Terms and Concepts BIO Exam 3

Heterotrophic

Organisms that obtain food by consuming other organisms.

Choanoflagellates

Single-celled protists closely related to animals.

Metazoa

Multicellular animals.

Eumetazoa

True animals with tissues and symmetry (everything except sponges).

Choanocytes

Collar cells in sponges that create water flow and capture food.

Porocytes

Sponge cells that form pores for water entry.

Amoebocytes

Mobile sponge cells that digest and transport nutrients.

Sclerocytes

Sponge cells that produce spicules.

Spicules

Structural elements that provide support in sponges.

Spongocytes

Sponge cells that make spongin fibers (flexible skeleton).

Secondary Metabolites

Chemicals made for defense or competition.

Trade-Offs

Situations where a gain in one trait causes a loss in another.

Sessile

Fixed in one place; not moving.

Benthic

Living on the bottom of a water body.

Pelagic

Living in the open water (not near bottom or shore).

Complex Life Cycle

Includes multiple stages or hosts.

Polyp

Sessile stage of cnidarians (e.g., coral).

Medusa

Free-swimming stage (e.g., jellyfish).

Gastrovascular Cavity

Central digestive cavity with one opening.

Nematocyst

Stinging capsule inside a cnidocyte.

Cnidocyte

Stinging cell in cnidarians.

Zooxanthellae

Symbiotic algae living in coral tissue.

Coral Bleaching

Loss of zooxanthellae due to stress, turning coral white.

Radial Symmetry

Body parts arranged around a central axis.

Bilateral Symmetry

Two mirror-image sides.

Diploblastic

Having two tissue layers: ectoderm and endoderm.

Triploblastic

Having three tissue layers: ectoderm, mesoderm, endoderm.

Nematode

Roundworm, often parasitic.

Chelicera

Pincer-like mouthpart in spiders/scorpions.

Head

Front body region containing sensory organs.

Thorax

Middle region with legs and wings.

Cephalothorax

Fused head and thorax (in spiders/crabs).

Abdomen

Rear body region containing organs.

Spinnerets

Silk-spinning structures in spiders.

Silk Gland

Produces silk for webs.

Food Web

Network of feeding relationships.

Pollination

Transfer of pollen for plant reproduction.

Forensic Entomology

Using insects in criminal investigations.

Disease Vectors

Organisms that transmit pathogens.

Zygote

Fertilized egg cell.

Blastula

Hollow ball of cells after cleavage.

Gastrulation

Formation of tissue layers from the blastula.

Protostome

Mouth forms first from blastopore.

Deuterostome

Anus forms first from blastopore.

Radial Cleavage

Cell divisions aligned top to bottom.

Spiral Cleavage

Cells divide at an angle (twisting).

Blastopore

Opening formed during gastrulation.

Enterocoelous

Coelom forms from outpocketing of gut.

Schizocoelous

Coelom forms by splitting mesoderm.

Madreporite

Entry point for water in echinoderms.

Water Vascular System

Hydraulic system for movement and feeding.

Ampulla

Bulb that controls tube foot extension.

Tube Feet

Small appendages for locomotion and feeding.

Keystone Species

Species that strongly influence ecosystem structure.

Notochord

Flexible rod for support in embryos.

Dorsal Hollow Nerve Cord

Nerve cord along back, forms brain and spine.

Post-Anal Tail

Tail extending beyond anus.

Pharyngeal Gill Slits

Openings in throat region for filter-feeding or respiration.

Cranium

Skull protecting the brain.

Vertebral Column

Backbone made of vertebrae.

Jaws

Evolved from gill arches for biting food.

Pharyngeal Gill Arch

Cartilage structure supporting gills.

Mineralized Skeleton

Bones hardened with calcium.

Appendicular Skeleton

Bones of limbs and girdles.

Pectoral Fins

Front paired fins.

Pelvic Fins

Rear paired fins.

Mineralized Teeth

Hard teeth formed from enamel and dentin.

Placoid Scales

Tooth-like scales in sharks.

Lung

Organ for air breathing.

Swim Bladder

Gas-filled organ controlling buoyancy.

Fin Rays

Bony supports in fins.

Ray-Finned Fish

Fish with fins supported by rays (Actinopterygii).

Tetrapod Limbs

Four-limbed body plan derived from fins.

Neck Evolution

Separation of head from shoulder girdle.

Granular Glands

Secrete toxins or defensive chemicals.

Mucous Glands

Keep amphibian skin moist.

Amniotic Egg

Egg with membranes for land development.

Osteoderms

Bony plates in skin (e.g., reptiles).

Keratin

Structural protein in hair, scales, and feathers.

Turtle Shell

Fusion of ribs and vertebrae.

Hair

Keratin structure for insulation.

Mammary Glands

Produce milk.

Cloaca

Single opening for excretion and reproduction.

Laurasia

Northern supercontinent.

Gondwana

Southern supercontinent.

Marsupium

Pouch of marsupials.

Convergence

Similar traits evolve independently.

Paedomorphosis

Retaining juvenile features in adults.

Cetaceans

Whales and dolphins.

Powered Flight

Active flight using wings.

Pterosaurs

Extinct flying reptiles.

Birds

Feathered vertebrates capable of flight.

Bats

Flying mammals with membranous wings.

Cretaceous-Tertiary (K-T) Boundary

Mass extinction ~65 MYA; ended dinosaurs.

Permian-Triassic (P-T) Boundary

Largest extinction ~245 MYA; ended many marine groups.

Ammonites

Extinct marine mollusks with coiled shells.

Hybodontid Sharks

Extinct group of early sharks.

Dinosaurs

Dominant land vertebrates; mostly extinct except birds.

Plesiosaurs

Extinct marine reptiles with long necks.

Ichthyosaurs

Extinct dolphin-like marine reptiles.