All of the following things occur during meiosis I with the exception of one thing.
A. the homologous chromosome are separated from each toehr
B. a single diploid (2n) cell has become two (n) haploid cells
C. Sister chromatids are separated from each other
D. Portions of maternal chromosomes crossover with equivalent portions of paternal chromosomes.
Select the statement which is true regarding independent assortment.
It is a significant source of genetic variation only during meiosis I
Select the statement which is false
A. Further genetic variation does not occur after meiosis I
B. Meiosis II is essential the same process as mitosis except the starting cells
C. Crossing over is a source of genetic variability seen in meiosis while independent assortment is a source of genetic variability seen in mitosis.
D. Meiosis II is essential the same process as mitosis except the starting cells are haploid (n).
E. It is a significant source of genetic variation only during meiosis I.
All but one of the following statements are true regarding the differences between early and late spermatids.
Early spermatids have not undergone meiosis and are still diploid
During spermiogenesis ____
the acrosome migrates towards the anterior end of the spermatid because its hydrolytic enzymes will be needed for penetration when the sperm contacts the egg during fertilization
All but one these events described below occur during spermiogenesis. Select the event that does NOT occur during spermiogenesis.
Mitochondrial DNA is packaged into the nucleus to be delivered to the egg during fertilization
All but one of the following statements is true with regard to the blood testis barrier. Select the one that is false.
The barrier is made up of astrocytes that surround blood vessels in the testis
All but one of the following statements is true of the uterine function. select the statement that is not true of uterine function.
The narrow portion of the uterus near the cervix is the most typical site of fertilization
The oral contraceptive pill, informally called "the pill" contains an estrogen and progesterone or a synthetic mimic of this hormone. The combination of these two hormones taken in the pill and circulating in the blood work because
the hormones cause the woman's body to mimic the activities of a pregnancy and disrupt the ovarian cycle, preventing ovulation
The dartos and cremaster muscles are important to the integrity of the male reproductive system. Which of the following is true about the role they play?
they regulate the temperature of the testes
The ability of sperm cells to move along the ductus deferens is due to
The most important risk for testicular cancer in young males is
failure of the testis to make their normal descent
Which of the following glands is responsible for 70% of the synthesis of semen?
Which of the following hormones controls the release of anterior pituitary gonadotropins?
The genetic determinate for the male reproductive development is
the SRY gene
The structures that receive the ovulated oocyte, providing a site for fertilization, are called the
If gametes were diploid like somatic cells, how many chromosomes would the zygote contain?
twice the diploid number, and with every succeeding generation, the chromosome number would continue to double and normal development could not occur
Human egg and sperm are similar in that ___
they have the same number of chromosomes
What destroys the zona pellucida sperm-binding receptors?
zonal inhibiting proteins
The result of polyspermy in humans is ___
a nonfunctional zygote
it is impossible for sperm to be functional (able to fertilize the egg) until after ___
they undergo capacitation
Milk ejection (the letdown reflex) is stimulated by which of the following hormones associated with pregnancy?
The corpus luteum prevents loss of the implanted embryo through menstruation by secreting ____
estrogens and progesterone
The placenta, vitally important metabolic organ, is made of a contribution from mother and fetus. Which portion is from the fetus?
Relaxin is a hormone produced by the placenta and ovaries. The function of this hormone is to ___
relax the pubic symphysis
Proteases and acrosin are enzymes. How d they function in reproduction?
they act to break down the protective barriers around the egg, allowing the sperm to penetrate
Which of the following is NOT a primary germ layer?
The formation of endodermal and ectodermal germ layers occurs at __
Which hormone maintains the viability of the corpus luteum?
human chorionic gonadotropin
Which of the following events does NOT occur during the first 8 weeks of development?
myelination of the spinal cord
Which of the following is NOT a correct matching of a fetal structure with what it becomes?
ductus ateriosus--ligamentum teres
Which body system of a pregnant woman undergoes the most dramatic physiological changes during pregnancy?
Thalidomide was once used to treat intense nausea and morning sickness in pregnant women. Unfor
Which of the following is not assessed as part of the Apgar score?
Prior to the let-down reflex, the mammary glands secrete a yellowish fluid
How long is the secondary oocyte viable and capable of being fertilized after is it ovulated?
Select the correct statement about fertilization.
millions of sperm cells are destroyed by vagina's acidic environment
Shortly after implantation ___
the trophoblast forms two distinct layers
Gastrulation begins when a groove with raised edges called the ___ appears on the dorsal surface of the embryonic disc.
Muscle tissue is formed by ____
Neural tissue is formed ___
The trophoblast is mostly responsible for forming the __
The cardiovascular system of a newborn must be adjusted after the infant takes its first breath. which of the following is also true?
the ductus arteriosus constricts and is converted to the ligamentum arteriosum
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 the uterine tubes
At which stage of labor is the "afterbirth" expelled?
Fertilization generally occurs in the ___
which of the following female structures is homologous to the male scrotum?
In humans, separation of the cells at the two-cell state following fertilization may lead to he production of twins, which in this case would be ____
how many alleles exist for a given gene?
each gene can have different number of alleles
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 in variation we see in a genetic individual trait
if a person is homozygous for a particular trait this means
the person has two identical alleles for the gene responsible for the trait
is it possible for a baby to have type O blood if neither parent is type O
Recessive allele is best defined
only expressed if present in a double dose
Of the different sources of genetic variability which one cause the variation in the combinations of homologs from paternal and maternal linage found within a haploid cell.
of the different sources of genetic variability which one produces the variation in the combinations of alleles on a single chromosome
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
of the different sources of genetic variability which one could be define as permanent, transmissible changes to the DNA coding sequence that are often caused by outside environmental factors?
in meiosis the spermatozoa that are produced are genetically unlike each other and unlike the cel that produces them. this is one reason for great variation. What causes this effect?
crossing over and independent assortment only