Introductory Terms

Question 0

Biradial symmetry

Answer 0

A combination of radial and bilateral symmetry, as in the Ctenophores. Here, the body components are arranged with similar parts on either side of a central axis, and each of the four sides of the body is identical to the opposite side but different from the adjacent side.

Question 1

Radial Symmetry

Answer 1

a basic body plan in which the organism can be divided into similar halves by passing a plane at any angle along a central axis, characteristic of sessile and bottom-dwelling animals, as the sea anemone and starfish.

Question 2

Bilateral symmetry

Answer 2

a basic body plan in which the left and right sides of the organism can be divided into approximate mirror images of each other along the midline.

Question 3

Dorsal

Answer 3

situated on or toward the posterior plane in humans or toward the upper plane in quadrupeds.

Question 4

Ventral

Answer 4

situated on or toward the lower, abdominal plane of the body; equivalent to the front, or anterior, in humans.

Question 5

anterior

Answer 5

pertaining to or toward the head or forward end of the body.

Question 6

Posterior

Answer 6

pertaining to or toward the rear or caudal end of the body.

Question 7

Lateral

Answer 7

Of or pertaining to the side; situated at, proceeding from, or directed to a side

Question 8

Medial

Answer 8

situated in or pertaining to the middle; median; intermediate.

Question 9

Reynolds number

Answer 9

a dimensionless number, v ρ l /η, where v is the fluid velocity, ρ the density, η the viscosity and l a dimension of the system. The value of the number indicates the type of fluid flow

Question 10

Cilia

Answer 10

minute hairlike organelles, identical in structure to flagella, that line the surfaces of certain cells and beat in rhythmic waves, providing locomotion to ciliate protozoans and moving liquids along internal epithelial tissue in animals.

Question 11

flagella

Answer 11

a long, lashlike appendage serving as an organ of locomotion in protozoa, sperm cells, etc.

Question 12

hydrostatic skeleton

Answer 12

A structure found in many cold-blooded organisms and soft-bodied animals consisting of a fluid-filled cavity, the coelom, surrounded by muscles. The pressure of the fluid and action of the surrounding circular, longitudinal, and/or helical muscles are used to change an organism’s shape and produce movement, such as burrowing or swimming.

Question 13

exoskeleton

Answer 13

an external covering or integument, especially when hard, as the shells of crustaceans

Question 14

endoskeleton

Answer 14

the internal skeleton or framework of the body of an animal

Question 15

sagittal plane

Answer 15

a vertical plane which passes from ventral (front) to dorsal (rear) dividing the body into right and left halves

Question 16

frontal plane

Answer 16

A plane parallel to the long axis of the body and perpendicular to the sagittal plane that separates the body into front and back portions.

Question 17

transverse plane

Answer 17

plane that divides the body into superior and inferior parts. It is perpendicular to the coronal and sagittal planes.

Question 18

Bilateria

Answer 18

All animals having a bilateral symmetry, i.e. they have a front and a back end, as well as an upside and downside.

Question 19

enterocoely

Answer 19

process by which some animal embryos develop in which a mesoderm is formed in a developing embryo, in which the coelom forms from pouches “pinched” off of the digestive tract (also known as the embryonic gut, or archenteron)

Question 20

schizocoely

Answer 20

A process by which some animal embryos develop. Animals which develop through schizocoely are known as schizocoelomates. Schizocoely occurs when a coelom (body cavity) is formed by splitting the mesodermal embryonic tissue.

Question 21

Pseudocoel

Answer 21

An internal body cavity of some primitive invertebrates, similar to a coelom but lacking a mesodermal lining.

Question 22

Coelom

Answer 22

the body cavity of many multicellular animals, situated in the mesoderm and containing the digestive tract and other visceral organs

Question 23

radial cleavage

Answer 23

holoblastic cleavage that is typical of deuterostomes and that is characterized by arrangement of the blastomeres of each upper tier directly over those of the next lower tier resulting in radial symmetry around the pole to pole axis of the embryo

Question 24

spiral cleavage

Answer 24

holoblastic cleavage that is typical of protostomes and that is characterized by arrangement of the blastomeres of each upper tier over the cell junctions of the next lower tier so that the blastomeres spiral around the pole to pole axis of the embryo

Question 25

blastula

Answer 25

an early embryonic form produced by cleavage of a fertilized ovum and consisting of a spherical layer of cells surrounding a fluid-filled cavity.

Question 26

Blastocoel

Answer 26

The fluid-filled, central cavity of a blastula. Also called segmentation cavity.

Question 27

Gastrula

Answer 27

An embryo at the stage following the blastula, consisting of a hollow, two-layered sac of ectoderm and endoderm surrounding an archenteron that communicates with the exterior through the blastopore.

Question 28

Gastrulation

Answer 28

the process in which a gastrula develops from a blastula by the inward migration of cells

Question 29

Germ layers

Answer 29

each of the three layers of cells (ectoderm, mesoderm, and endoderm) that are formed in the early embryo.

Question 30

Endoderm

Answer 30

the innermost layer of cells or tissue of an embryo in early development, or the parts derived from this, which include the lining of the gut and associated structures.

Question 31

Ectoderm

Answer 31

the outermost layer of cells or tissue of an embryo in early development, or the parts derived from this, which include the epidermis and nerve tissue.

Question 32

Mesoderm

Answer 32

the middle layer of an embryo in early development, between the endoderm and ectoderm.

Question 33

Diploblastic

Answer 33

having a body derived from only two embryonic cell layers (ectoderm and endoderm, but no mesoderm), as in sponges and coelenterates.

Question 34

Triploblastic

Answer 34

having a body derived from three embryonic cell layers (ectoderm, mesoderm, and endoderm), as in all multicellular animals except sponges and coelenterates

Question 35

Larvae

Answer 35

the active immature form of an insect, esp. one that differs greatly from the adult and forms the stage between egg and pupa, e.g., a caterpillar or grub.

Question 36

Indirect development

Answer 36

biologic development accompanied by a metamorphosis

Question 37

Settlement

Answer 37

a place, typically one that has hitherto been uninhabited, where people establish a community.

Question 38

Metamorphosis

Answer 38

a major change in the form or structure of some animals or insects that happens as the animal or insect becomes an adult

Question 39

Epidermis

Answer 39

The outer, protective, nonvascular layer of the skin of vertebrates, covering the dermis.

Question 40

Epithelium

Answer 40

Membranous tissue composed of one or more layers of cells separated by very little intercellular substance and forming the covering of most internal and external surfaces of the body and its organs.

Question 41

Cuticle

Answer 41

The noncellular, hardened or membranous protective covering of many invertebrates, such as the transparent membrane that covers annelids.

Question 42

Nephridia

Answer 42

(in many invertebrate animals) a tubule open to the exterior that acts as an organ of excretion or osmoregulation. It typically has ciliated or flagellated cells and absorptive walls.

Question 43

Protonephridia

Answer 43

A hollow cell in the excretory system of certain invertebrates, including flatworms and rotifers, containing a tuft of rapidly beating cilia that serve to propel waste products into excretory tubules.

Question 44

Metanephridia

Answer 44

excretory organs in invertebrates (mainly annelids), paired metameric tubules of ectodermal origin that open at one end through a ciliated funnel into the coelomic sacs (the secondary body cavity) and at the other end to the exterior. Developed evolutionarily from protonephridia.

Question 45

blood vascular system

Answer 45

The tissues and organs of an animal that transport blood through the body. In vertebrates it consists of the heart and blood vessels

Question 46

haemocoel

Answer 46

The body cavity in between organs whereby the hemolymph circulates through.In most vertebrates the oxygen is supplied to different organs of the body through capillaries in a closed circulatory system. In many invertebrates, the oxygen is supplied directly to the organs. That is, the hemolymph circulates through this and bathes the organs directly to supply them with oxygen.

Question 47

open circulatory system

Answer 47

Circulatory system that is common to molluscs and arthropods. It pumps blood into a hemocoel with the blood diffusing back to the circulatory system between cells. Blood is pumped by a heart into the body cavities, where tissues are surrounded by the blood.

Question 48

closed circulatory system

Answer 48

Vertebrates, and a few invertebrates, have a ______circulatory system. They have the blood closed at all times within vessels of different size and wall thickness. In this type of system, blood is pumped by a heart through vessels, and does not normally fill body cavities.

Question 49

Respiratory pigments

Answer 49

any of various permanently or intermittently colored conjugated proteins and especially hemoglobin that function in the transfer of oxygen in cellular respiration

Question 50

Photoreceptor

Answer 50

a light-sensitive cell or organ that conveys impulses through the sensory neuron connected to it

Question 51

chemoreceptor

Answer 51

A sensory nerve cell or sense organ, as of smell or taste, that responds to chemical stimuli.

Question 52

Mechanoreceptor

Answer 52

A specialized sensory end organ that responds to mechanical stimuli such as tension, pressure, or displacement.

Question 53

Statocyst

Answer 53

A small organ of balance in many invertebrates, consisting of a fluid-filled sac containing statoliths that stimulate sensory cells and help indicate position when the animal moves. Also called otocyst.

Question 54

Statolith

Answer 54

Any of the granules of calcium carbonate occurring in a statocyst: movement of ________, caused by a change in position of the animal, stimulates hair cells, which convey the information to the brain by nerve fibres

Question 55

Clone

Answer 55

an organism or cell, or group of organisms or cells, produced asexually from one ancestor or stock, to which they are genetically identical.

Question 56

Coloniality/colony

Answer 56

Refers to individual organisms of the same species living closely together, usually for mutual benefit, such as stronger defense or the ability to attack bigger. Colonial organisms were probably the first step toward multicellular organisms via natural selection

Question 57

broadcast spawning

Answer 57

animals release their eggs and sperm into the water, where fertilization occurs externally. Common in mollusks and other invertebrates

Question 58

internal fertilization

Answer 58

union of the gametes inside the body of the female, the sperm having been transferred from the body of the male by an accessory sex organ or other means.

Question 59

seminal vesicle

Answer 59

Either of a pair of pouchlike glands situated on each side of the male urinary bladder that secrete seminal fluid and nourish and promote the movement of spermatozoa through the urethra.

Question 60

seminal receptacle

Answer 60

A container that is used to hold semen. It is where the sperm is received in an earthworm.

Question 61

Gonoduct

Answer 61

a duct leading from a gonad to the exterior, through which gametes pass

Question 62

oviduct

Answer 62

the tube through which an ovum or egg passes from an ovary.

Question 63

sperm duct

Answer 63

The vas deferens, also called ductus deferens, is part of the male anatomy of many vertebrates; they transport sperm from the epididymis in anticipation of ejaculation.

Question 64

gonochoristic

Answer 64

describes the state of having just one of at least two distinct sexes in any one individual organism.

Question 65

dioecious

Answer 65

having the male and female reproductive organs in separate individuals.

Question 66

hermaphroditic

Answer 66

an organism, as an earthworm or plant, having normally both the male and female organs of generation.

Question 67

monoecious

Answer 67

having both the male and female reproductive organs in the same individual; hermaphrodite.

Question 68

protandry

Answer 68

(of hermaphrodite animals) producing male gametes before female gametes.

Question 69

protogyny

Answer 69

a state in hermaphroditic systems that is characterized by development of female organs or maturation of their products before the appearance of the corresponding male product thus inhibiting self-fertilization and that is encountered in apples, pears, figworts, and among several groups of invertebrate animals

Question 70

parthenogenesis

Answer 70

A form of reproduction in which an unfertilized egg develops into a new individual, occurring commonly among insects and certain other arthropods.

Question 71

benthic

Answer 71

of, relating to, or occurring at the bottom of a body of water

Question 72

pelagic

Answer 72

Of, relating to, or living in open oceans or seas rather than waters adjacent to land or inland waters

Question 73

epifauna(l)

Answer 73

Benthic animals that live on the surface of a substrate, such as rocks, pilings, marine vegetation, or the sea or lake floor itself.

Question 74

infauna(l)

Answer 74

Aquatic animals that live in the substrate of a body of water, especially in a soft sea bottom.

Question 75

sessile

Answer 75

the inability to move actively or spontaneously

Question 76

errant

Answer 76

(of a polychaete worm) of a predatory kind that moves about actively and is not confined to a tube or burrow.

Question 77

plankton(ic)

Answer 77

the small and microscopic organisms drifting or floating in the sea or fresh water, consisting chiefly of diatoms, protozoans, small crustaceans, and the eggs and larval stages of larger animals. Many animals are adapted to feed on them esp. by filtering the water.

Question 78

holoplanktonic

Answer 78

Plankton that remains free-swimming through all stages of its life cycle.

Question 79

meroplanktonic

Answer 79

Any of various organisms that spend part of their life cycle, usually the larval or egg stages, as plankton.

Question 80

symbiosis

Answer 80

interaction between two different organisms living in close physical association, typically to the advantage of both.

Question 81

parasite/parasitism

Answer 81

an organism that lives in or on another organism (its host) and benefits by deriving nutrients at the host's expense.

Question 82

suspension feeding

Answer 82

Type of feeding common in an aquatic animal, such as a clam, barnacle, or sponge, that feeds by filtering particulate organic material from water.

Question 83

deposit feeding

Answer 83

Feeding practiced by an aquatic animal that feeds on small specks of organic matter that have drifted down through the water and settled on the bottom.

Question 84

synonym

Answer 84

A scientific name that applies to a taxon that goes by a different scientific name, although zoologists use the term somewhat differentlyIn scientific nomenclature, a synonym is a scientific name that applies to a taxon that goes by a different scientific name, although zoologists use the term somewhat differently

Question 85

monophyletic

Answer 85

a taxon that is defined as one that includes the most recent common ancestor of a group of organisms, and all of its descendants

Question 86

paraphyletic

Answer 86

a taxon defined as one that includes the most recent common ancestor, but not all of its descendants

Question 87

polyphyletic

Answer 87

a taxon that does not include the common ancestor of all members of the taxon

Question 88

homology

Answer 88

a fundamental similarity based on common descent

Question 89

homoplasy

Answer 89

correspondence between parts or organs acquired as the result of parallel evolution or convergence

Question 90

clade

Answer 90

A grouping that includes a common ancestor and all the descendants (living and extinct) of that ancestor. Imagine clipping a single branch off the phylogeny.

Question 91

plesiomorphy

Answer 91

An ancestral or primitive character.

Question 92

symplesiomorphy

Answer 92

A character shared by a number of groups, but inherited from ancestors older than the last common ancestor.

Question 93

apomorphy

Answer 93

A derived or specialised character.

Question 94

synapomorphy

Answer 94

An apomorphy (derived or specialised character) shared by two or more groups which originated in their last common ancestor.

Question 95

sister taxa

Answer 95

a systematic term from cladistics denoting the closest relatives of a group in a phylogenetic tree.

Question 96

category vs. taxon

Answer 96

category: The name given to various taxonomic ranks. ex: Kingdom, Phylum, Class, Order, Family, Genus species--> these are categories taxon: the group of organisms occupying a particular taxonomic rank

Question 97

character vs. character state

Answer 97

-character: Any heritable attribute or feature of an organism that can be used for recognizing, differentiating or classifying a taxon. Biologists use characters from a variety of different sources, including morphological, behaviorial, developmental, and molecular data. -character state: Alternative forms of a character.

Question 98

grade

Answer 98

refers to a taxon united by a level of morphological or physiological complexity.

Question 99

Precambrian

Answer 99

the time period from the beginning of Earth, about 4.5 billion years ago, to the beginning of the Paleozoic era, about 543 million years ago.

Question 100

Paleozoic

Answer 100

this era spans the time from the end of the Precambrian, about 543 million years ago, to the beginning of the Mesozoic, about 248 million years ago. It is generally subdivided into six periods: Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian.

Question 101

Mesozoic

Answer 101

spans the time from the end of the Paleozoic, about 248 million years ago, to the beginning of the Cenozoic, about 65 million years ago. It is generally subdivided into three periods: Triassic, Jurassic, and Cretaceous.

Question 102

Cenozoic

Answer 102

spans the time from the end of the Mesozoic, about 65 million years ago, to the present. It is generally subdivided into two periods, the Tertiary and the Quaternary.