Exam 2 (slides)

Question 1

List three common characteristics of animals that are not found in other multicellular eukaryotes (4)

Answer 1

1. All animals are multicellular and heterotrophic, which means they must acquire nutrients from an external source. Animals ingest (eat) whole food and digest internally.
2. Animals have a variety of life cycles. Many reproduce sexually and some asexually and some combine both life cycles. Many animals have a diploid life cycle.
3. Animals are monophyletic. Within the animal lineage are two main branches: invertebrates and vertebrates. They are both descended from a single common ancestor.
4. They are characterized by muscle and nerve tissues.

Question 2

Summarize the colonial flagellate hypothesis as its relates to the origin of animals (7)

Answer 2

1. Animals are descended from an ancestor resembling a hollow spherical colony of flagellated cells.
2. Among protists, the choanoflagellates most resemble the last single-celled ancestor of animals.
3. A choanoflagellate is a single cell with a flagellum.
4. The transition from colonial flagellates to multicellular animals may have begun by aggregation of a few flagellated cells.
5. Individual cells within the colony may have specialized.
6. Two tissue layers may have arisen by infolding of certain cells into a hollow sphere.
7. This hypothesis is attractive because of its implications regarding animal symmetry

Question 3

Distinguish among the different body plans of animals

embryonic development) (symmetry) (cephalization) (cleavage) (11

Answer 3

1. Embryonic Development.
2. The first tissue layers that appear are called germ layers.
3. These give rise to organs and organ systems.
4. Diploblastic: Two tissue layers. Triploblastic: Three tissue layers.
5. Symmetry – A pattern of similarity that is observed in objects
6. Three types of symmetry in animal kingdom–
7. Asymmetry – No particular body shape (e.g., sponge)
8. Radial symmetry – Two identical halves (e.g., jellyfish)
   - Enables an animal to reach out in all directions from one center
9. Bilateral symmetry – Definite right and left halves
   - Animals tend to be active and to move forward at an anterior end
   - The localization of the brain and sensory organs at the anterior end is called cephalization.
10. Cleavage – Cell division without growth
11. Certain animals have a true coelom

Question 4

Differentiate between protostome and deuterostome development (2)

Answer 4

1. Protostomes – First opening becomes the mouth, Spiral cleavage, Coelom forms by a splitting of the mesoderm
2. Deuterostomes – First opening becomes the anus, and the second opening becomes the mouth, Radial cleavage, Coelom forms by an out-pocketing of primitive gut.

Question 5

Explain why sponges are considered to be the simplest animals

Answer 5

It is the only level of animal to lack true tissues and they have only a cellular level of organization. It has asymmetry meaning it has no particular body shape.

Question 6

Discuss how a sponge respires, feeds, and reproduces (3)

Answer 6

1. Saclike bodies are perforated by many pores. Beating of flagella produces water currents that flow through pores into central cavity and out osculum.
2. It is a sessile filter feeder. They stay in one place and filters food from water
3. They reproduce asexually by fragmentation or by budding. Sexual reproduction produces a flagellated larva that may swim to a new location. Sponges are capable of regeneration, growth of a whole from a small part.

Question 7

Compare the anatomical features of comb jellies to those of cnidarians, such as hydras

Answer 7

Both have tentacles. Comb jellies have long tentacles covered with sticky filaments. Hydras have 4 to 6 tentacles contacting nematocysts that surround the mouth. Both contain jellylike material called mesoglea.
Both comb jellies and hydras are solitary.

Question 8

Anatomical features of comb jellies (7)

Answer 8

1. They are solitary, free-swimming marine invertebrates.
2. They are small, transparent, and sometimes bioluminescent. Bioluminescent organisms can produce their own light.
3. The body is composed of mesoglea, a jellylike substance.
4. Comb jellies have been shown to contain DNA sequences more ancient than sponges.
5. Comb jellies may have been the first organisms to evolve.
6. They are the largest animals propelled by beating of cilia.
7. They capture prey with colloblasts.

Question 9

Anatomical features of cnidarians, such as hydra (11)

Answer 9

1. Tubular animals that most often reside in shallow marine waters
2. Polyp and medusa body forms
3. The polyp mouth is directed upward, while the mouth of a jellyfish or medusa is directed downward.
4. Specialized stinging cells (cnidocytes)–Fluid-filled capsule, nematocyst
5. Two-layered body sac.
   5a. Outer layer – Protective epidermis.
   5b. Inner layer – Gastrovascular cavity
6. Hydra: Freshwater cnidarian
7. Small tubular poly body about one-quarter inch in length
8. Gastrovascular cavity is central cavity
9. Tentacles can respond to stimuli.
10. Can reproduce sexually and asexually
11. Nerve net–Interconnected nerve cells

Question 10

List the basic features of lophotrochozoans. (6)

Answer 10

1. Bilaterally symmetrical
2. Embryos with three germ layers
3. Protostome pattern of development
4. Adults with organ level of organization
5. Some with true coelom
6. Divided into two groups: Lophophorans (bryozoans, brachiopods, phoronids) and Trocohozoans (flatworms, rotifers, mollusks, annelids)

Question 11

Describe the basic anatomy and physiology of a planarian (14)

Answer 11

1. Live in freshwater habitats
2. Head bluntly arrow shaped
3. Auricles function as sense organs.
4. It has two light-sensitive eye spots.
5. Three kinds of muscle layers: Outer circular layer, Inner longitudinal layer, and Diagonal layer
6. Excretory organ functions in osmotic regulation and water excretion
7. Can reproduce asexually or sexually
8. Hermaphroditic
9. Practice cross-fertilization
10. Also reproduce asexually by regeneration
11. Have undergone cephalization
12. Head has lateral extensions with chemosensory and tactile cells
13. Ladder-type nervous system
14. Paired ganglia function as a primitive brain

Question 12

Summarize the steps in the life cycle of Schistosoma (7)

Answer 12

1. The Schistosoma life cycle starts with the larvae penetrating the skin of a human, the primary host, and maturing in the liver.
2. Adult worms live and copulate in blood vessels of the human gut.
3. Eggs migrate into the digestive tract and are passed in feces.
4. Ciliated larvae hatch in water and enter a snail, the secondary host.
5. In the snail, a mother sporocyst encloses many developing daughter sporocysts.
6. Daughter sporocysts enclose many developing larvae.
7. This larvae breaks out of daughter sporocysts, escapes the snail, and enters water.

Question 13

Summarize the steps in the life cycle of Taenia (6)

Answer 13

1. The Taenia life cycle starts with the primary host ingesting meat containing bladder worms.
2. The bladder worm attaches to human intestines where it matures into a tapeworm.
3. As the tapeworm grows, proglottids mature, and eventually fill with the eggs.
4. Eggs leave the primary host in feces, which may contaminate water or vegetation.
5. Livestock may ingest the eggs, becoming a secondary host as each larvae becomes a bladder worm encysted in muscle.
6. Rare or uncooked meat from secondary hosts contains many bladder worms.

Question 14

Identify morphological features of mollusks (4)

Answer 14

1. Have three-part body plan
   a. ) Visceral Mass–Contains internal organs
   b. ) Mantle–May secrete shell and/or contribute to development of gills or lungs
   c. ) Foot–Muscle adapted for locomotion, attachment, or food capture
2. Nervous system consists of several ganglia connected by nerve cords.
3. True coelom is reduced, and largely limited to the region around the heart.
4. Heart pumps hemolymph through vessels into hemocoel.

Question 15

Identify morphological features of bivalves (10)

Answer 15

1. Shell of two hinged parts, closed by powerful muscles
2. No head, no radula
3. Little cephalization
4. Open circulatory system
5. Ciliated gills hang down within the mantle cavity on either side of the visceral mass.
6. Beating of cilia causes water to enter the mantle cavity.
7. Filter feeders – capture tiny food particles suspended in water
   In freshwater clams
8. The sexes are separate
9. Fertilization is internal
10. Specialized larvae are released from the clam

Question 16

Identify morphological features of rotifers (2)

Answer 16

1. Named for crown of cilia (known as the corona) resembling a rotating wheel
   a. ) Serves as both an organ of locomotion and aids direction of food to mouth
2. Mostly freshwater, although some marine and terrestrial forms exist

Question 17

Identify morphological features of annelids (6)

Answer 17

1. Segmented partitions (septa) divide the well-developed, fluid-filled coelom, which acts as a hydrostatic skeleton.
2. Specialized digestive tract
3. Closed circulatory system
4. Ventral solid nerve cord
5. Most are marine
6. Setae (bristles) help in movement

Question 18

Identify morphological features of annelids (earthworms)

11

Answer 18

1. Setae protrude in pairs directly from surface of body.
2. Specialized digestive system: Food is drawn into the mouth by action of the muscular pharynx.
3. Food is stored in a crop and ground up in a gizzard.
4. Digestion and absorption occur in a long internal intestine.
5. Typhlosole increases the surface for absorption.
6. Waste is eliminated through the anus.
7. Earthworm segmentation evidenced by:
   a. ) Body rings
   b. ) Coelom divided by septa
   c. ) Setae arranged in pairs on segments
   d. ) Ganglionic swellings and lateral nerves in each segment
   e. ) Nephridia in each segment
   f. ) Branched blood vessels in each segment
8. Hermaphroditic
9. Two worms lie in parallel to each other, facing in opposite directions.
10. Fused mid-body segment (clitellum) secretes mucus, protecting sperm from desiccation.
11. There is no larval stage.

Question 19

Identify morphological features of annelids (marine polychaetes (3), leeches(4))

Answer 19

Most annelids are marine polychaetes.
1. Setae are in bundles on parapodia.
2. Clam worms, like Nereis, are predators.
3. They have sex organs only during the breeding season.
Leeches are usually found in freshwater habitats. They have the same body plan as other annelids.
1. They have no setae.
2. Each body ring has several transverse grooves.
3. Two additional suckers
4. Keep blood flowing and prevent clotting by means of hirudin, a powerful anticoagulant in saliva

Question 20

Identify the characteristics unique to ecdysozoans. (5)

Answer 20

1. Ecdysis means “stripping off.”
2. They construct an outer covering called a cuticle.
3. Protects and supports animal and Is shed by molting
4. The ecdysozoans include roundworms and arthropods.
5. They have evolved separate sexes.

Question 21

Anatomical features of roundworms (2,a)

Answer 21

1. Nonsegmented, generally colorless worms
2. Contain a pseudocoelom: A “false” body cavity that is incompletely lined by mesoderm
   2a. ) Provides a space for internal organs and can serve as hydrostatic skeleton

Question 22

Anatomical features of arthropods (4)

Answer 22

1. Rigid, jointed exoskeleton composed of chitin
   a. ) Must molt as they grow
2. Segmented, but some segments are fused into regions
   2a. ) Head, thorax, abdomen
3. Well-developed nervous system
   3a. ) Brain and ventral nerve cord
   3b. ) Eyes simple or compound
4. Variety of respiratory organs: Gills, book lungs, tracheae

Question 23

Compare the anatomical features of roundworms and arthropods.

Answer 23

Roundworms and arthropods have some type of skeleton, and both of them are either unsegmented or have segments that are fused together. They are ecdysozoans that periodically shed their outer covering

Question 24

Describe the five characteristics responsible for the success of the arthropods (5)

Answer 24

1. Rigid, jointed exoskeleton composed of chitin that must molt as they grow
   - The exoskeleton serves for protection, attachment for muscles, locomotion, and prevention of desiccation.
2. Segmented (pair of jointed appendage), but some segments are fused into regions that are the head, thorax, abdomen
   - The appendages are modified for food gathering, reproduction, and locomotion. Some appendages associated with sensory structures are used for tactile purposes.
3. Well-developed nervous system that includes the brain and ventral nerve cord and eyes simple or compound
   - Many arthropods have well-developed touch, smell, taste, balance, and hearing.
   - They display complex behaviors and methods of communication.
4. Variety of respiratory organs that include gills, book lungs, tracheae
   - Marine forms use gills with vascularized, thin-walled tissue specialized for gas exchange. Terrestrial forms have book lungs (spiders) or air tubes called tracheae (insects) for transporting oxygen directly to cells.
5. Metamorphosis: Means “implying change”. This reduces competition because larvae require different food and environment than adults

Question 25

List the two major groups of animals in the Deuterostomia.

Answer 25

Deuterostomes include invertebrate echinoderms and chordates

Question 26

Identify the major morphological structures of the sea star, an echinoderm. (4)

Answer 26

1. Spines from exoskeletal plates offer protection.
2. On oral surface, each arm has a groove lined by little tube feet.
3. Pincer-like structures around the bases of spines keep the surface free of small particles
4. Skin gills are used for respiration.

Question 27

Describe how sea stars move, feed, and reproduce.

7

Answer 27

1. Tube feet are used to open clams, oysters, and bivalves.
2. Locomotion depends on water vascular system.
3. Water enters through the sieve plate and passes through a series of canals.
4. Contraction of an ampulla forces water into the tube foot.
5. Expansion and contraction of tube feet allow movement.
6. Echinoderms have no respiratory, excretory or circulatory system.
7. They reproduce asexually by fragmentation. Each fragment can regenerate a whole animal as long as a portion of the central disk is present. Spawning is the sexual reproduction method in echinoderms.

Question 28

Identify the four basic characteristics of a chordate (4)

Answer 28

1. Notochord:
   Dorsal-supporting rod located below nerve cord
2. Dorsal Tubular Nerve Cord:
   - Protected by vertebrae
   - Anterior portion becomes brain in most chordates
3. Pharyngeal Pouches
   –Aquatic vertebrates become gills
   –Seen only as embryos in most vertebrates
   –Terrestrial vertebrates modified for various purposes
4. Postanal Tail
   –Extends beyond the anus
   –In humans, tail disappears in the embryo stage.

Question 29

Name the two groups of nonvertebrate chordates

Answer 29

1. Lancelets (Cephalochordates)

2. Sea Squirts (Urochordates)

Question 30

Describe two features of each of the two groups of non vertebrate chordates (5)

Answer 30

Lancelets (Cephalochordates)
1. Shallow marine environments, filter feeders, segmented
Sea Squirts (Urochordates)
1. Adults contain a thick outer covering (tunic).
2. Marine organisms, filter feeders, bilateral symmetry
3. Many biologists hypothesize that these organisms are directly related to the vertebrates.
4. Larva may have become sexually mature without developing other adult characteristics.

Question 31

Describe four characteristics that are unique to vertebrates (4)

Answer 31

1. Vertebral column
   - Replaces the embryonic notochord
   - Evidence of segmentation
2. Skull
   - High degree of cephalization
   - Encloses and protects brain
   - Complex sense organs
3. Endoskeleton
   - Living tissue that grows with the animal
   - Protection for internal organs
   - Attachment for muscle
   - Paired appendages characteristic
4. Internal organs
   - Large coelom and complete digestive tract
   - Closed circulatory system
   - Respiratory system consisting of gills or lungs
   - Kidneys: Serve as excretory and water-regulating organs that regulate water balance in the body
   - Sexes are separate and reproduction is sexual.

Question 32

Explain how the terms tetrapod, gnathostome, and amniote relate to vertebrate evolution (3)

Answer 32

1. Tetrapod: First vertebrates to live on land were amphibians which were tetrapods. Tetrapods have four limbs, and this was an adaptation for land existence. Amphibians evolved from bony fishes. This led to an adaptation of lungs and bony skeleton.
2. Gnathostome: Gnathostomes have jaws. Jawed fishes and all other invertebrates (end Silurian) had jaws for predation, which were predictive for a land existence.
3. Amniote: Reptiles produced an amniotic egg that surrounds the embryo in amniotic fluid. This allowed reproduction on land.

Question 33

Identify the geologic era and periods in which chordates and the first vertebrates appear

Answer 33

Chordates appear 542 MYA, start of Cambrian

End of Ordovician, jawless and jawed fishes.

Question 34

List several features of jawless fishes (6)

Answer 34

1. They have a cartilaginous skeleton and persistent notochord
2. They have smooth non-scaly skin
3. They have cylindrical bodies and are up to a meter long
4. Many lampreys are filter feeders similar to their ancestors.
5. Parasitic lampreys have a round muscular mouth equipped with teeth; they attach themselves to fish and suck nutrients from the host’s circulatory system.
6. Small, jawless, and finless ostracoderms are the earliest vertebrate fossils.

Question 35

Describe four characteristics shared by all jawed fishes (4)

Answer 35

1. Ectothermy –Depend on environment to regulate their temperature
2. Gills: used for gas exchange
3. Cartilaginous or bony endoskeleton: the endoskeleton of jawed fishes includes the vertebral column, a skull with jaws, and paired pectoral and pelvic fins
4. Scales: cover and protect the skin

Question 36

Discuss the evolutionary significance of lobe-finned fishes (3)

Answer 36

1. Possess fleshy fins supported by bones
2. Gave rise to modern lobe-finned fishes and amphibians
3. Development of lungs

Question 37

List the seven characteristics that define the amphibians (7)

Answer 37

1. Contain limbs: Most are tetrapods.
2. Smooth and non-scaly skin
3. Lungs: Usually present in adults
4. Double-loop circulatory pathway with a three-chambered heart
5. Sense organs: Fine-tuned for life on land
6. Ectothermy: depending on the environment to regulate body temperature
7. Aquatic reproduction: Metamorphosis

Question 38

Describe the features of the three groups of living amphibians (3)

Answer 38

1. Salamanders and newts
   •Salamanders practice internal fertilization. They have a long body and tail, and two pairs of legs. Their s-shaped (sinusoidal) locomotion is similar to fish movements. Carnivorous, feed on insects and snails
2. Frogs and toads
   •Tailless as adults. hind limbs are specialized for jumping. They have the head and trunk fused. Glands in skin secrete poison. Frogs live near or in fresh water and toads live in damp places away from water.
3. Caecilians
   •Legless, sightless, worm shaped. Most burrow in soil and feed on worms

Question 39

Summarize the two hypotheses that explain the evolution of amphibians from lobe-finned fishes (2)

Answer 39

Hypotheses of tetrapod evolution

1. Lobe-finned fishes had an evolutionary advantage due to movement capability.
2. Further adaptations promoted by a supply of food on land and absence of predators

Question 40

List the seven features that define the reptiles (7)

Answer 40

1. Paired limbs
2. Reptiles have a thick, scaly skin that is impermeable to water.
3. Efficient breathing; Lungs with expandable rib cage
4. Efficient circulation: Ventricle is partially or completely divided by a septum
5. Efficient excretion: Well-developed kidneys
6. Ectothermy
7. Well-adapted reproduction: Internal fertilization, Shelled amniotic egg

Question 41

Explain why the reptiles are represented by more than one evolutionary lineage (4)

Answer 41

Three lineages of amniotes
1. Turtles 
-skull is anapsid
-Contains no openings behind the orbit
-Modern-day view of turtle evolution considers them highly specialized diapsids. This is still being debated.
2. All other reptiles including birds 
– skull is diapsid
–Contains two openings behind the orbit
3. Mammals –
- skull is synapsid
–Contains one opening behind the orbit
4. Reptiles have no common ancestor; they are paraphyletic

Question 42

Define traits of birds that are related to flight (5)

Answer 42

1. Feathers
   –Modified reptilian scale with a complex structure
   -help birds fly and steer
2. Modified skeleton
   –Collarbone and many other bones are fused
   –Sternum has a keel
3. Modified respiration
   –Lungs are connected to air sacs
   -Efficient supply of oxygen to muscles is vital for the level of muscle activity needed for flight.
4. Endothermy: they have the ability to maintain a constant, relatively high body temperature.
5. Well-developed sense organs and nervous system
   –Acute vision
   –Instinctual behavior

Question 43

Describe five features of mammals (5)

Answer 43

1. Hair: provides insulation against heat loss, color can provide camouflage to blend in to its surroundings, can serve sensory functions.
2. Milk-producing mammary glands: enable females to feed young without deserting them to obtain food.
3. Skeleton: Mammalian skull accommodates a larger brain relative to body size–Differentiated teeth
4. Internal organs: Efficient respiration and circulation, Double-loop circulatory pathway with a four-chambered heart, Kidneys adapted to conserve water, Highly developed nervous system
5. Internal development in most mammals: the young are born alive after a period of development in the uterus.

Question 44

Discuss the timeline of the evolution of mammals (7)

Answer 44

1. Mammals share an amniote ancestor with reptiles.
2. Immediate ancestors had a synapsid skull.
3. First true mammals appeared during the Triassic period.
4. Co-existed with the dinosaurs
5. Common ancestor of all mammal groups appeared in late Triassic/early Jurassic period (200 MYA).
6. Monotremes are the earliest mammalian group.
7. Placental mammals underwent adaptive radiation into habitats previously belonging to dinosaurs.

Question 45

Identify several features that define each of the three living lineages of mammals. (3)

Answer 45

1. Monotremes: Lay hard-shelled amniotic eggs, Single urogenital opening (cloaca)
2. Marsupials: Females contain pouch. Offspring begin development inside the mother’s body but are born in a very immature state, the newborns crawl up into a pouch on their mother’s abdomen. Inside a pouch they attach to the nipples of the mother’’s mammary glands and continue to develop
3. Placental mammals: Placenta is used for the exchange of maternal and fetal blood. The placenta supplies nutrients to and removes wastes from the blood of developing offspring. The placenta enables young to be born in a relatively advanced state of development. Placental Mammals are active mammals; they posses acute senses and relatively large brain.

Question 46

Features of cartilaginous fish (8)

Answer 46

Cartilaginous Fish

1. sharks, rays, skates
2. have a skeleton of cartilage instead of bone
3. Lack the gill cover of bony fishes
4. Can sense electric currents in water
5. Sharks and rays use a lateral line system.
6. Filter feeders and predators
7. In rays and skates, the pectoral fins are enlarged into large, wing-like fins.
8. Bodies are dorsoventrally flattened.

Question 47

Features of bony fish (10)

Answer 47

Bony Fishes

1. have a skeleton of bone.
2. Most are ray-finned fishes.
3. Lobe-finned fishes are a small subgroup with fleshy fins supported by central bones.
4. Lungfishes and coelocanths are modern-day lobe-finned fishes.
5. Lungfishes have lungs as well as gills.
6. Lacking external gill slits, gills are covered by an operculum.
7. Swim bladder
   - Gas-filled sac in bony fishes
   - Pressure can be altered to change buoyancy.
8. Well-developed brain and nervous system
9. Separate sexes
10. Majority of species undergo external fertilization.

Question 48

Compare and contrast cartilaginous and bony fish

Answer 48

They are both jawed fishes. Cartilaginous fish have a skeleton of cartilage, while bony fish have a skeleton of bone. Cartilaginous fish lack the gill covers found on bony fish.