Question

The skin of frog does not contain (a) cutaneous gland (b) lymph spaces (c) mucous glands (d) scales.

Short answer

The skin of a frog does not contain (d) scales.

Step-by-step solution

Background information on frog's skin

Understand the characteristics of a frog's skin. Frogs have permeable skin that is crucial for their respiratory process. It has various glands that serve different purposes.

Identifying the characteristics

Identify what structures are present in the skin of a frog. Frog skin typically has cutaneous glands and mucous glands. The cutaneous glands help keep the skin moist, which is vital for gas exchange and protection against pathogens. Mucous glands also aid in keeping the skin slimy to prevent drying out.

Eliminating incorrect options

Since options (a) Cutaneous gland and (c) Mucous glands are present in frog's skin, they can be eliminated. Lymph spaces are part of the frog's immune system and are also present. This leaves us with option (d) Scales, which are not present in the frog's skin as frogs do not have scales.

Concluding the correct answer

Based on the anatomical structure of a frog's skin, the correct answer to the given question is (d) Scales, as frogs do not have scales on their skin.

Key concepts

Cutaneous Glands

Frog skin is remarkable in its ability to serve multiple physiological functions. One of the most significant features of their skin is the presence of cutaneous glands. These glands are essential for maintaining a moist skin surface, which is critical for amphibians. The amphibian lifestyle is closely tied to water, and the cutaneous glands help them by secreting a mixture of mucous and serous (proteinaceous) fluids. This moisture serves two main purposes: it aids in respiration and provides protection.

The mucous secreted keeps the skin slippery, helping frogs avoid predators while also making it hard for potential pathogens to get a foothold. These secretions also have antimicrobial properties, which protect frogs against harmful microbes. Additionally, the moisture from cutaneous glands facilitates cutaneous respiration - the process by which frogs can absorb oxygen directly through their skin in water or damp environments. Understanding the role of these glands is crucial for comprehending how frogs interact with their environment and stay healthy.

Respiratory Process in Frogs

Frogs possess a versatile respiratory system, allowing them to live both in water and on land. This adaptability is thanks to several mechanisms for oxygen uptake, including their skin. Respiration through the skin, or cutaneous respiration, plays a significant part in a frog's ability to breathe. The moist skin of a frog, facilitated by the secretion from cutaneous glands, is permeable to gases.

In water, frogs can absorb dissolved oxygen directly through their skin. On land, although they rely more on their lungs for gas exchange, cutaneous respiration still provides supplemental oxygen, especially during periods of rest. Besides the direct absorption of oxygen, frogs can also expel carbon dioxide through their skin, making this organ a two-way respiratory channel. The efficiency of this process is greatly affected by environmental conditions such as temperature and humidity, as well as the health of the skin itself.

Anatomical Structure of Frog

The anatomical structure of a frog is uniquely evolved to suit its amphibious life. Frogs have a body plan that is streamlined for efficient movement in water and on land. Their muscular legs enable them to leap great distances and swim, while their skin plays crucial roles in protection, respiration, and water balance.

The skin, besides being respirative, is also part of the immune defense due to the presence of lymph spaces. These spaces are part of the larger lymphatic system, which helps in the regulation of fluids and filters out pathogens. It's noteworthy that while scales are a common feature in many reptiles, the frog's skin is scale-less, smooth, and often vividly colored. This feature can be indicative of their habitat, behaviors, or even potential toxicity. Their skin, coupled with other features like a streamlined body, makes up a complex yet efficient anatomical structure that supports their unique ecological niche.