chap. 29 development and inheritance

Sterility in males may result from a sperm count of fewer than __________.

20 million sperm per mL -Remember that not enough spermatozoa survive the journey through the female reproductive tract at or below this number

The total number of genes in human DNA, as identified by the Human Genome Project, is __________.

25,000 to 30,000

The normal chromosome complement of a typical somatic, or body, cell is __________.

46 -Remember that gametes have half this number.

Which of the following is NOT an effect of pregnancy on the mother?

Maternal blood volume decreases. -Remember that the mother needs to enhance oxygen transport for the growing fetus.

Which of the following does NOT happen during oocyte activation?

The first cleavage is completed. -Remember that this happens after fertilization.

The presence of freckles on the skin is __________.

an example of simple inheritance, with the recessive form being the absence of freckles on the skin

Karyotyping is the determination of __________.

an individual's chromosome complement -Remember the root word meaning "nucleus."

Gastrulation produces three germ layers. Which of the following is NOT one of the germ layers?

blastocoele -Remember that this is the hollow space inside a blastocyst.

The creation of different types of cells during the processes of development is called __________.

differentiation - process of specialization

Which of the following is the term for the events that occur during the first two months of development after fertilization?

embryological development -Remember this is the first part of prenatal development.

Embryologic development __________.

ends two months after conception -this precedes fetal development

The chorion develops from the __________.

mesoderm and trophoblast

The term for the event that occurs when the blastocyst contacts the endometrium and grows into the endometrium is __________.

implantation -Remember that this happens when the blastocyst is fully formed.

An ectopic pregnancy refers to __________.

implantation occurring somewhere other than within the uterus -Remember that this will not result in a viable pregnancy.

Which of the following is NOT an effect of aging on organ systems?

increase in peripheral blood flow -Remember that efficiency decreases during aging in all organ systems.

What is the term for a gene's position on a chromosome?

locus

If one female X chromosome of an allele pair contains a sex-linked character for color blindness, what would the individual be?

normal

What is the name of the medical specialty that focuses on the postnatal period from infancy through adolescence?

pediatrics -Remember the Greek root word that means "child."

During fertilization, the process of cortical reaction is important in __________.

preventing penetration of the egg by additional sperm -Remember that this limits interaction to between one of each gamete.

Throughout embryonic and fetal development, metabolic wastes generated by the fetus are eliminated by transfer to the __________.

maternal circulation -Remember that this belongs to the only individual that is capable of complete elimination.

The stretching of the myometrium during gestation is associated with a gradual increase in the __________.

rates of spontaneous smooth-muscle contractions -Remember that this is due to the growing fetus.

The first meiotic division __________.

reduces the number of chromosomes from 46 to 23 -Remember that gametes are created by this process.

If an allele is dominant, it will be expressed in the phenotype __________.

regardless of any conflicting instructions carried by the other allele

What does the term inheritance refer to?

transfer of genetically determined characteristics from generation to generation

Gestation is divided into __________.

trimesters

Fraternal, or dizygotic, twins result from __________.

two oocytes being ovulated in one cycle

Fertilization usually occurs in the __________.

uterine tube

In strict dominance, a dominant allele __________.

will be expressed 100 percent of the time when paired with a recessive allele

The extraembryonic membranes that develop from the endoderm and mesoderm are the __________.

yolk sac and amnion -Remember that blood cells and a protective cavity form from these.

The formation of extraembryonic membranes occurs in the correct sequential steps, which are __________.

yolk sac, amnion, allantois, and chorion

The development stages that occur during cleavage follow which sequence?

zygote, blastomeres, morula, blastocyst -Remember that this starts from a single cell and progresses to more complex structures.

Infancy lasts until a child is _________ old.

2 years

During gestation, the primary major compensatory adjustments include which of the following?

- increasing respiratory rate and tidal volume -increasing glomerular filtration rate -increasing maternal requirements for nutrients

Which of the following oppose(s) progesterone and begin(s) labor?

- rising oxytocin - prostaglandin production - rising estrogen

During adolescence, what are sex hormones responsible for?

-activation of the CNS centers for sexual activity -deposition of bone and promotion of the closure of the epiphyseal plates in long bone -stimulation of the growth of muscle fibers, increasing strength and endurance

The hormones produced by the placenta include which of the following?

-relaxin and human placental lactogen -estrogen and progesterone -human chronic gonadotropin hormone

Which of the following is NOT a physiological effect on the mother's body during pregnancy?

Folic acid needs decrease. -Remember that this is included in prenatal supplements.

How are gametes different from ordinary somatic cells?

They contain only half the normal number of chromosomes.

Which of the following occurs in the event of "fraternal," or dizygotic, twins?

Two separate eggs are ovulated and fertilized. -Remember that these twins are not genetically identical.

The normal male genotype is __________, and the normal female genotype is __________.

XY; XX

Embryogenesis is the process that establishes the foundation for __________.

all the major organ systems

What is the extraembryonic membrane that gives rise to the urinary bladder?

allantois -Remember that the umbilical cord contains this along with blood vessels and the yolk sac.

During implantation, the inner cell mass of the blastocyst separates from the trophoblast, creating a fluid-filled chamber called the __________.

amniotic cavity -Remember that the fetus is housed inside this during development.

The fusion of male and female pronuclei is an event termed __________.

amphimixis -Remember that after this, the cell is known as a zygote.

A hollow ball of cells created by cleavage is called a __________.

blastocyte

Which of the following forms the placenta?

chorion

A sequence of cell divisions that begins after fertilization is called __________.

clevage

The first secretion produced for the baby by the mammary glands, which contains more protein and less fat, is __________.

colostrum -Remember that many of the proteins are antibodies.

During oocyte activation, the process that is important in preventing penetration by more than one sperm is the __________.

cortical reaction

Alterations in genetic activity during development occur as a result of __________.

differences in the cytoplasmic composition of individual cells

The gradual modification of anatomical structures during development occurs during the period from __________.

fertilization to maturity - during the majority of the life cycle

Which of the following is the term for the developmental events that occur from nine weeks to birth?

fetal development

The most dangerous period in prenatal or postnatal life is the

first trimester

The completion of metaphase II, anaphase II, and telophase II produces __________.

four gametes, each containing 23 chromosomes

Germ-layer formation results from the process of __________.

gastrulation -Remember that this process produces the embryonic disc.

If albinism is a recessive trait, and an albino mother and a normal father with the genotype AA have an offspring, the child will __________.

have normal coloration

For a given trait, if the genotype is Aa, the individual is __________.

heterozygous

What is the term for having two different alleles for one gene?

heterozygous

For a given trait, if the genotype is AA, the individual is __________.

homozygous dominant -Remember that trait A is expressed here.

For a given trait, if the genotype is aa, the individual is __________.

homozygous recessive -Remember that this is the only condition where this trait will be expressed.

As development proceeds, the differentiation of other embryonic cells is affected by small zygotic cells that __________.

release RNA, polypeptides, and small proteins -Remember that this is also known as induction.

Organs and organ systems complete most of their development during the __________.

second trimester -Remember that this is soon after fetal development begins.

Which of the following is the term for aging, or growing old?

senescence -Remember that this period is associated with decreasing sex hormone levels.

What is the term for the type of inheritance in which the allele is found on the X chromosome and therefore most often affects males?

sex-linked inheritance - Remember that this is also known as X-linked inheritance.

Prostaglandins in the endometrium __________.

stimulate smooth muscle contractions -Remember that these are also known as tissue hormones.

The umbilical cord, or umbilical stalk, contains __________.

the allantois, blood vessels, and yolk stalk -Remember that this includes the source of blood cells, their transport structures, and the origin of the urinary system.

Exchange between the embryonic and maternal circulations occurs by diffusion across the syncytial and cellular trophoblast layers via __________.

the chorionic blood vessels -Remember that this is occurring in the placenta.

The first stage of labor, during which the cervix opens, is called

the dilation stage

In terms of genetic inheritance, the penetrance of a trait refers to __________.

the percentage of individuals with a particular genotype who show the "expected" phenotype -Remember that the presence of a pair of alleles does not affect the phenotype in the same way in every individual.

Which systems that were relatively nonfunctional during the fetus's prenatal period must become functional at birth?

the respiratory, digestive, and urinary systems -Remember what systems need exposure to the outside environment to be functional.