Question

Agar -agar, a mucilaginous substance occur in the cell wall of
A. Laminaria and Ascophyllum
B. Nostoc and Anabaena
C. Fucus and Rhodymenia
D. Gelidium and Gracilaria

Answer 1

Hint:-The cell wall is a protective structure around the cell. It helps to restrict high temperatures, chemical substances & to protect against mechanical stress from cells. Cell walls generally present in the plant cells and absent in the animal cells. Some of the prokaryotic organisms have a cell wall around its body. But the composition of the cell wall varies from one organism to other organisms.

Complete solution:
● Laminaria and Ascophyllum belong to the alga of Phaeophyceae.
● These are primarily marine habitats. The cell wall is generally made up of cellulose and align.
● It contains chlorophyll A,C, carotenoids and xanthophyll.
● Stored food materials are mannitol.
● Nostoc and Anabaena are eubacteria true bacteria that are characterized by the presence of a rigid cell wall.
● These refer to the” blue-green algae or cyanobacteria”. It has chlorophyll similar to higher plants generally present in polluted water bodies.
● They are heterotrophic organisms. Surrounded by a mucilaginous sheath.
● Fucus and Rhodymenia belong to the Phaeophyceae. They have 2 unequal flagella; they are in lateral position.
● Gelidium and Gracilaria belong to the Rhodophyceae commonly called red algae.
● It has chlorophyll A,D, and phycoerythrin.
● Stored food materials are Floridian starch.
● A cell wall composed of cellulose, pectin, and polysulphate esters ( agar e t.c.).
So, the correct answer is option D.

Note:- Gelidium and Gracilaria are red algae and are marine habitats .They don't have flagella. The red thalli of most red algae are multicellular. Stored food materials are Floridian starch composed of amylopectin and glycogen. Reproduce asexually by non-motile spore & sexually by motile spores.