Question 1

Cells that move about in the mesohyl,digest particles,and may specialize for other functions are the

Accepted Answer

A) archaeocytes. 
B) pinacocytes. 
C) choanocytes. 
D) spongocytes. 
E) lophocytes.Sponge cells are specialized for specific functions.Archaeocytes are found in the mesohyl and phagocytize particles at the pinacoderm.They also receive food particles from choanocytes and may be specialized for other functions. 
A) archaeocytes. 
B) pinacocytes. 
C) choanocytes. 
D) spongocytes. 
E) lophocytes.Sponge cells are specialized for specific functions.Archaeocytes are found in the mesohyl and phagocytize particles at the pinacoderm.They also receive food particles from choanocytes and may be specialized for other functions.

Question 2

Which one of the following statements regarding metazoan origins is true?

Accepted Answer

A) Origin of the metazoa has been clearly elucidated and involves ancestry from a colonial flagellate stock. 
B) Metazoans are derived twice.One lineage involves a colonial flagellate stock,and the other lineage involves placozoan-like ancestors. 
C) Metazoans arose from a multinucleate ciliate where cell boundaries eventually formed around each nucleus. 
D) Placozoans may be similar to the single ancestral state.Features like their small nuclear genome and their large mitochondrial genome are features that may be derived from a common ancestor shared with some animal outgroups.The nuclear and mitochondrial genomes of the Placozoa suggest ancestry with animal outgroups. 
A) Origin of the metazoa has been clearly elucidated and involves ancestry from a colonial flagellate stock. 
B) Metazoans are derived twice.One lineage involves a colonial flagellate stock,and the other lineage involves placozoan-like ancestors. 
C) Metazoans arose from a multinucleate ciliate where cell boundaries eventually formed around each nucleus. 
D) Placozoans may be similar to the single ancestral state.Features like their small nuclear genome and their large mitochondrial genome are features that may be derived from a common ancestor shared with some animal outgroups.The nuclear and mitochondrial genomes of the Placozoa suggest ancestry with animal outgroups.

Question 3

The water outlet in sponges is known as a/an __________________.

Accepted Answer

The answer of The water outlet in sponges is known...

Question 4

Which is NOT a trait of sponges?

Accepted Answer

A) They are sessile filter feeders 
B) Their body wall has two incipient "cell layers" 
C) Their flagellated collar cells move water 
D) Water enters through the osculum 
E) Amoeboid cells digest food and make skeletal fibers and gametes Water exits a sponge through the osculum. 
A) They are sessile filter feeders 
B) Their body wall has two incipient "cell layers" 
C) Their flagellated collar cells move water 
D) Water enters through the osculum 
E) Amoeboid cells digest food and make skeletal fibers and gametes Water exits a sponge through the osculum.

Question 5

Placozoans feed by

Accepted Answer

A) sharing food produced by symbiotic algae in their diffuse tissues. 
B) gliding over their food,secreting enzymes,and absorbing products. 
C) filtering food that moves through them in tiny pores. 
D) taking food in through a ventral tube,digesting it,and expelling wastes back out the tube. 
E) taking food in through a central tube,digesting it,and moving wastes out the anus.Placozoans lack organs,including digestive organs.They secrete digestive enzymes as they glide over their food.Products of digestion are absorbed by the ventral epithelium. 
A) sharing food produced by symbiotic algae in their diffuse tissues. 
B) gliding over their food,secreting enzymes,and absorbing products. 
C) filtering food that moves through them in tiny pores. 
D) taking food in through a ventral tube,digesting it,and expelling wastes back out the tube. 
E) taking food in through a central tube,digesting it,and moving wastes out the anus.Placozoans lack organs,including digestive organs.They secrete digestive enzymes as they glide over their food.Products of digestion are absorbed by the ventral epithelium.

Question 6

There are a few marine sponges that are large enough that a small person could crawl inside.Would you have to worry about your tissues being digested?

Accepted Answer

Marine sponges, known scientifically as

Question 7

Which one of the following statements regarding the origin of metazoans has the most support?

Accepted Answer

A) The choanoflagellates share features with the sponges,like having collars of microvilli surrounding a flagellum and being colonial.These shared features suggest a link to at least one metazoan lineage. 
B) Metazoans are derived from many separate lineages of unicellular organisms. 
C) Ancient metazoans,similar to members of the phylum Placozoa,have been ruled out as ancestral metazoans. 
D) Modern sponges have a genetic makeup that reflects their ancestral status.The origin of the metazoa is problematic.Morphological and functional similarities of sponges to choanocytes suggest a possible origin of that metazon lineage,however,the sponge genome is quite complex with more modern features.Placozoans have genetic features that suggest they may reflect the primitive state. 
A) The choanoflagellates share features with the sponges,like having collars of microvilli surrounding a flagellum and being colonial.These shared features suggest a link to at least one metazoan lineage. 
B) Metazoans are derived from many separate lineages of unicellular organisms. 
C) Ancient metazoans,similar to members of the phylum Placozoa,have been ruled out as ancestral metazoans. 
D) Modern sponges have a genetic makeup that reflects their ancestral status.The origin of the metazoa is problematic.Morphological and functional similarities of sponges to choanocytes suggest a possible origin of that metazon lineage,however,the sponge genome is quite complex with more modern features.Placozoans have genetic features that suggest they may reflect the primitive state.

Question 8

The tough protein fibers sometimes found in sponge skeletons are of a substance called _____________.

Accepted Answer

The answer of The tough protein fibers sometimes found in...

Question 9

Calcareous or siliceous elements of the sponge body wall provide support.These elements are called

Accepted Answer

A) amoebocytes. 
B) pinacocytes. 
C) choanocytes. 
D) spicules. 
E) spongin.Spicules are supportive,calcareous structures in the body wall of many sponges. 
A) amoebocytes. 
B) pinacocytes. 
C) choanocytes. 
D) spicules. 
E) spongin.Spicules are supportive,calcareous structures in the body wall of many sponges.

Question 10

New evidence suggests that the calcarea belong to a clade separate from other sponges.Discuss the evidence upon which this idea is based.

Accepted Answer

The new evidence suggesting that the cal

Question 11

The sponges date back to

Accepted Answer

A) the Devonian period or "age of fishes." 
B) the early time of anaerobic prokaryotes. 
C) the Cambrian period and probably earlier. 
D) the time of the first prokaryotes but the sponges left no fossil evidence for lack of hard parts.Ancestral members of the phylum Porifera arose at least by the early Cambrian period and probably into Precambrian times.Later evolution resulted in diversification into the classes present today. 
A) the Devonian period or "age of fishes." 
B) the early time of anaerobic prokaryotes. 
C) the Cambrian period and probably earlier. 
D) the time of the first prokaryotes but the sponges left no fossil evidence for lack of hard parts.Ancestral members of the phylum Porifera arose at least by the early Cambrian period and probably into Precambrian times.Later evolution resulted in diversification into the classes present today.

Question 12

Why are bath sponges so soft?

Accepted Answer

A) Silica is washed away and the calcium carbonate remains 
B) Spongin spicules are washed away and the silky silica remains 
C) The choanocytes and amoebocytes are softer 
D) Bath sponge support is provided primarily by spongin proteins 
E) All of the choices are correct Spongin is a soft protein present in the body wall of bath sponges.Bath sponges lack calcareous or siliceous spicules. 
A) Silica is washed away and the calcium carbonate remains 
B) Spongin spicules are washed away and the silky silica remains 
C) The choanocytes and amoebocytes are softer 
D) Bath sponge support is provided primarily by spongin proteins 
E) All of the choices are correct Spongin is a soft protein present in the body wall of bath sponges.Bath sponges lack calcareous or siliceous spicules.

Question 13

Flagellated canals of syconoid sponges form by evagination of the body wall and these sponges often develop through a simple vase-like stage.Which of the following is a logical hypothesis based on this evidence?

Accepted Answer

A) Asconoid sponges were derived from syconoid ancestors. 
B) Leuconoid sponges were derived from syconoid ancestors. 
C) Syconoid sponges were derived from leuconoid ancestors. 
D) Syconoid sponges were derived from asconoid ancestors. 
E) Leuconoid sponges were derived from asconoid ancestors.Syconoid sponges may have evolved through an asconoid body plan.All syconoid sponges,however,do not share a common ancestor.This transition to the syconoid stage may have occurred more than once. 
A) Asconoid sponges were derived from syconoid ancestors. 
B) Leuconoid sponges were derived from syconoid ancestors. 
C) Syconoid sponges were derived from leuconoid ancestors. 
D) Syconoid sponges were derived from asconoid ancestors. 
E) Leuconoid sponges were derived from asconoid ancestors.Syconoid sponges may have evolved through an asconoid body plan.All syconoid sponges,however,do not share a common ancestor.This transition to the syconoid stage may have occurred more than once.

Exam 12: Sponges and Placozoans

Cells that move about in the mesohyl,digest particles,and may specialize for other functions are the

Which one of the following statements regarding metazoan origins is true?

The water outlet in sponges is known as a/an __________________.

Which is NOT a trait of sponges?

Placozoans feed by

There are a few marine sponges that are large enough that a small person could crawl inside.Would you have to worry about your tissues being digested?

Which one of the following statements regarding the origin of metazoans has the most support?

The tough protein fibers sometimes found in sponge skeletons are of a substance called _____________.

Calcareous or siliceous elements of the sponge body wall provide support.These elements are called

New evidence suggests that the calcarea belong to a clade separate from other sponges.Discuss the evidence upon which this idea is based.

The sponges date back to

Why are bath sponges so soft?

Flagellated canals of syconoid sponges form by evagination of the body wall and these sponges often develop through a simple vase-like stage.Which of the following is a logical hypothesis based on this evidence?

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