Campbell Biology Chapter 33 Test Bank
Review 2025
Which cells in a sponge are primarily responsible for trapping and removing food particles from
circulating water?
A) choanocytes
B) mesoglea cells
C) pore cells (porocytes)
D) epidermal cells
Answer: A) choanocytes
Rationale: Choanocytes have flagella that create water currents and trap food particles with
their collars, making them the main feeding cells in sponges.
Which of the following is correctly associated with sponges?
A) osculum
B) body cavity
C) cnidocytes
D) spicules made of chitin
E) muscle cells and nerve cells
Answer: A) osculum
Rationale: The osculum is the large opening at the top of a sponge where water exits; sponges
lack true tissues and structures like nerves or muscles.
A sponge’s structural materials (spicules, spongin) are manufactured by the
A) pore cells
B) epidermal cells
C) choanocytes
D) zygotes
E) amoebocytes
Answer: E) amoebocytes
Rationale: Amoebocytes move through the mesohyl and produce spicules and spongin, giving
structural support to the sponge.
Which of these can be observed in the mesohyl of various undisturbed sponges at one time or
another?
1. amoebocytes
2. spicules
3. spongin
4. zygotes
5. choanocytes
A) 1 only
, B) 1 and 2
C) 1, 2, and 3
D) 1, 2, 3, and 4
E) all five of these
Answer: D) 1, 2, 3, and 4
Rationale: The mesohyl contains amoebocytes, spicules, spongin, and sometimes zygotes,
but choanocytes are located lining the internal chambers, not in the mesohyl.
Which chemical is synthesized by some sponges and acts as an antibiotic?
A) streptomycin
B) spongin
C) calcium carbonate
D) silica
E) cribrostatin
Answer: E) cribrostatin
Rationale: Cribrostatin is a sponge-derived compound with antibiotic and anti-tumor properties,
demonstrating medicinal importance of sponges.
In terms of food capture, which sponge cell is most similar to the cnidocyte of a Cnidarian?
A) zygote
B) choanocyte
C) gamete
D) epidermal cell
E) pore cell
Answer: B) choanocyte
Rationale: Like cnidocytes in cnidarians, choanocytes specialize in feeding. While mechanisms
differ (stinging vs filtering), both are unique feeding adaptations.
A radially symmetrical animal that has two embryonic tissue layers probably belongs to which
phylum?
A) Porifera
B) Cnidaria
C) Platyhelminthes
D) Nematoda
E) Echinodermata
Answer: B) Cnidaria
Rationale: Cnidarians are diploblastic (ectoderm and endoderm) and show radial symmetry,
unlike triploblastic animals.
Which of the following are characteristics of the phylum Cnidaria?
1. a gastrovascular cavity
2. a polyp stage
3. a medusa stage
4. cnidocytes
, 5. a pseudocoelom
A) 1 and 4
B) 2 and 3
C) 2, 3, and 4
D) 1, 2, 3, and 4
E) all five of these
Answer: D) 1, 2, 3, and 4
Rationale: Cnidarians have cnidocytes, a gastrovascular cavity, and may exhibit polyp
and medusa stages. They lack a pseudocoelom.
Which of the following is true of members of the phylum Cnidaria?
A) They are not capable of locomotion because they lack true muscle tissue.
B) They are primarily filter feeders.
C) They have either or both of two body forms: mobile polyps and sessile medusae.
D) They may use a gastrovascular cavity as a hydrostatic skeleton.
E) They are the simplest organisms with a complete alimentary canal (two openings).
Answer: D) They may use a gastrovascular cavity as a hydrostatic skeleton.
Rationale: The gastrovascular cavity provides support for movement in cnidarians by acting as a
hydrostatic skeleton.
The members of which class of the phylum Cnidaria occur only as polyps?
A) Hydrozoa
B) Scyphozoa
C) Anthozoa
D) Cubozoa
E) both B and D
Answer: C) Anthozoa
Rationale: Anthozoans (corals and sea anemones) exist only in polyp form, unlike other classes
that alternate between polyp and medusa.
Which class of the phylum Cnidaria includes “jellies” with rounded (as opposed to boxlike)
medusae?
A) Hydrozoa
B) Scyphozoa
C) Anthozoa
D) Cubozoa
E) Both A and C are referred to as “jellies”
Answer: B) Scyphozoa
Rationale: True jellies belong to Scyphozoa and are distinguished by their rounded medusae,
unlike box jellies (Cubozoa).
Corals are most closely related to which group?
A) jellies
B) freshwater hydras
C) sea anemones
D) sponges
Review 2025
Which cells in a sponge are primarily responsible for trapping and removing food particles from
circulating water?
A) choanocytes
B) mesoglea cells
C) pore cells (porocytes)
D) epidermal cells
Answer: A) choanocytes
Rationale: Choanocytes have flagella that create water currents and trap food particles with
their collars, making them the main feeding cells in sponges.
Which of the following is correctly associated with sponges?
A) osculum
B) body cavity
C) cnidocytes
D) spicules made of chitin
E) muscle cells and nerve cells
Answer: A) osculum
Rationale: The osculum is the large opening at the top of a sponge where water exits; sponges
lack true tissues and structures like nerves or muscles.
A sponge’s structural materials (spicules, spongin) are manufactured by the
A) pore cells
B) epidermal cells
C) choanocytes
D) zygotes
E) amoebocytes
Answer: E) amoebocytes
Rationale: Amoebocytes move through the mesohyl and produce spicules and spongin, giving
structural support to the sponge.
Which of these can be observed in the mesohyl of various undisturbed sponges at one time or
another?
1. amoebocytes
2. spicules
3. spongin
4. zygotes
5. choanocytes
A) 1 only
, B) 1 and 2
C) 1, 2, and 3
D) 1, 2, 3, and 4
E) all five of these
Answer: D) 1, 2, 3, and 4
Rationale: The mesohyl contains amoebocytes, spicules, spongin, and sometimes zygotes,
but choanocytes are located lining the internal chambers, not in the mesohyl.
Which chemical is synthesized by some sponges and acts as an antibiotic?
A) streptomycin
B) spongin
C) calcium carbonate
D) silica
E) cribrostatin
Answer: E) cribrostatin
Rationale: Cribrostatin is a sponge-derived compound with antibiotic and anti-tumor properties,
demonstrating medicinal importance of sponges.
In terms of food capture, which sponge cell is most similar to the cnidocyte of a Cnidarian?
A) zygote
B) choanocyte
C) gamete
D) epidermal cell
E) pore cell
Answer: B) choanocyte
Rationale: Like cnidocytes in cnidarians, choanocytes specialize in feeding. While mechanisms
differ (stinging vs filtering), both are unique feeding adaptations.
A radially symmetrical animal that has two embryonic tissue layers probably belongs to which
phylum?
A) Porifera
B) Cnidaria
C) Platyhelminthes
D) Nematoda
E) Echinodermata
Answer: B) Cnidaria
Rationale: Cnidarians are diploblastic (ectoderm and endoderm) and show radial symmetry,
unlike triploblastic animals.
Which of the following are characteristics of the phylum Cnidaria?
1. a gastrovascular cavity
2. a polyp stage
3. a medusa stage
4. cnidocytes
, 5. a pseudocoelom
A) 1 and 4
B) 2 and 3
C) 2, 3, and 4
D) 1, 2, 3, and 4
E) all five of these
Answer: D) 1, 2, 3, and 4
Rationale: Cnidarians have cnidocytes, a gastrovascular cavity, and may exhibit polyp
and medusa stages. They lack a pseudocoelom.
Which of the following is true of members of the phylum Cnidaria?
A) They are not capable of locomotion because they lack true muscle tissue.
B) They are primarily filter feeders.
C) They have either or both of two body forms: mobile polyps and sessile medusae.
D) They may use a gastrovascular cavity as a hydrostatic skeleton.
E) They are the simplest organisms with a complete alimentary canal (two openings).
Answer: D) They may use a gastrovascular cavity as a hydrostatic skeleton.
Rationale: The gastrovascular cavity provides support for movement in cnidarians by acting as a
hydrostatic skeleton.
The members of which class of the phylum Cnidaria occur only as polyps?
A) Hydrozoa
B) Scyphozoa
C) Anthozoa
D) Cubozoa
E) both B and D
Answer: C) Anthozoa
Rationale: Anthozoans (corals and sea anemones) exist only in polyp form, unlike other classes
that alternate between polyp and medusa.
Which class of the phylum Cnidaria includes “jellies” with rounded (as opposed to boxlike)
medusae?
A) Hydrozoa
B) Scyphozoa
C) Anthozoa
D) Cubozoa
E) Both A and C are referred to as “jellies”
Answer: B) Scyphozoa
Rationale: True jellies belong to Scyphozoa and are distinguished by their rounded medusae,
unlike box jellies (Cubozoa).
Corals are most closely related to which group?
A) jellies
B) freshwater hydras
C) sea anemones
D) sponges
