Bio 160 FINAL

Deuterostomes

-tripoblast -anus from blastopore -coelom from folds of archenteron -radial, indeterminate cleavage

Protostomes

-tripoblast -mouth from blastopore -coelom from solid masses of mesoderm -spiral, determinate cleavage

Fishes that have swim bladders can regulate their density and, thus, their buoyancy. There are two types of swim bladder: physostomous and physoclistous. The ancestral version is the physostomous version, in which the swim bladder is connected to the esophagus via a short tube (see the figure above). The fish fills this version by swimming to the surface, taking gulps of air, and directing them into the swim bladder. Air is removed from this version by "belching." The physoclistous version is more derived, and has lost its connection to the esophagus. Instead, gas enters and leaves the swim bladder via special circulatory mechanisms within the wall of the swim bladder. Sharks do not have a swim bladder. When a shark stops swimming, it _____. 1. sinks 2. quickly dies 3. oxygenates its blood less effectively

1 and 3.

Name three statements that are true in reference to germ layers and body cavities.

1) A diploblast has no mesoderm. 2) A pseudocoelom has the same functions as a true coelom. 3) In a coelomate, the tissue lining the inner side of the body cavity arises from the same germ layer as the tissue lining the outer side of the body cavity. *Triploblasts have tissues derived from three embryonic germ layers: endoderm inside, ectoderm outside, and mesoderm in the middle. The three basic body plans of triploblasts relate to the presence or absence of a body cavity. -No body cavity: acoelomate -Body cavity lined on the inner side by endoderm-derived tissue and on the outer side by mesoderm-derived tissue: pseudocoelomate -Body cavity lined entirely by mesoderm-derived tissue: coelomate

Which of the following are characteristics of arthropods? 1. protostome development 2. bilateral symmetry 3. a pseudocoelom 4. three embryonic germ layers 5. a closed circulatory system

1, 2 and 4

All arthropods _____. 1) undergo complete metamorphose 2) have jointed appendages 3) molt 4) have segmented bodies 5) have an exoskeleton or cuticle

2, 3, 4, 5

The number of phyla of animals currently recognized by biologists is approximately

30 to 35

What is significant about cephalization?

A concentration of sensory organs allows better detection of threats for motile organisms. *This is a major advantage of motile organisms.

Why is it logical that Platyhelminthes have flattened bodies?

A flat body provides a large surface area for gas exchange, which compensates for their lack of gas-exchange organs.

Which of the following statements about deuterostomes is false?

All deuterostomes exhibit radial symmetry in their bodies. *This statement is false; in the deuterostome lineage, only adult echinoderms exhibit radial symmetry.

Which of the following classes is comprised of carnivorous predators that are able to extend their stomachs through their mouths to feed?

Asteroidea

Where should the origin of the water vascular system be placed on the phylogenetic tree?

At the base of Echinodermata *This is a defining character of echinoderms.

Where should the origin of spiral cleavage be placed on the phylogenetic tree?

At the base of Lophotrocozoa *Nearly all in this group have spiral cleavage.

Where would you add a segmentation notation to this figure to indicate the independent evolution of this in mollusks?

At the base of Mollusca *If it evolved independently, it would need to be noted separate from the annelid segmentation event.

Where should the origin of a flattened, acoelomate body plan be placed on the phylogenetic tree?

At the base of Platyhelminthes

Where should the origin of extensive parental care be placed on the phylogenetic tree?

At the base of crocodiles, alligators + birds, and at the base of mammals. * This trait likely evolved separately in these groups.

One trait that is shared by the Lophotrochozoa and Ecdysozoa is

Both groups are bilaterally symmetric triploblasts with the protostome pattern of development.

What is the relationship between choanoflagellates and animals?

Choanoflagellates are an outgroup to the animal lineages. *The choanoflagellate lineage diverged before animal lineages diverged from one another.

You find an animal with a bilateral larval form but what appears to be a radial adult form. Which taxa would you presume it to belong to?

Cnidaria * Cnidarian larvae are bilaterally symmetrical whereas adults appear radially symmetrical.

Whiteflies are common pest insects found on cotton, tomato, poinsettia, and many other plants. Nymphs are translucent and mostly sessile, feeding on their host plants' phloem (sap) from the undersides of leaves. They undergo incomplete metamorphosis into winged adults. Because whitefly nymphs cannot escape predation by moving, you hypothesize that their translucent bodies make them hard to spot by predators. How could you directly test this hypothesis?

Compare rates of predation on whitefly nymphs coated with a nontoxic dye vs. undyed whitefly nymphs.

Why are the feeding structures of these worms so different?

Diversification in feeding reduces competition. *Natural selection favors a divergence of feeding types.

The protostome developmental sequence arose just once in evolutionary history, resulting in two main subgroups—Lophotrochozoa and Ecdysozoa. What does this finding suggest?

Division of these two groups occurred after the protostome developmental sequence appeared.

What characterizes an ecdysozoan?

Ecdysozoans grow by molting. *Ecdysozoa are defined by a clear synapomorphy: They grow intermittently by shedding the exoskeleton, or external covering.

Mammals and birds eat more often than reptiles. Which of the following traits shared by mammals and birds best explains this habit?

Endothermy. *evolved independently

Which structure is not an innovation that occurred during vertebrate diversification?

Exoskeleton. *Exoskeletons are present in groups other than the vertebrates, including some in the protostome lineage. **Bone, jaws and amniotic eggs were.

True or false? All multicellular animals are triploblasts.

False

True or false? An organism that is radially symmetric has many well-developed head regions.

False. *An organism that is radially symmetric does not have a well-developed head region.

What is the single unique characteristic that distinguishes extant birds from other extant vertebrates?

Feathers

Brown et al. and Morwood et al. reported in 2004 that they had found skeletal remains of a previously unknown type of hominin, now dubbed Homo floresiensis, on the Indonesian island of Flores. These hominins were small (approximately 1 meter tall) with small braincases (approximately 380 cubic centimeters) as compared with other hominins. The remains of H. floresiensis were found alongside handmade stone tools and the remains of dwarf elephants that also inhabited the island, suggesting that H. floresiensis was able both to make tools and to coordinate the hunting of animals much larger than itself. H. floresiensis is estimated to have lived at the site where the remains were found from at least 38,000 years ago to 18,000 years ago. Refer to the paragraph on Brown et al. and Morwood et al. It is speculated that H. floresiensis and H. sapiens may have lived on Flores concurrently. Suppose researchers obtained mitochondrial DNA samples from the H. floresiensis remains, amplified a 1000-base-pair sequence via PCR, and compared it to that of several currently living H. sapiens native to Indonesia, North Africa, and North America. Also suppose H. floresiensis were found to differ from the average Indonesian H. sapiens in 28 base pairs, from the average North African H. sapiens in 51 base pairs, and from the average North American H. sapiens in 53 base pairs, while two randomly selected H. sapiens differed from each other in an average of 21 base pairs. What would you surmise from these data?

H. floresiensis and H. sapiens probably lived on Flores concurrently and interbred to some degree.

Which of the following is consistent with the out-of-Africa hypothesis?

Homo sapiens have a common ancestor with Neanderthal and Homo erectus from Africa but did not interbreed with them.

With which of the following statements would a biologist be most inclined to agree?

Humans and other apes represent divergent lines of evolution from a common ancestor.

Radial symmetry

Hydra and jelly *in which the body is wheel- or spoke-shaped, with no obvious front, back, right, or left.

What reproductive trait is associated with terrestrial environments?

Internal fertilization *Internal fertilization greatly enhances the ability of sperm to successfully travel to the egg.

You find what you believe is a new species of animal. Which of the following characteristics would enable you to argue that it is more closely related to a flatworm than it is to a roundworm?

It has no coelom.

You believe that an adult animal you are examining is a vertebrate but concede that it may be an invertebrate chordate. Which of the following would ensure that you are indeed looking at a vertebrate?

It lacks a notochord.

How did the evolution of the jaw contribute to diversification of early vertebrate lineages?

It made additional food sources available.

On the back of your skull you can feel a small bump, below which is an opening where the spinal cord enters the skull. The location of this opening toward the bottom of the skull is significant in evolutionary biology for what reason?

It occurred as a result of the change to a bipedal stance.

You find a new species of worm and want to classify it. Which of the following lines of evidence would allow you to classify the worm as a nematode and not an annelid?

It sheds its external skeleton to grow.

A team of researchers has developed a poison that has proven effective against lamprey larvae in freshwater cultures. The poison is ingested and causes paralysis by detaching segmental muscles from the skeletal elements. The team wants to test the poison's effectiveness in streams feeding Lake Michigan, but one critic worries about potential effects on lancelets, which are similar to lampreys in many ways. Why is this concern misplaced?

Lancelets live only in saltwater environments.

Why would the absence of a particular trait not exclude a species from a particular clade that possesses that trait?

Loss of a trait is a key part of diversification. *The loss of a trait can be adaptive under a changed ecological condition.

Which group is most closely related to amphibians?

Mammalia and Aves *These are amniotes that are equally related to amphibians.

Which one of the following is a lophotrochozoan?

Mollusks

A new species of aquatic chordate is discovered that closely resembles an ancient form. It has the following characteristics: external armor of bony plates, no paired lateral fins, and a suspension-feeding mode of nutrition. In addition to these, it will probably have which of the following characteristics?

No jaws.

In which vertebrates did feathers first evolve?

Non-avian dinosaurs. *Feathers evolved in a series of steps, beginning with simple projections from the skin ("dinofuzz") that evolved into the complex, branched feathers of living birds.

What would be the best anatomical feature to look for to distinguish a gastropod from a chiton?

Number of shell plates.

Bilateral Symmetry

Octopus, turtle, snake and bobcat *in which the body has left and right sides, a front and back, and a top and bottom.

Why is the ancestral state considered aquatic and not terrestrial in this phylogeny?

Outgroups are aquatic. *The more ancestral groups of Cnidaria and Porifera were aquatic.

Which structure can be used for feeding and gas exchange?

Pharyngeal gill slit *A pharyngeal gill slit is an opening into the throat that can be used for feeding and gas exchange.

There is some evidence that pharyngeal gill slits occur in certain species of echinoderms that appear early in the fossil record. If confirmed, what do these data suggest?

Pharyngeal gill slits were present in the earliest echinoderms and lost later.

Which phylum includes the most basal lineages of animals?

Porifera *Sponges (phylum Porifera) include the two most basal animal lineages.

Which of the following is a characteristic of all chordates at some point during their life cycle?

Post-anal tail.

Which character would allow you to identify something as an echinoderm and not a chordate?

Radial symmetry

Why do skates and rays have flattened bodies, while sharks are torpedo shaped?

Sharks are streamlined for active swimming off the bottom, while skates move about mostly on the ocean bed.

Asymmetry

Sponge

What part of the squid is homologous to the snail foot?

Tentacles. *These two structures emerge from the same developmental tissue.

What is believed to be the most significant result of the evolution of the amniotic egg?

Tetrapods were no longer tied to the water for reproduction.

The common ancestor of the protostomes had a coelom. What does this suggest?

The body cavity evolved before the lophophore.

Why was the evolution of a coelom a critically important innovation for animals?

The coelom can act as a hydrostatic skeleton. * A soft-bodied animal with a coelom acting as a hydrostatic skeleton can move effectively even if it lacks fins or limbs.

Adaptations to terrestrial environments evolved independently in arthropods, mollusks, nematodes, and annelids. What logical conclusion would you make from this statement?

The common ancestor of all these groups was probably aquatic.

Which of the following statements about vertebrates is true?

The development of an amniotic egg and internal fertilization allowed vertebrates to reproduce away from water. *Reptiles and their descendants reproduce on land via an amniotic egg, which prevents the embryo from drying out.

Suppose a researcher for a pest-control company developed a chemical that inhibited the development of an embryonic mosquito's endodermal cells. Which of the following would be a likely mechanism by which this pesticide works?

The mosquito would have trouble digesting food, due to impaired gut function.

What do all deuterostomes have in common?

The pore (blastopore) formed during gastrulation becomes the anus.

Which characteristics define a chordate?

The presence of four specific morphological traits *Chordates are defined by the presence of four morphological traits: a notochord, a dorsal nerve cord, pharyngeal gill slits, and a tail behind the anus.

In chordates, what is the relationship between the dorsal hollow nerve cord and the spinal cord?

The spinal cord is a type of dorsal hollow nerve cord.

Which characteristic distinguishes echinoderms from the other two deuterostome lineages?

Their body plan. *Echinoderms exhibit a unique body plan characterized by an endoskeleton and a water vascular system.

It is believed that the coelacanths and lungfish represent a crucial link between other fishes and tetrapods. What is the major feature in these fish in support of this hypothesis?

Their fins have skeletal and muscular structures similar to amphibian limbs.

What does phylogenetic evidence tell us about protostomes?

There were multiple transitions from water to land. *Unlike deuterostomes, which made the transition once, each lineage of protostomes that includes terrestrial members made a separate transition.

Predict why annelids and arthropods were thought to be closely related, before the phylogenetic analyses in the late 1990s.

They have segmented bodies, unlike other protostomes.

What structure in a placental developing organism is greatly reduced (but not absent) as compared to an amniotic egg?

Yolk sac *The placenta replaces the core function of the yolk sac (to provide nutrients to the embryo).

Nematode worms and annelid worms share which of the following features?

a digestive tract with two openings (a mouth and an anus)

In a tide pool, a student encounters an organism with a hard outer covering that contains much calcium carbonate, an open circulatory system, and gills. The organism could potentially be a crab, a shrimp, a barnacle, or a bivalve. The presence of which of the following structures would allow for the most certain identification of the organism?

a mantle

A land snail, a clam, and an octopus all have

a mantle.

Due to its unusual habitat (inside the digestive tracts of other animals), the tapeworm lacks

a mouth and a digestive tract

Vertebrates and tunicates share _____.

a notochord and a dorsal, hollow nerve cord

Terry catches a ray-finned fish from the ocean and notices that attached to its flank is an equally long, snakelike organism. The attached organism has no external segmentation, no scales, a round mouth surrounded by a sucker, and two small eyes. Terry thinks it might be a marine leech, a hagfish, or a lamprey. Terry takes the body of the snakelike organism and slices it open along its dorsal side. If it is a hagfish, what should Terry see?

a notochord, located underneath the spinal cord

Which of the following organisms would you expect to have the largest surface-area-to-volume ratio? Assume that all of the following are the same total length.

a platyhelminth

The basic bilaterian body form plan can be thought of as simply

a tube within a tube *The inner tube is the individual's gut, with a mouth at one end and an anus at the other, and the outer tube forms the nervous system and skin.

Metamorphosis is

a type of life cycle *In animals that undergo metamorphosis, the larval form looks radically different from the adult form.

Why do adult urochordates (tunicates) lack notochords, even though larval urochordates have them? Larvae use notochords to _____.

aid in swimming; adults are sessile and thus no longer propel themselves.

Suppose, while out camping in a forest, you found a chordate with a long, slender, limbless body slithering across the ground near your tent. This critter could be

an amphibian

Arthropods invaded land about 100 million years before vertebrates did so. This most clearly implies that

arthropods have had more time to coevolve with land plants than have vertebrates

Due to its system of air sacs connected to the lungs, the respiratory system of birds is arguably the most effective respiratory system of all air-breathers. Upon inhalation, air first flows into posterior air sacs, then into the lungs, and then into anterior air sacs on the way to being exhaled. Thus, there is one-way flow of air through the lungs, along thousands of tubules called parabronchi. Which type of bird is most likely to benefit from air sacs which reduce its weight?

birds, such as geese, which migrate great distances

You find a wormlike animal while scuba diving and want to determine whether it is a nudibranch, a polychaete, or a flatworm. Finding which of the following traits would best help you classify the mystery animal?

bristle-like structures on tiny appendages

Long before humans invented it to power aircraft, jet propulsion evolved in

cephalopod mollusks. *Cephalopods have a mantle lined with muscle. When the cavity surrounded by the mantle fills with water and the mantle muscles contract, a stream of water is forced out the siphon, propelling the squid or octopus backward.

Which of the following would you classify as something other than an animal?

choanoflagellates

Which of the following is an example of homology (similarity due to common ancestry)?

cnidocytes (stinging cells) in jellyfish and sea anemones

The evolution of similar insulating skin coverings such as fur, hair, and feathers in mammals and birds is a result of

convergent evolution

Neither protostomes and deuterostomes are

diploblast

The vertebrate spinal cord develops from the embryonic _____.

dorsal hollow nerve cord

This phylum is exclusively marine and is named for having many spines and spikes.

echinoderms *Echinoderm means "spiny-skin."

In your body, the inside "tube" within a "tube" is derived from the

endoderm *The cell layers that form the gut are derived from the endoderm.

A cephalopod's tentacles are modified from its

foot

A farm pond, usually dry during winter, has plenty of water and aquatic pond life during the summer. One summer, Sarah returns to the family farm from college. Observing the pond, she is fascinated by some six-legged organisms that can crawl about on submerged surfaces or, when disturbed, seemingly "jet" through the water. Watching further, she is able to conclude that the "mystery organisms" are ambush predators, and their prey includes everything from insects to small fish and tadpoles. Sarah observed that the mystery pond organisms never come up to the pond's surface. If she catches one of these organisms and observes closely, perhaps dissecting the organism, she should find _____.

gills

Which of the following characteristics does not apply to cnidarians?

have a central nervous system *but they do undergo metamorphosis, usually diploblastic, possess a gastrovascular cavity with one opening

Arthropod exoskeletons and mollusk shells both

help retain moisture in terrestrial habitats

Animals that feed primarily or exclusively on plants and algae are classified as

herbivores

Both animals and fungi are heterotrophic. What distinguishes animal heterotrophy from fungal heterotrophy is that most animals derive their nutrition by

ingesting it

The presence of a lophophore in a newly discovered species would suggest that the species

is a suspension feeder.

The leading hypothesis for the origin of the jaw proposes that

it resulted from mutations in the developmental regulatory genes that determine the morphology of the gill arches. *The gill-arch hypothesis proposes that mutation and natural selection increased the size of the most anterior arch and modified its orientation slightly, producing the first working jaw.

Predict the circumstances under which sexual reproduction would be favored.

lack of resources, predation, infection

The molluscan body plan is based on three major components: the foot, the visceral mass, and the

mantle. *The mantle is an outgrowth of the body wall that covers the visceral mass, forming an enclosure called the mantle cavity. In many species, the mantle secretes a hard calcium carbonate shell.

Lophotrochozoan phyla include

mollusks, annelids, and flatworms

According to the evidence collected so far, the animal kingdom is

monophyletic

Wormlike lineages of lophotrochozoans are distinguished by specialized

mouthparts or feeding structures

Primate evolution and behavior, such as hunting skills, have been directed in part by the development of depth perception. What anatomical change made depth perception possible?

movement of the eyes to the front of the head

What synapomorphy (shared, derived trait) distinguishes animals as a monophyletic group, distinct from choanoflagellates?

multicellularity

Which of the following is (are) unique to animals

nervous system signal conduction and muscular movement

As a group, invertebrates are _____.

paraphyletic *This group does not include vertebrates and therefore is not a complete monophyletic group.

A placenta and viviparity are most likely adaptations for increasing

parental care and offspring survival *Placental mammals provide considerable maternal care, increasing offspring survival.

Some sea anemones can produce large colonies by reproducing asexually, but they can also produce planktonic larvae by reproducing sexually. Predict the circumstances under which asexual reproduction would be favored.

plenty of resources such as space and food

Which of the following is found in many tetrapods but not in fish?

production of amniotic eggs

The central nervous system is lacking in animals that have

radial symmetry

You have a unique opportunity to explore a pristine coral reef in the South Pacific. You come across a small organism that you do not recognize and that is not in your field guide. Which of the following suites of characteristics would be most helpful in identifying the organism's phylum?

radial symmetry, sessile, two tissue layers

If a tunicate's pharyngeal gill slits were suddenly blocked, the animal would have trouble

respiring and feeding

An elementary school science teacher decided to liven up the classroom with a saltwater aquarium. Knowing that saltwater aquaria can be quite a hassle, the teacher proceeded stepwise. First, the teacher conditioned the water. Next, the teacher decided to stock the tank with various marine invertebrates, including a polychaete, a siliceous sponge, several bivalves, a shrimp, several sea anemones of different types, a colonial hydra, a few coral species, an ectoproct, a sea star, and several herbivorous gastropod varieties. Lastly, she added some vertebrates—a parrotfish and a clownfish. She arranged for daily feedings of copepods and feeder fish. The bivalves started to die one by one; only the undamaged shells remained. To keep the remaining bivalves alive, the teacher would most likely need to remove the _____.

sea star

Which morphological trait evolved more than once in animals, according to the phylogeny based on DNA sequence data found in the figure above?

segmentation

You find a small animal with eight legs crawling up your bedroom wall. Closer examination will probably reveal that this animal also has

simple, but not compound, eyes

What would be the most direct effect of removing or damaging an insect's antennae? The insect would have trouble

smelling

Lophotrochozoan phyla have a lophophore, a specialized structure for

suspension feeding. *The lophophore is a specialized structure that rings the mouth and functions in suspension feeding.

Which adaptation is unique to insects among all protostomes?

the ability to move by flying

Which evolutionary innovation was most significant in helping tetrapods move to dry terrestrial environments?

the amniotic egg

The phyla Porifera, Cnidaria, and Ctenophora are

the most ancient of all animal lineages

An adult animal that possesses bilateral symmetry would most likely be

triploblastic

Among protostomes, which morphological trait has shown the most variation?

type of body cavity (coelom vs. pseudocoelom vs. no coelom)