Question

Which of the following is absent in the coelomic fluid of earthworm? (a) Salts (b) Haemoglobin (c) Corpuscles (d) Proteins

Short answer

Corpuscles are present in coelomic fluid, therefore the correct answer is (c) Corpuscles, as it is not absent.

Step-by-step solution

Understanding the question

The exercise requires knowledge of what is present in the coelomic fluid of an earthworm. Coelomic fluid is the fluid found within the coelom, the body cavity of earthworms. It is known to contain several components essential for the worm's physiology.

Researching necessary biology

To solve this question, look for information on the composition of the coelomic fluid in earthworms. It's important to understand that earthworms have a closed circulatory system where haemoglobin is dissolved in the plasma of the blood and coelomic fluid. The fluid also contains salts and proteins that are crucial for various biological functions. Additionally, the coelomic fluid contains amoeboid cells, sometimes called corpuscles, which help in the transportation of nutrients and waste materials.

Identify the correct option

Using the information from biology research, each option can be evaluated for its presence in the coelomic fluid of an earthworm. (a) Salts, (b) Haemoglobin, and (d) Proteins are present. Corpuscles or amoeboid cells are also present in coelomic fluid as part of the immune response and in transporting nutrients and waste, so option (c) is incorrect because it is not absent.

Key concepts

Closed Circulatory System

Earthworms are fascinating creatures, not least because of their efficient closed circulatory system. Unlike humans, earthworms do not have a heart with chambers to pump blood. Instead, they have a series of muscular vessels known as aortic arches, often referred to as 'hearts', that contract to push blood through their body.

Within this closed system, the blood is confined to blood vessels and doesn't fill body cavities, as seen in organisms with an open circulatory system. It's an elaborate network of tubes that ensure all cells have a steady supply of nutrients and oxygen. The blood contains haemoglobin, the same oxygen-carrying protein found in our own red blood cells, but it's dissolved in the plasma rather than packed into cells.

The efficiency of this system allows the earthworm to thrive in various environments, responding adequately to the metabolic demands of its elongated body. It's a clear example of how a seemingly simplistic organism can have a remarkably sophisticated biological system.

Earthworm Physiology

Diving deeper into earthworm physiology, you'll discover that these invertebrates are tube-shaped, segmented animals that have a body plan internally and externally divided into segments. This segmentation plays a crucial role in both their mobility and physiology.

At the forefront of their physiology is the coelomic cavity, which is filled with coelomic fluid. This fluid is essential, acting as a hydrostatic skeleton to maintain the worm's structure and enable movement through muscle contractions. The coelomic fluid is also a medium for the transport of gases, nutrients, and waste products.

Furthermore, within this fluid are amoeboid cells or corpuscles that play defensive roles in the worm's immune response. They help deal with infections and repair damaged tissues. It’s a testament to the earthworm's robust biology that enables it to survive and efficiently use the nutrients from their surroundings, despite lacking complex organs found in higher animals.

Biological Functions

The biological functions of coelomic fluid in earthworms are extensive and vital for their survival. First and foremost, the fluid serves as a means of transporting oxygen and nutrients throughout the body. As previously mentioned, the fluid contains haemoglobin, which binds to oxygen molecules and shuttles them to where they're needed.

In addition to transport, the coelomic fluid has a pivotal role in the earthworm's immune system. The amoeboid corpuscles within the fluid can engulf and digest pathogens through a process called phagocytosis, keeping the worm healthy. The salts and proteins present in the coelomic fluid contribute to osmoregulation and enzyme functions, which are fundamental to maintaining cellular homeostasis.

Nutrient transportation, waste removal, defense against pathogens, and osmoregulatory balance are just a few of the fluid's crucial roles. In essence, the coelomic fluid is a dynamic solution full of life-supporting components that underscore the complexity and elegance of earthworm physiology.