Test 6

Use the following information to solve the problem using a Punnett square. Assume that the dominant "B" allele encodes brown eyes and the recessive "b" allele encodes blue eyes. An individual with the genotype BB has children by mating with an individual of the genotype bb. What is the percent chance that they would have children with blue eyes?

0%

What is the probability of the same couple having three girls in a row?

1/8

At how many weeks of pregnancy can chorionic villus sampling (CVS) be safely performed?

10 weeks

The ability to roll the tongue into a U shape may be assigned to a single dominant allele, T. Suppose a homozygous tongue roller had a child with a heterozygous tongue roller. What proportion of their children could roll their tongues?

100%

An infant should normally be able to pull itself up and start waking by this time.

12 months

How long is the egg viable and capable of being fertilized after it is ovulated?

12-24 hours

Implantation of the blastocyst in the uterine wall is complete by day ________ after ovulation.

14

Given the information in Figure 29.1, if C were an incomplete dominant trait, what would the phenotype ratio be for the offspring?

1:2:1

Given the information in Figure 29.1, what is the phenotype ratio (assuming C is dominant and there is no incomplete dominance)?

1:3

If a cell has a diploid number of 22, how many total chromosomes should it have?

22

The number of different gametes that can be produced in a male, based on independent assortment alone, equals _____.

223

How many chromosomes are in a haploid human cell?

23

Humans have ____ pairs of chromosomes.

23

Heterozygous parents who have had one offspring with a recessive disease will have a ___ chance of their second child being born with the same recessive condition.

25%

Using the information provided in this figure, what is the probability of producing a homozygous dominant offspring?

25%

Using the information provided in this figure, what is the probability of producing an offspring who CANNOT roll his or her tongue?

25%

What is the probability of having a recessive trait child if both parents are heterozygous for the trait?

25%

This is the gestation period in humans from the last menstrual period.

280 days/ 40 weeks

For a cell with a five homologous pairs, calculate how many different gamete types can result from meiosis.

32

At what age are both amniocentesis and chorionic villus sampling routinely ordered when a woman is pregnant to test for Down syndrome?

35 years old

This apgar score represents a newborn with reduced function.

4

How many chromosomes are in a diploid human cell?

46

Chimpanzees have a diploid number of 48. How many total chromosomes should each of their diploid body cells have?

48

At least three genes control skin color. How many possible combinations of skin color result from those three genes?

64

If we are to consider the variation resulting only from independent assortment and random fertilization, any resulting offspring represents about one out of ________.

72 trillion zygotes possible

The ability to roll the tongue into a U shape may be assigned to a single dominant allele, T. Using the information provided in this figure, what is the probability of producing an offspring who can roll his or her tongue?

75%

The cleft chin trait follows a dominant-recessive inheritance pattern with cleft chin being the dormant trait. John is heterozygous for a cleft chin as is his wife Betty. John and Betty have three kids all of which have cleft chins. According to Punnett square prediction what is the likely hood that their next child will have a cleft chin?

75% chance the same probability for all subsequent children

An organism with three pairs of homologous chromosomes statistically could produce __________ different gametes strictly on the basis of independent assortment.

8

In the developing fetus, all body systems are present by __________.

8 weeks

Explain what triggers a baby's first breath.

A buildup of carbon dioxide in the baby's blood once the carbon dioxide is not being removed by the placenta causes acidosis. This excites respiratory control centers in the baby's brain and triggers the first inspiration.

A cross of two second-generation, straight-shorthaired individuals would yield what phenotype?

A cross of two second-generation, straight-shorthaired individuals would yield a straight-shorthaired phenotype.

_____________ extends from the last menstrual period until birth, approximately 280 days.

A gestation period

What is the definition of cleavage?

A period of fairly rapid mitotic divisions of the zygote without intervening growth

What is a placenta?

A temporary organ that originates from both embryonic and maternal tissues

What is chorionic villi sampling?

A test made in early pregnancy to detect congenital abnormalities in the fetus. A tiny tissue sample is taken from the villi of the chorion, which forms the fetal part of the placenta.

A couple whose blood types are A (IAi) and B (IBi) may have a child with which of the following blood types?

A, B, AB, or O

Rare type of dwarfism resulting from an impaired ability of the fetus to form cartilage bone.

Achondroplasia

Lack of skin pigmentation.

Albinism

What is the major stimulus triggering parturition?

All of the above

Breast-feeding provides several advantages to newborns. Which of the following is (are) (a) benefit(s) of breast-feeding?

All of the above are benefits of breast-feeding.

Sam has type A blood. Which of the following blood types are NOT at all possible for Sam's offspring?

All of the listed blood types are possible.

If two parents are heterozygous (Tt) for a trait, which of the following is NOT a possibility for their offspring?

All of their offspring would be dominant for the trait.

A 19-year-old, single, sexually active college student, who has not used birth control on a regular basis, is in her first trimester of pregnancy. She is at the OB/GYN clinic for her first prenatal visit. In assessing her nutrition, the nurse discovers that the patient drinks heavily on a regular basis, and also states that she does not like milk. What information should the nurse give the patient regarding nutrition?

All of these answers are correct.

Genes for the same trait that have different expressions.

Allele

Which statement is most correct?

Alleles are variations of the same gene.

What would happen in a premature infant if insufficient surfactant were available?

Alveolar collapse

________ is the most common type of fetal testing.

Amniocentesis

_____ is protective water-filled sac surrouding the embryo.

Amnion

What is maternal alpha-fetoprotein (AFP) test?

An alpha-fetoprotein (AFP) test is a blood test that measures the amount of AFP present in blood.

When in the female is meiosis II completed?

At fertilization

Chromosomes regulating most body characteristics.

Autosomes

This effect is possible if the sinus venosus does not contract first before the other areas of the primitive heart.

Blood flows backwards

________ is the process by which sperm become capable of penetrating the oocyte.

Capacitation

Which body system of a pregnant woman shows the most dramatic physiological changes during pregnancy?

Cardiovascular system

The placenta, a vitally important metabolic organ, is made up of a contribution from mother and fetus. Which portion is from the fetus?

Chorion

Which extraembryonic membrane contributes to the formation of the placenta?

Chorion

Which of the following structures form the placenta?

Chorionic villi and decidua basalis

_____ is extraembryonic membrane that develops from the trophoblast and some extraembryonic mesoderm, and forms part of the placenta.

Chorionic villus

Means by which genes trade places, some maternal and some paternal on each chromosome.

Chromosome crossover

Distribution of chromosomes to different gametes.

Chromosome segregation

Estrogen and progesterone maintain the integrity of the uterine lining and prepare mammary glands to secrete milk. Which of the following structures makes this possible during the first three months of pregnancy?

Corpus luteum

What reaction prevents more than one sperm from binding to an oocyte during fertilization?

Cortical reaction

Of the different sources of genetic variability which one produces the variation in the combinations of alleles on a single chromosome?

Crossing over

Which process listed below separates linked genes during meiosis?

Crossing over

A condition of drier excessively sticky mucus production.

Cystic fibrosis

____ is part of the endometrium that destined to be a part of the placenta.

Decidua basalis

____ is part of the endometrium that surrounds the uterine cavity face of the implanted embryo.

Decidua capsularis

This change occurs in the pH of the stomach in the hours after birth.

Decreases

Which of the following are the three components of somites?

Dermatome, myotome, sclerotome

What is the longest stage of labor, lasting 6-12 hours or more?

Dilation stage

What are the three stages of labor?

Dilation, expulsion, placental

What type of allele will be expressed if both dominant and recessive alleles are present for a given trait?

Dominant

The dominant gene is expressed when present; the recessive gene is expressed only in the absence of the dominant gene.

Dominant-recessive inheritance

An abnormally low maternal serum alpha-fetoprotein (MSAFP) blood test may result in amniocentesis to rule out anencephaly, trisomy 18, or trisomy 21. What is another name for a trisomy 21 disorder?

Down syndrome

Which of the following is true concerning environmental influence on genetic expression?

Drugs and nutrition can alter normal gene expression.

How many alleles exist for a given gene?

Each gene can have a different number of alleles

Often in neonatal care, health professionals look for the outward appearance of structures like the ears as indicators of internal organ development. Why might this be?

Ears form at the same time as certain internal organs and could indicate a malfunction of overall development during that time period.

Fingernails hair and glands all are derived from ________.

Ectoderm

The infant's head enters the true pelvis during this stage of labor.

Engagement

What is polyspermy?

Entry of several sperm into an egg

Define phenocopy.

Environmentally produced phenotypes that mimic conditions that may be caused by genetic mutations.

Which hormones stimulates the formation of oxytocin receptors on the uterus?

Estrogen

A pregnancy test involves antibodies that detect GH levels in a woman's blood or urine.

FALSE

Because lethal dominant genes are always expressed and result in the death of the embryo, fetus, or child, dominant gene disorders are NOT seen among adults.

FALSE

By 72 hours after fertilization, the egg has divided into more than 160 cells and is called the morula.

FALSE

Human placental lactogen initiates labor.

FALSE

Surfactant production in premature infants is rarely a factor in providing normal respiratory activity.

FALSE

The sole responsibility of the placenta is to supply the fetus with oxygen and nutrients.

FALSE

A person's genetic makeup is referred to as his or her phenotype.

False

A zygote is usually formed within the uterus.

False

Chromosomes that are not directly involved with sex determination are called sex-linked.

False

Fertilization occurs while the egg is still in the ovarian follicle.

False

For the first few days after birth, the mammary glands secrete colostrum which is very high in fat content and lactose and contains few antibodies.

False

Genetic segregation implies that the members of the allele pair determining each trait are distributed to different gametes during mitosis.

False

Genetic variation results from the crossing over and exchange of chromosomal parts that occur during meiosis II.

False

It takes a major deviation in the epigenetic marks of a specific chromosome to result in a devastating human illness.

False

Mitochondrial genes are free of errors. As a result, all genetic problems are due exclusively to nuclear genes.

False

Most genetic disorders are inherited through dominant genes.

False

Normal vision is dictated by autosomal dominant genes.

False

Sperm must reach the primary oocyte to be fertilized.

False

The ductus arteriosus becomes the ligamentum teres after birth.

False

The expression of all physical traits is strictly due to the inheritance of specific genes.

False

The term lethal dominant gene indicates that the gene causes death only when the individual is homozygous.

False

The two equally useful avenues for detecting carriers are pedigrees and the use of Punnett squares.

False

At what point is meiosis II completed for the female gamete?

Fertilization

It occurs when a sperm's chromosomes combine with those of an egg or zygote?

Fertilization

What is the transfer of sperm and harvested oocytes together into the woman's uterine tubes in the hopes that fertilization will take place there?

Gamete intrafallopian transfer (GIFT)

Which of the following is not a primary germ layer?

Gastroderm

Results in chromosomes that have mixed contributions from each parent.

Gene recombination

Select the statement that best describes the difference between a gene and an allele.

Genes express a specific trait while alleles are variations of a particular gene that result in the variation we see in a genetic individual trait.

Select the incorrect statement about chromosomes and genes.

Genes on neighboring but different chromosomes are called linked.

Actual genetic makeup.

Genotype

Suppose that a child received one of the purple chromosomes (top) from their father and one of the green ones (bottom) from their mother. What he or she look like?

He or she would have brown hair and brown eyes.

The gene allele that suppresses or masks the expression of the other allele. Situation in which an individual has different alleles making up the genotype for a particular trait.

Heterozygous

Genes not expressed unless they are present in homozygous condition. Situation in which an individual has identical alleles for a particular trait.

Homozygous

How many sperm cells are required to break through the outer corona radiata of the oocyte for fertilization to occur?

Hundreds

An unremitting, fatal nervous system disease involving degeneration of the basal nuclei.

Huntington's disease

How does pregnancy test determine if a female is pregnant or not pregnant?

If hCG is present it means they are pregnant

A urine test reveals a positive result for human chorionic gonadotropin (hCG). This indicates ____ was successful.

Implantation

A 30-year-old woman is admitted to the emergency room. Her husband, who rode in the ambulance with her, said that she had suddenly complained of severe pain in the right iliac region of her abdomen and then had collapsed. Upon examination, she was shown to have signs of internal hemorrhage and her abdominal muscles were rigid. Her menstrual history revealed that she had missed her last menstrual period. A diagnosis of ruptured tubal, or ectopic, pregnancy was made and surgery scheduled. What is an ectopic pregnancy, and why is it problematic?

In an ectopic pregnancy, the embryo implants in any site other than the uterus. It is problematic because it is unable to establish a placenta or accommodate growth, and could cause the uterine tube to rupture.

The heterozygote has a phenotype intermediate between those of the homozygous dominant and homozygous recessive.

Incomplete dominance

Which metabolic change does not occur as the placenta enlarges?

Increased levels of calcitonin

A particular gene's allele received by a gamete has no influence over selection of a different gene's allele.

Independent assortment

Of the different sources of genetic variability which one causes the variation in the combinations of homologs from paternal and maternal linage found within a haploid cell?

Independent assortment

How are the metabolic needs of the implanted embryo provided for?

Initially, the implanted embryo obtains nutrition by digesting the endometrial cells, but by the second month, the placenta is providing all the nourishment and oxygen the embryo requires. The placenta is also responsible for disposing of embryonic metabolic wastes.

Which of the following develops into the embryonic disc?

Inner cell mass

What is true of the structure of the human placenta?

It is disc-shaped.

Which of the following is true of the Punnett square?

It predicts only the probability of a particular genotype and phenotype.

Define karyotype.

Karyotype is the chromosomal content of a cell.

What phenotype is associated with the genotype 47, XXY?

Klinefelter's syndrome

What does the ductus arteriosus become at birth?

Ligamentum arteriosum

Which of the following is not an assisted reproductive technology procedure?

MAP

Shortly after birth a newborn baby passes this greenish anal discharge.

Meconium

Which of the following is NOT a primary germ layer from which all body organs derive?

Mesenchyme

________ is a tissue with star-shaped cells that are free to migrate widely throughout the embryo.

Mesenchyme

Fetal cells recovered during amniocentesis are grown in tissue culture. What mitotic phase are the chromosomes recovered from these cells arrested at for karyotype examination?

Metaphase

What is a correct statement about fertilization?

Million's of sperm cells are destroyed by the vagina's acidic environment

Which of the following events in reproduction does NOT contribute to an increase in variation among the offspring?

Mitosis

Failure of he foramen ovale to close at birth may result in?

Mixing of oxygenated and non-oxygenated blood

A solid sphere of undifferentiated cells.

Morula

Of the different sources of genetic variability which on could be defined as permanent, transmissible changes to the DNA coding sequence that are often caused by outside environmental factors?

Mutation

Which of the following is the first major event in organogenesis?

Neurulation

Is genetic diversity due entirely to inherited genes on the sex chromosomes?

No, because genetic diversity has nothing to do with the sex chromosomes but is due to crossing-over of chromosomes, independent assortment of chromosomes, and segregation of chromosomes.

Which of the following stages is the true moment of fertilization?

Once the chromosomes of the male and female pronucleus are united

The corpus luteum is formed at the site of _______.

Ovulation

Milk ejection or letdown reflex is stimulated by which of the following hormones associated with pregnancy?

Oxytocin

What role does oxytocin play in promoting labor?

Oxytocin stimulates the uterus to contract.

Implantation of the blastocyst is the result of all of the following except?

Phagocystosis by the trophoblast cells.

A 28-year-old woman has been in the first stage of labor for several hours. Her uterine contractions are weak, and her labor is not progressing normally. Because the woman insists upon a vaginal delivery, the physician orders that pitocin (a synthetic oxytocin) be infused. What will be the effect of pitocin?

Pitocin will act on the placenta to release prostaglandins and will also act directly on the uterine wall to cause muscle contractions.

What is the probability of the same couple having three boys in a row?

Polygene inheritance

Inheritance that results in continuous or qualitative phenotypic variations between two extremes; an example is skin color.

Polygenic inheritance

_______ stimulates milk production but ____- stimulates milk letdown.

Prolactin, oxytocin

Chadwick's sign refers to what changes during pregnancy?

Purplish hue of the vagina

Of the different sources of genetic variability which one produces the variation seen by the combination of any particular male gamete to any particular female gamete?

Random fertilization

Genes not expressed unless they are present in homozygous condition.

Recessive

During the development of the urinary system the cloaca becomes divided to form this __________.

Rectum and urethra

What does the hormone relaxin promote?

Relaxin promotes the widening and increased flexibility of the pelvic ligaments and pubic symphysis.

Sperm move to the uterine tube through uterine contractions and the energy of their own flagella. What other factor is involved in sperm movement?

Reverse peristalsis of the uterus and uterine tubes

Cells of the ____ gather around the notochord and neural tube and produce the vertebra and rib at their associated level.

Sclerotome

Which of the following statements is true concerning genetic screening?

Screening can be done before conception by carrier recognition or during fetal testing.

This stage of labor is the time period between maximum cervical dilation until the baby exits the vagina.

Second

A chromosome pair that may be very different in size.

Sex chromosomes

Which of the following occurs 9-12 weeks into pregnancy, during the fetal period:

Sex is readily detected by observing the genitals.

Inherited traits determined by genes on the X or Y chromosomes.

Sex-linked inheritance

What does it mean when sperm has to be capacitated?

Sperm is speed is enhanced and outer layer is weakened for it to release its juice

Steven has the dominant tongue rolling phenotype but he does not know his genotype. His wife has the recessive non-tongue rolling trait. If their son CANNOT roll his tongue this means ________.

Steven has a heterozygous genotype

Which fetal cells digest uterine cells?

Syncytiotrophoblasts

A Punnett square is a diagram that may be used to figure out the possible combinations of genes for a trait.

TRUE

A blastocyst is a hollow ball of cells, while the morula is a solid ball of cells.

TRUE

Implantation begins six to seven days after ovulation.

TRUE

In fetal circulation, one way in which blood bypasses the nonaerated lungs is by way of the foramen ovale.

TRUE

In humans, zonal inhibiting proteins destroy sperm receptors, preventing polyspermy.

TRUE

It is possible for a baby to have type O blood if neither parent is type O.

TRUE

Of the three germ layers, the mesoderm forms the most body parts.

TRUE

The "fluid-filled, hollow ball of cells" stage of development is the blastocyst.

TRUE

The X and Y sex chromosomes are NOT homologous.

TRUE

The birth control pill is the most common and most effective birth control method.

TRUE

The body systems of the developing embryo are present in at least rudimentary form at eight weeks.

TRUE

The embryo is directly enclosed in and protected by the amnion.

TRUE

The first major event in organogenesis is neurulation.

TRUE

The placenta and its attached fetal membranes are collectively called the afterbirth.

TRUE

While human chorionic gonadotropin levels spike and sharply decline to reach a low value by 4 months, estrogen and progesterone levels steadily increase over the course of the pregnancy.

TRUE

Your genotype is a description of your combination of alleles for a given phenotype.

TRUE

Your phenotype is the physical output of your genotype.

TRUE

________ disease is a disorder of brain lipid metabolism and is an example of a recessive trait.

Tay-Sachs

Which of the following statements about the acrosomal reaction is correct?

The acrosomal enzymes released from many sperm digest holes through the zona pellucida.

Mrs. Phang, eight months pregnant with her first child, makes an appointment with her obstetrician to investigate the cause of vaginal bleeding. Because it is actually more "spotting" than frank bleeding, and painless, she is becoming worried. Ultrasound visualization of her abdomen shows that the placenta is formed across the internal os of the cervix, and she is ordered to her bed for the remainder of the pregnancy. What name is given to Mrs. Phang's condition? Why is it an extremely serious condition?

The condition is called placenta previa. It is an extremely serious condition because stretching of the uterus and cervix could cause tearing of the placenta.

Which of the choices below occurs if fertilization of the ovum occurs and implantation takes place?

The corpus luteum is maintained until the placenta takes over its hormone-producing functions.

Pregnancy refers to?

The events that occur from the time of fertilization until the infant is born

Which of the following occurs 21-30 weeks into pregnancy, during the fetal period?

The eyes are open.

Why is it necessary to send some blood through the pulmonary circuit in a fetus?

The fetal lung tissue requires oxygen to allow for lung tissue development and growth

What would be the gametes of the first-generation individuals?

The gametes of the first-generation individuals from the original cross would be FT, fT, Ft, and ft.

What is (are) the genotype(s) of the first-generation offspring?

The genotypes of the first-generation offspring are all FfTt.

What were the genotypes of the parental (P1) individuals?

The genotypes of the parental individuals were FFTT and fftt.

A mother who has been nursing her infant for over seven months is beginning to have problems throughout the day with nausea. What might explain the nausea?

The mother was not taking birth control pills because she assumed that she could not get pregnant while nursing. This mother is probably pregnant again.

The patient is in her first trimester of pregnancy. She complains of feeling nauseated and has vomited on occasion. She tells the nurse that she did not have this with her first pregnancy. She asks the nurse, "What is causing this and when will it end?" How should the nurse respond?

The nausea is caused by elevated levels of progesterone and estrogen, and the nausea should end once her body adjusts to the increased hormone levels.

What would the parental gametes be from a cross of two second-generation, straight-shorthaired individuals?

The parental gametes from the cross would all be ft

Two tall red pea plants, when crossed, produced some offspring that were white and dwarf. Assuming that tallness and redness are dominant, what are the genotypes of the parents?

The parents must both be heterozygous for the dominant traits; therefore, their genotypes would be TtRr, where T = dominant trait for height, t = recessive trait for height, R = dominant trait for color, and r = recessive trait for color.

At what time in the pregnancy is the placenta fully prepared to fulfill the needs of the developing fetus?

The placenta is fully formed and functional as a nutritive, respiratory, excretory, and endocrine organ by the end of the third month of pregnancy.

A woman in her 24th week of pregnancy fails a glucose challenge test and is diagnosed with gestational diabetes. Once the baby is born, the woman's glucose regulation is back to normal. How can this be explained?

The placenta releases the hormone human placental lactogen, which interferes with glucose uptake

What is amniocentesis?

The sampling of amniotic fluid using a hollow needle inserted into the uterus, to screen for developmental abnormalities in a fetus.

The second-generation phenotypes would follow what ratio? (Pair the number with a phenotype in each case)

The second-generation phenotypes would appear in the following ratios: 9 fuzzy-longhaired, 3 fuzzy-shorthaired, 3 straight-longhaired, and 1 straight-shorthaired.

What possible genotype(s) could the second-generation, fuzzy-longhaired individuals possess?

The second-generation, fuzzy-longhaired individuals could be FFTT, FfTT, FFTt, or FfTt.

Which of the following statements about the events of fertilization is not true?

The two pronuclei divide

Select the correct statement about the special fetal blood vessels.

The umbilical vein becomes the ligamentum teres.

Proteases and acrosin are enzymes. How do they function in reproduction?

They act to break down the protective barriers around the egg, allowing the sperm to penetrate.

Which statement best describes the result of binding and fusion of the sperm's membrane to the oocyte plasma membrane?

They allow the contents of the sperm to enter the oocyte cytoplasm.

The major development of organ systems takes place at this time.

Third to eighth week of development

Forms the chorion.

Trophoblast

A pregnant woman urinates more often than usual because the uterus compresses the bladder her metabolic rate and blood volume are increased and she must also dispose of fetal metabolic wastes.

True

Alleles may code for alternative expressions of a genetic trait.

True

An episiotomy is an incision made to widen the vaginal orifice, aiding fetal expulsion.

True

By the end of the embryonic period, at 8 weeks all the adult organ systems are recognizable.

True

Conceptus is a term used to describe the developing human offspring.

True

Delayed action genes can result in fatal diseases.

True

Down syndrome is an example of nondisjunction of chromosomes.

True

Each human being (with the possible exception of identical siblings) has a unique genotype and phenotype.

True

Environmentally produced phenotypes that mimic conditions that may be caused by genetic mutation are called phenocopies.

True

Freshly deposited sperm are not capable of penetrating an oocyte.

True

Hemophilia is an X-linked condition caused by a recessive gene.

True

Hereditary characteristics are transmitted to offspring by genes.

True

In incomplete dominance, the heterozygote has a phenotype intermediate between that of homozygous-dominant and homozygous-recessive individuals.

True

Incomplete dominance is more uncommon in humans.

True

Small RNAs control the timing of programmed cell death during development.

True

Some segments of the Y chromosome have no counterpart on the X chromosome.

True

The X chromosome is considerably larger than the Y chromosome.

True

The embryonic stage lasts until the end of the eighth week.

True

The period from fertilization through week eight is called the embryonic period.

True

The same allele can have a different effect depending on which parent it comes from.

True

The total number of muscle fibers is established before birth and remains relatively constant thereafter.

True

When two genes are on the same chromosome, they are considered linked.

True

The lactation nurse visits a first-time mother six hours after her delivery of a healthy 8-pound boy. The patient is giving the baby boy a bottle of sugar water. She tells the lactation nurse that she does not seem to be producing milk. What should the nurse say to the patient?

True milk production will not start until two to three days after birth. During this delay, colostrum is produced. Continual milk production depends on mechanical stimulation of the nipples, normally provided by the suckling infant.

When do we begin to call the developing individual a fetus rather than an embryo?

We begin to call the developing individual a fetus at the beginning of the ninth week.

Sex chromosomes of a normal male are ________.

XY

Which of the following structures is enclosed by a tube of endoderm and develops into the primitive gut?

Yolk sac

_____ is site of early blood cell production and forms part of the gut (digestive tube).

Yolk sac

Which of the following INCORRECTLY matches an embryonic structure with its function?

Yolk sac/provides nutrients to developing embryo

What prevents polyspermy by destroying the sperm receptors?

ZIPs

Which of the following represents the correct chronological order?

Zygote, morula, blastocyst

The result of polyspermy in humans is ________.

a nonfunctional zygote

All exchanges between mother and embryo occur ________.

across the chorionic membrane

Which of the following is NOT a source of genetic variation?

age of either or both parents

What embryonic structure is the structural base for the umbilical cord?

allantois

Alternative forms of genes are called _______.

alleles

A person without a Y chromosome will _________.

always show female characteristics

Removing a sample of the fluid surrounding the fetus for the purpose of studying the chromosomes is a procedure called ________.

amniocentesis

What type of exam is used to identify the sex of children without the use of ultrasound?

amniocentesis

When a woman's "water breaks" just before delivery, it is the _______ that ruptures.

amnion

Which of these is the innermost (closest) structure that envelops the embryo?

amnion

A dominant allele is best defined as ________.

an allele that stops or hides the expression of the other allele

Once fertilization has occurred, the activities of development begin. The first such activity is ________.

an increase in cell number

Which of the following is not usually considered a teratogen?

aspirin

Onset of labor may be a result of all of the following factors except ________.

aspirin and similar drugs

Any two matched genes that are __________ are called alleles.

at the same locus on homologous chromosomes

The embryo implants in the uterus as a __________.

blastocyst

Which of the following implants in the mucosa of the endometrium?

blastocyst

During the ________ stage of development, the human embryo implants in the uterine wall.

blastula

Increased _______ stimulates the baby's first breath.

blood CO2 levels

Which of the following human traits are not dictated by dominant alleles?

blue eyes

Embryonic ectoderm gives rise to the _______ in the adult organism.

both a and b

Recessive genes are usually expressed in humans only when ________.

both alleles are exactly the same, or homozygous

The diploid genome contains chromosomes from ________.

both the mother and father, but only about half of the genome from each

What organs appear very early in development?

brain and heart

Which of the following structures is derived from the ectoderm?

brain and spinal cord

If the allele for brown hair was represented as "B" this would mean that _________.

brown hair was a dominant trait

Monospermy is ensured by the release of __________.

calcium

Sperm freshly deposited in the female vagina are incapable of fertilizing an egg. What must happen first?

capacitation

Pedigrees and blood tests are both means of __________.

carrier recognition

Heterozygous individuals that may pass on recessive, abnormal conditions are referred to as _________.

carriers

The reason recessive genetic disorders are more frequent than disorders inherited as dominant is that ________

carriers may pass them on to their offspring, unaware that they are carriers

Cleavage as part of embryonic development is distinctive because it involves _________.

cell division by mitosis with a little or no growth between successive divisions

What determines the frequency of a trait in the general population?

chance

Capacitation refers to __________.

changes occurring in sperm before fertilization

The trophoblast cells of the blastocyst form the ________, which extends elaborate villi into the blood-filled sinusoids of the uterine wall.

chorion

The blastocyst, or ________, consists of two distinct populations of cells.

chorionic vesicle

Which of the following methods for the detection of genetic abnormalities in the fetus could be done the earliest and give the most accurate results?

chorionic villi sampling

What type of fetal testing provides results within a day or so of the test?

chorionic villus sampling

Which of the following is the correct sequence of development from zygote to embryo?

cleavage, morula, blastocyst, gastrula

One sign of a newborn's physical condition that forms part of the Apgar score is which of the following?

color

For which of the following are newborn infants not routinely screened at birth?

color blindness

Prior to the let-down reflex, the mammary glands secrete a yellowish fluid called ____ that has less lactose than milk and almost no fat.

colostrum

The first "milk" the mother produces is called ________.

colostrum

Freckles are a completely dominant trait. Both of Jason's parents have freckles. Jason does NOT have freckles. What type of inheritance describes this situation?

complete dominance

Which of these genetic conditions is displayed by the tongue-rolling example in this figure?

complete dominance

Which term, by definition, includes all the other terms?

conceptus

The ovulated oocyte is surrounded by an outer capsule called the __________.

corona radiata

In meiosis the spermatozoa that are produced are genetically unlike each other and unlike the cell that produces them. This is one reason for the great variation among humans. What causes this effect?

crossing-over and independent assortment only

What structures forms the placenta?

decidua basilis and chronic villi

Huntington's disease involves ________.

degeneration of the basal nuclei of the brain

Huntingtonʹs disease is an example of a(n) ________ gene.

delayed-action

A chromosomal aberration in which part of a chromosome is lost is known as ________.

deletion

Initially, the implanted embryo obtains its nutrition by _________.

digestion of endometrial cells

A karyotype is a complete _________.

diploid complement display of homologous chromosome pairs

Developmental events during weeks 21-30 include _________.

distal limp bones beginning to ossify

An allele that completely masks the expression of the other alleles is called ________.

dominant

Which of the following is not a correct matching of a fetal structure with what it becomes at birth?

ductus arteriosus/ligamentum teres

What are the structures that exist in the fetus that are not in adult?

ductus venous, foramen ovale, ductus arteriosus

The neural tube and neural crest cells develop from the __________.

ectoderm

Which of the following is highly unlikely method of producing a child?

ectopic implantation

Both of Jason's parents are homozygous dominant for tall. Jason has inherited the homozygous dominant trait for tallness. Jason, however, is quite short. Which of the following could explain why Jason is short?

effect of the environment on gene expression

Implantation involves ________.

embedding of the blastocyst in the uterine wall

During development, the conceptus is called a (an) _______ from fertilization through week 8, and a (an) _______ from week 9 through birth.

embryo; fetus

Glandular organs most likely arise from the _______, as they share secretory properties with the gut.

endoderm

Which of the following is the primary germ layer that forms the basis for the digestive, respiratory, and urogenital systems, and associated glands?

endoderm

Derivatives of the mesoderm include ________.

endothelium of blood and lymph vessels

Which of the following is not a germ layer?

epiderm

Derivatives of the ectoderm include _________.

epithelium of the pineal and pituitary glands

Derivatives of the endoderm include ________.

epithelium of the respiratory tract

What is the product of codominance?

equal showing of both parents

In which stage of labor does crowning occur?

expulsion

During which stage of labor is the fetus delivered?

expulsion stage

Chorionic villi look like ________.

feathery extensions of the chorion in the uterine wall

Which fetal vascular shunt directly connects the right atrium to the left atrium so as to bypass the nonfunctional lungs?

foramen ovale

What does the foramen ovale become at birth?

fossa ovalis

How many chromatids are present in a tetrad?

four

Height is controlled by _________.

four gene pairs

When does an embryo become a fetus?

from 9 weeks till birth

The ________ stage of development is the first in which all three germ layers of tissue are evident.

gastrula

The formation of endodermal and ectodermal germ layers occur at _________.

gastrulation

What is incomplete dominance?

genetic situation in which one allele does not completely dominate another allele, and therefore results in a new phenotype

What do chiasmas promote?

genetic variability

Which of the following is specifically associated with the formation and dissociation of chiasmata?

genetic variability

What is the period called when the embryo is developing inside the womb?

gestation period

Given the information in Figure 29.1, what would be the genotype of the offspring designated by the blank square?

gg

After successful implantation has occurred, the corpus luteum is maintained by a hormone that is secreted by the trophoblast cells called _______.

hCG

Which hormone is required to maintain the corpus luteum and prevent menstruation?

hCG

The 46 chromosomes of a zygote come from _________.

half from the mother and half from the father

One of the plates of the lateral mesoderm forms _________.

heart, blood vessels, and most connective tissues

Which of the following exemplifies polygenic inheritance?

height

Two alleles expressing exactly the same information for a trait are designated as ________.

homozygous

What is the name of the condition when a person has inherited the genotype HH?

homozygous dominant

Which hormone maintains viability of corpus luteum?

human chronic gonadotropin

Development progresses ________.

in rostral to caudal and proximal to distal directions

Oogenesis occurs where?

in the ovaries

In what region of the uterus does implantation usually occur (as indicated by the position of the placenta)?

in the upper part of the uterus

An individual who is heterozygous for a particular trait, yet expresses both alleles of that trait, is an example of ________.

incomplete dominance

The gene responsible for the condition known as sickle-cell anemia demonstrates ________.

incomplete dominance

The function of cleavage is to ________.

increase the number of cells forming the blastocyst

A female infant is born with several hundred oocytes, each one genetically unique. This is due to ________.

independent assortment and random crossover

Which hormone is not produced by the placenta?

inhibin

The human blastocyst consists of two populations of cells with different functions. Select the correct match between population and its function.

inner cell mass (ICM); forms the embryo and three of the four extraembryonic membranes

What is codominance?

is a relationship between two versions of a gene. Individuals receive one version of a gene, called an allele, from each parent. If the alleles are different, the dominant allele usually will be expressed, while the effect of the other allele, called recessive, is masked

If a male inherits a sex-linked gene for color blindness _________.

it will always be expressed.

Genes that are located on the same chromosome are said to be _________.

linked

The decidua basalis is _________.

located between the developing embryo and the myometrium

The placenta is formed by ________.

maternal and fetal tissues

Primary oocyte goes through what process to become secondary oocyte?

meiosis I

Secondary oocyte goes through what process to become an ovum?

meiosis II

In the human, this germ cell layer gives rise to many of the organ systems, including the skeleton, skeletal muscles, walls of GI organs, urinary system, and circulatory system.

mesoderm

Muscle tissue is formed by the _________.

mesoderm

The notochord develops from the __________.

mesoderm

During what phase of meiosis do the tetrads align together in preparation for being separated?

metaphase I

Nuclear DNA is NOT the only source of genetic information in the cell. Which of the following is another source of DNA in the cell?

mitochondria

Gene mutations in the sex chromosomes of the human would tend to become visibly expressed ________.

more frequently in males

After fertilization, a loose collection of cells forms in the uterine tube. This cluster of cells is called a __________.

morula

Most human traits are determined by __________.

multiple alleles

The ABO blood type is a good example of a ________ inheritance.

multiple-allele

The genetic determination of blood type is based on __________ inheritance.

multiple-allele

Sam has type A blood. What type of inheritance produced that blood type?

multiple-allele inheritance

A change in the genetic structure of a gene is called _________.

mutation

Which of the following is NOT a source of genetic diversity that arises during meiosis?

mutation

All of the following are metabolic changes that occur in pregnant women EXCEPT __________.

negative calcium balance

What is the product of incomplete dominance?

new form of product will be made

The first axial support for the embryo is called the ________.

notochord

Which of the following is true in reference to what may pass through the placental barriers?

nutrients, respiratory gases, wastes, and alcohol

Recessive alleles are best defined as ________.

only expresses in present in a double dose

Teratogens may cause anatomical abnormalities in an embryo, but do not cause anatomical abnormalities in a pregnant woman because

organogenesis does not occur in adults

The act of giving birth is called ________.

parturition

Which of the following is a noninvasive method for predicting genetic disease?

pedigree

Which of the following is NOT a part of the genome control system?

phenocopies

A woman has blond hair and brown eyes. This statement is best described as indicating ________.

phenotype

Observable characteristics expressed by the genes for a trait are called the ________.

phenotype

The expression of genes is called the _______.

phenotype

Those characteristics that can be determined on superficial inspection of an individual are known as ________.

phenotypic

Together, what do the decidua basalis and the chorionic villi form?

placenta

At which stage of labor is the "afterbirth" expelled?

placental

The trophoblast is mostly responsible for forming the _________.

placental tissue

Inheritance of stature (height) in humans is probably due to ________.

polygene inheritance

Skin color, controlled by three separately inherited genes that each exist in two allelic forms (A, a; B, b; C, c), is an example of which form of inheritance?

polygene inheritance

One possible scientific explanation for siblings having very different skin color is ________

polygene inheritance, which results in continuous phenotypic variation between extremes

What type of inheritance is responsible for the great diversity of skin color, height, metabolic rate?

polygenic inheritance

What type of inheritance uses multiple gene loci to produce one overall phenotype?

polygenic inheritance

Which of the following terms applies to a continuous phenotypic variation between two extremes?

polygenic inheritance

During late pregnancy and during labor, the release of oxytocin is regulated by __________.

positive feedback

A dangerous complication of pregnancy called ____________ results in an insufficient placental blood supply, which can starve a fetus of oxygen. The pregnant woman becomes edematous and hypertensive, and proteinuria occurs.

preeclampsia

What is a conception?

pregnant woman's developing offspring

All of the following events produce variations in an individual's genotype except _________.

presence of ethnic genes

Cells on dorsal surface of the two-layered embryonic disc migrate to form a raised groove known as?

primitive streak

Gastrulation starts when the __________ appears.

primitive streak

As the newborn suckles, the mother's pituitary produces ________ to assist in producing milk.

prolactin

Which of the following serve(s) as the trigger to begin the vigorous, rhythmic contractions of true labor?

prostaglandins

The foramen ovale and the ductus arteriosus are both examples of __________.

pulmonary bypass shunts, which serve to bypass the lungs

Albinism is a good example of a ________ trait.

recessive

An allele that can be masked or suppressed by another allele is said to be __________.

recessive

When both parents are heterozygous for a recessive trait, they run a one-in-four chance that the ________ trait will be expressed in their children

recessive

Which of the following does NOT match the term to its correct definition/description?

recessive: gene expressed when present

What is the result of one chromatid segment forming a chiasma with a homologous chromatid segment?

recombinant chromosomes

Relaxin is a hormone produced by the placenta and ovaries. The function of this hormone is to ________.

relax the pubic symphysis

Amy's hand was exposed to X rays. A gene in a skin cell of her hand mutated. This mutant gene will ________.

replicate itself when the cell divides but will not be passed on to Amy's offspring

During metaphase of meiosis I, homologous chromosomes and the alleles they possess are distributed to different gametes. What is this called?

segregation

The 23rd pair of human chromosomes are called ________ chromosomes.

sex

Color blindness is a ________ trait.

sex-linked

The main way a recessive allele would be expressed even when only one copy is present would be ________.

sex-linked inheritance

Which type of inheritance involves genes found on an X chromosome?

sex-linked inheritance

Which of the following is an example of a disorder that exhibits incomplete dominance?

sickle-cell anemia

How many days after ovulation does the conceptus implant on the uterine wall?

six to seven

What is the difference between spermatogenesis and oogenesis?

spermatogenesis creates sperm and oogenesis makes eggs

AFP test is done to find out what abnormalities?

spina bifida and anencephaly

Dominant alleles are so called because under most circumstances they ________.

suppress the expression of other alleles

Which cells invade the endometrium, digesting the uterine cells they contact, so that implantation of the blastocyst can occur?

syncytial trophoblast cells

What is not assessed as a part of the apgar score?

temperature

Mitosis differs from meiosis because in meiosis we observe ________.

tetrads

Steven has the dominant tongue rolling phenotype but he does not know his genotype. His wife has the recessive non-tongue rolling trait. If their son CAN roll his tongue this means ________.

that it is impossible to tell Steven's genotype from this information alone

An example of multiple allele inheritance is ________.

the ABO blood group

The release of enzymes to digest holes through the zona pellucida is termed __________.

the acrosomal reaction

During amniocentesis, a needle withdraws fluid from __________.

the amniotic sac

The cardiovascular system of a newborn must be adjusted after the infant takes its first breath. Which of the following is true?

the ductus arteriosus constricts and is converted to the ligamentum arteriosum

All of the following develop from somites EXCEPT __________.

the heart

If a person is homozygous for a particular trait this means ________.

the person has two identical alleles for the gene responsible for the trait

The appearance of freckles is considered _________.

the phenotype

The dorsal surface cells of the inner cell mass form _________.

the primitive streak

Shortly after implantation ________.

the trophoblast forms two distinct layers

Males tend to inherit more sex-linked conditions because ______.

there is no corresponding allele on their Y chromosomes

It is impossible for sperm to be functional (able to fertilize the egg) until after ________.

they undergo capacitation

As the infant's head is forced against the cervix with each contraction, the cervix effaces, which means that it _______.

thins

Why are both paternal and maternal chromosomes present in some gametes?

to increase variability in the offspring

The ________ cells of the blastocyst will take part in placental formation.

trophoblast

Using the information provided in this figure, what is the genotype of a homozygous recessive offspring?

tt

This cord attaches the embryo to the placenta.

umbilical cord

Name the blood vessel that carries oxygen-rich blood to the fetus.

umbilical vein

Nutrients are carried from the placenta into the fetus by the __________.

umbilical vein

The ligamentum teres is the remnant of the __________.

umbilical vein

The umbilical arteries carry _________.

waste products to the placenta

At the time of birth, the uterus has enlarged to the level of the __________.

xiphoid process

What destroys the sperm receptors on the surface of the oocyte?

zonal inhibiting proteins

The fertilized egg is known as the ____________.

zygote

They act to break down the protective barriers around the egg, allowing the sperm to penetrate.

zygote, morula, blastocyst

The correct sequence of preembryonic structures is _________.

zygote, morula, blastocyt