Question 1

Which mammal is most likely to have the shortest gestation period?

Accepted Answer

A)  Horse 
B)  Rat 
C)  Cow 
D)  Cat 
E)  Dog 
A)  Horse 
B)  Rat 
C)  Cow 
D)  Cat 
E)  Dog

Question 2

Which statement about human prenatal development is true?

Accepted Answer

A)  Exposure to drugs or radiation is most harmful during the third trimester. 
B)  By the end of the first month, the developing human is considered a fetus. 
C)  At 4 weeks gestation, most of the embryo's organ systems have formed. 
D)  Growth occurs most rapidly during the first trimester. 
E)  Internal organs such as the lungs are mature by the end of the second trimester. 
A)  Exposure to drugs or radiation is most harmful during the third trimester. 
B)  By the end of the first month, the developing human is considered a fetus. 
C)  At 4 weeks gestation, most of the embryo's organ systems have formed. 
D)  Growth occurs most rapidly during the first trimester. 
E)  Internal organs such as the lungs are mature by the end of the second trimester.

Question 3

You examine an embryo that has just started to gastrulate and see that there is a deep indentation at the vegetal pole where the sheet of cells is bending inward.From this you are able to determine that this (is/is not) _______ an amphibian embryo.

Accepted Answer

The answer of You examine an embryo that has just...

Question 4

Which feature characterizes β-catenin in frogs?

Accepted Answer

A)  It can act as a transcription factor. 
B)  It is not present in the unfertilized egg. 
C)  It is found in lower concentrations in the gray crescent of a recently fertilized egg. 
D)  It is synthesized by glycogen synthase kinase-3 (GSK-3). 
E)  It is found in higher concentrations on the ventral side of the embryo. 
A)  It can act as a transcription factor. 
B)  It is not present in the unfertilized egg. 
C)  It is found in lower concentrations in the gray crescent of a recently fertilized egg. 
D)  It is synthesized by glycogen synthase kinase-3 (GSK-3). 
E)  It is found in higher concentrations on the ventral side of the embryo.

Question 5

The best time to conduct an obstetric ultrasound to evaluate the period of rapid fetal growth in humans is

Accepted Answer

A)  during the middle of the first trimester. 
B)  after the formation of the placenta. 
C)  after the formation of the limbs. 
D)  in the third trimester. 
E)  when the heart begins to beat. 
A)  during the middle of the first trimester. 
B)  after the formation of the placenta. 
C)  after the formation of the limbs. 
D)  in the third trimester. 
E)  when the heart begins to beat.

Question 6

In a cross section of a vertebrate embryo that has just completed neurulation, which is the correct order of structures and tissues encountered, starting at the dorsal surface and moving inward along the midline?

Accepted Answer

A)  Epidermis, notochord, neural tube, gut 
B)  Epidermis, neural tube, notochord, gut 
C)  Epidermis, vertebral column, gut, neural tube 
D)  Epidermis, neural tube, vertebral column, gut 
E)  Epidermis, vertebral column, neural tube, gut 
A)  Epidermis, notochord, neural tube, gut 
B)  Epidermis, neural tube, notochord, gut 
C)  Epidermis, vertebral column, gut, neural tube 
D)  Epidermis, neural tube, vertebral column, gut 
E)  Epidermis, vertebral column, neural tube, gut

Question 7

You find some marine eggs that were recently laid.The eggs are small with clear cytoplasm.You stain one egg for yolk and find faint staining relatively evenly distributed throughout the cytoplasm.When cleavage begins in the unstained eggs, you are not surprised to see that the pattern of cleavage is

Accepted Answer

A)  spiral. 
B)  discoidal. 
C)  incomplete. 
D)  superficial. 
E)  rotational. 
A)  spiral. 
B)  discoidal. 
C)  incomplete. 
D)  superficial. 
E)  rotational.

Question 8

If the endoderm cells that line the archenteron in a developing frog are altered, this will cause changes in

Accepted Answer

A)  the lining of the digestive tract. 
B)  the sense organs. 
C)  structures derived from skin. 
D)  the heart and blood vessels. 
E)  muscles and bones. 
A)  the lining of the digestive tract. 
B)  the sense organs. 
C)  structures derived from skin. 
D)  the heart and blood vessels. 
E)  muscles and bones.

Question 9

_______ is a birth defect caused by failure of the posterior region of the neural tube to close completely.

Accepted Answer

The answer of _______ is a birth defect caused by...

Question 10

Which structure(s) would be directly impaired by experimental destruction of somites?

Accepted Answer

A)  Vertebrae 
B)  Pancreas 
C)  Lungs 
D)  Epidermis 
E)  Stomach 
A)  Vertebrae 
B)  Pancreas 
C)  Lungs 
D)  Epidermis 
E)  Stomach

Question 11

Which statement about embryonic development is true?

Accepted Answer

A)  Determination is the process by which blastomeres differentiate into specific cell types. 
B)  Preimplantation genetic diagnosis is possible in humans because they have regulative development. 
C)  In Drosophila, pole cells are the last cells to become determined. 
D)  Determination occurs later in species with mosaic development than in species with regulative development. 
E)  If the cells of a roundworm embryo in the two-cell stage are separated, each will develop into a complete animal. 
A)  Determination is the process by which blastomeres differentiate into specific cell types. 
B)  Preimplantation genetic diagnosis is possible in humans because they have regulative development. 
C)  In Drosophila, pole cells are the last cells to become determined. 
D)  Determination occurs later in species with mosaic development than in species with regulative development. 
E)  If the cells of a roundworm embryo in the two-cell stage are separated, each will develop into a complete animal.

Question 12

Fertilization

Accepted Answer

A)  allows several sperm to enter before the egg sets up blocks against entry by additional sperm. 
B)  prevents ion fluxes across the egg cell membrane. 
C)  initiates a rapid series of cell divisions. 
D)  decreases the egg's metabolism. 
E)  changes protein synthesis without changing the pH of the egg cytoplasm. 
A)  allows several sperm to enter before the egg sets up blocks against entry by additional sperm. 
B)  prevents ion fluxes across the egg cell membrane. 
C)  initiates a rapid series of cell divisions. 
D)  decreases the egg's metabolism. 
E)  changes protein synthesis without changing the pH of the egg cytoplasm.

Question 13

Refer to the figure showing Hox gene expression in the mouse embryo.   From this figure you can conclude that

Accepted Answer

A)  only one Hoxb gene is expressed in the anterior region of the embryo. 
B)  more Hoxb genes are expressed in the posterior region of the embryo than in the anterior region. 
C)  Hoxb9 gene is only expressed in the posterior region of the spinal cord. 
D)  Hoxb4 gene is expressed in a more posterior region than Hoxb2. 
E)  Hoxb2 expression is higher in the spinal cord than the hindbrain. 
A)  only one Hoxb gene is expressed in the anterior region of the embryo. 
B)  more Hoxb genes are expressed in the posterior region of the embryo than in the anterior region. 
C)  Hoxb9 gene is only expressed in the posterior region of the spinal cord. 
D)  Hoxb4 gene is expressed in a more posterior region than Hoxb2. 
E)  Hoxb2 expression is higher in the spinal cord than the hindbrain.

Question 14

Which characterizes development in placental mammals but not birds?

Accepted Answer

A)  Epiblast cells migrate through the primitive groove to become endoderm and mesoderm. 
B)  The embryo proper forms from the epiblast. 
C)  The hypoblast contributes to extraembryonic membranes. 
D)  Signaling molecules in Hensen's node are similar to those found in the frog organizer. 
E)  Cleavage produces a blastocyst with an inner cell mass. 
A)  Epiblast cells migrate through the primitive groove to become endoderm and mesoderm. 
B)  The embryo proper forms from the epiblast. 
C)  The hypoblast contributes to extraembryonic membranes. 
D)  Signaling molecules in Hensen's node are similar to those found in the frog organizer. 
E)  Cleavage produces a blastocyst with an inner cell mass.

Question 15

If you experimentally delete one somite from the right side of a developing chick embryo, which of the following will likely be affected in the chick when it hatches?

Accepted Answer

A)  Left region of the brain 
B)  Peripheral nerves in one region on the right side 
C)  Notochord in the region of the deleted somite 
D)  Muscles and ribs in one region on the left side 
E)  Right chambers of the heart 
A)  Left region of the brain 
B)  Peripheral nerves in one region on the right side 
C)  Notochord in the region of the deleted somite 
D)  Muscles and ribs in one region on the left side 
E)  Right chambers of the heart

Question 16

Why would exposure to a harmful chemical during the first trimester be more likely to produce a major birth defect in a developing human than exposure to the same chemical during the last trimester?

Accepted Answer

Tissues and organs are forming

Question 17

Refer to the figure showing some of the manipulations carried out by Spemann on developing amphibians.   Do the results of these experiments on salamander development indicate that gray crescent material is necessary for normal development? Do these results indicate that gray crescent material is sufficient for normal development? Explain your answer.

Accepted Answer

The two experiments together do indicate

Question 18

Which feature characterizes the centriole contributed to the zygote by the sperm?

Accepted Answer

A)  It is one of several nonnuclear organelles contributed by the sperm. 
B)  It fuses with the egg's centriole. 
C)  It becomes the zygote's centrosome, which organizes mitotic spindles. 
D)  It is destroyed once it enters the egg cytoplasm, meaning all centrioles are maternally inherited. 
E)  It inhibits cytoplasmic reorganization following fertilization. 
A)  It is one of several nonnuclear organelles contributed by the sperm. 
B)  It fuses with the egg's centriole. 
C)  It becomes the zygote's centrosome, which organizes mitotic spindles. 
D)  It is destroyed once it enters the egg cytoplasm, meaning all centrioles are maternally inherited. 
E)  It inhibits cytoplasmic reorganization following fertilization.

Question 19

Which of the following is an extraembryonic membrane correctly paired with its function in the developing chick?

Accepted Answer

A)  Yolk sac: encloses yolk that will be digested in the gut of the embryo 
B)  Allantoic membrane: forms a sac that stores fecal wastes 
C)  Amnion: secretes a protective fluid that surrounds the embryo 
D)  Chorion: allows for transport of water between the embryo and the outside environment 
E)  Trophoblast: forms the outermost extraembryonic membrane that protects the embryo 
A)  Yolk sac: encloses yolk that will be digested in the gut of the embryo 
B)  Allantoic membrane: forms a sac that stores fecal wastes 
C)  Amnion: secretes a protective fluid that surrounds the embryo 
D)  Chorion: allows for transport of water between the embryo and the outside environment 
E)  Trophoblast: forms the outermost extraembryonic membrane that protects the embryo

Question 20

During cleavage, the positions of the mitotic spindles

Accepted Answer

A)  determine planes of cleavage. 
B)  are usually random. 
C)  are defined by cytoplasmic factors produced during early cleavage stages. 
D)  are unrelated to the organization of the blastomeres. 
E)  are similar in radially and spirally cleaving embryos. 
A)  determine planes of cleavage. 
B)  are usually random. 
C)  are defined by cytoplasmic factors produced during early cleavage stages. 
D)  are unrelated to the organization of the blastomeres. 
E)  are similar in radially and spirally cleaving embryos.

Exam 43: Animal Development

Which mammal is most likely to have the shortest gestation period?

Which statement about human prenatal development is true?

You examine an embryo that has just started to gastrulate and see that there is a deep indentation at the vegetal pole where the sheet of cells is bending inward.From this you are able to determine that this (is/is not) _______ an amphibian embryo.

Which feature characterizes β-catenin in frogs?

The best time to conduct an obstetric ultrasound to evaluate the period of rapid fetal growth in humans is

In a cross section of a vertebrate embryo that has just completed neurulation, which is the correct order of structures and tissues encountered, starting at the dorsal surface and moving inward along the midline?

If the endoderm cells that line the archenteron in a developing frog are altered, this will cause changes in

_______ is a birth defect caused by failure of the posterior region of the neural tube to close completely.

Which structure(s) would be directly impaired by experimental destruction of somites?

Which statement about embryonic development is true?

Fertilization

Refer to the figure showing Hox gene expression in the mouse embryo. From this figure you can conclude that

Which characterizes development in placental mammals but not birds?

If you experimentally delete one somite from the right side of a developing chick embryo, which of the following will likely be affected in the chick when it hatches?

Why would exposure to a harmful chemical during the first trimester be more likely to produce a major birth defect in a developing human than exposure to the same chemical during the last trimester?

Which feature characterizes the centriole contributed to the zygote by the sperm?

Which of the following is an extraembryonic membrane correctly paired with its function in the developing chick?

During cleavage, the positions of the mitotic spindles

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