CBSE Questions for Class 11 Medical Biology Plant Kingdom Quiz 1 - MCQExams.com

Coenocytic cells are present in diverse and unrelated groups of algae, including Xanthophyceae, e.g., Vaucheria and red algae, Griffithsia and green algae. A coenocyte is a multinucleate cell, which can result from multiple nuclear divisions without their accompanying cytokinesis. Thus, the correct answer is option A.

A. Correct option A

B. Explanation for correct option:

When the zygote divides meiotically or when zygote undergoes reduction division after division of nucleus i.e. after karyogamy it is called as zygotic meiosis. Zygote is a stage that is formed after fertilization.Chlamydomonas is haploid plant. Hence, zygotic meiosis occurs in chlamydomonas.

Agar is derived from polysaccharide agarose present in specific species of algae. These algae are known as agarophytes and belong to phylum Rhodophyta. It is a red algae. The nature of agar is gelatinous. The gelling agent in agar is an unbranched polysaccharide obtained from the cell walls of some species of red algae, primarily from the genera Gelidium and Gracilaria. For commercial purposes, it is derived primarily from Gelidium amansii. In chemical terms, agar is a polymer made up of subunits of the sugar galactose. Thus, the correct answer is option B.

• Chondrus crispus commonly called Irish moss or carrageen moss is a species of red algae that grows abundantly along with the rocky parts of the Atlantic coast of Europe and North America.   
• Irish moss can work wonders for congestion and mucous and holds anti-bacterial and anti-viral properties.
• So, the correct answer is "Chondrus'.

Correct Option: D

Explanation:

• According to Merriam Webster dictionary, a living fossil is defined as, “an organism that has remained essentially unchanged from earlier geologic times and whose close relatives are usually extinct.”
• In terms of evolution, gymnosperms are slightly more primitive than angiosperms. The majority of gymnosperm species have gone extinct, leaving only 900 species alive today.
• Cycas is considered a living fossil since it has not changed through time, whereas its related members or species have gone extinct or have been found in the form of fossils.

Hence, Cycas is termed as "living fossil" as they live as the undamaged representative of an extinct group, genus, or species.

It was F. E. Fritsch, who proposed the classification of algae that they should not be divided into phyta, i.e., divisions but only into classes. According to him, algae were classified into following eleven classes based on structure and reproduction of the algae (on basis of pigmentation, reserve food and flagellation, thallus structure, modes of reproduction and life cycles). He is well known as the Father of Phycology. 

Correct option: D

Explanation:

Agar-agar is a gelling agent with unbranched polysaccharides and is used in microbiology as a solidifying agent of liquid culture mediums. It is extracted from the cell wall of red algae, mostly from Gelidium, Gracilaria, and Gigartina species. 

• Angiosperms are the most diverse group of plants. Angiosperms are a group of plants with seeds that develop within an ovary. Hence, the seeds are said to be covered.
• Algae, bryophytes, and pteridophytes do not have seeds.

Algae are eukaryotic organisms that have importance in our ecosystem as primary producers. The study of algae is called as algalogy or phycology. The term phykos means algae or in general seaweed. Several prokaryotic forms of algae such as blue-green algae, cyanobacteria, microscopic algae, their evolution, taxonomy etc., are studied by phycologists.

$$\textbf{Correct option: D}$$

$$\textbf{Solution:}$$

Option A:

$$\bullet$$ Bryophyta plants are non-vascular plants i.e. they lack the vascular tissue.

$$\bullet$$ Thus, they do not have xylem vessels.

Option B:

$$\bullet$$ Pteridophytes contain both xylem and phloem vascular tissues but these are not well-developed because the xylem tissue lacks xylem vessels and phloem tissue lacks sieve tubes.

Option C:

$$\bullet$$ Both bryophytes and pteridophytes lack xylem vessels.

Option D:

$$\bullet$$ Angiosperms are the plants having well-developed xylem and phloem. 

$$\bullet$$ The xylem tissue of angiosperms has all components like xylem vessels, xylem tracheids, xylem fibers and xylem parenchyma. Similarly, the phloem tissue has sieve tubes, companion cells, phloem parenchyma and phloem fibers.

Hence the correct option is option D.

• In algae, sex organs are one-celled and not covered by a sterile jacket (naked), whereas in bryophytes sex organs are multicellular and covered. 
• Bryophytes are called amphibians of the plant kingdom. 
• Zygote is liberated from plants in the case of algae, whereas in bryophytes zygote remain enclosed in archegonium.