Problem 38 - Objective Biology for NEET

Question

Which of the following represent prokaryotic cell? (a) Blue-green algae (b) PPLO (c) Bacteria (d) All of these

Step-by-Step Solution

Answer

All of these (Blue-Green Algae, PPLO, and Bacteria) represent prokaryotic cells.

Step 1: Research about Blue-Green Algae

Blue-green algae, also known as Cyanobacteria, are a group of photosynthetic bacteria that many mistake for algae. They are prokaryotic and thus belong to the bacterial domain.

Step 2: Understand PPLO

Pleuropneumonia-like organisms (PPLO), also known as Mycoplasma, lack a cell wall and can vary in shape. They are known as the smallest living cells and can survive without oxygen, making them prokaryotic.

Step 3: Recognize Bacteria

Bacteria are the most well-known prokaryotic organism. They are single-celled organisms without a nucleus and are found in various shapes like rods, spirals, and spheres.

Step 4: Combine Findings

Upon examining each option, it is found that all the given organisms, i.e., Blue-Green Algae, PPLO, and Bacteria, are prokaryotic. Hence, all of the options represent a prokaryotic cell.

Key Concepts

Cyanobacteria: The Photosynthetic Innovators

Cyanobacteria, often referred to as blue-green algae, are a remarkable group of prokaryotic organisms.
Contrary to their name, they are not algae but rather a type of photosynthetic bacteria.
They played a crucial role in the Earth's history by contributing to the development of the planet's oxygen-rich atmosphere. Through the process of photosynthesis, cyanobacteria convert sunlight into energy, releasing oxygen as a byproduct.
Their ability to perform photosynthesis is due to the presence of chlorophyll, much like plants. Despite being simple in structure, having no nucleus or membrane-bound organelles, cyanobacteria are incredibly diverse.
They thrive in various environments, from marine ecosystems to freshwaters and even terrestrial habitats. Their adaptability makes them a fascinating subject of study in understanding the evolution and functioning of prokaryotic life on Earth.

Mycoplasma: The Minimalist Microbe

Mycoplasma, also known as Pleuropneumonia-like organisms (PPLO), hold the title of the smallest prokaryotes known to science.
Unlike other bacteria, Mycoplasmas lack a cell wall, making them exceptionally flexible and capable of taking on different shapes. This lack of a cell wall also sets them apart from many antibiotics that target cell wall synthesis. As a result, infections by Mycoplasmas can be challenging to treat and often require alternative approaches.
These organisms thrive in environments where they can avoid being eradicated easily, such as in the animal host environment. Despite their minimalistic structure, Mycoplasmas have developed ways to survive and adapt to various conditions, living as parasites or commensals on mucosal surfaces.
They are fascinating examples of how life can thrive with reduced structural components, providing insights into the essentials of cellular life.

Bacteria: The Ubiquitous Single-Celled Wonders

Bacteria are perhaps the most famous prokaryotic organisms, known for their incredible diversity and presence in almost every environment on Earth.
These single-celled organisms lack a true nucleus, having their genetic material float freely within the cell. Bacteria come in various shapes, such as rod-like bacilli, spherical cocci, and spiral-shaped spirilla.
They play a vital role in ecological systems, breaking down organic matter and recycling nutrients. Bacteria can be found in soil, water, and even in extreme environments such as hot springs and deep ocean vents.

• Many bacteria are beneficial, assisting in digestion and protecting against harmful pathogens.
• Some bacteria, however, are pathogenic and can cause diseases.

The study of bacteria has led to significant advancements in medicine, biotechnology, and our understanding of life itself.
Bacteria's ability to adapt and evolve rapidly makes them key subjects in evolutionary studies and an important part of the microbial world.