Bio Exam 3 IBA

Echinoderm key traits

Pentameral adult symmetry, bilateral larvae, water vascular system, tube feet, endoskeleton of ossicles.

Hemichordate key traits

Stomochord, pharyngeal slits for filter feeding, dorsal & ventral nerve cords.

Five chordate synapomorphies

Notochord, dorsal hollow nerve cord, pharyngeal slits, post-anal tail, endostyle/thyroid.

Evolutionary significance of the amniotic egg

Allows reproduction independent of water; protects embryo.

Major vertebrate lineages

Fish, amphibians, non-avian reptiles, birds, mammals.

Agnathans vs. Gnathostomes

Agnathans lack jaws; gnathostomes have jaws derived from pharyngeal arches.

Function of lateral line

Detects water movement and vibration.

Function of swim bladder

Controls buoyancy in bony fish.

Ray-finned vs. Lobe-finned fish

Ray-finned: thin rays supporting fins. Lobe-finned: fleshy, muscular fins (tetrapod ancestors).

Why amphibians need moist environments

Gas exchange through skin; eggs lack protective membranes.

Key reptile adaptations

Amniotic egg, keratinized skin, internal fertilization, ectothermy.

Four-chambered heart in reptiles

Only crocodilians (and birds & mammals).

Bird adaptations for flight

Furcula, keeled sternum, feathers, lightweight bones.

Bernoulli's principle in bird flight

Faster airflow over wing → lower pressure → lift.

Why bird lungs are most efficient

Unidirectional airflow + air sacs.

Traits unique to mammals

Hair/fur, mammary glands, three middle ear bones.

Monotremes

Egg-laying mammals (platypus, echidna).

Marsupials

Short gestation; development in pouch; long lactation.

Placentals

Longer gestation; shorter lactation; placenta nourishes embryo.

Primate key traits

Grasping hands/feet, forward-facing eyes, large brains, social behavior.

Human bipedal traits

Anterior foramen magnum, reshaped pelvis, aligned femur, arched foot.

Aposematism

Warning coloration signaling toxicity or danger.

Honest signaling

Costly traits reliably indicate fitness (e.g., bright colors).

Dishonest signaling (Batesian mimicry)

Harmless species mimics a toxic one.

Kin selection (Hamilton's Rule)

Helping relatives increases inclusive fitness: rB > C.

Sexual selection

Traits evolve because they increase mating success.

Landscape of fear

Prey alter behavior due to perceived predation risk.

Keystone species

Species with disproportionately large ecosystem impact.

Trophic cascade

Changes at the top predator level impact entire food web.

Deep-sea fish adaptations

Bioluminescence, large mouths, reduced eyes, weak muscles, elongated bodies.

Bird-dinosaur shared traits (besides feathers)

Furcula, hollow bones, three-digit hands, bipedal stance.

Yellowstone trophic cascade

Wolves ↓ elk → vegetation recovers → ecosystem reshaped.

Adult echinoderms vs larvae

Adults have pentameral radial symmetry & no cephalization; larvae bilateral.

Original function of early chordate pharyngeal slits

Filter feeding (later respiration).

Unique mammal trait combination

Hair/fur, mammary glands, three ear bones.

Human foramen magnum position

Anterior placement supports upright posture.