CH 2

Each molecule of DNA is called a(n):

chromosome.

Each human body cell contains

46 chromosomes.

Each reproductive cell contains

23 chromosomes

Reproductive cells are called

gametes

The total collection of genes that an individual has is called his or her

genotype

Each individual inherits 23 chromosomes from their mother and 23 chromosomes from their father. In addition, epigenetic effects create an individual’s appearance and behavior to create a:

phenotype

Timur and Juan are playing basketball. Timur shoots the ball and Juan blocks the shot. Timur says, "Wow, I didn’t realize how tall you were until you did that!" Timur’s comment refers to Juan’s:

phenotype

Brothers and sisters from the same parents share only half the same genes, making the possible combinations:

in the millions

Genetic___________distinguishes each person and allows for adaptation.

diversity

The name of the full set of genes that provide the instructions for making living organisms is the:

genome.

Each human has a total of about_____genes.

20,000-23,000

On the 23rd set of chromosomes, males have:

an X and a Y chromosome.

On the 23rd set of chromosomes, females have:

two X chromosomes.

Michelle and Greg are having a baby and are hoping for a boy. Who is responsible for the determining the sex of the baby?

Greg

Which statement is true?

Male embryos are more vulnerable than female embryos therefore less likely to survive prenatally.

Identical twins are also called _______twins

monozygotic

Fraternal twins are also called ____twins

dizygotic

Harold and Heather are twins. They are the result of:

Two separate ova that were fertilized by two different sperms

Justin and Jacob are identical twins. They are the result of:

One ovum fertilized by one sperm that split into two zygotes

the ______is a worldwide effort to map all human genes.

Human Genome Project

Historically, who was blamed for not producing an offspring of a particular gender?

mothers only

Due to understanding more about the role of genes in determining the sex of a child, couples can
select the sex of a child by all methods EXCEPT:

selecting only X eggs for fertilization.

When the effects of genes add up to make the phenotype, they are called ____genes

additive

Holly learned from her science teacher that her height resulted from about 180 genes, each contributing a tiny amount of genetic information. Holly learned that her height was due to:

additive genes.

Brown-eyed Alma has a blue-eyed mother and a brown-eyed father. In this case, her brown eyes were determined by a ______allele

dominant

Lacy has a recessive gene in her genotype that is not expressed in her phenotype. She is a(n) of
that gene.

carrier

Michael is color-blind. His gene for color blindness is most likely a:

recessive gene on his X chromosome.

Almost every trait is __________,which means it is affected by many genes.

polygenic

Cindy is doing a presentation on prenatal development and wants to present the three main periods of prenatal development in order from conception to birth. Cindy’s presentation uses the following order:

germinal, embryonic, and fetal.

Many obstetricians date the onset of pregnancy from the date:

of the woman’s last menstrual period

Before differentiation begins, the first cells of the zygote are called _____cells.

stem

During the germinal period of prenatal development, some cells become part of the brain, some
become part of the leg, and some become part of the stomach, etc. The term for this process is:
a. duplication.

differentiation.

During the germinal period, the first task of the zygote’s outer cells is:

. implantation.

The germinal period ends approximately________after conception.

2 weeks

About a week after conception, the outer layer of the multiplying cells forms a protective circle, or shell, that will become the:

placenta.

What is the main function of the placenta?

protecting and surrounding the developing fetus

Around day 14 of the embryonic period, the _______appears. It will eventually become the neural tube.

the primitive streak

The neural tube will become the

brain and spinal cord

The head begins to take shape in the______week after conception.

fourth

In the fourth week after conception, a miniscule blood vessel that is the start of the_______system begins to pulsate

cardiovascular

A woman who is pregnant is having an ultrasound done eight weeks into prenatal development. She is surprised by the size of the embryo’s head when she sees the image on the screen. The doctor reassures her that this is typical and due to the________pattern developement

cephalocaudal

Prenatally, development happens in a "near to far" pattern known as:

proximodistal.

The longest period of prenatal development is the ___________period.

fetal

The third period of gestation is the ____________period.

fetal

In the _________after conception, sex organs develop and are soon visible via ultrasound

ninth week

What happens to the brain during the fetal period of development?

It increases in size and begins to wrinkle.

. The age of viability is the time when the preterm newborn

might survive outside the uterus.

Harry was a preterm newborn who was born after 26 weeks of prenatal development. He now is a healthy, happy 2-year-old. Harry’s ability to survive after being born so early was due in part to his
reaching the:

age of viability.

On average, fetuses gain about ________pounds during the last trimester of pregnancy, which brings the average birth weight to about 7.5 pounds.

4.5 pounds

The critical factor in attaining the age of viability is

. having adequate brain development.

The____starts the sequence of events that prepares the fetus for delivery and starts labor.

fetal brain

Full-term pregnancies typically last_______from the date of conception

38 weeks

In a first birth, the average length of active labor is

about 12 hours.

The Apgar scale is used at one minute and five minutes after birth to:

evaluate the health of the newborn.

A baby is assessed at one minute after birth according to the Apgar scale. Three of the five vital signs
are good, but the baby is weak and inactive and grimaces. The two vital signs the medical team is concerned about are:

muscle tone and reflex irritability.

Virginia Apgar was a(n):

anesthesiologist.

In the third stage of labor, the:

placenta is delivered.

In the United States, more than ______of births occur via C-section.

1/3

Compared to vaginal births, C-section births:

increase the risk of complications.

Epidurals, often used in hospital births to manage pain during childbirth, have been shown to:

inhibit the newborn’s readiness to suck.

Which country has the highest rate of C-section births in the world?

China

An alternative to giving birth in a hospital is to arrange to give birth at home. This option is
especially popular in Europe, where home births appear to have:

fewer complications than those in hospitals.

Parents of newborn Renata are amazed at their daughter’s responsiveness and reflexes when a
professional administers the:

Brazelton Neonatal Behavioral Assessment Scale.

When infants turn their heads and suck in response to a touch on the cheek, they are demonstrating the:

rooting reflex.

Newborn babies do NOT have reflexes designed to:

adjust to the difference between day and night.

The phenomenon in which fathers experience symptoms of pregnancy and birth is known as:

couvade.

Maternal depression:

can have a long-term impact on the newborn.

Julia had a baby 3 weeks ago. She has been feeling sad and inadequate as a mother, which has made caring for her newborn difficult. Julia may be experiencing:

maternal depression.

Kelley just had a baby and now is experiencing a sense of inadequacy and sadness. She may have:

postpartum depression.

Studies indicate that _________may mitigate maternal depression by in part by increasing levels of the bonding hormone oxytocin.

breast-feeding

Rumasia places her baby on her chest so that they are skin to skin. This is called

kangaroo care.

Approximately once in every _________births, an infant is born with 45, 47, or even 48 or 49 chromosomes instead of the usual 46.

200

Down syndrome is also called:

trisomy-21.

Most of the known single-gene disorders are:
a. recessive.

dominant.

Jeremy inherited ____________, a genetic disorder characterized by uncontrollable tics and explosive verbal outbursts.

Tourette syndrome

. A teratogen is any agent or condition that increases the risk for:

damage to the placenta.

Jill is 3 years old. She is hyperactive and learning-disabled. Her doctor suggests that Jill’s problems could be the result of prenatal exposure to _________

behavioral teratogens

Chantal and Larry are considering having a baby. Chantal’s doctor recommends that they stop using
recreational drugs and update their immunizations:

before Chantal gets pregnant.

The first days and weeks after conception (the germinal and embryonic periods) are_________for body formation, but the entire fetal period is a _______period for brain development

d. critical; sensitive

Anoxia refers to:

a lack of oxygen.

Thresholds, as they relate to harm from any teratogen, are difficult to set because one teratogen may ________the harm from another teratogen.

increase

Some teratogens have a threshold effect, which means that they are:

harmless up to a certain Level:.

Mandy is pregnant yet she still smokes cigarettes, drinks alcohol, and does not eat well. Her baby may be at increased risk for the development of:

a. fetal alcohol syndrome.

One reason male fetuses are more vulnerable than female fetuses may be that the:

X chromosome seems to have a protective effect. b

Low folic acid in during pregnancy can result in:

neural-tube defects.

What percentage of all serious defects occur for unknown reasons?

. 20 percent

Early prenatal care can help decrease the risk of prenatal abnormalities. However, it CANNOT
provide pregnant women with information about:

exact thresholds for teratogens.

Babies born under 1,000 grams (2 pounds 3 ounces) are considered:
a. low birthweight

extremely low birthweight.

Babies born slightly under 1,500 grams (3 pounds 5 ounces) are considered:

very low birthweight.

Babies born slightly under 2,500 grams (5 pounds 8 ounces) are considered:

low birthweight.

A baby born three or more weeks early is called:

. preterm.

Babies considered small for gestational age:

can be full-term or preterm babies

Cigarette smoking is implicated in___________percent of all low-birthweight births worldwide

25

Bruno and Juliana moved to the United States from Mexico 2 years ago and just had their first baby.
Although Bruno and Juliana’s SES is lower than their native-born peers, their baby was born at a healthy weight, due in part, to the support of their social network. This phenomenon is called the:

Hispanic paradox.

Adults who were low-birthweight babies have higher rates of:

betes.

Which is NOT a possible consequence of low birthweight?

speech impediment

The frequency of LBW in the United States ________throughout most of the twentieth century, and then______in the 1990s and early 2000s.

decreased; increased

Statistically, which woman is MOST apt to have a baby with LBW?

Kate, who regularly misses meals

In the United States, which is NOT a potential reason for the rise in the frequency of LBW babies?

genetic factors

As of 2008, the rate of low-birthweight babies in the United States babies is_________percent.

8.2

Greg and Allen are at bar watching a football game. Over the course of the game, each one drinks
three beers. Greg is sweating and red-faced while Allen is not. A likely reason for the difference in their physiological reactions to the alcohol is that:

Greg’s and Allen’s bodies metabolize the alcohol differently.

Age impacts alcoholism in that ___________get drunk more often and experience more pleasure and less pain from drinking.

adolescents

Research indicates that alcoholism may be caused by:
a. just nature.

a combination of nature and nurture.

. Eyeballs change shape at typical stages of development, including puberty and middle adulthood.This makes it more likely that ___________will increase at puberty, and________will decrease during middle adulthood.

nearsightedness; nearsightedness

The statistic that indicates how much of the variation in a particular trait can be traced to genes is called:

heritability.

Eight-year-old Joe has no difficulty seeing things near him but sometimes struggles to see things in the distance. Joe gets his eyes checked and is told that he does not yet need corrective lenses for
nearsightedness. Instead, drawing on current research, the ophthalmologist advises that he:

play outside more.

Risks to development at apparent at conception, pregnancy, and birth but the risks can be________if

mothers and fathers, professionals, and the community work to promote healthy prenatal development.

minimized

Genes are located on chromosomes.

T

With just one exception, each body cell in a human being has 23 single chromosomes

F

An individual’s collection of genes is called a phenotype

F

Any two individuals share 99.5 percent of their genetic code.

T

All humans have about 100,000 genes.

F

If the 23rd pair of chromosomes contains two X chromosomes than that individual is a male.

F

. Every ovum a woman creates contains an X chromosome.

T

. It is the mother’s ovum that determines whether the developing baby will become a boy or a girl.

F

Dizygotic twins originate from the same zygote; therefore, they have the same genotype.

F

When a person inherits a recessive gene that is not expressed in the phenotype, that person is a carrier of the gene.

T

Every person starts life as a single cell called a stem cell.

F

The first two weeks of prenatal development are called the fetal period.

F

Couvade is when the zygote embeds itself into the lining of the uterus.

F

. Fetal development follows a cephalocaudal and a proximodistal pattern.

T

The fetus gains about 2 pounds in the third trimester.

F

Birth takes place around 266 days after conception.

T

The Apgar scale refers to the age at which a fetus might survive if born.

F

The newborn’s cry can earn a 2 for respiratory effort on the Apgar scale.

T

The Apgar scale measures color, heart rate, cry, muscle tone, and breathing.

T

. The rate of both cesarean sections and induced labor is declining worldwide.

F

Home births are more common in European nations than in the United States

T

Doulas have been shown to have little benefit in helping women during the birth process.

F

The rooting reflex helps a newborn infant find a nipple.

T

. Birth-related complications are more likely when there is a father listed on the birth record.

F

Between 8 and 15 percent of all women experience postpartum depression in the days and weeks
after giving birth

T

The strong, loving bond that forms as parents hold and feed their newborn is known as couvade.

F

About 20 percent of all children have difficulties that could be connected to behavioral teratogens.

T

The term for a temporary lack of oxygen is anoxia.

T

Alcohol is one teratogen that results in dose-related damage.

T

Some teratogens are virtually harmless until exposure reaches a certain Level:.

T

Taking even one drink of alcohol during pregnancy will result in a baby with fetal alcohol syndrome

F

. Embryos exposed to large amounts of alcohol may develop distorted facial features

T

A small for gestational age baby means the same as an underweight preterm newborn.

F

Low-birthweight is defined as a newborn that weighs less than 2,500 grams.

T

Fathers do not seem to have any impact on birth outcomes.

F

The nations of sub-Sahara Africa have low rates of low birthweight babies.

F

Genes and alleles for alcoholism have been found exclusively on the Y chromosome.

F

Heritability indicates how much of the variation of a trait can be traced to genes.

T

Genes affect disorders such as alcoholism and nearsightedness, but research indicates that the
environment plays a role as well.

T

_____are units of instructions for cells located on chromosomes.

genes

Every human body cell contains_____chromosomes, with the exception of the gametes.

46

Each variation of a gene is called a(n)_____.

allele

A person’s collection of genes is referred to as his or her_____.

genotype

An individual’s genotype plus the epigenetic effects results in his or her______.

phenotype

If the 23rd pair of chromosomes is a(n) ______, the individual will be female

XX

If the 23rd pair of chromosomes is a(n)_____, the individual will be male.

XY

Identical twins are also called_______twins.

monozygotic

Fraternal twins are also called_____twins

dizygotic

When the effects of genes combine to form the phenotype, they are called _____genes.

additive

When someone inherits a recessive gene that is not expressed, that person is a(n)_______of that gene.

carrier

__________is the process in which the developing organism embeds itself into the lining of the uterus.

Implantation

A(n)_______uses sound waves to generate an image of a fetus in utero.

ultrasound

The age at which a fetus may survive if born is known as the______

age of viability

The fetus usually gains at least _____ pounds in the third trimester

4.5 (4½)

On average, a first baby is born after_____hours of active labor.

12

Violeta is in labor and has requested a pain reliever known as a(n)_______which is an injection given in the spine to alleviate pain

epidural

The______ is used to assess the newborn’s health at one minute and five minutes.

Apgar scale

A newborn’s involuntary response to a particular stimulus is a(n) ________

reflex

__________refers to the practice of a newborn lying skin-to-skin between the mother’s breasts.

: Kangaroo care

Risk of fetal neural-tube defects may be substantially reduced by a maternal diet adequate in______.

folic acid

A newborn that weighs less than 1,000 grams would be considered ______________

extremely low birthweight,

_______is the primary reason teenage girls often have small babies.

Malnutrition

___________is the statistic that indicates how much of a variation in a particular trait can be traced to genes.

Heritability

As urbanization, video games, homework, and fear of strangers has kept more American children
indoors, the rate of ______has increased

nearsightedness (myopia),

Define genotype and phenotype and explain the impact of both on an individual’s traits.

: Genotype refers to the collection of genes a person carries in his or her DNA. Phenotype is a person’s actual appearance and behavior. The genes a person inherits, epigenetic factors, and the interaction among genes determine the actual traits expressed in each person.

Describe at least two of the surprises revealed upon the completion of the Human Genome Project.

Answers will vary but should highlight surprising findings including that any two people share 99.5 percent of their genetic code; humans and chimpanzees share 98 percent of their genetic code; genomes for humans and other mammals are at least 90 percent the same; humans only have about 20,000-23,000 genes; and dogs and mice have more genes than humans

Explain how the sex of an infant is determined and which parent is responsible for gender.

: Sex is determined by the 23rd set of chromosomes. If the set contains two X chromosomes, then the infant is female. If it contains an X and a Y, then the infant is a boy. The father’s sperm determines the sex of the infant since the sperm can carrier either and X or a Y chromosome.

Describe the difference between monozygotic and dizygotic twins.

Monozygotic twins result when one ovum is fertilized by one sperm and the zygote splits apart after duplication. This results in two identical zygotes (identical twins). Dizygotic (fraternal) twins result when two ova are fertilized by two separate sperm.

Explain how color blindness is inherited and why it is much more common in boys than in girls

Color blindness is an X-linked recessive gene. This means that it is passed down to a son from a mother on the X chromosome. Since boys have one X and one Y chromosome, they inherit one recessive gene on the X chromosome and have no dominant chromosome to overpower it on the Y chromosome.Girls, who have two X chromosomes, will usually have a dominant gene on the other X chromosome so they may carry the trait but will not express it.

Describe kangaroo care and its benefits.

In kangaroo care, mothers hold their infants to their chests skin-to-skin, allowing them to feel their body heat. Infants who benefit from kangaroo care experience deeper sleep, more time alert, and more responsiveness to their mothers.

Describe the symptoms of postpartum depression. What are possible outcomes of prolonged postpartum depression for the mother and the baby?

Symptoms of postpartum depression include deep sadness and feelings of inadequacy. Possible outcomes for the baby include inadequate food and care, behavior problems later on, lack of social stimulation, and possible abuse or neglect.

8. Define reflexes. Describe the three kinds of reflexes that are necessary for newborn survival and give an example of each.

Reflexes are unlearned actions that are involuntary responses to particular stimuli. Those that are necessary for newborn survival are ones that maintain oxygen supply (such as the breathing, hiccupping, or sneezing), maintain constant body temperature (such as crying, shivering, or pushing off blankets), and those that manage feedings (such as the sucking and rooting reflexes).

Explain the procedure known as a cesarean section, and discuss the benefits and risks associated with this kind of delivery.

A cesarean section (C-section) is also known as a surgical birth, in which incisions through the mother’s abdomen and uterus allow the fetus to be removed quickly, instead of being delivered through the vagina. Generally, cesareans are safe for mother and baby; advantages for hospitals include ease in scheduling, quicker than vaginal deliveries, and more expensive than vaginal deliveries; drawbacks are a longer recovery period after delivery for the mother, complications after birth, and a reduction in breast- feeding.

What are behavioral teratogens, and what are the potential consequences of exposure to them?

Behavioral teratogens are substances and conditions that increase the risk of harm to the developing brain in a fetus. Consequences of exposure to behavioral teratogens include hyperactivity, learning disabilities, and antisocial behavior.

What are four of the factors that contribute to low birthweight?

: Answers will vary from the following: genetic vulnerability, maternal drug use, low pregnancy weight, low maternal body fat, low total maternal weight gain, inadequate vitamins, and poor nutrition.

Explain two of the hypotheses developed to explain the increase in low birthweight in the United
States.

Answers will vary from the following: 1) increasing rates of assisted reproduction that lead to twins and triplets (multiple babies always weigh less than one infant); 2) a lack of adequate maternal nutrition; 3) an increase in food insecurity; and 4) increased maternal drug use.

Explain how nature and nurture can interact to result in alcoholism.

In some individuals, genes can create the addictive desire to drink to excess. In addition, each body metabolizes alcohol differently. Other inherited personality traits make alcoholism more likely. The cultural context is also important in that some environments encourage alcohol use (while others discourage it).

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