Plant Classification: Thallophyta

Plant Classification: Thallophyta

• Thallophytes lack differentiated plant bodies (roots, stems, leaves).
• Examples include algae, fungi, lichens and bacteria.
• Their body is called a thallus.
• They lack vascular systems (xylem and phloem).
• They do not form embryos.

Algae

• They are green thallophytes containing chlorophyll, although other pigments can mask this color, leading to blue-green, brown, or red algae.
• They are autotrophic, meaning they produce their own food using chlorophyll.
• Their cell walls are made of cellulose.
• Algae are mostly aquatic, but some grow on trees, rocks, or moist soil.
• They can be unicellular or multicellular.
• Multicellular forms often resemble ribbons.
• Examples include Chlamydomonas (unicellular) and Ulothrix (multicellular).

Alginic Acid

• Brown seaweeds like Macrocystis, Ascophyllum, and Laminaria are used to produce alginic acid.
• It is a naturally occurring, edible polysaccharide found in brown algae.
• Alginic acid is hydrophilic, meaning it absorbs water readily and forms a viscous gum when hydrated.
• Its salts with metals like sodium and calcium are called alginates.

Uses of Alginic Acid

• Food industry: Thickener for drinks, ice cream, and cosmetics; gelling agent for jellies (E401).
• Textiles and paper: Used in manufacturing.
• Pharmaceutical preparations: Antacids to prevent gastroesophageal reflux.
• Dentistry: Impression-making material and wound dressings.

Red Algae (Rhodophyta)

• Red algae are characterized by the presence of phycoerythrin, a red pigment.
• Phycoerythrin absorbs green, yellow, and red light, which penetrate deep into seawater.
• This allows red seaweed to survive in low-light conditions.
• The red pigment absorbs light, but chlorophyll is still needed for photosynthesis.
• Phycoerythrin is a food dye and medical marker.
• Red algae store floridean starch and amylopectin, which stain red with iodine.

Gelidium

• Gelidium is a red algae species.
• It is a source of agar or agar-agar, a polysaccharide extracted from dried Gelidium species.

Benefits of Algae

• Contains bioactive compounds with antioxidative, anti-inflammatory, and anticancer properties.
• Sources include agar and alginic acid.
• Used as demulcents and nutritives due to their mucilage content.

This quiz covers the classification of Thallophyta, including the attributes and examples of algae, fungi, and other thallophytes. Learn about their unique characteristics such as lack of vascular systems and differentiated bodies. Test your knowledge on the formation and significance of alginic acid from brown algae.