Download Answers to End-of-Chapter Questions – Brooker et al ARIS site

Answers to End-of-Chapter Questions – Brooker et al ARIS site
Chapter 33
Test Yourself Questions
1. Choanocytes are
a. a group of protists that are believed to have given rise to animals.
b. specialized cells of sponges that function to trap and eat small particles.
c. cells that make up the gelatinous layer in sponges.
d. cells of sponges that function to transfer nutrients to other cells.
e. cells that form spicules in sponges.
Answer: b. Choanocytes are specialized cells of sponges that function to trap and eat small particles.
2. Which of the following is not a characteristic of ctenophores?
a. complete gut
b. bioluminescence
c. stinging cells
d. ciliary locomotion
e. All of the above are characteristics of ctenophores.
Answer: c. Ctenophores do not have stinging cells.
3. Which of the following organisms can produce female offspring through parthenogenesis?
a. cnidarians
b. flukes
c. choanocytes
d. rotifers
e. annelids
Answer: d. Rotifers can produce female offspring by parthenogenesis.
4. A lophophore is
a. a contractile structure that aids in movement through the water column.
b. a ciliated structure that aids in movement through the water column.
c. a ciliated structure that functions primarily in feeding.
d. a contractile structure that moves food into the coelom.
e. a contractile structure important for defense.
Answer: c. A lophophore is a cililated feeding device.
5. In the annelids, the metanephridia function in
a. transport of nutrients.
b. movement.
c. cellular communication.
d. waste removal
e. reproduction.
Answer: d. Metanephridia are excretory organs that remove waste products from the blood and
coelomic fluid.
6. A defining feature of the Ecdysozoa is
a. a segmented body.
b. a closed circulatory system.
c. a cuticle.
d. complete gut.
e. lophophore.
Answer: c. All ecdysozoans possess a cuticle, a nonliving cover that provides support and protection.
7. In arthropods, the tracheal system is
a. a unique set of structures that function in ingestion and digestion of food.
b. a series of branching tubes extending into the body that allow for gas exchange.
c. a series of tubules that allow waste products in the blood to be released into the digestive
tract.
d. the series of ommatidia that form the compound eye.
e. none of the above.
Answer: b. The tracheal system is a series of branching tubes extending into the body that allow for gas
exchange.
8. Characteristics of the class Arachnida include
a. two tagmata.
b. six walking legs.
c. an aquatic lifestyle.
d. a lobed body.
e. both b and d.
Answer: a. Characteristics of the class Arachnida include two tagmata and six pairs of appendages,
including four pairs of walking legs, one pair of fangs (chelicerae), and one pair of pedipalps. Arachnids
are terrestrial.
9. Incomplete metamorphosis
a. is characterized by distinct larval and adult stages that do not compete for resources.
b. is typically seen in arachnids.
c. involves gradual changes in life stages where young resemble the adult stage.
d. is characteristic of the majority of insects.
e. always includes a pupal stage.
Answer: c. Insects that undergo incomplete metamorphosis do not exhibit drastic changes in body form.
The young nymphs resemble the adult life stage. There may be competition between the different life
stages for resources.
10. In the phylum Echinodermata, the tube feet function in
a. movement.
b. gas exchange.
c. feeding.
d. excretion.
e. all of the above.
Answer: e. The tube feet of echinoderms are branches of the water vascular system. They function in
movement, gas exchange, feeding, and excretion.
Conceptual Questions
1. Define hermaphrodite.
Answer: Hermaphrodites are individuals that can produce both sperm and eggs.
2. Define nematocyst and explain its function.
Answer: The nematocyst is a powerful capsule with an inverted coiled and barbed thread that functions
to immobilize small prey so they can be passed to the mouth and ingested. It is a unique and
characteristic feature of the cnidarians.
3. Explain the difference between complete metamorphosis and incomplete metamorphosis.
Answer: Complete metamorphosis has four stages: egg, larva, pupa, and adult. The larval stage is often
spent in an entirely different habitat from that of the adult, and larval and adult forms utilize different food
sources. Incomplete metamorphosis has only three stages: egg, nymph and adult. Young insects, called
nymphs, look like miniature adults when they hatch from their eggs.
Experimental Questions
1. What was the hypothesis tested by Fiorito and Scotto?
Answer: The researchers tested the hypothesis that an octopus can learn by observing the behavior of
another octopus.
2. What were the results of the experiment? Did these results support the hypothesis?
Answer: The results indicated that the observer learned by watching the training of the other octopus.
The observer was much more likely to choose the same color ball that the demonstrator was trained to
attack. These results seem to support the hypothesis that octopuses can learn by observing the
behavior of others.
3. What is the significance of performing the experiment on both observer and untrained octopuses?
Answers: The untrained octopuses had no prior exposure to the demonstrators. The results indicated
that these octopuses were as likely to attack the white ball as the red ball. No preference for either color
was indicated. The untrained octopuses acted as a control. This is an important factor to ensure the
results from the trials using observers indicate response to learning and not an existing preference for a
certain color.
Collaborative Questions
1. Discuss some of the characteristics of the phylum Mollusca.
Answer: There are over 100,000 living species within the phylum Mollusca, including octopuses, clams,
snails, and slugs. Although there is great variation within this phylum, all mollusks have a body plan
consisting of three main parts: a visceral mass that contains the internal organs; a mantle that covers
the visceral mass and produces the shell (in species that have one) and a foot that is used for
locomotion. They are bilateral with respect to body symmetry and are triploblastic, which means they
have endoderm, ectoderm, and mesoderm. Most mollusks have an open circulatory system. Instead of
having a complex system of blood vessels, they have open sinuses where the internal organs are
bathed in blood. Aquatic mollusks have gills for respiration, while terrestrial mollusks have simple lungs
or respire across the surface of their skin. Most mollusks have separate sexes, although some species
are hermaphrodites, containing both male and female reproductive tissues. In aquatic species, gametes
are released into the water, where they mix and fertilization occurs. After fertilization, a free swimming
larva forms and usually joins the plankton at the surface of the water until it matures and settles out of
the plankton to continue its life on the bottom.
2. Discuss the four defining characteristics of chordates.
Answer: All chordates have four basic features common to all species within the phylum Chordata.
These characteristics are not persistent throughout the life of all chordates, but appear during some
time in the organism’s life.
Notochord - At some point in the life of a chordate, it has a support rod that lies between the digestive
tract and the nerve cord. In higher vertebrates, the notochord is replaced by a jointed structure called
the vertebral column and only remains as the soft material within the discs of the vertebrae.
Dorsal, hollow nerve cord - In nonchordate invertebrates, the nerve cord is a solid tube that lies ventral
to the digestive system. In the chordates, it is hollow and lies dorsal to the digestive system and the
notochord. In vertebrates, this structure commonly called the spinal cord and attaches to the brain, and
sends and receives information to and from the body.
Pharyngeal slits - In lower chordates such as the tunicate and the cephalochordates, the pharyngeal gill
slits are used primarily for removing particulate matter from the water, which is known as filter feeding.
In fish and some amphibians, the gill slits are used for respiration. In higher vertebrates, the pharyngeal
pouches are only present during embryonic development and give rise to structures in the neck and
head region.
Postanal tail - All chordates posses a tail during some time in the organism’s life. In most chordates,
this tail is kept throughout the life of the organism and serves a wide variety of functions. In some
vertebrates such as humans, this tail is only present during embryonic development.