Question 1

In the famous Spemann-Mangold experiment, what detail was crucial to understanding the result?
A)transplanting the new dorsal lip cells to the same dorsal lip location in the second embryo
B)using genetically different donor and host frogs
C)placing the dorsal lip cells deep inside the archenteron
D)treating the dorsal lip cells with morphogens before transplanting them

Accepted Answer

The answer of In the famous Spemann-Mangold experiment, what detail...

Question 2

In 1998, researchers found that genes similar to the Drosophila gene tinman are necessary for heart development in vertebrates.What can you conclude about the ancient bilaterian ancestor of insects and vertebrates over 500 million years ago?
A)The fly species that eventually gave rise to vertebrates used tinman to make a heart.
B)Something about heart development requires a gene to have a tinman-like sequence, but the vertebrate and invertebrate genes arose by convergent evolution -- so the ancestor had a similar but not homologous gene.
C)The ancient ancestor lacked a heart, but already had a tinman-like gene.
D)The ancestor had a heart-like structure that was specified by a tinman-like gene.

Accepted Answer

Since both insects and vertebrates have genes similar to Drosophila tinman necessary for heart development, it suggests that their common ancestor, which lived over 500 million years ago, also had a heart-like structure that was specified by a tinman-like gene. This scenario is supported by the fact that the last common ancestor of bilaterians is thought to have had a rudimentary heart-like structure already.

Question 3

In a normal mammalian birth, how does the body guarantee that birth proceeds to completion?
A)Via positive feedback -- stretching of the uterus by the descending fetus induces release of oxytocin from the posterior pituitary causing even stronger uterine contractions.
B)Via negative feedback -- stretching of the uterus by the descending fetus induces release of FSH and LH from the posterior pituitary causing even stronger uterine contractions.
C)Via positive feedback -- stretching of the uterus by the descending fetus induces release of prolactin from the posterior pituitary causing even stronger uterine contractions.
D)Via negative feedback -- stretching of the uterus by the descending fetus induces release of prostaglandins from the posterior pituitary causing weaker uterine contractions.

Accepted Answer

The body guarantees that birth proceeds to completion through positive feedback. As the fetus descends and stretches the uterus, it induces the release of oxytocin from the posterior pituitary, which in turn causes even stronger uterine contractions. This positive feedback loop continues until the baby is delivered.

Question 4

What problem would result from disrupted development of the allantois in both birds and mammals?
A)Inability to retain the fluid that surrounds the embryo
B)Inability to form the placenta
C)Problems with gas exchange
D)Loss of nutritional stores

Accepted Answer

The allantois plays a critical role in gas exchange in both birds and mammals by serving as a membrane where oxygen and carbon dioxide are exchanged between the embryo and the surrounding environment. Disrupted development of the allantois would result in problems with gas exchange, which could be detrimental to the survival and development of the embryo.

Question 5

What is critical to the development of neural crest cell derivatives?
A)close contact with the notochord
B)regulation of N-cadherin
C)muscle development genes like muscle myosin
D)strong cellular adhesions that lock the cells in the place of their origin

Accepted Answer

Regulation of N-cadherin is critical for the development of neural crest cell derivatives because it plays a key role in the process of epithelial-to-mesenchymal transition (EMT), which is essential for the migration of neural crest cells to their various target locations in the embryo.

Question 6

What would result if too many cells left the surface of the embryo to move inside during gastruation?
A)Too little endoderm, resulting in missing gut and organs
B)Too little ectoderm, resulting in missing nervous system or skin
C)Problems in muscle development
D)Too little protoderm, resulting in missing organs

Accepted Answer

Too many cells leaving the surface of the embryo during gastrulation would result in too little ectoderm, which could lead to missing parts of the nervous system or skin, among other structures that develop from this layer.

Question 7

What basic developmental challenge is solved by the organizer?
A)enhancing migration of cells into the interior of the blastula
B)assigning developmental fates to cells along the anterior-posterior axis
C)creating an anterior-posterior axis by responding to maternally-deposited protein factors
D)creating a dorsal-ventral axis from a spherical ball of cells

Accepted Answer

The organizer plays a crucial role in early embryonic development by inducing the formation of the dorsal-ventral axis from a spherical ball of cells, guiding the spatial organization necessary for proper development.

Question 8

In blind cave fish, eyes do not form.However, transplantation of the lens from a closely-related aboveground fish into the optic cup of the cave fish induces eye development.What does this suggest about the loss of vision in the cave fish?
A)Primary induction of the eye fails in the cave fish because the lens lacks some critical signal.
B)Secondary induction of the eye fails in the cave fish because the lens lacks some critical signal.
C)Primary induction of the eye fails in the cave fish because the optic cup lacks the ability to receive some critical signal.
D)Secondary induction of the eye fails in the cave fish because the optic cup lacks the ability to receive some critical signal.

Accepted Answer

The fact that transplantation of the lens from a closely-related aboveground fish into the optic cup of the cave fish induces eye development suggests that the primary induction of the eye is not the issue in the cave fish. Rather, it is the secondary induction of the eye that fails due to a lack of a critical signal. Therefore, the best choice is B.

Question 9

What would result if an error inside gastrulation caused too few cells inside the archenteron?
A)Too little endoderm, resulting in missing gut and organs
B)Too little ectoderm, resulting in missing nervous system or skin
C)Problems in muscle development
D)Too little protoderm, resulting in missing organs

Accepted Answer

Gastrulation is critical in forming the three germ layers, including the endoderm, which gives rise to the gut and internal organs. If too few cells enter the archenteron during gastrulation, there would be a deficiency in endoderm, resulting in missing gut and organs.

Question 10

The snakes include some rather short and some incredibly long species, with a variation from about 100 to over 300 vertebrae.What developmental mechanism is the best candidate for changing the number of vertebrae in evolution?
A)Changes in genes that lay down extracellular matrix in bone
B)Changes in genes necessary for neural crest development
C)Changes in genes that control mitosis
D)Changes in the somitogenesis clock

Accepted Answer

The process of somitogenesis creates the vertebrae in developing embryos. Changes in the somitogenesis clock, which is controlled by genes such as clock and wavefront, could potentially lead to variation in the number of vertebrae in different snake species.

Question 11

To your chagrin, you and your labmate have discovered that you both labeled your petri dishes "A", "B", and "C".How can you distinguish your sea urchin gastrula embryos from her frog gastrula embryos?
A)Unlike frogs, sea urchins are deuterostomes which form the anus first and the mouth second.
B)Sea urchin cells migrate inside to form the archenteron, whereas in frogs proliferation of dividing cells from the dorsal lip populate the inside of the embryo.
C)Sea urchins have relatively yolk-poor eggs with similar animal and vegetal poles, whereas frogs have large amounts of yolk distinguishing the vegetal pole from the animal pole.
D)Frogs have an animal pole and vegetal pole, whereas urchins have only a vegetal pole.

Accepted Answer

The answer of To your chagrin, you and your labmate...

Question 12

What human organ is formed from two genetically-different tissues?
A)neural crest
B)neural tube
C)placenta
D)uterus

Accepted Answer

The placenta is formed from both fetal tissues (derived from the trophectoderm) and maternal tissues (derived from the endometrium). The fetal portion contains cells of the chorion, while the maternal portion contains cells of the decidua. These tissues have different genetic origins, with the fetal tissue containing DNA from the developing embryo and the maternal tissue containing DNA from the mother.

Question 13

What would result if a defect in gastrulation caused too little mesoderm inside the embryo?
A)Too little endoderm, resulting in missing gut and organs
B)Too little ectoderm, resulting in missing nervous system or skin
C)Problems in muscle development
D)Too little protoderm, resulting in missing organs

Accepted Answer

Mesoderm gives rise to muscles, bones, and other connective tissues. If there is too little mesoderm, there may be problems in the development of these structures.

Question 14

400 micrograms a day of folic acid are recommended for all women of child-bearing age.Folic acid helps prevent neural tube defects in the first weeks of pregnancy, before most women even realize they are pregnant (and almost half of pregnancies in the U.S.are unintended).Knowing that folic acid promotes proper neural tube closure, which disease can be prevented by this supplement?
A)Spina bifida -- the vertebrae are unfused and may allow the spinal cord to protrude outside the body
B)Horseshoe kidney -- the two kidneys are fused together across the midline
C)Esophageal atresia -- the esophagous ends in a pouch, unconnected to the stomach
D)Chronic otitis media -- frequent ear infections that can result from blocked eustachian tubes

Accepted Answer

Folic acid supplementation helps prevent neural tube defects such as spina bifida, where the vertebrae do not close completely around the spinal cord.

Question 15

What prevents menstruation from occurring in the 10^th week when the corpus luteum regresses? A)The follicle takes over secretion of hCG. B)The follicle takes over secretion of estradiol and progesterone. C)The placenta takes over secretion of estradiol and progesterone. D)The cervix takes over secretion of oxytocin and prostaglandins.

Accepted Answer

The placenta takes over secretion of estradiol and progesterone, preventing menstruation from occurring in the 10th week when the corpus luteum regresses. This is because the placenta develops by the 10th week of gestation and is able to secrete sufficient levels of estradiol and progesterone to maintain the endometrium and prevent shedding.

Quiz 53: Animal Development

In the famous Spemann-Mangold experiment, what detail was crucial to understanding the result?

In 1998, researchers found that genes similar to the Drosophila gene tinman are necessary for heart development in vertebrates.What can you conclude about the ancient bilaterian ancestor of insects and vertebrates over 500 million years ago?

In a normal mammalian birth, how does the body guarantee that birth proceeds to completion?

What problem would result from disrupted development of the allantois in both birds and mammals?

What is critical to the development of neural crest cell derivatives?

What would result if too many cells left the surface of the embryo to move inside during gastruation?

What basic developmental challenge is solved by the organizer?

In blind cave fish, eyes do not form.However, transplantation of the lens from a closely-related aboveground fish into the optic cup of the cave fish induces eye development.What does this suggest about the loss of vision in the cave fish?

What would result if an error inside gastrulation caused too few cells inside the archenteron?

The snakes include some rather short and some incredibly long species, with a variation from about 100 to over 300 vertebrae.What developmental mechanism is the best candidate for changing the number of vertebrae in evolution?

To your chagrin, you and your labmate have discovered that you both labeled your petri dishes "A", "B", and "C".How can you distinguish your sea urchin gastrula embryos from her frog gastrula embryos?

What human organ is formed from two genetically-different tissues?

What would result if a defect in gastrulation caused too little mesoderm inside the embryo?

What prevents menstruation from occurring in the 10th week when the corpus luteum regresses?

What prevents menstruation from occurring in the 10^th week when the corpus luteum regresses?