than __________ million per milliliter is considered infertile.
20
As identified by the Human Genome Project, the total number of protein-encoding genes in human DNA is __________.
20,000-25,000
The total number of genes in human DNA, as identified by the Human Genome Project, is __________.
25,000-30,000
What is the meaning of the world gestation?
ALL of prenatal development
Uterine contractions that are irregular and brief that occur toward the end of gestation are called
Braxton-Hicks
Which of the following forms the PLACENTA?
CHORION
The period of gestation when organs and organ systems complete most of their development and the fetus looks distinctly human is the ________ trimester.
SECOND
At puberty, increased hormone production and sexual maturation are promoted by each of the following EXCEPT one. Identify the exception. The hypothalamus increases its production of GnRH, the gonadotropin-releasing hormone. The anterior lobe of the pituitary gland becomes more sensitive to GnRH and elevates the circulating levels of follicle-stimulating hormone (FSH) and luteinizing hormone (LH). Ovarian and testicular cells become more sensitive to the pituitary gonadotropins. Sex hormones from the gonads stimulate the hypothalamus, producing GnRH, the gonadotropin-releasing hormone.
Sex hormones from the gonads stimulate the hypothalamus, producing GnRH, the gonadotropin-releasing hormone.
Which of the following statements concerning placentation is FALSE? The fetus is connected to the placenta by the umbilical cord. The decidua parietalis is the portion of the uterine endometrium in direct contact with the chorion. The decidua capsularis of the placenta does not participate in nutrient exchange. Placental functions are concentrated in a disc-shaped area called the decidua basalis.
The decidua parietalis is the portion of the uterine endometrium in direct contact with the chorion.
Which of the following syndromes would be found in a female who has only one sex chromosome?
Turner syndrome
Which of the following occurs in the event of "fraternal," or dizygotic, twins? Two separate eggs are ovulated and fertilized. The inner cell mass splits before gastrulation. The blastomeres separate early during cleavage. All of the listed responses are correct.
Two separate eggs are ovulated and fertilized.
Which of the following does NOT occur during the transition from fetus to neonate? Materials collected in the relatively inactive fetal digestive tract are excreted in the first few days of life. The pattern of cardiovascular circulation changes after the lungs expand. Typical heart and respiratory rates are lower in neonates than in adults. The lungs at birth are collapsed and must be inflated by massive and powerful inspiratory movements.
Typical heart and respiratory rates are lower in neonates than in adults
polyspermy results in
a nonfunctional zygote
After fertilization, the first cell division is completed
about 30 hours later
The presence of freckles on the skin is __________.
an example of simple inheritance, with the recessive form being the absence of freckles on the skin
________ are nearly identical cells that are produced by early cleavages
blastomeres
Which of the following statements is NOT related to differentiation?
changes in the DNA of the cell
What is the correct sequence of events going from the zygote to the fetus?
cleavage implantation placentation embryogenesis
The first secretion produced by the mammary glands for the baby is __________.
colostrum
What is the difference between colostrum and breast milk?
colostrum has more protein and less fat than breast milk
The layer of follicle cells that surround the unfertilized egg is called the
corona radiata
If fertilization occurs, the ________ is maintained because the embryo secretes ________.
corpus luteum; human chorionic gonadotropin
During oocyte activation, the process that is important in preventing penetration by more than one sperm is the __________.
cortical reaction
Which of the following is NOT a reason why maternal blood volume increases during pregnancy? decreased maternal PCO2 rapid fetal metabolic activity decreased maternal blood PO2 increased blood flow in placenta
decreased maternal PCO2
During gestation, the primary compensatory adjustments include all of the following except ______________.
decreasing respiratory rate and tidal volume
premature delivery
delivery from 28 to 36 weeks
In polygenic inheritance, phenotypic characters are
determined by interactions among several genes
What is the correct sequence of stages in the process of delivering a baby?
dilation; expulsion; placenta
The gradual modification of anatomical structures during development occurs during the period from __________.
fertilization to maturity
What is the "moment of conception"?
fusion of the male and female pronuclei
What triggers the activation of the secondary oocyte?
fusion of the sperm and secondary oocyte membranes
Germ-layer formation results from the process of __________.
gastrulation
What is the hormone that is produced by the placenta and stimulates the mother's ovaries to continue the production of progesterone?
hCG
Throughout embryonic and fetal development, metabolic wastes generated by the fetus are eliminated by their transfer to the __________.
maternal circulation
The AMNION contains contributions from which germ cell layer(s)?
mesoderm and ectoderm
The YOLK SAC contains contributions from which germ cell layer(s)?
mesoderm and endoderm
The chorion develops from the
mesoderm and trophoblast
The region known as the primitive streak is the site of
migration of ECTODERMAL cells to form the mesoderm
twins that occur when blastomeres separate are called
monozygotic
Alterations in genetic activity during development result from __________.
the differences in the cytoplasmic compositions of individual cells
the embryo becomes a fetus at
the end of the 8th week
Complete dilation of the cervix marks the beginning of __________.
the expulsion stage (NOT the dilation stage)
Which of the following does NOT happen during oocyte activation? Meiosis II is completed. Cortical reaction prevents polyspermy. Enzymes are activated to increase the ovum's metabolic rate. The first cleavage is completed.
the first cleavage is completed
during amphimixis
the male and female pronuclei fuse
In terms of genetic inheritance, the penetrance of a trait refers to __________.
the percentage of individuals with a particular genotype who show the "expected" phenotype
Why does a pregnant women experience breathing difficulty?
the uterus infringes on the diaphragm
What happens in the process of hatching?
the zona pellucida is shed from the blastocyst