Problem 154 - Objective Biology for NEET

Question

Animal belonging to phylum chordata shows (a) Bilateral symmetry, triploblastic and the coelom (b) Organ system level of organization (c) Closed circulatory system (d) All of these

Step-by-Step Solution

Answer

The correct answer is (d) All of these.

Step 1: Recognize Biological Characteristics

Bilateral symmetry is a basic body plan in which the left and right sides of the organism can be divided into approximate mirror images of each other along the midline. Triploblastic is a condition where an organism's body structure has three basic layers of tissues, namely the ectoderm, endoderm and mesoderm. A Coelom is a cavity lined by an epithelium derived from mesoderm, and they exist in several forms among different groups of animals.

Step 2: Understanding Organ Level System of Organization

Organ system level of organization refers to a form where organs work together as part of a system. In chordates, organs are grouped into organ systems such as the digestive system, the respiratory system and the reproductive system with each serving a particular function.

Step 3: Understanding the Closed Circulatory System

A closed circulatory system is a system in which blood is enclosed within blood vessels and is distinct from the body's interstitial fluid. Chordates typically have a closed circulatory system.

Step 4: Decision Making

Now that we have discussed all the given characteristics, it is clear that animals belonging to phylum chordata show all of them: bilateral symmetry, triploblastic and coelom, organ system level of organization, and closed circulatory system. Therefore, the correct answer is 'All of these'.

Key Concepts

Bilateral Symmetry

Bilateral symmetry is a fascinating characteristic found in the animal kingdom, especially predominant in the phylum Chordata. This symmetry layout means that the body can be split into two identical halves along a single plane, usually the sagittal plane. Each half mirrors the other, providing balance and aiding in movement. Some of the advantages of bilateral symmetry include:

• Streamlined movement: The balanced structure allows for efficient swimming, crawling, or walking, depending on the organism.
• Enhanced sensory perception: Organisms have sensory organs on both sides of their body, improving their interaction with the environment.

This trait is common in higher animals, including mammals, birds, and even certain plants and invertebrates.

Triploblastic

The triploblastic trait is related to the development of animals in the embryonic phase. Triploblastic organisms have three primary layers of cells, known as germ layers, which develop into various tissues and organs. These three layers are called:

• Ectoderm: It forms the outermost layer, giving rise to the skin and nervous system.
• Mesoderm: Situated between the ectoderm and endoderm, it forms muscles, the circulatory system, bones, and more.
• Endoderm: This forms the innermost layer, responsible for developing into the gastrointestinal tract, lungs, liver, and several other organs.

Such a body plan enables greater complexity in body structure and organization, setting the foundation for advanced physiological functions.

Closed Circulatory System

A closed circulatory system is a highly efficient method of transporting nutrients, gases, and wastes throughout the body. In this system, blood travels through a network of vessels distinct from other body liquids. Key features include:

• Blood Vessels: Arteries, veins, and capillaries direct the flow of blood, ensuring efficient nutrient delivery.
• Cardiac Pump: The heart acts as the central pump, maintaining blood movement and pressure.
• Regulation: Allows for better regulation of blood flow and pressure compared to open systems.

In chordates, this system provides increased efficiency for resource transportation and gas exchange, vital for active lifestyles and larger body sizes.

Organ System Level of Organization

The organ system level of organization is a sophisticated structure seen in complex organisms like those in phylum Chordata. It involves the interaction of multiple organs, each performing different roles, but collectively working towards a common goal. Here are a few examples:

• Digestive System: Breaks down food into nutrients, a process involving organs such as the stomach and intestines.
• Respiratory System: Consists of parts like lungs or gills, facilitating the exchange of gases and supplying oxygen to the body.
• Reproductive System: Engaged in producing offspring, including organs like ovaries and testes.

These systems are more than just the sum of their parts, working in harmony to sustain life and enable adaptation to diverse environments.

Coelom

A coelom refers to a fluid-filled cavity found within the bodies of many animals, situated between the digestive tract and the outer body wall. It is lined entirely with mesoderm tissue, which is crucial for the development of complex body structures. The presence of a coelom has numerous advantages:

• Protection: Provides a cushion for internal organs, safeguarding them against shocks and injuries.
• Facilitates Growth and Development: Allows for the development of complex organs and organ systems by providing space and support.
• Movement: Supports muscle movement and structure by acting as a hydrostatic skeleton in some animals.

In chordates, this trait is crucial for efficient functioning of organs and enhancing overall body plan complexity, allowing greater adaptability.