Algae MCQ Quiz in বাংলা - Objective Question with Answer for Algae - বিনামূল্যে ডাউনলোড করুন [PDF]

The correct answer is All of these

Concept:

• Agar is a gelatinous substance derived from certain types of algae, specifically red algae. It is widely used in various industries for its gelling, thickening, and stabilizing properties.
• The primary sources of agar are the algae species Gelidium and Gracilaria.
• Agar has numerous applications, including microbiological media, food industry, and pharmaceuticals.

Explanation:

• Gelidium: This type of red algae is a significant source of agar. Agar obtained from Gelidium is known for its high-quality gel strength and purity. It is commonly used in microbiological media to grow microbes, as it provides a solid surface for microbial culture.
• Gracilaria: Another important source of agar, Gracilaria is used extensively in the food industry. Agar from Gracilaria is utilized in the preparation of ice cream, as it acts as a stabilizer and thickener, improving texture and preventing the formation of ice crystals.
• Gelidium (again): Besides its use in microbiological media, agar from Gelidium is also used in the preparation of jellies, providing a smooth and firm texture.

Therefore, the correct answer is "All of these" as all the provided options are correct and describe different uses of agar obtained from specific algae.

The correct answer is Trees, shrubs, and herbs

Concept:

• Aristotle, the Greek philosopher, is often credited with creating one of the earliest systems of biological classification.
• He made significant contributions to the classification of living organisms, including plants.
• His system was based on observable characteristics and was used for many centuries.

Explanation:

• Trees, shrubs, and herbs: Aristotle classified plants based on their physical structure and growth habits. Trees were large plants with a single main stem, shrubs were smaller plants with multiple stems, and herbs were small, non-woody plants. This classification was based on the plant’s size and form.
• Flowering & non-flowering plants: This classification is a modern one and was not used by Aristotle. It distinguishes plants based on their ability to produce flowers. Flowering plants (angiosperms) produce flowers, while non-flowering plants (gymnosperms, ferns, mosses) do not.
• Sexually reproducing & asexually reproducing plants: This classification focuses on the mode of reproduction. Sexually reproducing plants reproduce through the fusion of gametes, while asexually reproducing plants can reproduce without gametes. This is a more modern classification and was not used by Aristotle.
• Seed forming & vascular plants: This classification distinguishes between plants that produce seeds and those that have a vascular system. Seed-forming plants include gymnosperms and angiosperms, while vascular plants include ferns and horsetails. This is also a modern classification and was not part of Aristotle's system.

Concept:

• The kingdom Plantae, also known as the plant kingdom, includes all plants which are primarily multicellular, eukaryotic organisms that carry out photosynthesis.
• Plants are distinguished by their ability to produce their food via photosynthesis, which involves the green pigment chlorophyll.
• Though most plants are autotrophic, some plants have evolved to be parasitic or insectivorous.

Explanation:

• Kingdom Plantae includes all prokaryotic & eukaryotic chlorophyll-containing organisms: This statement is incorrect because prokaryotic organisms (like cyanobacteria) are not part of the Plantae kingdom. The Plantae kingdom includes only eukaryotic, chlorophyll-containing organisms.
• Member of kingdom Plantae may be a parasite: This is the correct answer. Some plants, such as mistletoe and dodder, are parasitic and derive nutrients by parasitizing other plants.
• Insectivorous plants are totally heterotrophic: This statement is incorrect. Insectivorous plants, like the Venus flytrap, are not totally heterotrophic. They are primarily autotrophic but supplement their nutrient intake by digesting insects.
• Plant cell wall is mainly made of chitin: This statement is incorrect. The cell wall of plants is primarily composed of cellulose, not chitin. Chitin is found in the cell walls of fungi and the exoskeletons of arthropods.

The correct answer is Ulothrix - Filamentous, Isogamous

Concept:

• Ulothrix is a genus of filamentous green algae, commonly found in freshwater environments. It is known for its simple, unbranched, filamentous structure.
• The reproduction in Ulothrix can be both sexual and asexual. In sexual reproduction, it typically exhibits isogamy, where gametes are of similar size and shape.

Explanation:

• Ulothrix - Filamentous, Isogamous: Ulothrix is characterized by its filamentous structure, meaning it forms long, thread-like chains of cells.
  • The term 'isogamous' refers to the type of sexual reproduction in which the gametes (reproductive cells) are of similar size and shape.
• Volvox - Colonial, Oogamous: Volvox forms spherical colonies of individual cells, each with two flagella.
  • The term 'oogamous' refers to a form of sexual reproduction involving a large, non-motile egg and a smaller, motile sperm. 

Fig:Volvox

• Spirogyra - Colonial, Oogamous: Spirogyra is a filamentous green alga known for its spiral chloroplasts.
  • It is not colonial but filamentous, and its sexual reproduction is typically through conjugation, not oogamous.
• Ulothrix - Colonial, Isogamous: Ulothrix is isogamous, but it is not colonial; it is filamentous. Therefore, this option is incorrect in describing the structure of Ulothrix.

The correct answer is More than one of the above

Explanation:

• Chlorophyceae, also known as green algae, is a class of algae that is predominantly found in freshwater habitats. They are an important group of photosynthetic organisms that contribute to the oxygen supply and act as a primary producer in aquatic ecosystems.
• Members of the Chlorophyceae class are characterized by their green color, which is due to the presence of chlorophyll a and b.
• They store food in the form of starch and have cell walls made of cellulose.
  • Chara: This is a genus of green algae in the family Characeae. However, Chara is not classified under Chlorophyceae; it belongs to the class Charophyceae.
  • Volvox: This is a genus of green algae in the family Volvocaceae and is correctly classified under Chlorophyceae. Volvox forms spherical colonies of up to 50,000 cells and is known for its interesting reproductive and motility behaviors.
  • Ulothrix: This is a genus of filamentous green algae, specifically in the family Ulotrichaceae, and is also classified under Chlorophyceae. Ulothrix is found in freshwater and marine environments and is known for its simple, unbranched filaments.
• Both Volvox and Ulothrix belong to Chlorophyceae, therefore the correct answer is More than one of the above.

The correct answer is i - b, ii - a, iii - d, iv - c. Key Points

• Chlorophyceae:-
  • It is a class of green algae, distinguished mainly on the basis of ultrastructural morphology.
  • They are usually green due to the dominance of pigments chlorophyll a and chlorophyll b.
  • The chloroplast may be discoid, plate-like, reticulate, cup-shaped, spiral- or ribbon-shaped in different species.
  • Most of the members have one or more storage bodies called pyrenoids located in the chloroplast.
  • Pyrenoids contain protein besides starch. Some green algae may store food in the form of oil droplets.
• Phaeophyceae:-
  • It also known as brown algae, is a class of multicellular algae that are found primarily in marine environments.
  • They are distinguished by their brown color, which is due to the presence of the pigment fucoxanthin.
  • Brown algae range in size from microscopic filaments to giant kelp forests that can reach over 60 meters in length.
• Cyanophyceae:-
  • It is known as Cyanobacteria, is a class of prokaryotic organisms that obtain energy via photosynthesis.
  • It is known as Blue-green algae.
  • They are considered to be the oldest form of life on Earth, with fossils dating back over 3.5 billion years.
  • Cyanobacteria are found in a wide variety of habitats, including freshwater, marine, and terrestrial environments.
• Rhodophyceae:-
  • It also known as red algae, is a class of eukaryotic algae that are found primarily in marine environments.
  • They are distinguished by their red color, which is due to the presence of the pigment phycoerythrin.
  • Red algae range in size from microscopic filaments to large, complex seaweeds.

Key Points

• Holdfast, stipe, and frond constitute the plant body in the case of Phaeophyceae.
• Phaeophyceae refers the brown algae.
• These are marine habitats and show great variation in size and form.
• They possess chlorophyll a and c, carotenoids, and xanthophylls.
• They vary in colour from olive green to various shades of brown depending upon the amount of the xanthophyll pigment, and fucoxanthin present in them.
• The plant body of Phaeophyceae is differentiated into holdfast, stipe, and frond.
• The plant body is usually attached to the substratum by a holdfast and has a stalk, the stipe.
• The leaf-like photosynthetic organ is called the frond.
• The common brown algae are Ectocarpus, Dictyota, Laminaria, Sargassum, Fucus, etc.

Additional Information

• Rhodophyceae-
  • ​The members of Rhodophyceae are commonly called red algae because of the predominance of the red pigment, r-phycoerythrin in their bodies.
  • E.g., Polysiphonia, Porphyra, Gracilaria, Gelidium, etc.
• Chlorophyceae-
  • ​The members of Chlorophyceae are commonly called green algae.
  • They are usually grass green due to the dominance of pigments chlorophyll a and b.
  • E.g., Chlamydomonas, Volvox, Ulothrix, Spirogyra, etc.

Hence, the correct option is (3) Phaeophyceae.

The correct answer is Spirogyra.

Key Points

• Spirogyra is a multicellular filamentous green alga consisting of thin unbranched chains of cylindrical cells and found in floating masses near the surface of streams and ponds.
• Spirogyra, belonging to the genus Spirogyra, encompasses approximately 400 species of free-floating green algae found in freshwater environments globally.
• Named for their distinctive spiral chloroplasts, spirogyras are filamentous algae composed of thin, unbranched chains of cylindrical cells.
• These algae often form masses that float near the surface of streams and ponds, buoyed by oxygen bubbles produced during photosynthesis.
• They are frequently employed in laboratory demonstrations. Spirogyra species reproduce both sexually and asexually.
• Asexual, or vegetative, reproduction occurs through the simple fragmentation of the filaments.
• Sexual reproduction takes place through a process called conjugation, wherein cells from two filaments lying adjacent to each other become connected through outgrowths known as conjugation tubes.

Important Points

• Ectocarpus is a genus of filamentous brown algae renowned as a model organism for studying the genomics of multicellularity.
• Laminaria, commonly referred to as kelp, is a genus of brown seaweed characterized by its large and intricate structure. Native to the northern Pacific and north Atlantic Oceans, Laminaria is a significant component of marine ecosystems.
• Chlorella comprises approximately thirteen species of single-celled green algae within the division Chlorophyta. 

Concept:

• Algae are mostly aquatic (freshwater and marine), simple, thalloid, autotrophic organisms that contain chlorophyll.
• They can be found in numerous other habitats.
• Algae are classified into Chlorophyceae (green algae), Phaeophyceae (brown algae), and Rhodophyceae (red algae).

Explanation:

• Pyrenoids are the thick bodies of some algae and other plants found inside the chloroplast, or simply the subcellular microcompartments, of these organisms.
• Members of the Chlorophyceae contain one or more storage bodies.
• Storage bodies are located in the chloroplast and are known as pyrenoids.
• Pyrenoids are composed of a central, viscous granular core that resembles proteins and is encircled by densely clustered microscopic plates known as starch plates or starch cells.
• These are specific to the chloroplasts of algae and are involved in the polymerization of carbohydrates into starch (reserve polymers).
• Pyrenoids are also found in some Bryophytes.

So, the correct answer is option 1 (Proteinaceous center and starchy sheath).

Additional Information

•  A lot of algae and bryophytes exhibit pyrenoids.
• They are little spheres that are found in the cytoplasm of plant cells.
• They have a starchy coating around them and are high in proteins.
• Pyreno-crystal is the name for the predominant protein mass.
• The form and ultrastructure of pyrenoid vary widely among algae species.

Concept:

• Algae are mostly aquatic (freshwater and marine), simple, thalloid, autotrophic organisms that contain chlorophyll.
• They can be found in numerous other habitats.
• Algae are classified into Chlorophyceae (green algae), Phaeophyceae (brown algae), and Rhodophyceae (red algae).

Explanation:

• Pyrenoids are the thick bodies of some algae and other plants found inside the chloroplast, or simply the subcellular microcompartments, of these organisms.
• Members of the Chlorophyceae contain one or more storage bodies.
• Storage bodies are located in the chloroplast and are known as pyrenoids.
• Pyrenoids are composed of a central, viscous granular core that resembles proteins and is encircled by densely clustered microscopic plates known as starch plates or starch cells.
• These are specific to the chloroplasts of algae and are involved in the polymerization of carbohydrates into starch (reserve polymers).
• Pyrenoids are also found in some Bryophytes.

So, the correct answer is option 1 (Proteinaceous center and starchy sheath).

Additional Information

•  A lot of algae and bryophytes exhibit pyrenoids.
• They are little spheres that are found in the cytoplasm of plant cells.
• They have a starchy coating around them and are high in proteins.
• Pyreno-crystal is the name for the predominant protein mass.
• The form and ultrastructure of pyrenoid vary widely among algae species.