MCAT Biology : Gastrulation and Embryonic Germ Layers

Study concepts, example questions & explanations for MCAT Biology

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Example Questions

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Example Question #11 : Gastrulation And Embryonic Germ Layers

Which of the following structures does not arise from the mesoderm?

Possible Answers:

Circulatory system

Respiratory system

Genitourinary system

Musculoskeletal system

Correct answer:

Respiratory system

Explanation:

The mesoderm gives rise to muscles, bones, the circulatory system, the gonads, and the kidneys. Think of the mesoderm as the means by which your body gets around on a daily basis: muscles and bones, heart to pump blood, and kidneys to excrete waste.

The respiratory system arises from the endoderm.

Example Question #12 : Gastrulation And Embryonic Germ Layers

From which of the following germinal layers does the retina of the eye originate?

Possible Answers:

Ectoderm

Mesoderm

Somites, which are not associated with a germ layer

Endoderm

Correct answer:

Ectoderm

Explanation:

The retina of the eye originates as an outpouching of the diencephalon. The diencephalon is one of the five secondary vesicles in the early development of the neural tube, which is derived from the ectodermal germ layer.

The ectoderm gives rise to the epidermis, central nervous system, inner ear, and the lens of the eye.

Somites are small regions of specialized mesoderm, which give rise to the skeletal muscles and bones of the body.

Example Question #13 : Gastrulation And Embryonic Germ Layers

From which of the following germ layers does the circulatory system arise?

Possible Answers:

Neural crest

Endoderm

Ectoderm

Mesoderm

Correct answer:

Mesoderm

Explanation:

The circulatory system arises from the mesoderm. Other mesoderm structures include the muscles, bones, gonads, and kidneys.

The ectoderm gives rise to the epidermis, nervous system, and lens of the eye. The neural crest originates from ectoderm cells.

The endoderm gives rise to several internal organs, including the liver and pancreas, as well as the linings of the digestive and respiratory tracts.

Example Question #14 : Gastrulation And Embryonic Germ Layers

Which embryonic structure is a precursor to the spinal cord?

Possible Answers:

Blastocoel

Spemann's organizer

Neural tube

Notochord

Correct answer:

Neural tube

Explanation:

The neural tube is a structure derived from the ectoderm that is found in chordates. The neural tube is formed by the closing of the neural folds, and runs along the dorsal-ventral axis of the developing embryo. Cells within the neural tube give rise to the neural crest. Additionally, the mature neural tube continues to develop into the central nervous system.

Example Question #91 : Mcat Biological Sciences

All of the following are formed from the same primary germ layer as the heart, except __________.

Possible Answers:

kidneys

the lungs

bones

muscles

Correct answer:

the lungs

Explanation:

The circulatory system is part of the mesoderm germ layer, and includes development of the heart. We know that three answer choices must also be part of the mesoderm, while one is not (the correct answer). The mesoderm is responsible for generating muscle, blood, and bone tissue, kidneys and gonads, as well as the heart.

This leaves us with lungs, the correct answer, which develop from the endoderm layer.

Example Question #16 : Gastrulation And Embryonic Germ Layers

Which of the following organs does not develop from the mesoderm?

Possible Answers:

Kidney

Bladder

Skeletal muscle

Bone

Heart

Correct answer:

Bladder

Explanation:

The bladder develops from the endoderm. The heart, kidney, skeletal muscle, and bone develop from the mesoderm.

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