Question

Differentiate between red algae and brown algae.

Answer 1

Hint: Algae are chlorophyll bearing plants belonging to the plant kingdom. The algae are further subdivided into three classes- green algae, red algae, and brown algae. Algae are classified into three groups based on the pigments they contain. They are also differentiated on the basis of the food they store.

Complete answer:

Red algae	Brown algae
Some red algae are found in freshwater, brackish water, and mostly in saltwater.	Brown algae are found in freshwater (rarely), brackish water, and saltwater.
They contain the photosynthetic pigment chlorophyll a, d, and phycoerythrin.	They contain the photosynthetic pigment chlorophyll a, c, and fucoxanthin.
Stored food in them is floridean starch.	Stored in food in them is mannitol or laminarin.
They are grouped under the Rhodophyceae class of algae.	They are grouped under the Phaeophyceae class of algae.
Flagella are absent in them.	Two unequal, lateral flagella are present in them.
They have a cell wall made of cellulose, pectin, and poly sulfate esters.	They have a cell wall made of cellulose and align.

Additional Information: -Floridean starch which is then stored in red algae has a structure similar to amylopectin and glycogen.
-In brown algae, asexual reproduction mostly occurs through motile, pear-shaped biflagellate zoospores that are having two unequal flagella that are attached laterally. While in the case of Red algae, the asexual reproduction occurs via non-motile spores.
-Sexual reproduction in brown algae may be isogamous, anisogamous, or oogamous. The gametes are pyriform (pear-shaped), the union of gametes may take place in water or within oogonium. Sexual reproduction in red algae is oogamous and is accompanied by post-fertilization events.

Note: Brown algae are represented by Ectocarpus, Dictyota, Laminaria, Sargassum, and Fucus. Red algae are represented by Polysiphonia, Porphyra, Gracilaria, and Gelidium. Gelidium and Gracilaria are used to grow microbes and prepare ice creams. Many species of marine algae are used as sources of food. Algae fix approximately half of the total carbon dioxide on earth.