A+P 1 Test #2 CHAPTER 6
When does the placenta become sufficiently functional to continue the pregnancy?
After the first trimester
The extra-embryonic membrane that forms a fluid-filled sac is ...
Amnion
How do autosomes and sex chromosomes differ?
Autosomes are the 22 of the 23 pairs of chromosomes that are matching
Define homozygous and heterozygous
Homozygous: PP or pp. Carries two of the same alleles. Heterozygous: Pp. Carries two different alleles.
Attachment to and penetration of the endometrium by the blastocyst is referred to as ...
Implantation
Fertilization
Process in sexual reproduction in which male and female reproductive cells join to form a new cell
During gestation, contraction of the myometrium is inhibited by ________, produced by the placenta.
Progesterone
Which hormone causes the milk ejection (milk let-down) reflex?
Prolactin
The hormone that increases the flexibility of the pubic symphysis during pregnancy is
Relaxin
A person's original chromosomes and their component genes constitute that person's.........
genotype
gestation
growth process from conception to birth
The process of cell division that divides the cytoplasm of the zygote among blastomeres is called
cleavage
The presence of which hormone in the urine provides a reliable indicator of pregnancy, as detected by home pregnancy tests?
hCG
Organogenesis
organ formation that takes place during the first two months of prenatal development
trophoblast
outer layer of blastocyst
What does happen during amphimixis?
the male and female pronuclei fuse.
Deoxygenated blood is carried to the placenta by the
umbilical arteries
A portion of the allantois, blood vessels, and remnants of the yolk sac forms the
umbilical cord
Oxygenated blood is carried away from the placenta by the
umbilical veins
Name the four extra-embryonic membranes.
yolk sac, amnion, allantois, chorion
The individual cells produced by cleavage are called
zygotes
define single nucleotide polymorphism
A site on a chromosome where animals in a population have different nucleic acids
chorionic villi.
-grow into placenta -support maternal-fetal gas exchange
A zygote whose genotype is XX will develop as a
Female
The infancy stage of life is considered to be over when the baby reaches ________ of age.
2
How many chromosomes are contained within a human zygote?
46
How many chromosomes do human somatic cells contain?
46
The trophoblast has many of the characteristics of ________ cells.
Cancer
The extra-embryonic membrane that forms the fetal portion of the placenta
Chorion
The gradual modification of anatomical structures during the period from conception to maturity is
Development
The first stage of labor is the ________ stage.
Dilation
The oval, three-layered sheet produced by gastrulation is called the
Embryonic Disc
Which of the following hormones is the cause of most puberty-related changes in a female?
Estrogen
Which chemicals are primarily responsible for initiating contractions of true labor?
Estrogen and Oxytocin
is the time spent in growing within the uterus.
Gestation
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 colorblind?
Half
Why does a mother's blood volume increase during pregnancy?
Heart rate increases
The region known as the primitive streak is the site of
Migration of ectodermal cells
After fertilization, the first cell division is completed
More than a day later
After 3 days, a pre-embryo becomes a solid ball of cells known as a ....
Morula
Stretching of the cervix causes an increase in the blood levels of
Oxytocin
Which hormone stimulates the milk let-down reflex?
Oxytocin
The placenta is expelled from the uterus during the ________ stage of labor.
Placental
List and describe the factors involved in initiating labor contractions.
Relaxin, Distortion of uterus, Stretched muscles
The period of gestation that is characterized by the largest fetal weight gain and fat deposition is the ________ trimester.
Third
Which trimester does a fetus undergoes its largest absolute weight gain?
Third Trimester
The embryonic heart starts beating as blood begins to flow through chorionic vessels at approximately ________ of development.
Week 3
The extra-embryonic membrane that forms blood cells is .......
Yolk sac
