Problem 99 - Objective Biology for NEET

Question

Which of the following organisms have cell wall made up of cellulose, galactans, mannans, and minerals like calcium carbonates? (a) Fungi (b) Plants (c) Algae (d) All of these

Step-by-Step Solution

Answer

The correct answer is (c) Algae.

Step 1: Identification of Cell Wall Components

First, identify and recognize the components mentioned in the question. These are cellulose, galactans, mannans, and minerals like calcium carbonates. It's important to know that these elements are part of certain cell walls.

Step 2: Match Components with Organisms

Next, it's necessary to match these components with the organisms they can be found in. Cellulose is a component mainly found in plant cells. However, some marine species of Algae also have these components along with the minerals like calcium carbonates. Fungi, however, have a different component called chitin in their cell walls, not cellulose, galactans, or mannans.

Step 3: Conclude Based on the Information

Based on the information about cell wall components, it is clear that only Plants and some species of Algae have cell walls made up of cellulose, galactans, mannans, and minerals like calcium carbonates.

Key Concepts

Cellulose

Cellulose is a crucial component in the structure of many living organisms' cell walls. It is an organic compound and polysaccharide consisting of linear chains containing glucose molecules linked together.
Cellulose is notable for its abundance, being an essential structural material across the natural world, especially in plants.
In plants, cellulose provides rigidity and strength, contributing to the mechanical integrity of the plant tissue. As part of the cell wall, it helps maintain the plant's shape and protects the internal cellular components from potential damage. The presence of cellulose also plays a significant role in a plant's ability to grow tall and withstand various environmental stresses.

• Cellulose fibers are highly resistant to tensile stress.
• They organize into thicker structures known as microfibrils, which enhance the durability of the cell wall.

Beyond plants, other organisms can also incorporate cellulose in their cell walls, most notably some types of algae, underscoring its importance in nature's design.

Algae

Algae are diverse aquatic organisms capable of photosynthesis, similar to plants. They range from simple, single-celled organisms to complex multicellular forms such as seaweeds.
One of the fascinating aspects of algae is their ability to assimilate a variety of compounds into their cell walls, particularly in marine environments. Some species of algae have cell walls that are uniquely adapted, containing mixtures of cellulose, galactans, mannans, and minerals such as calcium carbonate.
These components play distinct roles in providing structural support and protection:

• Cellulose: Contributes to basic structural integrity.
• Galactans and Mannans: Add flexibility and modulation to the cell wall composition.
• Calcium Carbonate: Offers additional rigidity and protection, especially in species residing in harsh marine settings.

The adaptability of algae's cell walls is a critical factor for their survival, enabling them to thrive across a vast array of aquatic environments.

Calcium Carbonate

Calcium carbonate is a common substance found naturally in rocks and is also a critical component of certain organisms, offering increased durability to cell walls.
In the context of biological systems, it is often associated with marine organisms such as coral and shellfish. Interestingly, some species of algae also integrate calcium carbonate into their cell walls.
This mineral serves a dual purpose:

• Firstly, it enhances the rigidity of the cell wall, providing necessary support and protection.
• Secondly, it helps them withstand the abrasive nature and chemical conditions of their marine habitats.

The presence of calcium carbonate in algae's cell walls is one of nature's many strategies to enhance survival and maintain ecological balance in marine ecosystems. This composition allows organisms to adapt efficiently, demonstrating nature's ingenious use of materials for life sustainability.