Euglenoids are mostly freshwater organisms that are commonly found in stagnant water such as ponds, ditches and pools. These environments are rich in organic matter and nutrients, which support the growth of these organisms. Euglenoids are microscopic protists that often occur as part of plankton in freshwater ecosystems. Their presence in stagnant water bodies makes them an important component of aquatic microbial communities.
2. In euglenoids, instead of a cell wall, there is a protein-rich layer called ________ which makes their body flexible.
Correct Answer: A
Euglenoids do not possess a typical cell wall like plants. Instead, their body is covered by a flexible protein-rich layer called a pellicle. The pellicle allows the organism to change its shape and move easily in water. This flexibility is an important feature that helps euglenoids survive in aquatic environments. Because of the pellicle, their body remains firm yet flexible.
3. Euglenoids possess:
Correct Answer: B
Euglenoids typically possess two flagella arising from a reservoir at the anterior end of the cell. One of these flagella is long and projects outside the cell, helping in locomotion. The other flagellum is short and usually remains within the reservoir and does not extend outside. The long flagellum helps the organism swim through water, allowing it to move towards light or nutrients in aquatic environments.
4. Euglenoids are photosynthetic in sunlight but behave like heterotrophs in the absence of sunlight. This type of nutrition is called:
Correct Answer: C
Euglenoids show a special type of nutrition called mixotrophic nutrition. In the presence of sunlight, they perform photosynthesis and behave like autotrophs by producing their own food using chlorophyll. However, when sunlight is not available, they can feed on smaller organisms or organic matter and behave like heterotrophs. Because they can switch between autotrophic and heterotrophic modes of nutrition depending on environmental conditions, their nutrition is called mixotrophic.
5. The pigments present in euglenoids are identical to those found in:
Correct Answer: B
Euglenoids possess photosynthetic pigments such as chlorophyll a and chlorophyll b, which are the same pigments present in higher plants. Because of these pigments, euglenoids are able to perform photosynthesis in the presence of sunlight. This similarity in pigment composition makes them resemble plant cells in their photosynthetic function. A common example of a euglenoid is Euglena, which lives mainly in freshwater environments.
6. Why were euglenoids earlier called 'Plant-Animals'?
Correct Answer: B
Euglenoids such as Euglena were earlier called 'Plant-Animals' because they show characteristics of both plants and animals. Like plants, they contain chlorophyll and can perform photosynthesis in the presence of sunlight. However, like animals, they are motile and move using flagella, and in the absence of sunlight they can feed on other organisms. Because they possess both plant-like and animal-like features, scientists earlier referred to them as Plant-Animals.
7. Slime moulds are:
Correct Answer: B
Slime moulds are saprophytic protists that feed on dead and decaying organic matter. They obtain their nutrition by absorbing nutrients from decomposing plant material, leaves and other organic substances. Because they depend on dead organic matter for food, they are called saprophytes. Slime moulds are commonly found in moist and shady environments where decaying organic material is present.
8. The body of slime moulds moves over decaying twigs and leaves mainly to:
Correct Answer: B
Slime moulds are saprophytic protists that live on decaying organic matter. Their body moves slowly over moist surfaces such as decaying leaves and twigs. As they move, they engulf and absorb organic particles and microorganisms present in the decomposing material. This mode of feeding allows them to obtain nutrients from dead and decaying organic substances in their habitat.
9. Under suitable conditions, slime moulds form an aggregation called:
Correct Answer: B
Under favourable environmental conditions, slime moulds aggregate to form a mass called a plasmodium. This plasmodium is a large, multinucleate, amoeboid structure that can grow and spread over decaying organic matter such as leaves and twigs. It may extend over several feet while moving slowly in search of food. The plasmodium stage is an important phase in the life cycle of slime moulds.
10. During unfavourable conditions, the plasmodium of slime moulds forms:
Correct Answer: B
When environmental conditions become unfavourable, the plasmodium of slime moulds differentiates and develops fruiting bodies. These fruiting bodies produce spores at their tips. The spores are resistant structures that can survive harsh conditions. When favourable conditions return, the spores germinate and give rise to new slime mould organisms, continuing the life cycle.
11. The spores of slime moulds possess:
Correct Answer: B
During unfavourable environmental conditions, the plasmodium of slime moulds differentiates and forms fruiting bodies. These fruiting bodies produce numerous spores at their tips. The spores have true walls that protect them from harsh environmental conditions such as dryness or lack of nutrients. When favourable conditions return, the spores germinate and develop into new individuals, continuing the life cycle of slime moulds.
12. The spores of slime moulds are extremely resistant and can survive:
Correct Answer: C
The spores produced by slime moulds are very resistant structures. They possess strong protective walls that help them withstand harsh environmental conditions such as dryness, lack of nutrients and temperature extremes. Because of this resistance, the spores can remain dormant and survive for many years. When favourable conditions return, these spores germinate and develop into new slime mould organisms.
13. The spores of slime moulds are mainly dispersed by:
Correct Answer: C
The spores of slime moulds are extremely resistant and can survive for many years even under adverse environmental conditions. These spores are very light and dry, which allows them to be easily carried and dispersed by air currents. Wind dispersal helps the spores spread to new suitable habitats where they can germinate and grow when favourable environmental conditions return.
14. All protozoans are:
Correct Answer: B
Protozoans are unicellular eukaryotic organisms that belong to Kingdom Protista. All protozoans are heterotrophs, meaning they cannot produce their own food through photosynthesis. Instead, they obtain nutrition by feeding on other organisms or organic matter. Many protozoans live as predators that consume bacteria or smaller organisms, while some live as parasites inside the bodies of plants, animals or humans and may cause diseases.
15. Protozoans are believed to be primitive relatives of:
Correct Answer: B
Protozoans are unicellular heterotrophic organisms that belong to Kingdom Protista. They obtain food by ingesting other organisms and often show animal-like characteristics such as movement using pseudopodia, cilia or flagella. Because of these similarities in feeding behaviour and mobility, protozoans are considered primitive relatives of animals and are sometimes referred to as animal-like protists.
16. Protozoans are broadly divided into how many major groups?
Correct Answer: C
Protozoans are classified into four major groups based on their mode of locomotion and other structural features. These groups include amoeboid protozoans (which move using pseudopodia), flagellated protozoans (which move using flagella), ciliated protozoans (which move using cilia) and sporozoans (which are generally non-motile and often parasitic). This classification helps scientists study the diversity and behaviour of protozoans more systematically.
17. Amoeboid protozoans are commonly found in:
Correct Answer: B
Amoeboid protozoans are unicellular organisms that move and capture food using pseudopodia. They are widely distributed in nature and are commonly found in freshwater bodies such as ponds, in seawater and also in moist soil. These environments provide sufficient moisture which is necessary for their survival and movement. Examples include Amoeba and Entamoeba.
18. Amoeboid protozoans such as Amoeba move and capture prey using:
Correct Answer: C
Amoeboid protozoans move and obtain food by extending temporary finger-like projections of the cytoplasm called pseudopodia, which means 'false feet'. These pseudopodia help the organism move from one place to another and also surround and engulf food particles or prey in a process called phagocytosis. Amoeba is a common example of an organism that uses pseudopodia for locomotion and feeding.
19. Entamoeba is an example of:
Correct Answer: C
Entamoeba is a parasitic amoeboid protozoan that lives inside the body of its host, usually in the human intestine. Some species such as Entamoeba histolytica cause diseases like amoebic dysentery. Unlike free-living amoebae found in water or soil, parasitic forms depend on their host for nutrition and survival. Because they live inside a host and may cause disease, they are classified as parasitic protozoans.
20. Entamoeba can ingest ______ as food.
Correct Answer: B
Entamoeba is a parasitic amoeboid protozoan that lives in the human intestine. It feeds by extending pseudopodia and engulfing food particles. In pathogenic species such as Entamoeba histolytica, the organism can ingest red blood cells (RBCs) from the host tissues. The presence of ingested RBCs inside the parasite is often used as an important diagnostic feature in identifying Entamoeba histolytica infection.
21. Flagellated protozoans are usually:
Correct Answer: C
Flagellated protozoans are a group of protozoans that move using whip-like structures called flagella. Members of this group may live freely in aquatic environments such as ponds and lakes, or they may live as parasites inside plants, animals or humans. Parasitic forms may cause diseases, while free-living forms feed on bacteria and organic matter in water.
22. Parasitic flagellated protozoans can cause diseases such as:
Correct Answer: B
Flagellated protozoans possess flagella that help in locomotion. Members of this group may be free-living in aquatic environments or parasitic in plants and animals. Some parasitic forms cause serious diseases in humans. For example, Trypanosoma is a flagellated protozoan parasite that causes sleeping sickness in humans. This disease is transmitted through the bite of the tsetse fly.
23. Which flagellated protozoan causes sleeping sickness?
Correct Answer: B
Flagellated protozoans move with the help of flagella and may be free-living or parasitic. Some parasitic members cause diseases in humans and animals. A well-known example is Trypanosoma, a flagellated protozoan parasite that causes sleeping sickness in humans. The disease is transmitted through the bite of the tsetse fly and mainly occurs in certain regions of Africa.
24. Ciliated protozoans move actively because they possess:
Correct Answer: C
Ciliated protozoans are mostly aquatic organisms that move actively in water. Their movement is made possible by the presence of numerous short hair-like structures called cilia covering the surface of the cell. These cilia beat in a coordinated manner, allowing the organism to swim through water and also help in capturing food particles. Paramecium is a common example of a ciliated protozoan.
25. In ciliated protozoans, the cavity that opens to the outside of the cell surface is called:
Correct Answer: A
Ciliated protozoans such as Paramecium possess a special feeding structure called a gullet. This cavity opens to the outside of the cell surface and functions in ingestion of food. Food particles are swept into the gullet by the beating of cilia and then enclosed in food vacuoles for digestion. This specialized structure helps the organism efficiently capture and process food in aquatic environments.
26. In ciliated protozoans, food particles are directed into the gullet by:
Correct Answer: C
Ciliated protozoans possess numerous hair-like structures called cilia on their body surface. These cilia beat in a coordinated manner, creating water currents around the organism. The movement of these currents helps carry water containing food particles towards the oral region and into the gullet. Once inside, the food particles are enclosed in food vacuoles where digestion takes place. This mechanism helps the organism capture food efficiently.
27. In Paramecium, the coordinated movement of cilia helps in:
Correct Answer: B
Paramecium is a ciliated protozoan that lives in aquatic environments. Its body surface is covered with numerous cilia. The coordinated beating of these cilia produces water currents that direct food particles suspended in water towards a cavity called the gullet. The food particles are then taken inside the cell and enclosed in food vacuoles where digestion occurs.
28. Sporozoans are characterized by the presence of which stage in their life cycle?
Correct Answer: B
Sporozoans are a group of protozoans that include many parasitic organisms. A distinctive feature of this group is the presence of an infectious spore-like stage in their life cycle. These spores help in transmission from one host to another. Sporozoans generally lack locomotory structures such as cilia or flagella and often live as parasites in animals or humans. A well-known example is Plasmodium, the organism that causes malaria.
29. Which sporozoan protozoan causes malaria in humans?
Correct Answer: C
Plasmodium is a parasitic protozoan belonging to the group Sporozoa. It is the causative organism of malaria, a serious disease that affects millions of people worldwide. The parasite enters the human body through the bite of an infected female Anopheles mosquito. Inside the human host, it infects liver cells and red blood cells, leading to symptoms such as fever, chills and weakness. Because of its wide impact on human health, Plasmodium is considered one of the most notorious parasitic protozoans.