Multiple Choice Questions (MCQs): Algae - Grade 11 MCQ

The gelling agent in agar is an unbranched polysaccharide obtained from the cell walls of some species of red algae, primarily from tengusa (Gelidiaceae) and ogonori (Gracilaria). ... In chemical terms, agar is a polymer made up of subunits of the sugar galactose.

Topic in NCERT: Algae and their commercial uses

Line in NCERT: "agar, one of the commercial products obtained from gelidium and gracilaria are used to grow microbes and in preparations of ice-creams and jellies."

• Most of the algae reproduce using spore formation.
• Asexual spores are called as zoo-spores and the reproductive part in algae is called zoosporangium.
• Under favourable conditions, these organisms germinate to form new organism.
• Zoo-spores are motile and flagellated.

Topic in NCERT: Algae

Line in NCERT: "they are flagellated (motile) and on germination gives rise to new plants."

Red algae (Rhodophyceae) contain Chl a and d and main pigment is Phycoerythrin . Red algae are red due to Phycoerythrin.it helps in photosynthesis in great depth in ocean and also on surface of water.

Topic in NCERT: Rhodophyceae

Line in NCERT: "the members of rhodophyceae are commonly called red algae because of the predominance of the red pigment, r-phycoerythrin in their body."

The term thallus is a botanical term that refers to the body of a plant that does not have leaves, stems and roots. In botany, historically, this term has been applied to algae, fungi and the various divisions of bryophytes.

Topic in NCERT: Algae reproduction

Line in NCERT: "each fragment develops into a thallus."

Classification of algae is mainly based upon the nature of their pigments.
Red Algae (Rhodophyceae) are characterized by the pigments - Phycoerythrin and Phycocyanin.
Brown Algae (Phaeophyceae) are brown due to the pigment Fucoxanthin.
Green Algae (Chlorophyceae) are characterized by pigments Chlorophyll-a, b, Carotenes, Xanthophyll. Hence option C is correct.

Topic in NCERT: Algae classification

Line in NCERT: "pigment possesed and the type of stored food, algae are classfied into three classes, namely chlorophyceae, phaeophyceae and rhodophyceae."

It Is cycas besides paddy fields it also found in vegetative part of cycas ..And being a cyanobacteria it acts as a symbiont and readily perform activity of nitrogen fixation so cycad is more correct answer.

Correct option is D. Fucus
 Fucus are brown algae which is found in the intertidal zones of rocky seashores. These algae belong to the class Phaeophyceae and order Fucales, which stored food in the form of laminarin, mannitol, and oil. Mannitol is stored as a food reserve in Fucus. They are common littoral seaweed growing in the hard-rocky areas of the sea.

• The vegetative cells in Phaecophyceae are made up of two layers with the inner one being made of cellulose and the other being made of gelatinous coating of algin.
• A leaf like photosynthetic organ in Phaecophyceae is called as frond.
• They also have a stalk called stipe and a substratum called as holdfast.

Topic in NCERT: Algae

Line in NCERT: "the plant body is usually attached to the substratum by a holdfast, and has a stalk, the stipe and leaf like photosynthetic organ - the frond."

Starch is stored in plants as food reserve. Starch is present in two forms- Amylose- which is linear chain of glucose and Amylopectin is a branched chain polymer of glucose Algae are chlorophyll-bearing, simple, thalloid, autotrophic and largely aquatic (both. fresh water and marine) organisms. They occur in a variety of other habitats: moist stones, soils and wood. Some of them also occur in association with fungi (lichen) and animals.

Topic in NCERT: Rhodophyceae

Line in NCERT: "the food is stored as floridean starch which is very similar to amylopectin and glycogen in structure."

The vegetative cells of brown algae are primarily composed of cellulose, which provides structural support.