Biology Chapter 43: Gastrulation and Germ Layers

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What is the main purpose of gastrulation in animal embryos?

To create the three main germ layers (correct)

To form the blastopore

To initiate skeletal rod formation

To develop the nervous system

Which germ layer eventually gives rise to the muscles and organs in animal embryos?

Mesoderm (correct)

Endoderm

Micromeres

Ectoderm

In sea urchin gastrulation, what does the blue color represent?

Mesoderm precursor

Micromeres

Ectoderm precursor (correct)

Endoderm precursor

Which model systems are used to examine gastrulation?

Sea urchin, frog, chick Signup and view all the answers

What is the eventual fate of the endoderm layer in animal embryos?

Becomes the digestive and respiratory tract Signup and view all the answers

Which structure is crucial during sea urchin gastrulation for future skeletal rod formation?

Archenteron Signup and view all the answers

What do micromeres represent in sea urchin gastrulation?

Specialized cell type Signup and view all the answers

'Mesoderm' is responsible for the formation of which of the following?

'Muscles and organs' Signup and view all the answers

What is the main difference between the blastula formation in chicks and other organisms?

Chicks have a flat disk of cells called a blastodisc, while other organisms have a ball of cells. Signup and view all the answers

What is the purpose of the hypoblast layer that forms underneath the epiblast during chick blastula development?

The hypoblast supports the epiblast during gastrulation. Signup and view all the answers

What is the function of the Koller's sickle in the development of the chick primitive streak?

The Koller's sickle forms the primitive streak. Signup and view all the answers

During the formation of the primitive streak in chicks, where do the congregated cells migrate from and to?

The cells migrate from the posterior end to the anterior end of the blastodisc. Signup and view all the answers

What happens to the primitive streak as it migrates across the blastodisc during chick gastrulation?

The primitive streak deepens to form the primitive groove. Signup and view all the answers

What structure eventually accumulates calcium carbonate to form a hard shell around the developing chick embryo?

A membrane that forms around the developing structure Signup and view all the answers

Which of the following is not a key structure or event in the gastrulation of the chick blastodisc?

Formation of the yolk sac Signup and view all the answers

At what stage of chick embryo development does the primitive streak first begin to form?

Within the first 3-4 hours of incubation Signup and view all the answers

What is the signal that gastrulation has ended?

Yolk Plug Signup and view all the answers

When does the space formed between the dorsal and ventral lips get filled?

After the yolk plug forms Signup and view all the answers

What does the yolk plug eventually become in frogs?

Anus Signup and view all the answers

Which structure forms underneath the dorsal lip in the gastrulation process?

Ventral lip Signup and view all the answers

Which of the following best describes the initial shape and arrangement of the primary mesenchyme cells before they begin to dissociate and move?

Cube-shaped and held together by cell-adhesion proteins Signup and view all the answers

What is the role of the basal lamina in the movement of primary mesenchyme cells during sea urchin gastrulation?

It acts as a barrier that the cells must penetrate to enter the blastocoel Signup and view all the answers

What is the primary role of the extracellular matrix fibril in the context of primary mesenchyme cell movement during sea urchin gastrulation?

It facilitates the elongation and shape changes of the cells as they move Signup and view all the answers

Which of the following best describes the archenteron in the context of sea urchin development?

It is the primitive gastric cavity that eventually becomes the anus Signup and view all the answers

What is the fate of the blastopore during sea urchin development?

It becomes the anus opening Signup and view all the answers

Which of the following statements best describes the relationship between the primary and secondary mesenchyme cells in sea urchin development?

The secondary mesenchyme cells are a heterogeneous population with different fates and behaviors from the primary mesenchyme cells Signup and view all the answers

What is the primary event that triggers the dissociation and movement of the primary mesenchyme cells into the blastocoel?

The loss of cell-adhesion proteins between the cells Signup and view all the answers

Which of the following best describes the initial location of the primary mesenchyme cells before their dissociation and movement?

They are located in the vegetal hemisphere Signup and view all the answers

What is the function of the Hensen's node in the formation of the three germ layers?

It directs the ingression of cells that form the head of the organism. Signup and view all the answers

What is the role of the primitive pit in the formation of the three germ layers?

It marks the anterior end of the primitive groove. Signup and view all the answers

What is the origin of the ectoderm in the formation of the three germ layers?

It is formed from the remaining epiblast cells on the surface after ingression. Signup and view all the answers

What is the function of the hypoblast during the formation of the three germ layers?

It serves as a support layer between the blastodisc and the yolk during gastrulation. Signup and view all the answers

What is the role of the primitive streak in the formation of the three germ layers?

It marks the anterior-posterior axis on the surface of the early embryo. Signup and view all the answers

What is the process that leads to the formation of the three germ layers?

The ingression of epiblast cells into the blastodisc. Signup and view all the answers

What is the significance of the primitive groove in the formation of the three germ layers?

It serves as the entry point for the ingression of cells into the blastodisc. Signup and view all the answers

What is the relationship between the primitive groove and the primitive streak in the formation of the three germ layers?

The primitive streak is formed as a result of the formation of the primitive groove. Signup and view all the answers

What is the primary role of the notochord in neural tube formation?

To signal the neural ectoderm to form the neural tube Signup and view all the answers

What is the primary function of the neural crest cells?

To differentiate into the peripheral nervous system Signup and view all the answers

What is the eventual fate of the neural tube?

It gives rise to the central nervous system Signup and view all the answers

Which of the following is not a step in the formation of the neural tube?

The notochord differentiates into the neural tube Signup and view all the answers

What is the primary function of the brain vesicles during embryonic development?

To give rise to different regions of the brain Signup and view all the answers

Which of the following statements is true regarding the neural plate?

It is part of the ectoderm that becomes the brain and spinal cord Signup and view all the answers

What is the relationship between the neural crest cells and the peripheral nervous system?

The neural crest cells give rise to the peripheral nervous system Signup and view all the answers

Which of the following structures is responsible for signaling the neural ectoderm to form the neural tube?

The notochord Signup and view all the answers

What is the primary function of the neural folds during neurulation?

To give rise to the neural crest cells Signup and view all the answers

Which of the following statements is true regarding the neural tube and the central nervous system?

The neural tube develops into the central nervous system Signup and view all the answers