Chapter 9 Flashcards
Taxonomy
the system we use to name and classify all organisms (living and extinct)
Taxonomy is based on the system developed by
Carl Linnaeus (Carl von Linne) developed in 18th century
System of binomial nomenclature
because every organism has a two part name i.e homo sapiens, panthera leo (lion)
Linnaeus classified every organism in a
hierarchy, taxa, or levels of organization
The taxa are:
*king phillip
domain, kingdom, phylum, class, order, family, genus, and species
Kingdom
- the most general
- consists of the most varied organisms
Species
- the most specific
- consists of organisms that are the most similar
1950s /60s
all organisms were placed into only 3 kingdoms
60s - 1990
scientists expanded the system to 5 kingdoms : Monera (no longer used), Protists, Fungi, Plantae, and Animalia
1990
some scientists added a 6th kingdom, Archaebacteria which included extremophiles (microorganisms that live in extreme environments) and that seemed so different from bacteria that they had to placed into a separate kingdom
Today most scientists use the
3 domain system
based on DNA analysis
The 3 domain system more accurately
reflects evolutionary history and the relationships among organisms
All life is organized into 3 domains
Bacteria, Archaea, and Eukarya
superkingdoms
eukaryota, prokaryota
separate by cell structure
-3 domain system is now favored
Why is monera not used anymore?
because prokaryotes are spread across two different domains , Archaea and Bacteria
Why did scientists switch from the superkingdoms to the 3 domain kingdom?
because Archaea have so little in common with bacteria that they must have their own group
Why did archaebacteria have to be changed to archaea?
because the Archaea are not bacteria
Bacteria:
What are bacteria?
All are single-celled prokaryotes w/ no internal membranes (no nucleus, mitochondria, or chloroplasts)
Some bacteria are _____,some are ______.
anaerobes, aerobes
Bacteria are decomposers that
recycle dead organic matter
Bacteria play a vital role in
genetic engineering (bacteria from the human intestine, escherichia coli, are used to manufacture human insulin)
Some bacteria are _____(blue-green algae); others are _________.
autotrophic
heterotrophic
Do bacteria have introns?
bacteria don’t have introns (noncoding regions within DNA)
Bacteria have a thick,
rigid cell wall
Member species correspond roughly to the old grouping _______ and include:
Eubacteria
- blue-green algae
- bacteria like E.coli that live in the human intestine
- those that cause disease like Clostridium botulinum and Streptococcus
- those necessary in the nitrogen cycle, like nitrogen-fixing bacteria
Archaea:
unicellular and prokaryotic
-no internal membranes such as a nucleus
Archaea include
extremophiles, microorganisms that live in extreme environments
Extremophiles in archaea include
- methanogens
- halophiles
- thermophiles
Methanogens
obtain energy by producing methane from hydrogen
Halophiles
thrive in environments with high salt concentrations like Utah’s Great Salt Lake
Thermophiles
thrive in high temps, like hot springs in Yellowstone, or deep-sea hydrothermal vents
Are introns present in archaea?
introns are present in some genes
All animals belong in the domain
Eukarya
In eukarya
All organisms have a nucleus and internal organelles
Eukarya includes the
4 remaining kingdoms
4 kingdoms in Eukarya are
protista
fungi
plantae
animals
Protista includes organisms that do not fit into the fungi or plant kingdoms such as
seaweeds and slime molds
Protista include
the widest variety of organisms but all are eukaryotes
Most protista are
single-celled, but many are primitive multi celled organisms
What do protista include?
- Includes heterotrophs (such as amoeba and paramecium)
- autotrophs (euglenas which have a red eyespot to locate light and chlorophyll to carry out photosynthesis)
How do protists move?
by various means
amoeba use psuedopods
paramecium use cilia
euglena use a flagellum
Some protists (i.e. paramecium, algae) sometimes carry out
conjugation, a primitive form of sexual reproduction where individuals exchange genetic material
Some protists also cause
serious diseases like amoebic dysentery and malaria
Fungi
All are heterotrophic eukaryotes
Can be unicellular or multicellular
What role do fungi play in ecology?
decomposers
Digestion in Fungi
Carry out extracellular digestion by secreting hydrolytic enzymes outside the body
[fungi] After digestion ,
the building blocks of the nutrients are absorbed into the body of the fungus by diffusion
Fungi are saprobes,
organisms that obtain food from decaying organic matter. As such they recycle nutrients in an ecosystem.
What are cell walls in fungi composed of?
chitin, not cellulose
Certain fungi combine with algae in a
symbiotic relationship forming various lichens which are photosynthetic.
Lichens can survive
harsh, cold environments and even live on bare rock.
Lichens are often the pioneer organisms,
the 1st to colonize a barren environment in an ecological succession
How do fungi reproduce?
Reproduce asexually by budding (yeast), spore formation (bread mold), or fragmentation whereby single parent breaks into parts that regenerate into whole new individuals
-they also reproduce sexually
Examples of fungi:
- yeast
- mold
- mushrooms
- fungus that causes athlete’s foot
Plantae
All are multicellular, nonmotile, autotrophic eukaryotes
Plantae cell walls are made of
cellulose
Plants carry out photosynthesis using
chlorophyll a and b
Plants store their carbohydrates
as starch
How do plants reproduce?
Reproduce sexually by alternating between gametohpyte (n) and sporophyte (2n) generations (known as alternation of generations)
Some plants have vascular tissue (_______), and some have no vascular tissue (________)
tracheophytes
bryophytes
Examples of plantae
- mosses
- ferns
- cone-bearing/flowering plants
Animalia
- All are heterotrophic, multicellular eukaryotes
- Most are motile, can move on their own
How do most animals reproduce?
Most animals reproduce sexually with a dominant diploid (2n) stage
Animalia: In most species, a small flagellated sperm fertilized
a larger, nonmotile egg
What is traditional way of classifying animals?
primarily based on anatomical features (homologous structures) and embryonic development
Animalia are grouped in ____ phyla but we commonly discuss _____
35
9
What are the 9 commonly discussed phyla?
porifera, platyhelminthes, annelids, arthropods, cnidarians, chordates, nematodes, echinoderms, mollusks
PPAACCNEM
Evolutionary Trends in Animals
Organisms began as tiny, primitive, and single celled → lived in oceans → 1st multicellular eukaryotes evolved about 1.5 billion years ago
Appearance of each phylum of animal represents
the evolution of a new and successful body plan
Important evolutionary trends in animals include:
- specialization of tissues
- germ layers
- body symmetry
- development of a head end
- body cavity formation
Cell
basic unit of all forms of life, ex. Neuron
Tissue
group of similar cells that perform one particular function, ex. Sciatic nerve
Organ
group of tissues that work together to perform related function, ex. Brain
Sponges (Porifera) consist of a
loose federation of cells, which are not considered tissue because the cells are relatively unspecialized
Sponges possess cells that can
sense and react the environment but have no real nerve or muscular tissue
Cnidarians like the hydra and jellyfish possess only the
most primitive and simplest forms of tissue
As larger and more complex animals evolved ____________.
, specialized cells joined to form real tissues, organs, and organ systems.
Flatworms have organs but no
organ system
More complex animals like annelids (earthworms) and arthropods (grasshoppers)
have organ systems
The main layers that form various tissues and organ of the body are formed
early in embryonic development and include the ectoderm, endoderm, and mesoderm
Ectoderm (Outermost layer)
becomes the skin and the nervous system, including the nerve cord and brain
Endoderm (innermost layer)
becomes the viscera (guts) or the digestive system
Mesoderm (middle layer)
becomes the blood, muscles, and bones
Examples of animals with only 2 cell layers are porifera and cnidarians
Porifera and cnidarians’ bodies consist of
the ecto/endoderm and mesoderm, which holds the two layers together (middle glue)
More complex animal phyla are
triploblastic, having 3 true cell layers
What type of symmetry do primitive animals exhibit? What about sophisticated ones?
Primitive animals exhibit radial symmetry , sophisticated ones exhibit bilateral
How are echinoderms an exception in body symmetry?
Echinoderms are an exception because they are an advanced phylum and exhibit bilateral symmetry as larvae but revert to radial symmetry as adults
Bilateral Symmetry
Body is organized along a longitudinal axis with right and left sides that mirror each other
Most bilaterally symmetrical animals are
triploblastic, w/ ectoderm, mesoderm, and endoderm
What came along with bilateral symmetry?
the development of a head- the anterior, and a rear end- the posterior
What’s clustered at the anterior end?
Sensory apparatus and a brain (or simply ganglia)
What’s located at the posterior end?
Digestive, excretory, and reproductive structures
These organs at the anterior and posterior ends enable animals to
move faster to flee or to capture prey
Simple animals
sponges and cnidarians- don’t have a head
Sophisticated animals beginning with flatworms and ending with chordates all show
cephalization
Coelom
a fluid-filled body cavity that is completely surrounded by mesoderm tissue
What does coelom represent?
a significant advance in the course of animal evolution because provides a space for elaborate organ systems
Primitive animals like flatworms do not have a coelom and are known as
acoelomates→ their bodies are flat and all cells are in direct contact with their watery environment
Nematodes or roundworms are called
pseudocoelomates → they have a fluid-filled tube between the endoderm and the mesoderm that acts as a hydrostatic skeleton to support the animal
Coelomates are the animals with
coelom and are the most complex in the kingdom
Coelomates include the following phyla:
Annelida, Mollusca, Anthropoda, and Chordata
3 Main characteristics of Porifera-Sponges
- No symmetry
- No nerve or muscle tissue- sessile (don’t move)
- Consist of 2 cell layers only → ectoderm and endoderm connected by noncellular mesoglea
Porifera-Sponges have specialized cells but
no true tissues or organs, each cell carries out many function
What did porifera-sponges evolve from?
colonial organisms?
If you squeeze a sponge through fine cheesecloth,
it will separate into individual cells that will spontaneously re-aggregate into a sponge
How do porifera-sponges reproduce?
Reproduce asexually by fragmentation
Also reproduce sexually, hermaphrodites
Cnidarians include
hydra and jellyfish
Body plan of Cnidarians
Body plan is the polyp (vase shaped) which is mostly sessile, or medusa (upside-down bowl shaped), which is mostly motile
Life cycle of cnidarians
Life-cycle →
* some go through planula larva (free swimming) stage then go through 2 reproductive stages,
asexually reproducing (polyp) and sexually reproducing (medusa)
Cnidarians consist of only
2 cell layers → ectoderm and endoderm connected by noncellular mesoglea
Characteristics of cnidarians digestion include:
- Have a gastrovascular cavity where extracellular digestion occurs
- Carry out intracellular digestion inside body cells in lysosomes
Cnidarians have no transport system because
every cell is in direct contact with the environment
All cnidarians members have
stinging cells-cnidocytes- containing stingers, which are called nematocysts
Platyhelminthes
Flatworms including Tapeworms
Platyhelminthes are
- simplest animals with bilateral symmetry
- an anterior end and three distinct cell layers: ectoderm, endoderm, and mesoderm
Digestion in Platyhelminthes
- The digestive cavity has only one opening for both ingestion and egestion so food cannot be processed continuously
- They have a solid body and have no room for true digestive or respiratory systems to circulate food or oxygen. Flatworms have solved this problem in a unique way
In Platyhelminthes, the body is so flat and thin that many
body cells can exchange nutrients and wastes by diffusion with the environment
Nematods
roundworms
Nematods are
unsegmented worms with bilateral symmetry but little sensory apparatus
Many nematods are
parasitic, trichinella causes trichinosis, which is contracted by eating uncooked pork
What species of nematods are widely used as an animal model in studying genes and embryonic development?
C. elegans
Annelids
Segmented Worms like Earthworms, Leeches
What type of symmetry do annelids have?
Bilateral symmetry with little sensory apparatus
Digestion in Annelids
- Digestive tract is a tube-within-a-tube consisting of crop, gizzard, and intestine
- Nephridia for excretion of the nitrogen waste, urea
Circulatory system of Annelids
- Closed circulatory system- heart consists of 5 pairs of aortic arches
- Blood contains hemoglobin and carries oxygen
Annelids diffusion
Diffusion of oxygen and carbon dioxide through moist skin
Annelids are
hermaphrodites
Mollusks
Squids, Octopuses, Slugs, Clams, and Snails
Circulatory system of Mollusks
Open circulatory system with blood-filled spaces called hemocoels or sinuses
Symmetry of Mollusks
Have bilateral symmetry with 3 distinct body zones
What are the 3-distinct body zones of mollusks?
- Head-foot which contains both sensory and motor organs
- Visceral mass which contains the organs of digestion, excretion, and reproduction
- Mantle a specialized tissue that surrounds the visceral mass and secretes the shell
Mollusks have a radula, which is
a movable, tooth-bearing structure, acts like a tongue
Most mollusks have
gills and nephridia
Arthropods
Insects (Grasshopper), Crustacea (Shrimp, Crab), Arachnida (Spider)
2 Main Arthropods Characteristics
- Jointed appendages
- Segmented into head, thorax, abdomen
What protects arthropods and helps their movement?
Chitinous exoskeleton
Compare arthropods and annelids
arthropods more sensory apparatus than in annelids, giving them more speed and freedom of movement
Circulatory of Arthropods
Open circulatory system with a tubular heart and hemocoels, sinuses
Digestion of Arthropods
Mapighian tubules for removal of nitrogenous wastes, uric acid
Respiratory System of Arthropods
Air ducts called trachea bring air from the environment into hemocoels
Echinoderms
Sea Stars (Starfish) and Sea Urchins
Echinoderms are
sessile or slow moving
Symmetry of Echinoderms
Bilateral symmetry as an embryo → primitive radial symmetry as an adult , the radial anatomy of the adult is an adaptation to a (sedentary) inactive life
Echinoderm’s water vascular system creates
hydrostatic support for the tube feet, the locomotive structures
How do echinoderms reproduce?
- Reproduce by sexual reproduction with external fertilization
- Can also reproduce by fragmentation and regeneration→ any piece of a sea star that contains part of the central canal will form a completely new organism
Sea stars have an endoskeleton consisting of
calcium plates
Sea stars have an endoskeleton consisting of
consisting of calcium plates (endoskeleton grows w/ the body, exoskeleton doesn’t and must be shed periodically)
Chordates
Fish, Amphibians, Reptiles, Birds, Mammals
Chordates
Fish, Amphibians, Reptiles, Birds, Mammals
Chordates have a notochord
a rod that extends the length of the body and serves as a flexible axis
The tail aids in _______and ________, the coccyx bone in humans is a _______ of a tail
movement and balance
vestige
Birds+mammals are homeotherms meaning
they maintain a consistent body temp.
Other than birds/mammals, all other chordates are
cold-blooded although some reptiles are endotherms (heat from within) and are able to raise their body temp
Mammals belong to the phylum
cordata
Main 3 characteristics of mammals
- Mothers nourish children w/ milk from mammary glands
- Have hair or fur
- Endotherms (warm-blooded)
Most mammals are
placental
‘eutherians’
Eutherians means
the embryo develops internally in a uterus connected ot the mother by a placenta where nutrients diffused from mother to embryo
What happens if a marsupial is born very early in embryonic development?
the ‘joey’ completes its development while nursing in the mother’s pouch attached to a tea
What are monotremes?
egg-laying mammals
Examples of monotremes
the duck-billed platypus and the spiny anteater, derive nutrients from a shelled egg
What did primates descend from?
insectivores, small-tree dwelling mammals
Primates have dexterous hand and
opposable thumbs, making it possible to do fine-motor tasks
Primate’s nails replaces
claws + hands and fingers contain many more nerve endings and are sensitive
How do primate’s forward facing/set close together eyes help them?
face-to-face communication
Who engages in the most intense parenting of any mammal?
primates
Primates include
humans, gorillas, chimps, orangutans, gibbons, and the old and new world monkey
Cladograms and Phylogenetic Trees
These are diagrammatic representations of evolutionary history based on DNA sequences
How do you build a cladogram?
you must distinguish the difference between shared traits - those that organisms have in common- and
derived traits- new characteristics or innovations that are not shared with ancestors
How do you build a cladogram?
you must distinguish the difference between shared traits - those that organisms have in common- and derived traits- new characteristics or innovations that are not shared with ancestors
