AP Biology : Reproductive System

Study concepts, example questions & explanations for AP Biology

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Example Questions

Example Question #31 : Reproductive System

Which of the following best describes when the zona pellucida disintegrates?

Possible Answers:

Before the onset of cleavage to allow for growth

After implantation into the uterine wall

Immediately following fertilization as a result of the cortical reaction

After an increase in blastocyst size and subsequent zona pellucida "hatching"

Correct answer:

After an increase in blastocyst size and subsequent zona pellucida "hatching"

Explanation:

The zona pellucida is a glycoprotein layer secreted by follicle cells that surrounds the released oocyte and developing embryo. Once the blastocoel grows in size during blastula development, the blastocyst “hatches” out of the zone pellucida, which then disintegrates.

Example Question #32 : Reproductive System

Which of the following steps does not precede blastocyst implantation in the uterine wall?

Possible Answers:

Initial loose contacts between the blastocyst and the uterine wall

Irreversible connections between the blastocyst and the uterine wall

Breakdown of the endometrial extracellular matrix

"Hatching" from the zona pellucida

Correct answer:

Irreversible connections between the blastocyst and the uterine wall

Explanation:

Implantation is the process in which a blastocyst adheres to the female uterine wall. This is preceded by the exit of the blastocyst form the zona pellucida as well as the degradation of the endometrial extracellular matrix by proteolytic enzymes secreted by the blastocyst and initial loose connections with the endometrium. The blastocyst then adheres to the uterine wall through ligand-receptor systems and cell invasion.

Example Question #1226 : Ap Biology

Which of the following is the leading cause of implantation failure?

Possible Answers:

Foreign substance interference

Medication

Decreased uterine receptivity

Embryo abnormalities

Correct answer:

Decreased uterine receptivity

Explanation:

The leading cause of implantation failure is decreased uterine receptivity. Other causes include problems with the developing embryo. Certain medications can be administered to increase chances of successful implantation.

Example Question #1227 : Ap Biology

Which of the following cell layers both ingressions and invaginates during gastrulation?

Possible Answers:

Hypoblast

Blastocoel

Trophoblast

Epiblast

Correct answer:

Epiblast

Explanation:

The epiblast is an inner cell layer in the blastocoel that sits above the hypoblast. The epiblast ingresses to form the mesoderm and invaginates to form the endoderm.

Example Question #1228 : Ap Biology

Which of the following is established by the primitive streak during gastrula development?

Possible Answers:

All of these

Left/right axes

Bilateral symmetry

Cranial/caudal axes

Correct answer:

All of these

Explanation:

The primitive streak is an arrangement of cells that forms during gastrula development. The location of the primitive streak establishes the left/right axes, cranial/caudal axes, and bilateral symmetry of the developing embryo.

Example Question #1229 : Ap Biology

The process of ingression forms which of the following germ layers during gastrula development?

Possible Answers:

Ectoderm

None of these

Endoderm

Mesoderm

Correct answer:

Mesoderm

Explanation:

In gastrulation, the process of ingression forms the mesoderm. In this process, the epiblast ingresses at the primary streak into the area between the epiblast and hypoblast cell layers.

Example Question #1230 : Ap Biology

During which of the following stages of embryonic development does the process of invagination occur?

Possible Answers:

Fertilization

Gastrulation

Blastula development

Implantation

Correct answer:

Gastrulation

Explanation:

Invagination is the infolding of the epiblast cell layer to form the endoderm germ layer. This process takes place during gastrulation.

Example Question #1231 : Ap Biology

Which of the following structures is referred to as the “blastocoel”?

Possible Answers:

The glycoprotein layer around the blastocyst

The fluid-filled cavity of the blastocyst

The area of cellular invasion during implantation

Outer layers of cells in the blastocyst

Correct answer:

The fluid-filled cavity of the blastocyst

Explanation:

The “blastocoel” is a fluid-filled cavity in the blastocyst. It is enclosed by trophoblast cells.

Example Question #1232 : Ap Biology

During what stage of embryonic development do cells differentiate into primary germ layers?

Possible Answers:

Fertilization

Gastrulation

Implantation

Blastula development

Correct answer:

Gastrulation

Explanation:

Germ layers are primary layers of cells that form during embryogenesis. In mammals, they are the endoderm, ectoderm, and mesoderm. In embryo development, the germ layers differentiate during gastrulation.

Example Question #31 : Understanding Embryogenesis And Development

Which of the following does not develop from the mesoderm?

Possible Answers:

Muscle cells

Red blood cells

Kidney cells

Pigment cells

Correct answer:

Pigment cells

Explanation:

The mesoderm is a primary germ layer that forms during gastrulation. The mesoderm develops into most of the organ systems of the human body, including the muscular system, circulatory system, and excretory system.

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