Chapter 33: Animal Form, Function, and Evolutionary History Flashcards
The life cycle of animals is dominated by the _______ stage
diploid
_______ gametes are made by meiosis in animals
haploid
Haploid gametes are made by _______ in animals
meiosis
Haploid gametes are made by ______ in plants and fungi
mitosis
What is the asexual reproduction used by bacteria and archaea?
binary fission
What is the asexual reproduction used by yeast?
budding
What is the asexual reproduction used by some molds, algae, worms, sea stars, and corals?
fragmentation
What is a type of asexual reproduction used by a lot of invertebrates and a few special vertebrates?
Parthenogenesis
How do organisms offset the fail rate during external fertilization?
- need lots of gametes 2. need to get sperm close to eggs
Internal fertilization is generally seen as an adaptation for being _____, with some exception
terrestrial
What are two types of symmetry in animals?
radial and bilateral symmetry
Radial symmetry
has many planes of symmetry around the axis
Bilateral symmetry
has a single plane of symmetry; bilaterally symmetric animals have a distinct front and back, top and bottom, and right and left
diploblastic
describes animals in which the embryo has two germ layers, the endoderm and the ectoderm, from which the adult tissues develop
In cnidarians, do they have diploblastic or triploblastic germ cells?
diploblastic
triploblastic
Describes animals in which the embryo has three germ layers, with the mesoderm between the endoderm and ectoderm
In bilaterians, do they have diploblastic or triploblastic germ cells?
triploblastic
The evolution of the mesoderm in triploblasts allowed for…
the development of new types of tissues and organs (muscles and circulatory systems)
bilaterians animals are divided into two groups
the protostomes and the deuterostomes
Protostomes
A bilaterian in which the blastopore, the first opening to the internal cavity of the developing embryo, becomes the mouth. Includes: mollusks and arthropods (mouth then anus)
Deuterostomes
A bilaterian in which the blastopore, the first opening to the internal cavity of the developing embryo, becomes the anus. Includes: humans and other chordates (anus then mouth)
_____________ comparisons confirm that choanoflagellates are the closest protistan relatives of animals
Molecular sequences (DNA)
coelom
a body cavity surrounding the gut
The ______ cushions the internal organs against hard blows to the body and enables the body to turn without twisting these organs
coelom
Once molecular studies were conducted, researchers discovered that they did not support this traditional phylogenetic division of bilaterians into what 3 groups?
acoelomate, coelomate, and pseudocoelomate groups
Acoelomates
do not have a cavity outside the digestive tract
Coelomates and pseudocoelomates
both have a body cavity, but differ in the embryonic origin of the cells lining the cavity
Amnion
more freedom from water for reproduction, the amnion, a membrane surrounding a fluid-filled cavity that allows the embryo to develop in a watery environment
Development of all animals involves…
coordinated events from the molecules to the organism level
Larva
a free-living stage; different in form than adult
On a cellular level, there are changes in…
cell form, cell-cell communication and cell position
Changes in________ are unique to animal development
cell position
The cells of most animals are organized into 4 types of tissues:
epithelial, connective, muscle, and nervous
tissues
collections of cells that carry out a specific function
Epithelial tissue
provides a lining for all of the spaces inside and outside the body (composed of closely packed cells)
Connective Tissue
a type of animal tissue that underlies epithelial tissues and is found elsewhere as well; has an extensive extracellular matrix and few cells
Muscle Tissue
made up of cells that are able to shorten or contract, resulting in movement
True muscle tissue is present in ______ but not _______
bilaterians; cnidarians
What 3 types of muscle tissue do vertebrate animals have?
skeletal, cardiac, and smooth
Nervous tissue
found in the nerve nets of cnidarians and in the brain, spinal cord, and peripheral nerves of vertebrates; it takes in sensory info from the environment, processes it, and sends signals to target organs to elicit a response
In ______, multiple tissues can combine to make an organ
bilaterians
Cnidarians have a set of nerves called a…
nerve net (their nerves are not organized into a brain or CNS)
How do cnidarians exchange gases?
by diffusion (rather than by using lungs or gills)
How do cnidarians digest food?
in a central cavity with a single opening for both eating and excretion
Mollusks, arthropods, mammals, and other bilaterians have…
true organs (made up of one or more types of tissue)
Homeostasis is a…
negative feedback loop
Negative feedback
a stimulus acts on a sensor that communicates with an effector, producing a response that opposes the initial stimulus.
Nerve cells in the ______ act as the body’s thermostat or sensor
hypothalamus
What is a set point in homeostasis?
a steady-state value in homeostatic regulation
Ediacaran fossils
simple shaped, fluid-filled, without identifiable mouths or other organs; may have formed colonies (forming complexity through colonial growth and differentiation)
When on Earth did the atmosphere and oceans come to contain sufficient amounts of oxygen to support the metabolism of large, active animals?
During the Ediacaran Period
The animal body plans we see today emerged during the…
Cambrian Period
Cambrian fossils
commonly include skeletons made of the minerals silica, calcium carbonate, and calcium phosphate, and they record the presence of arthropods, echinoderms, mollusks, brachiopods, and other bilaterian animals in the oceans
___________ have changed the trajectory of animal evolution during the past 500 million years
Five mass extinctions
If we were to walk on an Ordovician beach, the shells washing about your feet would have belonged to…
brachiopods
Why as the Ordovician world so distinct form our own?
At the end of the Permian period, a mass extinction eliminated most genera in the oceans
When did animals begin to colonize the land?
420 million years ago
Did animals move to land before or after plants?
after
During what period did land animals arise?
The Silurian Period (420 mya)
Cope’s rule
suggests that there is a trend through time toward increasing size among animals
Who are the deuterostomes?
chordates and echinoderms
Who are the protostomes?
nematode, arthropods, mollusks, annelid worms, flat worms