Final Exam

Question 1

coelem mate benefits

Answer 1

organ cushioning protection independant organ movement effieceint circulation of gasses and nutreints hydrostatic skeleton for movemtn greater body size and complexity

Question 2

proto vs deuterosomes

Answer 2

proto blastopore becomes mouth deutoro blastopore becomes anus deutero makes bigger better animals

Question 3

8 animal phyla

Answer 3

Porifora cnideria platyhelminthes molluska annelida arthropoda echinodermata chordata

Question 4

6 Features That Distinguish Animal Clades

Answer 4

1. Symmetry (radial, bilateral, asymmetry)
   
   2. Germ layers (diploblastic vs. triploblastic)
   3. Body cavity type (acoelomate, pseudocoelomate, coelomate)
   4. Segmentation
   5. Presence of a notochord
   6. Type of development (protostome vs. deuterostome)

Question 5

Porifera

Answer 5

Sponges; no true tissues; asymmetrical; filter feeders

Question 6

Cnidaria

Answer 6

Radial symmetry; diploblastic; cnidocytes; gastrovascular cavity

Question 7

Platyhelminthes

Answer 7

Flatworms; bilateral symmetry; acoelomate; triploblastic

Question 8

Mollusca

Answer 8

Soft-bodied; coelomate; foot, mantle, radula; many have shells

Question 9

Annelida

Answer 9

Segmented worms; coelomate; closed circulatory system; segmentation

Question 10

Arthropoda

Answer 10

Exoskeleton; jointed appendages; segmented; open circulatory system

Question 11

Echinodermata

Answer 11

Pentaradial adults; water vascular system; endoskeleton; deuterostomes

Question 12

Chordata

Answer 12

Notochord, dorsal nerve cord, pharyngeal slits, post-anal tail

Question 13

Why Sponges Are Basal

Answer 13

Sponges lack true tissues and organs.

Question 14

Sponge Feeding & Digestion

Answer 14

Water enters through pores (ostia).
2. Food particles are trapped by choanocytes (collar cells).
3. Amoebocytes transport nutrients to other cells.
• Digestion is intracellular (inside cells).

Question 15

Cnidarian Characteristics

Answer 15

Radial symmetry
• Diploblastic (ectoderm & endoderm)
• Gastrovascular cavity
• Cnidocytes (stinging cells)
• Alternating polyp and medusa forms

Question 16

Specialized Cnidarian Cells

Answer 16

Cnidocytes: Contain nematocysts (stinging organelles) used for prey capture and defense.

Question 17

Cnidarian Characteristics

Answer 17

Radial symmetry
• Diploblastic (ectoderm & endoderm)
• Gastrovascular cavity
• Cnidocytes (stinging cells)
• Alternating polyp and medusa forms

Question 18

Cnidarian Body Variants

Answer 18

Polyp – sessile, cylindrical, mouth up; reproduces asexually.
2. Medusa – free-floating, umbrella-shaped, mouth down; reproduces sexually.

Question 19

Lophotrochozoa Clade

Answer 19

• Named for lophophore (ciliated feeding structure) and trochophore larva (free-swimming larval stage).
• Includes phyla like Platyhelminthes, Mollusca, and Annelida.

Question 20

Mollusca Distinguishing Characteristics

Answer 20

Coelomate, soft-bodied, usually with a calcareous shell
• Body divided into: head-foot, visceral mass, and mantle
• Radula for feeding (except bivalves)
• Most have trochophore larvae

Question 21

Mollusk Body Plan & Modifications

Answer 21

Basic: Foot (movement), visceral mass (organs), mantle (shell)
• Bivalves: Foot modified for burrowing
• Gastropods: Foot for crawling; torsion twists body
• Cephalopods: Foot modified into tentacles; highly mobile and predatory

Question 22

Ecdysozoa Clade

Answer 22

Named for ecdysis = molting of exoskeleton
• Includes Arthropods and Nematodes

Question 23

Open vs. Closed Circulatory Systems

Answer 23

Open (molluscs/arthropods): Blood pumped into cavities; bathes organs directly; slower, less efficient
• Closed (annelids): Blood contained in vessels; faster transport; better control of distribution

Question 24

3 Features for Arthropod Success

Answer 24

Exoskeleton (protection, support, limits water loss)
2. Segmentation + jointed appendages (mobility & specialization)
3. Advanced sensory organs & nervous system

Question 25

Exoskeleton Advantages & Disadvantages

Answer 25

Advantages: Protection, support, prevents dehydration, attachment for muscles • Disadvantages: Must molt to grow, limits size, energy-intensive to produce

Question 26

Chelicerates (a clade)

Answer 26

Chelicerates are a group of arthropods defined by having chelicerae, which are specialized mouthparts used for feeding (often claw- or fang-like). They lack antennae and typically have two main body segments: the cephalothorax and the abdomen. Distinguishing Features: • Body divided into cephalothorax (fused head and thorax) and abdomen. • Six pairs of appendages on the cephalothorax: • 1 pair of chelicerae (feeding) • 1 pair of pedipalps (sensory or reproductive) • 4 pairs of walking legs • No antennae. Examples: • Spiders (Araneae) • Scorpions • Horseshoe crabs • Mites and ticks

Question 27

Insects (part of Pan-crustacean clade)

Answer 27

Insects are terrestrial arthropods that are part of the Pan-crustacean clade, meaning they are evolutionarily related to crustaceans. They are the most diverse group of animals on Earth. Distinguishing Features: • Body divided into three segments: head, thorax, and abdomen. • Three pairs of legs attached to the thorax. • Usually one or two pairs of wings (though some are wingless). • One pair of antennae. • Undergo metamorphosis (complete or incomplete). Examples: • Beetles (Coleoptera) • Butterflies and moths (Lepidoptera) • Grasshoppers (Orthoptera) • Flies (Diptera)

Question 28

Marine crustaceans (part of Pan-crustacean clade)

Answer 28

Definition: Marine crustaceans are primarily aquatic arthropods in the Pan-crustacean clade. They usually have two pairs of antennae and biramous (branched) appendages, which distinguish them from insects. Distinguishing Features: • Two pairs of antennae (sensory structures). • Biramous appendages (limbs branch into two parts). • Body often divided into cephalothorax and abdomen, sometimes with a carapace covering the cephalothorax. • Mostly aquatic, living in marine or freshwater environments. Examples: • Crabs • Lobsters • Shrimp • Krill • Barnacles

Question 29

Four derived traits that define phylum Chordata

Answer 29

Notochord – Flexible rod along the dorsal side; provides skeletal support. 2. Dorsal hollow nerve cord – Develops into the central nervous system (brain and spinal cord). 3. Pharyngeal slits or pouches – Openings in the pharynx; function in filter feeding or develop into gills/jaws. 4. Post-anal tail – Extension of the body beyond the anus; provides locomotion in many aquatic species.

Question 30

Lancelets (Cephalochordata)

Answer 30

Structure: Small, fish-like, marine chordates; retain all four chordate traits as adults. • Way of life: Burrow in sand, filter-feed using pharyngeal slits. • Evolutionary significance: Lancelets suggest that the chordate brain evolved from a simple dorsal nerve cord, with regional specialization occurring in vertebrates.

Question 31

Larval vs. Adult tunicates (Urochordata)

Answer 31

Feature Larva Adult Motility Free-swimming Sessile (attached) Feeding Non-feeding larval stage uses yolk Filter-feeding via pharyngeal slits Cephalization Present (brain, sensory organs) Lacks distinct head/brain Chordate traits All 4 present Mostly lost; only pharyngeal slits remain functional

Question 32

Importance of Hox gene duplication

Answer 32

Hox genes control body plan development. • Duplication allows more complex structures and specialization, contributing to vertebrate diversity (e.g., jaws, limbs, complex brains).

Question 33

Derived features of vertebrates

Answer 33

Vertebral column – Replaces notochord in adults. • Cranium/skull – Protects the brain. • Endoskeleton – Provides strong internal support. • Evolution of jaws: Evolved from anterior gill arches, allowing active predation and diversification of feeding strategies.

Question 34

Shared, derived characters of jawed vertebrates (Gnathostomes)

Answer 34

Jaws (from modified gill arches) • Paired fins or limbs • Additional Hox gene duplication • Enhanced sensory systems (lateral line, olfaction, vision)

Question 35

Shark adaptations for predatory lifestyle

Answer 35

Streamlined body – Fast swimming • Cartilaginous skeleton – Light, flexible • Teeth – Continuously replaced • Sensory adaptations: Lateral line (vibrations), electroreceptors (detect prey) • Buoyancy – Oil-filled liver instead of swim bladder

Question 36

Cartilaginous vs. bony fish

Answer 36

Feature Cartilaginous (Chondrichthyes) Bony fish (Osteichthyes) Skeleton Cartilage Bone Swim bladder None (use liver) Present (buoyancy control) Scales Placoid Cycloid or ctenoid Reproduction Internal fertilization Mostly external fertilization Examples Sharks, rays Salmon, trout

Question 37

Shark adaptations for predatory lifestyle

Answer 37

Streamlined body – Fast swimming • Cartilaginous skeleton – Light, flexible • Teeth – Continuously replaced • Sensory adaptations: Lateral line (vibrations), electroreceptors (detect prey) • Buoyancy – Oil-filled liver instead of swim bladder

Question 38

Two main subgroups of bony fish

Answer 38

Ray-finned fish (Actinopterygii) – Fins supported by rays. 2. Lobe-finned fish (Sarcopterygii) – Muscular fins with bones; 3 living lineages: • Coelacanths • Lungfish • Tetrapods (descended from lobe-fins)

Question 39

Define jawed vertebrates, tetrapods, amniotes

Answer 39

Jawed vertebrates (Gnathostomes): Vertebrates with jaws and paired fins/limbs. • Tetrapods: Four-limbed vertebrates adapted to life on land. • Amniotes: Tetrapods with an amniotic egg (reptiles, birds, mammals); can reproduce away from water.

Question 40

Fossil evidence for tetrapod origin

Answer 40

Tiktaalik: Fins with bones similar to wrists; transitional aquatic/terrestrial features. • Acanthostega: Early tetrapod with limbs and digits; mostly aquatic. • Implication: Tetrapods evolved gradually from lobe-finned fishes adapting to shallow water/land.

Question 41

Amphibians

Answer 41

Traits: Moist skin, lungs, metamorphosis from larval (aquatic) to adult (semi-terrestrial). • Salamanders: Long bodies, tails, mostly walk/crawl. • Frogs: Jumping locomotion, tailless adults, specialized legs.

Question 42

Amniotic egg

Answer 42

Structure: Contains amnion (protective sac), yolk (nutrients), chorion (gas exchange), allantois (waste storage). • Significance: Allows reproduction entirely on land, freeing vertebrates from water-bound eggs.

Question 43

Birds as reptiles

Answer 43

Birds share scales (feathers), egg structure, skeletal traits with reptiles. • Phylogenetically, they are theropod dinosaurs, making reptiles a paraphyletic group unless birds are included.

Question 44

Adaptive reptile features for land

Answer 44

Scales with keratin (prevent water loss) • Thoracic breathing (rib muscles) • Amniotic eggs • Internal fertilization

Question 45

Snake adaptations for predation

Answer 45

Kinetic skull/jaws – Can swallow large prey • Forked tongue – Smell/chemoreception • Heat-sensing pits (in some) • Venom glands (in many) • Elongate, limbless body for stealth and burrowing

Question 46

Bird adaptations for flight

Answer 46

Feathers for lift and insulation • Hollow bones (lightweight skeleton) • Large pectoral muscles, keeled sternum • Efficient respiratory system (air sacs) • High metabolic rate

Question 47

Evidence birds evolved from theropods

Answer 47

Fossils show feathers, wishbones (furcula), hollow bones • Similar skeletal structures (limb arrangement, pelvis, skull) • Some small theropods had flight-related features, linking them to modern birds

Question 48

Derived characteristics of mammals

Answer 48

Hair/fur • Mammary glands (milk production) • Endothermy (warm-blooded) • Specialized teeth (heterodont dentition) • Three middle ear bones

Question 49

Mammal types

Answer 49

Monotremes Eggs Marsupials Pouch Eutherians Placenta