BIO 169 Chapter 27 Exam

A child born with an XXY chromosome pattern will have

Klinefelter's syndrome

Non-sex chromosomes are called

autosomal

The individual cells produced by cleavage are called

blastomeres

The oval, three-layered sheet produced by gastrulation is called the

embryonic disc

The stage of labor during which the fetus emerges from the vagina is called the ________ stage.

expulsion

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

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

The region known as the primitive streak is the site of

migration of ectodermal cells to form the mesoderm

After 3 days, a pre-embryo becomes a solid ball of cells known as a

morula

The mesoderm forms

muscle

The ectoderm forms

neural tissues

Which hormone stimulates the milk let-down reflex?

oxytocin

The traits of an individual controlled by his or her genotype are his or her

phenotype

The hormone that increases the flexibility of the pubic symphysis during pregnancy is

relaxin

The prostaglandins produced in the endometrium

stimulate smooth muscle contractions

Deoxygenated blood is carried to the placenta by the

umbilical arteries

A person's original chromosomes and their component genes constitute that person's

genotype

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

hollow ball of cells

If an individual carries a pair of alleles that are the same, the individual is ________ for the trait.

homozygous

A zygote whose genotype is XY will develop as a

male

After fertilization, the first cell division is completed

more than a day later

The placenta is expelled from the uterus during the ________ stage of labor.

placental

The "P" in the abbreviation SNP stands for

polymorphism

During gestation, contraction of the myometrium is inhibited by ________, produced by the placenta.

progesterone

The clinical term for "growing old" is

senescence

At fertilization, the "moment of conception" occurs in

step 5, amphimixis and cleavage

During implantation, the

syncytial trophoblast erodes a path through the endometrium

Each of the following statements concerning development is true except

the first trimester is when the fetus looks distinctively human

During amphimixis,

the male and female pronuclei fuse

The endoderm forms

the urinary bladder

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

The ________ is formed by the allantois, blood vessels, and yolk sac.

umbilical cord

Which of the following is not one of the extraembryonic 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 2

Which of the following descriptors regarding the trophoblast is false?

is derived from the inner cell mass

All of the following are true of the allantois except

it acts as the fetal bone marrow

The various forms of any one gene are called

alleles

The extraembryonic membrane that forms a fluid-filled sac is the

amnion

A space opens within the inner cell mass that will form the

amniotic cavity

The almost identical cells produced by cleavage divisions are called

blastomeres

Endoderm + mesoderm = which extraembryonic membrane?

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

The extraembryonic membrane that forms the fetal portion of the placenta is the

chorion

The mesoderm and the trophoblast combine to form 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 first stage of labor is the ________ stage.

dilation

Which of the following hormones is the cause of most puberty-related changes in a female?

estrogen

A zygote whose genotype is XX will develop as a

female

Embryonic and early fetal development occurs in the ________ trimester.

first

The inner cell mass of the blastocyst will

form the embryo

By day 12 of embryonic development, mesoderm begins to form through

gastrulation

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?

1/2

How many chromosomes do human somatic cells contain?

46

Trisomy 21 is the clinical term for

Down syndrome

Molly is homozygous for the dominant black hair trait. Therefore,

Molly has black hair

In simple autosomal inheritance, phenotypic characters are determined, or controlled, by

a single pair of alleles

In simple autosomal inheritance, phenotypic characters are determined, or controlled, by Select one:

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

The infancy stage of life is considered to be over when the baby reaches ________ of age.

2 years

By the end of gestation, maternal blood volume normally increases by almost ________ percent.

50

Completion of cytokinesis leads to

All of the answers are correct

Contact of a sperm with the oocyte membrane causes

All of the answers are correct

Progesterone calms the myometrium and prevents contraction. What factors antagonize progesterone and trigger labor and delivery?

All of the answers are correct

The placenta is a source of which of the following hormones?

All of the answers are correct

Which of the following is one of the critical events of the first trimester?

All of the answers are correct

________ is the time spent in growing within the uterus.

Gestation

All of the following occur at puberty except

GnRH levels decline