Protozoa and Porifera Practice Questions
20 free Protozoa and Porifera practice questions for the NCERT Biology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
Which of the following is a characteristic feature of the water transport or canal system in sponges?
- A Water enters through the osculum
- B Water exits through minute pores called ostia
- C Water enters via ostia into the spongocoel
- D The system is primarily used for locomotion
Correct answer: Water enters via ostia into the spongocoel
In Phylum Porifera, water enters through minute pores called ostia in the body wall into a central cavity, the spongocoel, from where it goes out through the osculum. This pathway of water transport is helpful in food gathering, respiratory exchange, and removal of waste.
Which specialized cells line the spongocoel and the canals in Phylum Porifera?
- A Choanocytes
- B Cnidoblasts
- C Choanoflagellates
- D Nematocytes
Correct answer: Choanocytes
Choanocytes, or collar cells, are unique flagellated cells that line the spongocoel and the canals of sponges. They play a critical role in maintaining water flow and trapping food particles.
The skeleton of sponges is made up of:
- A Calcareous shells
- B Chitinous exoskeleton
- C Cartilaginous plates
- D Spicules or spongin
Correct answer: Spicules or spongin
Sponges possess a body supported by a skeleton made of spicules or spongin fibres. These structures provide structural integrity to the multicellular but loosely organized body.
Sponges are mostly hermaphrodite, which means:
- A One individual produces both eggs and sperms
- B They reproduce only asexually
- C Male and female are found in different colonies
- D They do not perform sexual reproduction
Correct answer: One individual produces both eggs and sperms
Being hermaphrodite means that the sexes are not separate; a single individual produces both eggs and sperms. They reproduce asexually by fragmentation and sexually by the formation of gametes.
In Porifera, fertilization is _____ and development is _____.
- A Internal, indirect
- B External, direct
- C External, indirect
- D Internal, direct
Correct answer: Internal, indirect
Fertilization in sponges occurs internally within the body of the sponge. Development is indirect, meaning it involves a larval stage that is morphologically distinct from the adult.
Which of the following is commonly known as the 'Fresh water sponge'?
- A Sycon
- B Euspongia
- C Scypha
- D Spongilla
Correct answer: Spongilla
Spongilla is a member of the Porifera phylum that lives in freshwater habitats. Most other sponges, like Sycon and Euspongia, are exclusively marine.
Euspongia is popularly known as the:
- A Common bath sponge
- B Glass rope sponge
- C Venus flower basket
- D Fresh water sponge
Correct answer: Common bath sponge
Euspongia is known as the bath sponge because its dried spongin skeleton was historically used for bathing and scrubbing. It belongs to the class Demospongiae.
Digestion in Phylum Porifera is strictly:
- A Extracellular
- B Intercellular
- C None of the above
- D Intracellular
Correct answer: Intracellular
Sponges lack a true digestive tract or organs; therefore, digestion takes place within individual cells (intracellularly). Food particles trapped by choanocytes are digested inside food vacuoles.
All protozoans are believed to be primitive relatives of animals because they are:
- A Unicellular and heterotrophic
- B Multicellular and autotrophic
- C Multicellular and heterotrophic
- D Unicellular and saprophytic
Correct answer: Unicellular and heterotrophic
Protozoans are unicellular eukaryotic organisms that live as heterotrophs (predators or parasites). Due to their heterotrophic nature and animal-like movement, they are considered primitive relatives of the Animal Kingdom.
Which group of protozoans moves and captures prey by putting out pseudopodia (false feet)?
- A Flagellated protozoans
- B Ciliated protozoans
- C Sporozoans
- D Amoeboid protozoans
Correct answer: Amoeboid protozoans
Amoeboid protozoans, such as Amoeba, live in fresh water, sea water, or moist soil. They move and capture prey using pseudopodia, which are temporary extensions of the cytoplasm.
Which of the following is a well-known amoeboid parasite in humans?
- A Amoeba
- B Entamoeba
- C Plasmodium
- D Trypanosoma
Correct answer: Entamoeba
Entamoeba histolytica is a parasitic amoeboid protozoan that causes amoebic dysentery in humans. Unlike free-living amoebas, it inhabits the human intestine.
Sleeping sickness is caused by a member of which protozoan group?
- A Amoeboid protozoans
- B Flagellated protozoans
- C Ciliated protozoans
- D Spore-forming protozoans
Correct answer: Flagellated protozoans
Sleeping sickness is caused by Trypanosoma, which is a flagellated protozoan. These organisms are either free-living or parasitic and possess flagella for locomotion.
Which protozoan group is characterized by thousands of hair-like projections that create a coordinated movement of water?
- A Flagellated protozoans
- B Ciliated protozoans
- C Amoeboid protozoans
- D Sporozoans
Correct answer: Ciliated protozoans
Ciliated protozoans, like Paramecium, are aquatic organisms that use cilia for movement and to steer food-laden water into their gullet (cavity).
The gullet in a Paramecium opens to the:
- A Interior of the cell nucleus
- B Outside of the cell surface
- C Contractile vacuole
- D Pseudopodia
Correct answer: Outside of the cell surface
Ciliated protozoans have a cavity (gullet) that opens to the outside of the cell surface. The coordinated movement of rows of cilia causes the water laden with food to be steered into the gullet.
Sporozoans are distinct from other protozoans because they:
- A Have flagella throughout their life cycle
- B Produce an infectious spore stage
- C Move using large cilia
- D Are all free-living
Correct answer: Produce an infectious spore stage
Sporozoans include diverse organisms that have an infectious spore-like stage in their life cycle. The most notorious example is Plasmodium (the malaria parasite).
Which organism causes the most notorious disease, malaria, and belongs to the sporozoans?
- A Trypanosoma
- B Entamoeba
- C Plasmodium
- D Paramecium
Correct answer: Plasmodium
Plasmodium is a sporozoan that causes malaria, a disease which has a staggering effect on the human population. It requires a mosquito vector to complete its complex life cycle.
In sponges, the central cavity into which water flows from the ostia is the:
- A Excurrent osculum
- B Spongocoel
- C Gullet
- D True coelom
Correct answer: Spongocoel
The spongocoel is the large central cavity of sponges. Water is drawn into it through the ostia and exits through a larger opening called the osculum.
Marine amoeboid protozoans often have which of the following on their surface?
- A Calcium shells
- B Chitinous plates
- C Cellulose cell walls
- D Siliceous shells
Correct answer: Siliceous shells
Marine forms of amoeboid protozoans often have silica shells on their surface. This provides structural protection in the high-pressure marine environment.
Which of the following statements about Porifera is INCORRECT?
- A They are generally marine and asymmetrical
- B They are multicellular organisms with cellular level of organization
- C They possess a well-developed nervous system
- D They reproduce asexually by fragmentation
Correct answer: They possess a well-developed nervous system
Sponges are very primitive animals and do not possess a nervous system, muscles, or true tissues. They have a cellular level of organization where cells perform specialized functions somewhat independently.
The flagellated cells in sponges that create water currents are:
- A Pinacocytes
- B Amoebocytes
- C Scleroblasts
- D Choanocytes
Correct answer: Choanocytes
Choanocytes (collar cells) possess flagella. The beating of these flagella creates a water current that moves water through the canal system, bringing in food and oxygen.