Chapter 27 Development and Heredity

The 16-cell stage is known as the:

morula.

April has an abundance of freckles a physical expression of her genes known as the:,

phenotype.

What makes estrogen and progesterone after the fourth month of pregnancy to maintain the uterine lining?

placenta

What is the afterbirth?

placenta and attached fetal extraembryonic membranes

What does the ectoderm form?

plate and neural tube

Inherited traits controlled by two or more genes are called:

polygenic inheritance.

By what week of prenatal development will the placenta be established?

week 12

By what week of prenatal development will organogenesis be complete?

week 8

In humans from which extraembryonic membrane will the first blood cells arise?

yolk sac

Which cardiovascular changes are NOT typically expected in a pregnant female?

decreased blood volume

The Apgar score is assigned for several criteria measured at birth. What is NOT measured?

defecation

This germ layer forms most of the cardiovascular system.

mesoderm

This germ layer forms the gonads kidneys, and spleen of the developing embryo.,

mesoderm

Which germ layer forms the gonads and kidneys?

mesoderm

During which month of prenatal development will the fetus begin to develop reflexes?

month 4

Which antibodies are found in colostrum?

IgA

Approximately how many days after fertilization is a fetus considered full-term and ready to be born?

266 days

The gestation period is approximately:

280 days.

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.,

75% of the offspring will have a widow's peak.

What do the umbilical arteries transport?

deoxygenated blood away from the fetal heart

Labor progresses through the following three stages:

dilation, expulsion, and placental stages.

The first stage of labor is:

dilation.

Which of the following fetal vascular shunts bypasses the liver?

ductus venosus

A birth defect known as spina bifida results from the incomplete closure of the embryonic neural tube. Which germ layer is affected?

ectoderm

The pigment cells of the skin cells of the adrenal medulla, and connective tissue cells are formed by this germ layer.,

ectoderm

This germ layer forms the majority of the nervous system and sense organs.

ectoderm

The organ systems rudimentarily form during the:

embryonic period.

Which of the following vascular shunts connects the fetal left and right atria?

foramen ovale

The fusion of the pronuclei can occur after the oocyte completes:

meiosis II.

Joanne is ready to give birth. How much should her cervix be dilated?

10 cm

Determine the series of hormonal events that leads to birth. 1. Oxytocin stimulates the placenta to secrete prostaglandins. 2. Fetal cortisol stimulates the placenta to secrete estrogen. 3. Prostaglandins dilate the cervix and with oxytocin, increase the strength of uterine contractions. 4. The high estrogen level stimulates the uterus to form oxytocin receptors,

A) 2, 4, 1, 3 2. Fetal cortisol stimulates the placenta to secrete estrogen. 4. The high estrogen level stimulates the uterus to form oxytocin receptors, 1. Oxytocin stimulates the placenta to secrete prostaglandins. 3. Prostaglandins dilate the cervix and with oxytocin, increase the strength of uterine contractions.

Which of the following is an inherited trait influenced by multiple alleles?

ABO blood types

During month 4 of prenatal development the fetus turns upside down in the vertex position.

FALSE

Fetal heart rate and respiratory rate are both lower than those of adults.

FALSE

Sperm entry into the secondary oocyte triggers the acrosomal reaction.

FALSE

The fetal period extends from the beginning of week 4 until the end of week 8.

FALSE

The four extraembryonic membranes that arise from the bilaminar embryonic disc are the mesoderm, ectoderm, and placenta.,

FALSE

The pre-embryonic period starts with a process called gastrulation.

FALSE

A female will express the trait for an X-linked disorder only if she is homozygous for the recessive allele.

TRUE

A pregnant woman typically needs about 300 extra calories each day to support both herself and the fetus.

TRUE

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.,

TRUE

Corticotropin-releasing hormone (CRH)released by the placenta, increases the production of cortisol from the adrenal cortex, which is needed for the maturation of the fetal lungs and the production of surfactant.,

TRUE

Dilation is the longest of the three stages of labor.

TRUE

The ductus arteriosus is a fetal vascular shunt that allows blood to flow from the pulmonary trunk directly into the aorta.

TRUE

The embryonic period of prenatal development occurs from week 3 until week 8.

TRUE

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.,

TRUE

The three germ layers are the endoderm mesoderm, and ectoderm.,

TRUE

What major event occurs during the first stage of labor?

The cervix thins and dilates.

Predict the possible blood types or phenotypes of offspring in which the father has blood type O and the mother has blood type AB.

The possible blood types of the offspring are phenotypes A or B only.

Which reaction releases enzymes such as hyaluronidase and acrosin that allow sperm to penetrate the corona radiata of the secondary oocyte?

acrosomal reaction

From what do both lanugo and the vernix caseosa protect the fetus?

amniotic fluid

Where does fertilization usually occur?

ampulla of the uterine tube

Which of the following implants in or attaches to the endometrium of the uterus?

blastocyst

After fertilization a zygote rapidly divides to produce small, genetically identical cells known as:,

blastomeres.

What is NOT allowed to pass through the placental barrier between maternal and fetal blood supplies?

blood cells

Along which line of the embryo does the primitive streak form?

cephalic-caudal

Parturition is also known as:

childbirth.

Which extraembryonic membrane forms the embryonic part of the placenta?

chorion

What contributes to the fetal portion of the placenta?

chorionic villi

What follows immediately after fertilization occurs?

cleavage

In the case of blood types both alleles A and B may be expressed as the phenotype. This exemplifies:,

codominance.

When does the prenatal period begin?

conception

How is polyspermy prevented?

cortical reaction

Which fetal hormone initiates labor?

cortisol

The majority of the liver the gallbladder, and pancreas are formed by this germ layer.,

endoderm

The thyroid gland parathyroid glands, and the thymus are formed by this germ layer.,

endoderm

Which of the following is the inner germ layer?

endoderm

Which hormones stimulate the growth of alveoli in the mother's mammary gland?

estrogen and prolactin

During which stage of labor does the fetal head crown?

expulsion

The fusion of a sperm cell and secondary oocyte is known as:

fertilization.

By which period of prenatal development will the placenta be fully formed?

fetal period

The initial stimulus for labor comes from the:

fetus.

What does gastrulation accomplish?

formation of the three germ layers

What process starts at the embryonic period?

gastrulation

Which of the following steps must occur first during the embryonic period?

gastrulation

The rearrangement and migration of the cells of the bilaminar embryonic disc forms the trilaminar embryonic disc in a process called:

gastrulation.

Cephalocaudal folding creates the:

head and buttocks regions.

In order for a male to inherit a sex-linked (X-linked) disorder he must receive the allele from:

his mother only.

If two alleles code for the same trait (such as blond hair) they are said to be:

homozygous.

Which of the following does NOT occur during the embryonic period?

implantation

An adult heart should have a:

ligamentum arteriosum.

After birth the mother may lose excess fluids as a discharge from the uterus known as:,

lochia.

Mrs. Floyd developed an accentuated lumbar curvature during the last few months of her pregnancy. Determine this spinal curvature.

lordosis

When environmental factors influence gene expression this is referred to as:

multifactorial inheritance.

What is the first major event of organogenesis?

neurulation

During which process is exposure to teratogens most devastating for the development of the embryo's organs?

organogenesis

The differentiation of the germ layers into organs and organ systems is known as:

organogenesis.

Krista is having difficulty with the progression of labor. Her obstetrician administers a hormone to assist with her uterine contractions. This hormone is a synthetic version of:

oxytocin.

Which hormone makes the medullary respiratory center more sensitive to carbon dioxide levels during pregnancy?

progesterone

A positive feedback mechanism initiates the rhythmic contractions of labor. Determine the hormones involved in this feedback loop.

prostaglandins and oxytocin

Which of the following is NOT a function of amniotic fluid?

provides nutrition for the developing embryo

Which hormone suppresses uterine contractions until birth?

relaxin

When do the extraembryonic membranes form?

second week of development

Which of the following releases human chorionic gonadotropin (hCG)?

syncytiotrophoblast

What is the neonatal period?

the first four weeks of life

The head and tail regions ventral and dorsal regions, right and left sides are established by

the primitive streak.

Which part of the embryo contributes to the fetal portion of the placenta?

trophoblast

What connects the placenta to the fetus?

umbilical cord

Failure of the allantois to fully develop will impact the formation of the:

urinary bladder.

The best fetal position for birth is the:

vertex position.