Comparative Embryology Quiz 2

2.

In the Hensen's node transplantation experiment, a secondary body axis developed (birds).

True
False

Correct Answer

A. True

Explanation

In the Hensen's node transplantation experiment, a secondary body axis developed in birds. This suggests that the Hensen's node, which is a group of cells responsible for organizing the body axis during embryonic development, has the ability to induce the formation of a new body axis when transplanted. This experiment provides evidence for the importance of the Hensen's node in determining body axis formation in birds.

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3.

During the first week of human developent.

Cleavage is occurring
The embryo is moving down the oviduct to the uterus
Implantation is completed
A and b above
All of the above

Correct Answer

A. A and b above

Explanation

During the first week of human development, both cleavage and the movement of the embryo down the oviduct to the uterus occur. Cleavage refers to the rapid cell division that takes place after fertilization, leading to the formation of a multicellular embryo. At the same time, the embryo moves down the oviduct, guided by the beating cilia and contractions of the oviduct muscles, towards the uterus where implantation will eventually occur. Therefore, the correct answer is "a and b above".

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4.

Bird embryos

Undergo gastrulation via the primitive streak.
Develop a blastocoel during late cleavage.
Have telolecithal eggs and discoidal cleavage.
A and b above
All of the above

Correct Answer

A. All of the above

Explanation

The correct answer is "all of the above". This means that all of the statements given in the options are true for bird embryos. Bird embryos undergo gastrulation via the primitive streak, develop a blastocoel during late cleavage, and have telolecithal eggs and discoidal cleavage.

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5.

In birds, _________ is when the primitive streak is at its full length but there is no neurulation occurring yet.

Late cleavage
Early gastrulation
Mid gastrulation
Late gastrulation
None of the above

Correct Answer

A. Mid gastrulation

Explanation

Mid gastrulation is the correct answer because it refers to the stage in bird development where the primitive streak has reached its full length but neurulation has not yet begun. Neurulation is the process of forming the neural tube, which gives rise to the central nervous system. Therefore, mid gastrulation is the stage between the initial formation of the primitive streak and the start of neurulation in bird embryos.

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6.

For cells that enter the embryo at the primitive streak, which cell-movement process do they never use before reaching their final destination?

Epiboly
Involution
Ingression
Amoeboid movement
Those cells use all of the above cell-movement processes

Correct Answer

A. Epiboly

Explanation

Epiboly is the process by which cells spread and move over the surface of the embryo. It involves the expansion and thinning of cell layers to cover a larger area. Cells that enter the embryo at the primitive streak do not use epiboly before reaching their final destination. Therefore, the correct answer is epiboly.

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7.

Koller's sickle

Develops at the future posterior end of the embryo
Is a site of accelerated (rapid) mitosis
Is the point at which cells ingress into the blastocoel
A and b above
All of the above

Correct Answer

A. A and b above

Explanation

Koller's sickle develops at the future posterior end of the embryo and is a site of accelerated (rapid) mitosis. This means that Koller's sickle is a region in the embryo that undergoes rapid cell division and is located at the posterior end. Therefore, both statements a and b are correct.

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8.

Mammals have isolecithal eggs and radial cleavage.

True
False

Correct Answer

A. False

Explanation

Mammals do not have isolecithal eggs and radial cleavage. Mammals have telolecithal eggs, which means that the yolk is concentrated at one end of the egg. Additionally, mammals have holoblastic cleavage, which is a type of cleavage that occurs in a specific pattern rather than radial cleavage. Therefore, the statement is false.

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9.

The epiblast gives rise to

Ectoderm
Mesoderm
Amnion
A and b above
All of the above

Correct Answer

A. All of the above

Explanation

The epiblast is the innermost layer of the embryonic disc, and it is responsible for giving rise to the ectoderm, mesoderm, and amnion. The ectoderm develops into the skin, nervous system, and other external structures. The mesoderm develops into the muscles, bones, circulatory system, and other internal structures. The amnion is a membrane that surrounds and protects the developing embryo. Therefore, the correct answer is "all of the above" because the epiblast gives rise to all of these structures.

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10.

Which of the following do both birds and mammals have?

Trophoblast
Morula
Primitive streak
A and b above
All of the above

Correct Answer

A. Primitive streak

Explanation

Birds and mammals both have a primitive streak. The primitive streak is a structure that forms during embryonic development and plays a crucial role in establishing the body plan of the organism. It is the first visible sign of gastrulation, the process by which the three primary germ layers (ectoderm, mesoderm, and endoderm) are formed. The primitive streak is responsible for organizing the cells in the embryo and directing their differentiation into various tissues and organs. Therefore, the presence of a primitive streak is a shared characteristic between birds and mammals.

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1

Comparative Embryology Quiz 2

The primitive streak is at its full length in early gastrulation.

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In the Hensen's node transplantation experiment, a secondary body axis developed (birds).

During the first week of human developent.

Bird embryos

In birds, _________ is when the primitive streak is at its full length but there is no neurulation occurring yet.

For cells that enter the embryo at the primitive streak, which cell-movement process do they never use before reaching their final destination?

Koller's sickle

Mammals have isolecithal eggs and radial cleavage.

The epiblast gives rise to

Which of the following do both birds and mammals have?