Algae MCQ Quiz - Objective Question with Answer for Algae - Download Free PDF

The correct answer is Rhodophyceae

Explanation:

• The characteristics described are representative of the class Rhodophyceae, commonly known as red algae.
• Red algae (Rhodophyceae) are primarily marine organisms, although some can be found in freshwater habitats. They are known for their reddish color, which results from the dominance of the pigment phycoerythrin.
• Their cell walls not only contain cellulose and pectin but are also rich in sulfated polysaccharides like agar and carrageenan. These compounds provide structural support and are commercially valuable.

Classes of algae and their main characteristics have been summarised in the table given below:

The correct answer is (ii) and (iv) are correct 

Explanation:

• The given figure belongs to Laminaria which belongs to Class Phaeophyceae (Brown algae)
• Sexual reproduction in Brown algae may be isogamous, anisogamous or oogamous. The union of gametes may take place in water or within the oogonium (oogamous species).
• They possess chlorophyll a, c, carotenoids and xanthophylls.
• They vary in colour from olive green to various shades of brown depending upon the amount of the xanthophyll pigment,
• pigment, fucoxanthin present in them
• Food is stored as complex carbohydrates, which may be in the form of laminarin or mannitol.

Therefore, the correct statements are ii and iv only.

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 Rhodophyceae

Explanation:

• Rhodophyceae: The red algae mainly store floridean starch, which is very similar to amylopectin and glycogen in structure.
• Phaeophyceae: These brown algae store food in the form of laminarin. Laminarin is a branched polysaccharide that serves as an energy reserve.
• Chlorophyceae: Green algae store starch, which is less branched compared to amylopectin and glycogen. Starch is a mixture of amylose (linear) and amylopectin (branched) but does not match the high branching of glycogen.
• Cyanophyceae: Blue-green algae, also known as cyanobacteria, store food primarily as cyanophycean starch or glycogen. However, their storage material is not as closely similar to amylopectin as floridean starch is.

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 a - iv, b - iii, c - ii, d - i.

Key Points

• Blue-green Algae (Cyanobacteria)
  • Blue-green algae are actually bacteria and are also known as Cyanobacteria.
  • They are photosynthetic organisms and can live in a wide variety of environments, including freshwater, seawater, damp soil, or rocks.
  • Cyanobacteria are known for their significant contribution to the Earth's oxygen atmosphere.
  • They can exist as single cells or can form colonies.
• Red Algae (Rhodophyta)
  • Red algae, often called Rhodophyta, have been identified as one of the oldest groups of eukaryotic algae.
  • They are mostly found in the warmer waters of the ocean.
  • Red algae are of great economic value because of their use in the production of agar and carrageenan, substances used as thickening agents in various food products.
  • Their red colour is due to the pigment, phycoerythrin.
• Green Algae (Chlamydomonas)
  • Green algae are a diverse group of algae from which plants evolved. Chlamydomonas is a genus of unicellular green algae.
  • Chlamydomonas species are widely distributed worldwide and are found in soil and freshwater.
  • They have two flagella that allow them to move.
  • They are known for their green colour due to the presence of chlorophyll.
• Brown Algae (Sargassum)
  • Brown algae are the most complex type of algae; many are seaweeds.
  • Sargassum is a brown algae, known for forming massive floating forests in the ocean.
  • It is primarily marine and is found in warm-temperate and tropical oceans.
  • They provide important ecological functions such as providing habitats for a wide variety of marine species.
  • The brown colour is due to the presence of a pigment called fucoxanthin, which masks the green colour of chlorophyll.

The correct answer is Rhodophyceae.Key Points

• Red algae:-
  • It is a type of marine algae that are predominantly red in color due to the presence of pigments such as phycoerythrins and phycocyanins.
  • They are found in both tropical and temperate waters and play an important role in marine ecosystems as primary producers and as a food source for herbivorous marine animals.
  • Some species of red algae are also used by humans for various purposes such as food, medicine, and cosmetics.
  • Red algae are known for their ability to survive in extreme environments such as deep-sea hydrothermal vents and polar regions.

Additional Information

• Chlorophyceae:
  • This is a class of green algae that are mostly freshwater species and are commonly found in ponds, lakes, and streams.
• Liverwort:
  • This is a type of non-vascular plant that grows in damp habitats such as forests, bogs, and riverbanks.
  • They are commonly found in temperate and tropical regions and play an important role in soil formation and nutrient cycling.
• Phaeophyceae:
  • This is a class of brown algae that are predominantly marine and are commonly found in temperate and cold waters.
  • They are important primary producers in coastal ecosystems and are also used by humans for food and other purposes.

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.

Concept-

• Bacteria are the sole members of the Kingdom Monera.
• Blue-green algae come under Kingdom Monera.
• Blue-green algae are also known as cyanobacteria.
• Blue-green algae are photosynthetic autotrophs.

Explanation-

• Some of the Blue-green algae can perform Nitrogen fixation.
• Blue-green algae fix nitrogen through specialized cells called heterocysts.
• They convert atmosphere nitrogen into nitrogenous compounds like amino acids, nitrates. These nitrates increase the fertility of the soil.
• Hence blue-green algae improve the fertility of the soil by nitrogen fixation.

Examples of blue-green algae that fix nitrogen are Nostoc.

Important Points

• Cyanobacteria were the first organisms that produced oxygen on our earth.

Additional Information

• Brown algae, green algae, and red algae are the algae that come under Kingdom Plantae.
  • Member of Chlorophyceae is commonly known as 'green algae'.
  • Member of Phaeophyceae is commonly known as 'brown algae'.
  • Member of Rhodophyceae is commonly known as 'red algae'.

The corrrect answer is Phaeophyceae.Key Points

• Brown algae is a class of algae known as Phaeophyceae.
• They are called brown algae because they contain a pigment called fucoxanthin which gives them their characteristic brown color.
• Phaeophyceae are mostly found in cold waters and are commonly found in the intertidal zone.
• They are important ecologically as they provide habitat and food for many marine organisms.

Additional Information

• Rhodophyceae is a class of algae commonly known as red algae.
  • They are typically found in warmer waters and are important as a source of food and as a component of coral reefs.
• Chlorophyceae is a class of algae commonly known as green algae.
  • They are found in a variety of habitats and are important as a source of food and as a model organism in research.
• Chrysophyceae is a class of algae commonly known as golden algae.
  • They are found in freshwater habitats and are important as a source of food for aquatic organisms.

The correct Answer is Option 3.

Concept: 

• Algae is described as chlorophyll bearing, simple, thalloid, autotrophic, and largely aquatic both freshwater and marine organisms. 
• Algae are classified into three main classes: Chlorophyceae, Phaeophyceae, and Rhodophyceae.
• Each of these classes of algae differs in its food storage, pigments, habitat, and cell wall.

Explanation:

​Phaeophyceae

• The Phaeophyceae family includes brown algae.
• They are mostly found in habitats that are marine.
• Their color varies from brown to dark olive.
• This color is major because of the presence of fucoxanthin pigment.
• Brown algae also contain chlorophyll a and c as other major pigments.​​
• Complex carbohydrates, such as laminarin or mannitol, are stored in the form of food.
• The plant body is differentiated into Holdfast, Stipe and Frond
• Holdfast helps to attach the plant body to the substratum. It has branched rhizoids that give the appearance of a bird’s foot.
• Stipe resembles the stem of land plants and is flexible and somewhat elastic.
• Frond is a leaf like photosynthetic organ.
• A few examples are Ectocarpus, Dictyota, Laminaria, Sargassum, and Fucus.

So, the correct answer is option 3.

Additional Information

The correct answer is Gelidium.

Key Points

• Gelidium is a source of Agar.
• Agar, also called agar-agar is a gelatin-like product made primarily from the red algae Gelidium and Gracilaria.
  • It is a galactose-based heterogenous polysaccharide derived from red algae.
  • A typical agar composition is 70% agarose and 30% agaropectin.
  • It is used as an ingredient in desserts throughout Asia.
  • It is also used as a solid substrate to contain culture media for microbiological work.
• Gelidium is a genus of thalloid red algae.
  • Nowadays, Gracilaria and Gelidium are the principal seaweeds for commercially producing agar.
  • Gelidium are widely distributed globally, specifically in tropical to temperate regions.

Additional Information

• Ulva or sea lettuce.
  • It is a type of flat green algae of the family Ulvaceae.
  • Ulva blooms occur mainly in shallow waters and the decomposition of this alga can produce dangerous vapors.
  • It is considered one of the most usable seaweeds, with applications that include its use in food, agriculture, pharmacology and medicine.
• Ectocarpus is a genus of filamentous brown alga.
  • It serves as a model organism for the study of genomics of multicellular organisms.
• Volvox is a polyphyletic genus of chlorophyte green algae.
  • It is widely used by researchers as a genetic and developmental model to further understand cellular differentiation.

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

Key Points

• Blue-green Algae (Cyanobacteria)
  • Blue-green algae are actually bacteria and are also known as Cyanobacteria.
  • They are photosynthetic organisms and can live in a wide variety of environments, including freshwater, seawater, damp soil, or rocks.
  • Cyanobacteria are known for their significant contribution to the Earth's oxygen atmosphere.
  • They can exist as single cells or can form colonies.
• Red Algae (Rhodophyta)
  • Red algae, often called Rhodophyta, have been identified as one of the oldest groups of eukaryotic algae.
  • They are mostly found in the warmer waters of the ocean.
  • Red algae are of great economic value because of their use in the production of agar and carrageenan, substances used as thickening agents in various food products.
  • Their red colour is due to the pigment, phycoerythrin.
• Green Algae (Chlamydomonas)
  • Green algae are a diverse group of algae from which plants evolved. Chlamydomonas is a genus of unicellular green algae.
  • Chlamydomonas species are widely distributed worldwide and are found in soil and freshwater.
  • They have two flagella that allow them to move.
  • They are known for their green colour due to the presence of chlorophyll.
• Brown Algae (Sargassum)
  • Brown algae are the most complex type of algae; many are seaweeds.
  • Sargassum is a brown algae, known for forming massive floating forests in the ocean.
  • It is primarily marine and is found in warm-temperate and tropical oceans.
  • They provide important ecological functions such as providing habitats for a wide variety of marine species.
  • The brown colour is due to the presence of a pigment called fucoxanthin, which masks the green colour of chlorophyll.

The correct answer is Rhodophyceae.Key Points

• Red algae:-
  • It is a type of marine algae that are predominantly red in color due to the presence of pigments such as phycoerythrins and phycocyanins.
  • They are found in both tropical and temperate waters and play an important role in marine ecosystems as primary producers and as a food source for herbivorous marine animals.
  • Some species of red algae are also used by humans for various purposes such as food, medicine, and cosmetics.
  • Red algae are known for their ability to survive in extreme environments such as deep-sea hydrothermal vents and polar regions.

Additional Information

• Chlorophyceae:
  • This is a class of green algae that are mostly freshwater species and are commonly found in ponds, lakes, and streams.
• Liverwort:
  • This is a type of non-vascular plant that grows in damp habitats such as forests, bogs, and riverbanks.
  • They are commonly found in temperate and tropical regions and play an important role in soil formation and nutrient cycling.
• Phaeophyceae:
  • This is a class of brown algae that are predominantly marine and are commonly found in temperate and cold waters.
  • They are important primary producers in coastal ecosystems and are also used by humans for food and other purposes.

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.