Problem 43 - Objective Biology for NEET

Question

Which of the following has a closed blood vascular system? (a) Cockroach (b) Hydra (c) Sponge (d) Earthworm

Step-by-Step Solution

Answer

The Earthworm (Option D) has a closed blood vascular system.

Step 1: Examine Option A: Cockroach

Cockroaches do not have a closed blood vascular system. They have an open system where the blood, or hemolymph, fills up their body cavity.

Step 2: Examine Option B: Hydra

Hydras are simple multicellular organisms and their body systems are also simple. They do not have a circulatory system at all.

Step 3: Examine Option C: Sponge

Sponges are another type of simple multicellular organisms. They also lack a circulatory system.

Step 4: Examine Option D: Earthworm

Earthworms have a closed blood vascular system. Blood in earthworms is always contained within vessels.

Key Concepts

Circulatory System

Understanding the circulatory system is fundamental in comprehending how multicellular organisms, including humans, function. This system, often synonymous with the cardiovascular system, is responsible for transporting nutrients, gases, hormones, and waste products throughout the body.

At the heart of this system is the heart itself, which acts as a powerful pump, pushing blood through a vast network of vessels. These vessels come in three main varieties: arteries, which carry blood away from the heart; veins, which return blood to the heart; and capillaries, the tiny bridges between arteries and veins where exchanges with body tissues take place.

In organisms with a closed blood vascular system, the blood circulates within vessels, ensuring efficient delivery of oxygen and nutrients to tissues, and removal of carbon dioxide and wastes. This contrasts with an open circulatory system, where the fluid (hemolymph) bathes the organs directly. A closed system offers greater control over the distribution of blood and is found in more complex organisms, such as vertebrates and some invertebrates—like the earthworm from our exercise.

Biology NEET Exam

The biology portion of the NEET (National Eligibility cum Entrance Test) is a significant hurdle for students aspiring to enter medical fields in India. Test preparation requires a deep understanding of concepts like the circulatory system and categorization of organisms based on their physiological traits, like the presence or absence of a circulatory system.

Candidates are tested on their knowledge about the complexities of animal and plant anatomy, physiology, and the relationships between different life forms. Questions similar to the exercise about vascular systems are common, and it is crucial for students to not just memorize facts but to truly understand the characteristics that differentiate one organism from another. This will enable them to apply their knowledge and reasoning skills successfully when faced with multiple-choice questions during the exam.

Multicellular Organisms

Multicellular organisms are composed of more than one cell, exhibiting a division of labor among specialized cells, tissues, and organs. This enables these organisms to perform complex functions. For instance, sponges, while multicellular, have a relatively simple organization and do not possess a circulatory system. In contrast, multicellular organisms like earthworms have evolved more complex structures, such as a closed blood vascular system, to support their life processes.

A closed circulatory system allows these more complex multicellular organisms to maintain a higher metabolic rate and sustain active lifestyles. As students of biology, understanding the relationship between the complexity of an organism and its physiological systems is pivotal. It demonstrates the evolutionary advancements that allow organisms to occupy various environmental niches and adapt to different challenges for survival.