Biological Principles 2 -- HW#33

1.      The arthropods are the most successful group of animals; several key features explain their success. Check all of the features that one would use to classify members into this phylum.

·         Growth takes place through ecdysis; A rigid exoskeleton made of chitin; Jointed appendages; Segments specialized into functional tagmata

2.      What phylum do clams belong to? Mollusks

3.      You and another biologist are digging in the mud and you find what you think is a clam. Your fellow biologist disagrees with you. To explain yourself, which characters that are unique to clams do you point out? Adductor muscle; Mantle; foot

4.      Most cnidarians possess two distinct body forms: the polyp, which is sessile, and the medusa, which is motile.

5.      The change of a larval form of insect to a different adult form is known as complete metamorphosis

6.      Certain small fish are able to live among the tentacles of the Portuguese man-of-war being nearly immune to the poison from the stinging cells. These fish are said to have a commensalistic relationship with the Portuguese man-of-war because the fish benefit and have no effect on the host. What is the most likely benefit for small fishes living among the tentacles of the Portuguese man-of-war? They are protected from predators.

7.      What characteristics of animals are exemplified by the man-of-war? Heterotrophy; Active movement; tissue

8.      Match the molluscan body part to its function.

·         Mantle: secretes the shell

·         Mantle cavity: houses gills

·         Foot: movement

·         Visceral mass: houses organs

9.      Segmentation in the annelid worms has facilitated locomotion and specialization of different parts of these animals. Evaluate the following statements about segmentation in the annelids and determine if they are true or false.

·         Excretion is accomplished by paired protonephridia with flame cells in every segment of the body. False

·         If the organs in one segment fail, the organs of another segment will still function. True

·         Annelids possess both circular and longitudinal muscles that produce waves of contraction that are propagated down through the series of segments. True

·         Segmentation has allowed for specialization in the anterior of the annelid body, which has provided for a more sophisticated nervous system. True

·         The circulatory system found in annelids is usually open. False

10.  Molecular data suggests that the Lophotrochozoa is a new clade of bilaterally symmetric animals that originally included phyla separated by differences in body plan (those lacking a coelom, possessing a pseudocoelom, or possessing a true coelom). Platylhelminthes; Mollusca; annelida

11.  Chordates possess several distinguishing characteristics that separate them from other animal groups.

·         Postanal tail; Pharyngeal slits; Notochord; Dorsal hollow nerve cord

12.  Animals in the phylum Arthropoda grow through the process of ecdysis. Evaluate the following statements about ecdysis and the cuticle and determine if they are true or false.

·         The cuticle is a non-living cover that serves to both support and protect the animal. True

·         The cuticle is porous and the diffusion of respiratory gases, even through the thickest areas, is not a problem. False

·         The cuticle limits growth and must be periodically shed to allow a new larger cuticle to be formed. True

·         A disadvantage in possessing a cuticle is that it forces fertilization to be external. False

·         Nematodes and arthropods utilize similar hormones in the molting process, suggesting that these two phyla are closely related within the Ecdysozoa. True

13.  If a mutation occurred in a flatworm such that the flame cells no longer functioned, what do you predict would be the consequence? Excretory function would be impaired.

14.  Because ticks are arthropods, they have exoskeletons and jointed appendages. True

15.  The deer tick relies on sensory receptors to locate its potential host. What substances do these receptors detect? Heat and carbon dioxide

16.  According to the information in the video, what association best describes the relationship of the deer tick to the deer? Parasitic: one individual benefits while the other is negatively impacted

17.  Cnidarians belong to a phylum with an extensive fossil record. They possess several unifying characteristics. Evaluate the following statements about cnidarian structure and determine if they are true or false.

·         The epidermis, mesoglea, and gastrodermis represent the triploblastic condition found in all cnidarians. False

·         Cnidarians can exhibit one of two life forms: a sessile polyp and/or a free-swimming medusa form. True

·         Cnidarians consume food brought inside the gastrovascular cavity using extracellular digestion. True

·         Cnidarians are able to capture prey by stinging them with microscopic harpoon-like projectiles released by special cells called nematocytes. True

·         Cnidarians can detect and react to prey using a centralized nervous system. False

18.  Adult echinoderms display pentaradial symmetry; however, their larvae display bilateral symmetry.

19.  The mollusks constitute a large phylum with many different types of organisms. Associate the following attributes with the 4 different groups of mollusks.

·         Cephalopoda: tentacles surrounding the mouth; closed circulatory system; jet propulsion via siphon

·         Gastropoda: aquatic or terrestrial; coiled shell

·         Bivalvia: filter feeders with siphons; marine or freshwater; shell with two halves

·         Polyplacophora: eight-plated shell

20.  Animals that lack a vertebral column are known as invertebrates

21.  Picture

22.  Your lab group is charged with the identification of an unknown creature. Your lab partners believe that is a small annelid because of its worm-like appearance. You argue it is a nematode. To convince your lab partners, you point out certain distinguishing characteristics. Check the characteristics that are associated with the nematodes.

·         Nematodes secrete a cuticle, which is made primarily of collagen

·         Their pseudocoelom functions both as a circulatory system and a hydrostatic skeleton

·         Fertilization takes place internally

23.  Although a medusa and a polyp look different, they have similar body plans. True

24.  An animal that is attached to the substrate and cannot move from one place to another is said to be sessile

25.  How does an open circulatory system differ from a closed one? The open circulatory system has a combination of blood vessels and large thin-walled sinuses whereas a closed circulatory system has only vessels.

26.  As you examine a soil sample under your microscope, you note the presence of tiny, worm-like organisms. You immediately suspect that these creatures are nematodes. The presence of which characteristics would support your hypothesis? Longitudinal but no circular muscles; Separate male and female individuals; Shedding of the integument; A tough, collagen-based cuticle

27.  The choanocytes have a flagellum that moves water through the sponge and a collar that extracts food particles from the water. In what group have you encountered very similar cells before? The choanoflagellates

28.  Sperm and eggs of the various corals are released into the water around the coral reef, yet cross fertilization between species does not occur. What assumption underlies this statement? There is some type of incompatibility between the sperm and eggs of different species.

29.  Select all of the following that are true about cephalopods.

·         They may be very large and can weigh as much as two tons; They are very intelligent and are capable of learning by observation; They have a closed circulatory system

30.  Each arm of the starfish differs internally, one being specialized for reproduction, another for respiration, a third for digestion, a fourth for the water vascular system, and the fifth for the nervous and circulatory systems. False

31.  Describe the characteristics of the Phylum Platyhelminthes. They are acoelomate; They are triploblastic; They exchange respiratory gases through body wall

32.  What is the advantage to the segmentation that is exemplified in the Phylum Annelida? Vital structures are repeated in each segment; The annelid may still survive if one segment is damaged; Locomotion is more efficient; Segments can be specialized

33.  Characterize the life cycle of cnidarians. Some have only polyps, some have both polyps and medusae, and others have medusae and a reduced polyp stage.

34.  Sponges are comprised of several cell types, which are similar to those found in the Eumetazoa, but also display a unique degree of flexibility. Complete each sentence to correctly describe these cell types as they relate to the sponges.

·         Sponge cells are unique because throughout their development they can differentiate from one type of cell to another.

·         Sponges are truly multicellular organisms.

·         Sponges have flagellated cells called choanocytes that line internal cavities and are responsible for pumping water and small particles into the sponge.

·         The exterior of a sponge is comprised of flattened cells that form an outer epithelium

·         The inner layer of a sponge, the mesohyl, contains several types of amoeboid cells, which secrete materials to form a skeleton-like structure for support.

35.  There are advantages and disadvantages to having an exoskeleton. Complete the following sentences selecting from the terms provided.

·         The exoskeleton is made of chitin, which is an extremely strong and flexible

·         The exoskeleton provides antagonism for muscle action

·         The exoskeleton protects against water loss

·         As the arthropod grows, the exoskeleton must become thicker to bear the force of the muscles

·         To grow the arthropod must undergo ecdysis, during which time they are extremely vulnerable to predators.

36.  The nervous system of a cnidarian consists of a central ganglion leading into a nerve net. False

37.  The two body forms of some Radiata is an example of alternation of generations. False