Problem 4 - Campbell Biology

Question

Knowledge/Comprehension What structural adaptation in chickens allows them to lay their eggs in arid environments rather than in water? (A) extraembryonic membranes (B) yolk (C) cleavage (D) gastrulation

Step-by-Step Solution

Answer

The correct answer is (A) extraembryonic membranes.

Step 1: Understand the Question

The question is asking which structural adaptation in chickens enables them to lay eggs in dry environments instead of water. Carefully consider each option and how it relates to egg-laying in arid conditions.

Step 2: Evaluate Option (A) extraembryonic membranes

Extraembryonic membranes, such as the amnion, chorion, allantois, and yolk sac, are adaptations in the eggs of birds and reptiles, allowing embryos to develop in a terrestrial environment by providing protection, waste removal, and nutrient supply.

Step 3: Evaluate Option (B) yolk

The yolk is the nutrient-rich part of the egg that feeds the growing embryo. While essential, it does not relate to adaptation for laying eggs in an arid environment.

Step 4: Evaluate Option (C) cleavage

Cleavage is the early division of cells in the embryo, which occurs after fertilization. This process is crucial for development but does not affect where eggs can be laid.

Step 5: Evaluate Option (D) gastrulation

Gastrulation is the phase during embryonic development where cells reorganize into layers. Like cleavage, this is a developmental process and not related to the environmental conditions of egg-laying.

Step 6: Identify the Correct Answer

Based on the evaluations, extraembryonic membranes are the structural adaptation that allows chickens to lay eggs in arid environments by providing necessary support and protection.

Key Concepts

Extraembryonic Membranes

Extraembryonic membranes are vital structures that form around the embryo during development. These include the amnion, chorion, allantois, and yolk sac. Together, they provide protection, facilitate gas exchange, remove waste, and supply nutrients. The amnion creates a fluid-filled cavity that cushions the embryo. The chorion aids in gas exchange with the external environment. The allantois stores waste and also contributes to gas exchange, while the yolk sac supplies essential nutrients. These membranes work collectively to ensure the developing embryo thrives, even in harsh conditions like arid environments.

Avian Reproduction

Avian reproduction involves the laying of eggs outside the mother's body, a process known as oviparity. Birds have adapted to this reproductive strategy through various mechanisms. The hard, calcified shell of the egg protects the developing embryo from physical damage and dehydration. Additionally, the presence of extraembryonic membranes ensures the embryo receives adequate nutrition, breathes properly, and can excrete waste. This adaptation allows birds to inhabit a range of environments, including those where water might be scarce.

Egg-Laying in Arid Environments

Egg-laying in arid environments presents unique challenges, primarily related to water conservation and temperature regulation. Chickens and other birds have evolved to lay eggs with structural features that address these challenges. The hard shell of the egg minimizes water loss, while the extraembryonic membranes manage the exchange and storage of gases, nutrients, and waste. This setup allows birds to successfully reproduce in environments where standing water is limited or absent. The development of these specialized eggs provides a significant advantage in arid habitats, ensuring the survival and continuation of the species.