What is the primary characteristic of organisms belonging to the phylum Porifera?
a) Presence of a true body cavity
b) Radial symmetry
c) Lack of tissues and organs
d) Segmentation
Answer: c) Lack of tissues and organs
Which of the following best describes the feeding mechanism of sponges?
a) Predatory hunting with tentacles
b) Filter-feeding through specialized cells called choanocytes
c) Herbivorous grazing on algae
d) Parasitic absorption of nutrients from other organisms
Answer: b) Filter-feeding through specialized cells called choanocytes
What is the main function of spicules in sponges?
a) Reproduction
b) Locomotion
c) Support and protection
d) Digestion
Answer: c) Support and protection
Sponges are primarily found in which aquatic environment?
a) Freshwater lakes and rivers
b) Deep-sea hydrothermal vents
c) Coral reefs
d) Polar ice caps
Answer: c) Coral reefs
How do sponges reproduce asexually?
a) Through the release of gametes
b) By budding
c) Via external fertilization
d) Through the formation of a larval stage
Answer: b) By budding
Which of the following is true regarding the body structure of sponges?
a) They have a distinct head and tail region.
b) They exhibit bilateral symmetry.
c) They lack a true body cavity and organs.
d) They possess a segmented body.
Answer: c) They lack a true body cavity and organs.
What is the name of the specialized cells responsible for water circulation in sponges?
a) Cnidocytes
b) Choanocytes
c) Amoebocytes
d) Collencytes
Answer: b) Choanocytes
Which of the following statements about sexual reproduction in sponges is true?
a) Sponges are hermaphroditic, having both male and female reproductive organs.
b) Sponges reproduce exclusively through internal fertilization.
c) Sperm and eggs are released into the water for external fertilization.
d) Sponges do not engage in sexual reproduction.
Answer: c) Sperm and eggs are released into the water for external fertilization.
Which class of Porifera includes the simplest and most primitive sponge forms?
a) Calcarea
b) Demospongiae
c) Hexactinellida
d) Homoscleromorpha
Answer: a) Calcarea
What role do amoebocytes play in sponges?
a) They are involved in filter-feeding.
b) They provide structural support.
c) They are responsible for reproduction.
d) They transport nutrients and perform various functions, including producing spicules.
Answer: d) They transport nutrients and perform various functions, including producing spicules.
Which of the following is NOT a major body form or structure found in sponges?
a) Asconoid
b) Synconoid
c) Leuconoid
d) Bilateral
Answer: d) Bilateral
What is the function of the osculum in sponges?
a) Filter-feeding
b) Reproduction
c) Water exit and waste removal
d) Gas exchange
Answer: c) Water exit and waste removal
What type of symmetry do most sponges exhibit?
a) Radial symmetry
b) Bilateral symmetry
c) Spherical symmetry
d) Asymmetry
Answer: d) Asymmetry
What is the primary function of collar cells (choanocytes) in sponges?
a) Protection against predators
b) Digestion of food particles
c) Locomotion
d) Generating water currents for filter-feeding
Answer: d) Generating water currents for filter-feeding
Which class of sponges is known for having a skeleton made of silica spicules?
a) Demospongiae
b) Hexactinellida
c) Calcarea
d) Homoscleromorpha
Answer: b) Hexactinellida
How do sponges respond to physical stimuli, such as touch or changes in water flow?
a) They exhibit a rapid escape response.
b) They contract their bodies.
c) They release toxins.
d) They do not respond to physical stimuli.
Answer: d) They do not respond to physical stimuli.
What is the function of the mesohyl in sponges?
a) Digestion of food particles
b) Defense against predators
c) Transport of nutrients
d) Filling the spaces between cells
Answer: d) Filling the spaces between cells
Which of the following is a characteristic feature of the phylum Porifera?
a) A closed circulatory system
b) A well-developed nervous system
c) Exoskeleton made of chitin
d) Lack of specialized sensory organs
Answer: d) Lack of specialized sensory organs
What is the primary mode of reproduction in sponges when conditions are unfavorable?
a) Sexual reproduction
b) Asexual reproduction by budding
c) Fragmentation
d) Regeneration
Answer: c) Fragmentation
Which environmental factor is essential for the survival of sponges?
a) Sunlight for photosynthesis
b) Oxygen-rich water
c) Low salinity levels
d) High temperatures
Answer: b) Oxygen-rich water