Campbell Biology Chapter 33 Exam
Questions With All Correct Answers
Verified Answers 2025 Marking
Scheme New Update
Invertebrates - Answer- Animals without a backbone. About 95% of known animal
species.
Calcarea and Silicea - Answer- phylum that includes sponges; no symmetry, tissues,
body cavity, organs, nervous system; basal animals; mostly marine; contain spicules;
most are hermaphrodites; free-swimming during larval stage and sessile (non motile) as
adults; suspension/filter feeders
Suspention feeders - Answer- small and large organisms that use filtering and trapping
techniques to collect minute food particles suspended in the water
Spongocoel - Answer- large central cavity of the sponge
Osculum - Answer- A large opening on a sponge through which filtered water is
expelled
Choanocytes - Answer- specialized cell in sponges that uses a flagellum to move a
steady current of water through the sponge
mesohyl - Answer- a gelatinous region between the two layers of cells of a sponge
amoebocytes - Answer- the "do-all" cells of sponges, moving by means of pseudopodia,
they digest and distribute food, transport oxygen, and disposes of waste. they
manufacture the fibers that make up a sponges skeleton
Eumetazoa - Answer- Members of the subkingdom that includes all animals except
sponges. (true tissues)
Cnidaria - Answer- animal phylum characterized by having diploblastic tentacled polyp
and/or medusa (jelly) body forms with radial symmetry; tentacles bear cells called
cnidocytes that have weapons called cnidae (e.g., stinging barbs called nematocysts).
Gastrovascular cavity with a single opening. - corals, jellies and hydras
gastrovascular cavity - Answer- digestive chamber with a single opening, in which
cnidarians, flatworms, and echinoderms digest food
, Polyps - Answer- The sessile variant of the cnidarian body plan. The alternate form is
the medusa. Cylindrical forms that adhere to the substrate by the aboral end of their
body, waiting for the prey. - hydras
Medusa - Answer- The floating, flattened, mouth-down version of the cnidarian body
plan. The alternate form is the polyp.
Cnidocytes - Answer- a specialized cell for which the phylum Cnidaria is named;
consists of a capsule containing a fine coiled thread, which, when discharged, functions
in defense and prey capture
Nematocytsts - Answer- a type of cnidocyte that has a long filament coiled up inside it
and can penetrate the prey.
4 major classes of phylum Cnidaria - Answer- Hydrozoa, Scyphozoa, Cubozoa,
Anthozoa
Hydrozoans - Answer- A class of Cnidaria where most of the organisms alternate
between polyp and medusa except hydras, which are only polyp. They can reproduce
both asexually and sexually.
Scyphozoans - Answer- Group of cnidarians,all marine, polyp stage is greatly reduced,
free swimming medusae is up to 2 m in diameter. (Jellies,sea nettles)
Cubozoans - Answer- Class of Cnidaria with a box-shaped medusa stage and complex
eyes. Often equipped with toxic cnidocytes.
Anthozoans - Answer- class of cnidarian; sea anemones and corals occurring only as
polyps. Corals excrete an exoskeleton of calcium carbonate, form symbioses with
algae.
Lophotrochozoans - Answer- Member of a group of animal phyla identified as a clade by
molecular evidence. Lophotrochozoans include organisms that have lophophores or
trochophore larvae. Includes about 18 phyla - introduced 6 are flatworms, rotifers,
ectoprocts, brachiopods, molluscs and annelids.
Bilateria - Answer- A member of a major lineage of animals (Bilateria) that are bilaterally
symmetrical at some point in their life cycle, have three embryonic germ layers, and
have digestive tract with two opening and a coelom. All protostomes and deuterostomes
are bilaterians.
3 major clades of Bilateria - Answer- 1. lophotrochozoa
2. ecdysozoa
3. deuterostomia
Questions With All Correct Answers
Verified Answers 2025 Marking
Scheme New Update
Invertebrates - Answer- Animals without a backbone. About 95% of known animal
species.
Calcarea and Silicea - Answer- phylum that includes sponges; no symmetry, tissues,
body cavity, organs, nervous system; basal animals; mostly marine; contain spicules;
most are hermaphrodites; free-swimming during larval stage and sessile (non motile) as
adults; suspension/filter feeders
Suspention feeders - Answer- small and large organisms that use filtering and trapping
techniques to collect minute food particles suspended in the water
Spongocoel - Answer- large central cavity of the sponge
Osculum - Answer- A large opening on a sponge through which filtered water is
expelled
Choanocytes - Answer- specialized cell in sponges that uses a flagellum to move a
steady current of water through the sponge
mesohyl - Answer- a gelatinous region between the two layers of cells of a sponge
amoebocytes - Answer- the "do-all" cells of sponges, moving by means of pseudopodia,
they digest and distribute food, transport oxygen, and disposes of waste. they
manufacture the fibers that make up a sponges skeleton
Eumetazoa - Answer- Members of the subkingdom that includes all animals except
sponges. (true tissues)
Cnidaria - Answer- animal phylum characterized by having diploblastic tentacled polyp
and/or medusa (jelly) body forms with radial symmetry; tentacles bear cells called
cnidocytes that have weapons called cnidae (e.g., stinging barbs called nematocysts).
Gastrovascular cavity with a single opening. - corals, jellies and hydras
gastrovascular cavity - Answer- digestive chamber with a single opening, in which
cnidarians, flatworms, and echinoderms digest food
, Polyps - Answer- The sessile variant of the cnidarian body plan. The alternate form is
the medusa. Cylindrical forms that adhere to the substrate by the aboral end of their
body, waiting for the prey. - hydras
Medusa - Answer- The floating, flattened, mouth-down version of the cnidarian body
plan. The alternate form is the polyp.
Cnidocytes - Answer- a specialized cell for which the phylum Cnidaria is named;
consists of a capsule containing a fine coiled thread, which, when discharged, functions
in defense and prey capture
Nematocytsts - Answer- a type of cnidocyte that has a long filament coiled up inside it
and can penetrate the prey.
4 major classes of phylum Cnidaria - Answer- Hydrozoa, Scyphozoa, Cubozoa,
Anthozoa
Hydrozoans - Answer- A class of Cnidaria where most of the organisms alternate
between polyp and medusa except hydras, which are only polyp. They can reproduce
both asexually and sexually.
Scyphozoans - Answer- Group of cnidarians,all marine, polyp stage is greatly reduced,
free swimming medusae is up to 2 m in diameter. (Jellies,sea nettles)
Cubozoans - Answer- Class of Cnidaria with a box-shaped medusa stage and complex
eyes. Often equipped with toxic cnidocytes.
Anthozoans - Answer- class of cnidarian; sea anemones and corals occurring only as
polyps. Corals excrete an exoskeleton of calcium carbonate, form symbioses with
algae.
Lophotrochozoans - Answer- Member of a group of animal phyla identified as a clade by
molecular evidence. Lophotrochozoans include organisms that have lophophores or
trochophore larvae. Includes about 18 phyla - introduced 6 are flatworms, rotifers,
ectoprocts, brachiopods, molluscs and annelids.
Bilateria - Answer- A member of a major lineage of animals (Bilateria) that are bilaterally
symmetrical at some point in their life cycle, have three embryonic germ layers, and
have digestive tract with two opening and a coelom. All protostomes and deuterostomes
are bilaterians.
3 major clades of Bilateria - Answer- 1. lophotrochozoa
2. ecdysozoa
3. deuterostomia
