Bio midterm page one study guide

Auxin

A plant growth regulator responsible for elongation and phototropism.

Gibberellins

Plant growth regulators that promote stem elongation and germination.

ABA (Abscisic Acid)

A plant growth regulator involved in stress responses and dormancy.

Ethylene

A plant growth regulator that stimulates fruit ripening.

Jasmonates

Plant growth regulators associated with defense mechanisms.

Essential element

A nutrient required for a plant to complete its life cycle with a specific function.

Photomorphogenesis

Growth and development in response to light.

Photoperiodism

The response of plants to the length of day and night.

Phytochrome

A light receptor that exists in two forms: Pr (inactive) and Pfr (active).

How phytochrome works

Red light converts Pr to Pfr (active); darkness converts Pfr back to Pr, controlling growth and flowering.

Water potential

The potential energy of water in a plant; solutes decrease it, while pressure increases it.

Zygote

A fertilized egg in the early stages of development.

Blastula

A hollow ball of cells formed during early embryonic development.

Blastomere

A cell produced by cleavage during early embryonic development.

Cleavage

The rapid cell division of a fertilized egg without growth.

Blastopore

The first opening that forms in the embryo.

Gastrulation

The process in which the embryonic germ layers form.

Hox genes

Genes that control the body plan and development of organisms.

Endoderm

The innermost germ layer that forms the digestive system.

Mesoderm

The middle germ layer that forms muscles and bones.

Ectoderm

The outermost germ layer that forms skin and the nervous system.

Acoelomate

An organism with no body cavity.

Eucoelomate

An organism with a true coelom.

Pseudocoelomate

An organism with a false coelom.

Schizocoel

A type of coelom that forms by splitting the mesoderm.

Enterocoel

A type of coelom that forms from gut outpocketing.

Protostome

An organism in which the mouth forms first during development.

Deuterostome

An organism in which the anus forms first during development.

Radial symmetry

Body symmetry where parts are arranged around a central axis.

Bilateral symmetry

Body symmetry that has left and right sides.

Diploblastic

An organism with two layers of cells.

Triploblastic

An organism with three layers of cells.

Ecdysozoa

A group of animals characterized by molting (ecdysis).

Bilateria

Organisms with bilateral symmetry and three germ layers.

Protostomia

A clade where the mouth forms first.

Deuterostomia

A clade where the anus forms first.

Lophotrochozoa

A group of protostomes characterized by a lophophore or trochophore larva.

Sponges characteristics

Aquatic animals with no tissues, choanocytes, and a sessile lifestyle.

Cnidarians characteristics

Animals with true tissues, cnidocytes, and radial symmetry.

Flatworms group

Also known as Platyhelminthes, a group of flat-bodied invertebrates.

Mollusk characteristics

Soft-bodied animals with a mantle and a muscular foot.

Cephalopods shell

Mollusks such as squids and octopuses with reduced or absent shells.

Gastropods shell

Mollusks characterized by a single shell.

Bivalves shell

Mollusks that possess two shells.

Polychaetes vs oligochaetes

Polychaetes have many setae and are marine; oligochaetes have few setae and are terrestrial.

Cryptobiosis

A state of extreme dormancy with near-zero metabolism.

Arthropod characteristics

Jointed appendages, exoskeleton, and molting.

Insects

Arthropods with six legs.

Chelicerates

Arthropods with eight legs and no antennae.

Crustaceans

Arthropods with two pairs of antennae.

Myriapods

Arthropods characterized by having many legs.

Echinoderms

Deuterostomes with a water vascular system and radial symmetry.

Echinoderm symmetry

Adults have radial symmetry; larvae exhibit bilateral symmetry.

Chordate synapomorphies

Shared traits of chordates include a notochord, dorsal nerve cord, pharyngeal slits, and a post-anal tail.

Urochordates

Chordates that display chordate traits only in the larval stage.

Cephalochordates

Chordates that retain chordate traits throughout their life.

Vertebrates

Animals with a backbone.

Tetrapoda

Four-limbed vertebrates.

Amniotes

Tetrapods with an amniotic egg.

Gnathostomes

Jawed vertebrates.

Agnatha

Jawless vertebrates.

Craniata

Animals with a skull.

Chondrichthyes

Fish with cartilage skeletons and no swim bladder.

Osteichthyes

Bony fish with a swim bladder.

Amphibian characteristics

Tetrapods with moist skin and undergo metamorphosis.

Anura

An order of amphibians without tails.

Urodela

An order of amphibians with tails.

Apoda

An order of amphibians without limbs.

Amnion

The protective fluid sac surrounding an embryo.

Chorion

The membrane involved in gas exchange in eggs.

Allantois

The fetal membrane that stores waste.

Yolk sac

The structure that provides nutrients to the developing embryo.

Shell

The protective covering of eggs that prevents drying out.

Diapsid

A group of reptiles and birds characterized by two openings in the skull.

Synapsid

A group of mammals characterized by one opening in the skull.

Non-avian reptiles

Ectothermic animals with scales, amniotic eggs, and lungs.

Earliest reptile group

The group that includes turtles.

Earliest archosaur group

The group that includes crocodilians.

Bird characteristics

Animals characterized by feathers, wings, and adaptations for flight.

Mammal characteristics

Animals characterized by hair and mammary glands.

Marsupials

Mammals with short gestation and a pouch for immature young.

Eutherians

Mammals with long gestation and a placenta.