tesy 2
If a color- blind (X- linked recessive trait) man marries a woman who is heterozygous for the trait, what proportion of their male offspring can be expected to be color blind?
1/4
The infancy stage of life is considered to be over when the baby reaches ________ of age.
2 years
The extra- embryonic membrane that forms a fluid- filled sac is the
amnion.
The mesoderm and the cytotrophoblast combine to form the
chorion.
Identify what process is occurring at the structure labeled "6."
cleavage
If an individual carries a pair of alleles that are the same, the individual is ________ for the trait.
homozygous
Embryonic and early fetal development occurs in the ________ trimester.
second
A person's original chromosomes and their component genes constitute that person's
genotype.
Which of the following does not describe non- sex chromosomes?
haploid
Which of the following traits is a sex- linked inheritance?
hemophilia
If an individual carries two different alleles for the same trait, the individual is ________ for the trait.
heterozygous
A blastocyst is a(n)
hollow ball of cells.
A zygote whose genotype is XY will develop as a
male.
During implantation, the
maternal blood vessels in the endometrium are walled off from the blastocyst.
The region known as the primitive streak is the site of
migration of ectodermal cells to form the mesoderm.
After fertilization, the first cell division is completed
more than a day later.
A pre- embryo that consists of a solid ball of cells is known as what type of structure? (Module 27.3A)
morula
After 3 days, a pre- embryo becomes a solid ball of cells known as a
morula.
The endoderm forms
muscle.
The mesoderm forms
muscle.
Fertilization is complete when which of the follow occurs?
oocyte activation
Each of the following statements concerning development is true except
organ development is complete by the end of the 6th month.
Which hormone stimulates the milk let- down reflex?
oxytocin
Stretching of the cervix causes an increase in the blood levels of
oxytocin.
The traits of an individual controlled by his or her genotype are his or her
phenotype.
Identify the structure labeled "4."
placenta
The placenta is expelled from the uterus during the ________ stage of labor.
placental
Identify the structures labeled "4."
polar bodies
The "P" in the abbreviation SNP stands for
polymorphism.
During gestation, contraction of the myometrium is inhibited by ________, produced by the placenta.
progesterone
The placenta is not a source of which of the following hormones?
prolactin
Progesterone calms the myometrium and prevents contraction. What factor does not antagonize progesterone and trigger labor and delivery?
relaxation of the cervix
The hormone that increases the flexibility of the pubic symphysis during pregnancy is
relaxin.
The clinical term for "growing old" is
senescence.
Which of the following does not occur during the first trimester?
separation of blastomeres to form monozygotic twins
The prostaglandins produced in the endometrium
stimulate smooth muscle contractions.
The ectoderm forms
the lining of the stomach and small intestine.
During amphimixis,
the male and female pronuclei fuse.
The period of gestation that is characterized by the largest fetal weight gain and fat deposition is the ________ trimester.
third
During gastrulation,
three germ layers are formed.
Deoxygenated blood is carried to the placenta by the
umbilical arteries.
Identify the structure labeled "3."
umbilical cord
The ________ is formed by a portion of the allantois, blood vessels, and remnants of the yolk sac.
umbilical cord
Which of the following is not one of the extra- embryonic membranes?
umbilical cord
Oxygenated blood is carried away from the placenta by the
umbilical vein.
The embryonic heart starts beating as blood begins to flow through chorionic vessels at approximately ________ of development.
week 3
The extra- embryonic membrane that forms blood cells is the
yolk sac.
All of the following occur at puberty except
FSH levels rise.
Define fertilization. (Module 27.2A)
Fertilization is the fusion of a secondary oocyte and a sperm to form a zygote.
In pregnancy, expansion of the uterus results from
hypertrophy of smooth muscle cells.
Attachment to and penetration of the endometrium by the blastocyst is referred to as
implantation.
All of the following are true of the allantois except
it acts as the fetal bone marrow.
Molly is homozygous for the dominant black hair trait. Therefore,
Molly has black hair.
What is postnatal development? (Module 27.1C)
Postnatal development begins at birth and continues to maturity.
A ________ is used to show all possible combinations of genes that can result from a given parental cross.
Punnett square
By the end of gestation, which of the following has not occurred?
The bladder size has been reduced.
Describe the trophoblast. (Module 27.3B)
The trophoblast is the cell layer surrounding the blastocyst.
A child born with one lone X chromosome will have
Turner's syndrome.
Contact of a sperm with the oocyte membrane does not cause
a decrease in calcium released from the oocyte.
In simple autosomal inheritance, phenotypic characters are determined, or controlled, by
a single pair of alleles.
All of the following occur during pregnancy except
a woman's bladder capacity increases.
Which of the following is a puberty- related change caused by increased testosterone levels?
accelerated bone deposition and skeletal growth
The developmental period heralded by the onset of puberty is known as
adolescence.
Identify the stage labeled "8."
advanced morula
The various forms of any one gene are called
alleles.
Identify the structure labeled "6."
amnion
Identify the structure labeled "5."
amniotic cavity
A space opens within the inner cell mass that will form the
amniotic cavity.
Identify the stage labeled "12."
blastocyst
The almost identical cells produced by cleavage divisions are called
blastomeres.
The individual cells produced by cleavage are called
blastomeres.
Endoderm + mesoderm = which extra- embryonic membrane(s)?
both yolk sac and allantois
Under the influence of the trophoblast, maternal blood vessels in the endometrium
break down and form lacunae.
The trophoblast has many of the characteristics of ________ cells.
cancer
Which of the following descriptors regarding the trophoblast is false?
causes maternal blood vessels to break down
Identify the structure labeled "7."
chorion
The extra- embryonic membrane that forms the fetal portion of the placenta is the
chorion.
The process of cell division that divides the cytoplasm of the zygote among blastomeres is called
cleavage.
Which of the following is not part of fertilization?
completion of meiosis I
In polygenic inheritance, phenotypic characters are
determined by interactions among several genes.
The gradual modification of anatomical structures during the period from conception to maturity is
development.
The first stage of labor is the ________ stage.
dilation
The oval, three- layered sheet produced by gastrulation is called the
embryonic disc.
Which of the following hormones is the cause of most puberty- related changes in a female?
estrogen
The stage of labor during which the fetus emerges from the vagina is called the ________ stage.
expulsion
A zygote whose genotype is XX will develop as a
female.
The period of gestation when the rudiments of all major organ systems are established is the ________ trimester.
first
The neonatal period extends
for the first month of life.
The inner cell mass of the blastocyst will
form the embryo.
Completion of cytokinesis does not lead to
formation of a polar body.
What is the developmental fate of "9?"
forms the embryo
By day 12 of embryonic development, mesoderm begins to form through
gastrulation.
How many chromosomes are contained within a human zygote? (Module 27.2B)
46
How many chromosomes do human somatic cells contain?
46
Why are numerous sperm required to fertilize a secondary oocyte? (Module 27.2C)
Acrosomal enzymes from multiple sperm are needed to penetrate the corona radiata.
Trisomy 21 is the clinical term for
Down syndrome.
Distinguish among embryonic, fetal, and prenatal development. (Module 27.1B)
Embryonic development refers to the events that occur during the first 2 months after fertilization. Fetal development begins at the 9th week and continues until birth. Prenatal development consists of both embryonic and fetal development.
Describe the process that forms the primary germ layers and cite the layer that contributes to nearly all body systems. (Module 27.4A)
Gastrulation forms the primary germ layers from the embryonic disc. The mesoderm contributes to nearly all body systems.
________ is the time spent in growing within the uterus.
Gestation
Define gestation. (Module 27.1A)
Gestation is the time a developing embryo and fetus spends in the uterus.