Bi 11: Chapter
25 Study Guide: Flatworms, Roundworms,
Mollusks & Annelids
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Chapter 25–1 flatworms & 25-2 Roundworms: Section review
In this section you were introduced to the group of animals known as unsegmented worms. Segmented
worms include
and
.
You learned that flatworms are the simplest animals with
that most members of this phylum exhibit enough
symmetry. You also learned
to have what is called the head.
You discovered that roundworms are amongst the simplest animals that have a digestive system with two
openings, a
and an
. Several parasitic roundworms that cause
diseases in humans were discussed, including
, Trichinella, and hookworms.
Understanding definitions: building vocabulary skills: Each of the statements below describes either
flatworms, roundworms, or both. If the statement describes flatworms, write an F in the blank before the
statement. If the statement describes roundworms, write an R. If the statement describes both, right both
an F and an R.
_____ 1. Are invertebrates
_____ 2. Are members of phylum Nematoda
_____3. Includes blood flukes
_____4. Includes free living and parasitic animals
_____ 5. Have a digestive system with only one opening
_____ 6. May have asexual reproduction
_____ 7. Eliminate undigested waste through the anus
_____ 8. Includes Ascaris
Applying concepts: understanding the main ideas
The body plan of a free-living flatworm is shown at right.
1. Label each letter structure on the diagram.
2. Label the anterior and posterior ends of the worm.
3. What type of symmetry does the body show?
4. What is the purpose of the branches on structure E?
5. What evidence does this diagram show of cephalization?
6. What is the function of the structure labeled C?
Bi 11: Chapter
25 Study Guide: Flatworms, Roundworms,
Mollusks & Annelids
7. What is the function of the structure labeled D?
Concept mapping: Consider the concepts presented in section 25 – 1 and how you would
organize them into a concept map. Now look at the map for the chapter 25 below. Notice that
the concept map has been started for you. Add the key facts and concepts you feel are
important for section 25 – 1.
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Bi 11: Chapter
25 Study Guide: Flatworms, Roundworms,
Mollusks & Annelids
3
Section 25-3: Mollusks
What is a mollusk? In the first part of the section you discovered that a wide diversity of animals are
classified as mollusks. These animals are classified together in one phylum because all show similar
features during early
and all exhibit different forms of the same
.
You then explored the wide varied of form and function among mollusks. You also learned about three
classes of mollusks. Gastropods, such as
and
, move by means of a
broad, ventral
; many have a one-piece
. Bivalves,
such as
, have two
that are joined by a
.
Cephalopods, such as
and
, have
.
Mollusks affect humans in a variety of ways. Many mollusks are popular as
, and
the oyster is not only important as a food source but as a producer of
. Some
mollusks also impact negatively on humans by serving as intermediate hosts for
and by doing damage to gardens and
.
Relating Definitions: Building Vocabulary Skills
Many of the important terms in this section relate to the way mollusks carry out basic life functions.
Listed below are the seven basic functions that animals must carry out in order to survive. Following is a
list of terms from this section. In the blank following each term, write the function or functions that the
term relates to. Some functions may be used more than once, and others may not be used.
Feeding
Excretion
reproduction
respiration
1. Trochophore:
2. Foot:
3. Mantle:
4. Radula:
response
internal transport
movement
5. Open circulatory system:
6. Nephridia:
7. Closed Circulatory system:
8. Gills:
Classifying Mollusks: Understanding the Main Ideas
Each of the following statements describes one of the three main classes of mollusks. In the blank before
each statement, write a G if the statement describes the gastropod, a B if the statement describes a
bivalve, and a C if the statement describes a cephalopod.
1.
2.
3.
4.
5.
6.
7.
8.
9.
Scallops are members of this group.
They feed using a structure called a radula.
Sometimes they produce pearls.
The chambered nautilus is a member of this group.
The are highly intelligent; perhaps more than some vertebrates.
They have two shells
Most have small internal shells or no shells at all
Most have a broad, muscular foot located on their stomach.
Most are sessile, but some can move around by flapping their shells
Bi 11: Chapter
25 Study Guide: Flatworms, Roundworms,
Mollusks & Annelids
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Making a diagram: internal structure of a bivalve
A clam is a typical bivalve. The diagram below shows the internal structures of a clam. Us the terms
listed to correctly label the diagram.
Anterior adductor muscle
intestine
stomach
Gill
Ganglion
Nephridium
Anus
Excurrent Siphon
Incurrent Siphon
Heart
Posterior adductor muscle
mouth
Food
Gonad
Concept mapping
Consider the concepts presented in Section 25-3 and how you would organize them into a concept map.
Now look at the concept map for Chapter 25 at the end of this package. Notice that the concept map has
been started for you. Add the key facts and concepts you fell are important for Section 25-3. When you
have finished the chapter, you will have a completed concept map.
Section 25-4: Annelids
In this section you were introduced to members of the phylum Annelida. These animals, which are also
known as
, include the familiar
as well as about 9000 other species, such as sandworms,
, and
.
You learned that annelids are characterized by a long,
body and that they live both
in water and on
. By studying in detail the earthworm’s body systems, you learned how
annelids carry out essential life functions.
Bi 11: Chapter
25 Study Guide: Flatworms, Roundworms,
Mollusks & Annelids
Annelids are important in many habitats. Small annelids that live in the ocean serve as
for other organisms. Earthworms and similar annelids are important in soil
Earthworms also perform the valuable function of processing
organisms into substances that can be used by
.
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.
from dead
Applying Concepts: Basic Function in Annelids
Complete each sentence below to describe how the indicated function is carried out by annelids. You
may add additional sentences if you wish.
1. Respiration. Aquatic Annelids typically breathe
2. Internal Transport: The circulatory system in annelids
3. Excretion: Annelids produce two kinds of wastes. Solid wastes
4. Response: Annelids have a well-developed nervous system
5. Movement: Muscles in annelid
6. Reproduction: Most annelids reproduce
Relating Concepts: Understanding the Main Ideas
Listed in the left column are the major organs that make up the digestive system of the earthworm. Listed
in the right column are words that describe the basic function of each organ. Match each function if the
right column with the corresponding organ in the left column by writing the correct letter in the blank.
1. Intestine
2. Anus
3. Gizzard
4. Crop
5. Esophagus
6. Pharynx
7. Mouth
a. Chops food into small pieces
b. pumps food and soil or grabs prey
c. Entrance for food
d. Eliminates Waste
e. Storage area for food
f. Digests food
g. Passageway for food
Bi 11: Chapter
25 Study Guide: Flatworms, Roundworms,
Mollusks & Annelids
Label the following diagrams of an earthworm.
Side View
Concept Mapping.
Consider the concepts presented in Section 25-4 and how you would organize
them into a concept map. Now look at the concept map for Chapter 25 at the end
of this package. Notice that the concept map has been started for you. Add the
key facts and concepts you fell are important for Section 25-4. When you have
finished the chapter, you will have a completed concept map.
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