Question 1

Which statement about the chick allantois is true?

Accepted Answer

A)  Its membrane is formed from ectoderm and mesoderm. 
B)  It functions in storing metabolic waste. 
C)  It has no function in mammalian development. 
D)  It is part of the body of the embryo. 
E)  It is avascular.

Question 2

You find a clay model of an embryo undergoing gastrulation and realize it must represent a reptile or bird and not an amphibian because

Accepted Answer

A)  a structure on the side of the model is labeled "Dorsal lip of the blastopore." 
B)  the endoderm cells located at the vegetal pole of the embryo are undergoing involution. 
C)  cells moving anteriorly from a thickening labeled "Hensen's node" are labeled "Notochordal mesoderm." 
D)  a region of yolky cells is labeled "Yolk plug." 
E)  a large central cavity surrounded by endoderm is labeled "Archenteron."

Question 3

What two organelles does a sperm contribute at fertilization, and why is each one important?

Accepted Answer

The answer of What two organelles does a sperm contribute...

Question 4

A researcher wanted to know if the dermis below the wing epidermis in a chick embryo sent inductive signals to the epidermis that resulted in the epidermis forming wing feathers.The researcher therefore did three experiments with the following results:  From these results, can we conclude that wing dermis induces epidermis to form wing feathers? Explain your answer.

Accepted Answer

The answer of A researcher wanted to know if the...

Question 5

In a placental mammal, destruction of cells within the inner cell mass is most likely to impair which event?

Accepted Answer

A)  Creation of the blastocoel 
B)  Formation of structures in the body of the embryo 
C)  Implantation 
D)  Formation of the placenta 
E)  Position of the asters in the second and third cleavage

Question 6

In the 1950s, thalidomide was given to pregnant women to ease nausea and insomnia.What happened to some fetuses exposed to this drug?

Accepted Answer

A)  Exposure in the last trimester resulted in babies missing their forebrains, a condition called anencephaly. 
B)  Exposure during gastrulation resulted in babies with organs on the wrong side, a condition called situs inversus. 
C)  Exposure in the first trimester when organs are forming resulted in babies with missing or severely malformed arms and legs. 
D)  Exposure during neurulation resulted in babies with regions of open neural tubes, a condition called spina bifida. 
E)  Exposure in the last trimester when growth is rapid resulted in babies with sleep abnormalities.

Question 7

A pregnant woman who is close to her due date has been feeling mild uterine contractions for several hours when suddenly she feels a fluid flowing down her legs.This is an indication that the _______ around the baby has/have ruptured.

Accepted Answer

The answer of A pregnant woman who is close to...

Question 8

A researcher exposes a sea urchin blastula to a protein that inhibits filopodia formation.Which event will most immediately be compromised in the manipulated blastula?

Accepted Answer

A)  Flattening of the vegetal hemisphere 
B)  Shape changes in cells of the vegetal pole 
C)  Formation of primary mesenchyme 
D)  Elongation of the archenteron 
E)  Invagination of the animal pole

Question 9

Which feature characterizes β-catenin's role in amphibian embryos?

Accepted Answer

A)  Its overexpression in a particular region of the blastula induces a second axis of embryo formation. 
B)  It acts as an inductive signal by phosphorylating other proteins that enter the nucleus and act as transcription factors. 
C)  When its mRNA transcripts are increased by injecting them into the egg, gastrulation does not occur. 
D)  It interacts with signals from cells in the animal hemisphere to set up signaling pathways. 
E)  It is necessary but not sufficient for formation of the primary embryonic organizer.

Question 10

The first organizer cells to enter an amphibian embryo move toward the anterior and eventually induce nearby cells to form structures of the _______.

Accepted Answer

The answer of The first organizer cells to enter an...

Question 11

Which statement about cleavage and early development in placental mammals is true?

Accepted Answer

A)  Cells of the inner cell mass initiate implantation. 
B)  Premature hatching of the blastocyst from the zona pellucida can result in ectopic pregnancy. 
C)  Mammalian cleavage produces a blastocyst, which produces the body of the embryo, while the maternal tissues produce all the tissues of the placenta. 
D)  Cells of the trophoblast are pluripotent stem cells. 
E)  Cells derived from the trophoblast form the amnion and yolk sac.

Question 12

Which embryonic structure contributes directly to the mammalian placenta?

Accepted Answer

A)  Yolk sac 
B)  Chorion 
C)  Uterus 
D)  Amnion 
E)  Blastocoel

Question 13

Which animals have a blastodisc?

Accepted Answer

A)  Sea urchins 
B)  Amphibians 
C)  Reptiles 
D)  Placental mammals 
E)  Roundworms

Question 14

Refer to the figure showing a 9-day chick embryo.  Based on the figure, which statement is true?

Accepted Answer

A)  The blood vessels of the structure at point 6 develop from endoderm. 
B)  The structure at point 8 stores waste products. 
C)  The structure at point 5 includes contributions from endoderm and mesoderm. 
D)  The structure at point 6 limits water loss from the egg. 
E)  Yolk passes through the structure at point 4 to nourish the developing embryo.

Question 15

The _______ of the blastopore is the primary organizer in amphibian embryos.

Accepted Answer

The answer of The _______ of the blastopore is the...

Question 16

The developmental process during which germ layers form and take specific positions relative to one another is called _______.

Accepted Answer

The answer of The developmental process during which germ layers...

Question 17

A researcher working with fruit fly embryos removes the cells containing the pole plasm at the posterior end of an embryo.In a second embryo, the researcher removes several cells just lateral to the ones containing pole plasm.If both embryos develop into larvae, it is most likely that

Accepted Answer

A)  the first larva will have gonads that lack germ cells, and the second larva will have gonads that contain germ cells. 
B)  the first larva will lack gonads and germ cells, and the second larva will lack germ cells. 
C)  both larvae will contain germ cells but no gonads. 
D)  both larvae will contain gonads but no germ cells. 
E)  both larvae will be able to regulate and form normal larvae.

Question 18

Explain how identical and non-identical twins form in humans.

Accepted Answer

The answer of Explain how identical and non-identical twins form...

Question 19

Refer to the figure showing a scanning electron micrograph of a chick embryo.  In this image the overlying epidermal ectoderm has been removed, and we are looking down on the embryo from above.The tissue labeled "a" will soon form a(n) _______, which lies posterior to the structures labeled "b."

Accepted Answer

The answer of Refer to the figure showing a scanning...

Question 20

_______ is the process by which surface cells roll over the lip of the blastopore and move into the blastocoel during amphibian gastrulation.

Accepted Answer

A)  Invagination 
B)  Involution 
C)  Epiboly 
D)  Convergent extension 
E)  Ingression

Exam 43: Animal Development