Question

Which of the following extraembryonic membranes stores waste products? (A) chorion (B) amnion (C) allantois (D) yolk sac (E) eggshell

Short answer

C. Allantois

Step-by-step solution

Get Familiar With the Extraembryonic Membranes

First, understand each of the given extraembryonic membranes. The chorion surrounds the embryo and other membranes and is primarily involved in gas exchange. The amnion forms a fluid-filled sac that cushions the embryo. The yolk sac encloses the yolk of an egg and provides nutrients. The eggshell is the protective outer coating of the egg. The allantois is a membranous sac that grows from the embryo and encloses waste products.

Identify the Extraembryonic Membrane That Stores Waste Products

Recall what you know about each membrane's function. In this case, the allantois is the membrane that serves as a repository for waste products, including nitrogenous wastes and carbon dioxide, produced by the developing embryo.

Provide the Correct Answer to the Question

Since the allantois is the embryonic membrane that is responsible for storing waste products, C is the correct answer to the question.

Key concepts

Understanding Extraembryonic Membranes

Extraembryonic membranes are crucial structures that support the development of many vertebrates, including birds, reptiles, and mammals, during gestation. These membranes form outside the embryo but play an integral role in protecting and nourishing it.

• The chorion participates in gas exchange between the embryo and the external environment.
• The amnion creates a fluid-filled cavity serving as a cushion for the embryo, providing shock absorption.
• The yolk sac contains nutrients that support the embryo in its early stages of development.
• The allantois is involved in waste storage and also aids respiration, similar to the chorion.

These structures ensure the embryo develops safely, maintaining a suitable environment until it is ready to survive independently.

The Role of the Chorion

The chorion is one of the most important extraembryonic membranes, as it facilitates crucial exchanges between the embryo and its surroundings. Found in many vertebrates, the chorion primarily aids in gas exchange, an essential process for developing embryos. While it does not directly provide nutrients or store waste, the chorion allows for the diffusion of oxygen into the embryo and the release of carbon dioxide, an essential function for the embryo's survival. Additionally, in mammals, the chorion contributes to the development of the placenta, a vital organ that further takes on roles of nutrient and waste exchange, demonstrating the chorion's adaptability across different species.

Allantois and Waste Management

In the intricate system of extraembryonic membranes, the allantois plays a key role in managing the embryo's waste. Known as a membranous sac that emerges from the rear end of the embryo, it efficiently stores metabolic wastes, primarily nitrogen-based ones like uric acid, produced throughout embryonic development. This storage function is particularly important in species where an enclosed egg environment limits the direct expulsion of waste materials. As the embryo grows, the allantois also extends to facilitate gas exchange by interacting with the chorion, further contributing to the embryo's respiratory needs. In placental mammals, components of the allantois even assist in forming the umbilical cord, a critical connection between the mother and the developing fetus, illustrating its multifaceted importance.

Key Aspects of Embryo Development

Embryo development is a complex and astonishing process that transforms a single cell into a fully functional organism. Throughout this journey, extraembryonic membranes like the chorion and allantois play supportive and protective roles. Key stages include:

• Cleavage: Rapid division of cells after fertilization, forming a multicellular structure.
• Blastula Formation: Cells reorganize into a hollow ball, marking the start of differentiation.
• Gastrulation: Cells further differentiate into three layers, setting the stage for organ development.
• Organogenesis: Cells continue to specialize, forming vital organs and structures.

Throughout these stages, the interaction with extraembryonic membranes ensures that the embryo receives the right nutrients, protection, and waste management, leading it to grow healthily and prepare for life beyond the egg or womb.