Ch 33: Animal Form, Function, and Evolutionary History Flashcards
Porifera
Sponges; a phylum characterized by an irregular form with no clearly defined plane of symmetry
Cnidaria
A phylum characterized by radial symmetry, two germ tissues in the embryo, a closed internal gastric cavity, and well developed tissues but not organs; included jellyfish, sea anemones, and corals
Bilateria
The monophyletic group of animals with bilateral symmetry
Cephalization
The concentration of nervous system components at one end of the body
Segmentation
The formation of discrete repeating parts or segments in the developing body of many animal embryos.
Dipoblasitc
Describes animals in which the embryo has two germ layers, the endoderm and the ectoderm, from which the adult tissues develop.
Tripoblastic
Describes animals in which the embryo has three germ layers, with the mesoderm between the endoderm and ectoderm.
Protostomes
A bilaterian in which the blastopore, the first opening to the internal cavity of the developing embryo, becomes the mouth. The taxonomic name is Protostomia, and the group includes mollusks and arthropods.
Deuterostomes
A bilaterian in which the blastopore, the first opening to the internal cavity of the developing embryo, becomes the anus. The taxonomic name is Deuterostomia and includes humans and other chordates.
Coelom
A body cavity surrounding the gut.
Tissue
A collection of cells that work together to perform a specific function.
Organ
Two or more tissues that combine and function together.
Epithelial tissue
A type of animal tissue that provides a lining for all of the spaces inside and outside the body; it is composed of closely packed cells.
Connective tissue
A type of animal tissue that underlies epithelial tissues and is found elsewhere as well; it has an extensive extracellular matrix and few cells.
Muscle tissue
A type of animal tissue made up of cells (fibers) that are able to shorten or contract, resulting in movement.
Nervous tissue
A type of animal tissue found in the nerve nets of cnidarians and in the brain, spinal cord, and peripheral nerves of vertebrates; it takes in sensory information from the environment, processes information, and sends signals to target organs to elicit a response.
Organ System
A group of organs that have related functions. For example, the intestine is one organ of the digestive system, which also includes the stomach, liver, pancreas, and other organs.
Homeostasis
The active regulation and maintenance, in organisms, organs, or cells, of a stable internal physiological state in the face of a changing external environment.
Negative Feedback
The effect in which the final product of a biochemical pathway inhibits the first step; the process in which a stimulus acts on a sensor that communicates with an effector, producing a response that opposes the initial stimulus. Negative feedback is used to maintain steady conditions, or homeostasis.
Set Point
A steady-state value in homeostatic regulation.
Cambrian Explosion
A transition period in geologic time during which the body plans characteristic of most bilaterian phyla diversified.
Mass Extinction
A catastrophic drop in recorded diversity, which has occurred five times in the past 541 million years.
Isometry
An increase in body size while keeping the same overall shape; literally, “same measure.”
Allometry
An increase in body size accompanied by a change in shape; literally, “different measure.”
T/F: Homologies are helpful for reconstructing evolutionary relationships because they show the evolutionary development of characters among groups.
True
A tissue is a collection of:
cells that perform a specific function.
“The ability to maintain a steady physiological state in the face of a changing environment” is the definition of:
Homeostasis
T/F: Nearly all dinosaurs became extinct at the end of the Cretaceous Period as a result of direct competition with mammals.
False
T/F: Circulation in your body is controlled through the action of the heart, lungs, arteries, and veins. Circulatory function in your body is controlled by an organ system.
True
T/F: A woman is taking a hike and sees a rattlesnake appear on the path near her feet. She is startled and as a result, her heart rate increases and she runs in the opposite direction. The woman’s heart rate is able to increase because heart rate is not maintained through homeostasis.
False
T/F: Coral reefs and tropical rain forests have existed on Earth for hundreds of millions of years, but the taxonomic composition of both has varied enormously.
True
T/F: The division of bilaterians into coelomate, acoelomate, and pseudocoelomate groups is supported by molecular studies.
False
T/F: All animal phyla are characterized by having their cells organized into different kinds of tissues.
False
T/F: Body temperature is maintained within a specific range because many physiologic and cellular functions are optimal only within a specific range. If someone goes outside on a hot day, they begin to get hot and their body temperature can rise. The body can respond by producing sweat from sweat glands to try and cool the body down. The cooling of the body from the production of sweat provides negative feedback to the hypothalamus.
True
On a phylogenetic tree, distantly related species diverge from branch points nearer to the tree’s:
base
T/F: Nervous tissue is found in all animal phyla except poriferans.
True
T/F: Different cells in the human body will maintain different homeostatic ion concentrations. These ion concentrations are controlled primarily by the composition and function of their cell membranes.
True
________ growth in animals is seen as they get larger to accommodate changes in surface area to volume ratio that occur with larger size and the need to support more mass with increasing size.
Allometric
T/F: A very healthy person should always have a constant heart rate and blood pressure.
False
Speciation is the divergence of two populations from a common ancestor. How does it contribute to biological diversity?
Speciation increases biological diversity.
The ability to maintain certain physical conditions (blood pH, body temperature, and so forth) within a narrow range of values most often depends on:
negative feedback
On a phylogenetic tree, more closely related species branch from points ______ the tips of the tree.
closer to
T/F: Patterns in early embryological development sometimes tell us more about phylogenetic relationships than adult characters.
True
T/F: You find an organism that is previously unknown to you. You see that it has bilateral symmetry and, therefore, expect that it will have muscle tissue.
True
Biologists have described about ___ species of eukaryotic organisms, of which about ___ are animals. The majority of eukaryotic species are ___.
1.8 million; 1.3 million; insects
Connective tissue is formed of loosely connected cells and a large portion of extracellular matrix. The function of each specific type of connective tissue is related to:
the composition of the proteins in its extracellular matrix.
T/F: With the exception of poriferans, all animal phyla contain true muscle tissue.
false
Different groups of organisms are defined by the unique characters they possess. The relative timing of when a particular character arose can be estimated by determining:
shared presence of the character in descendants of the population in which the character first arose.
T/F: Nervous tissue is found in all animal phyla except poriferans.
True
Because they lack well-defined and complex organ systems, we hypothesize that _____ diverged from all other animals early in the evolution of animals.
Poriferans
T/F: During childbirth the release of a hormone, oxytocin, causes an increase of uterine contractions. The increase in uterine contractions causes an increase in the amount of oxytocin produced and increasing strength of contractions. This is an example of negative feedback.
false
