Honors Biology Final Study Guide

Griffith's experiment
-Griffith studied a bacterium called Streptococcus pneumoniae and was trying to develop a vaccine against a disease-causing strain of the bacterium
-each virulent bacterium is surrounded by a capsule
-the strain that is virulent (disease causing) grows as smooth-edged colonies and called the S strain
-the non-virulent strain lacks a capsule, and grows into rough colonies, so it is called the R strain
-Griffith used the two strains of S. pneumonaie on mice in his experiments:
-1. he injected R cells into a mouse, and the mouse lived
-2. he injected S cells into a mouse, and the mouse died
-3. he injected heat-killed S bacteria into the mouse, and the mouse survived
-4. mixed heat-killed S and R cells and injected it, and the mouse died, because the heat-killed S transforms the R cells
-Griffith concluded that heat-killed virulent bacterial cells release a hereditary factor that transfers the disease-causing ability to the live harmless cells
-this type of transfer of genetic material from one cell to another cell or from one organism to another organism is called transformation
Hershey-Chase experiment
-Hershey and Chase set out to test whether DNA or protein was the hereditary material viruses transfer when viruses enter a bacterium:
1. they used radioactive isotopes to label the protein and DNA in the phage
-they used radioactive sulfur (35S) to label protein and radioactive phosphorus (32P) to label DNA
-they allowed protein-labeled and DNA-labeled bacteria to separately infect E. coli
-2. they removed the phage coats from the cells in a blender
-3. used a centrifuge to separate the phage from the E. coli
-they found that all of the viral DNA and little of the protein had entered E. coli cells
-concluded that DNA is the hereditary molecule
DNA structure
-a nucleic acid made of two long chains (called strands) of repeating subunits called nucleotides
-each nucleotide consists of three parts:
-a five-carbon sugar
-called deoxyribose
-a phosphate group
-consists of a phosphorus (P) atom bonded to four oxygen (O) atoms
-a nitrogenous base
-contains nitrogen (N) atoms and carbon (C) atoms
-is a base (accepts hydrogen ions)
base pairing
-in DNA, cytosine on one strand pairs with guanine on the opposite strand
-and adenine pairs with thymine
-these pairs are called complementary bases
-A goes with T, G goes with C
DNA replication
-1. helicases separate the DNA strands
-2. DNA polymerases add complementary nucleotides, forming covalent bonds between the adjacent nucleotides
-3. DNA polymerases finish replicating the DNA and fall off
-an enzyme that separates the DNA strands in DNA replication
-it moves along the DNA molecule, breaking hydrogen bonds between the complementary nitrogenous bases
-this allows the 2 DNA strands of the double helix to separate from each other (the replication fork)
enzyme that makes primer, and primer starts the DNA synthesis
DNA polymerase
-an enzyme that adds complementary nucleotides (found floating freely inside the nucleus) to each of the original strands in replication
-covalent bonds form between the deoxyribose sugar of one nucleotide and phosphate group of the next nucleotide on the growing strand
-hydrogen bonds form between the complementary nitrogenous bases on the original and new strands
-DNA replication leaves gaps in the newly synthesized strand
-ligase is an enzyme that joins the gaps together
semi-conservative replication
-a type of replication that describes DNA
-called this because each of the new DNA molecules has kept (or conserved) one of the two (or semi) original DNA strands
-a change in the nucleotide sequence of a DNA molecule
-when mistakes in DNA replication occur, the base sequence of the newly formed DNA differs from the base sequence of the original DNA
-can have serious effects on the function of an important gene and disrupt important cell functions
-sometimes, mutations that are not repaired can cause diseases such as cancer
-for example, mutations that affect genes that control how a cell divides can lead to an abnormal mass of cells called a tumor
central dogma
-the process of producing proteins is irreversible: a protein cannot be used to create DNA
-it goes DNA→RNA→protein
-ribonucleic acid
-the gene directs that making of the protein called melanin (a pigment) in hair follicle cells through an intermediate, which is RNA
differences between DNA and RNA
-RNA contains the sugar ribose, NOT the sugar deoxyribose found in DNA
-RNA contains the nitrogenous base uracil instead of the nitrogenous base thymine found in DNA
-RNA is usually single stranded rather than double stranded like DNA
-RNA is usually much shorter in length than DNA
three types of RNA-functions
-messenger RNA (mRNA):
-carries the genetic "message" from DNA in the nucleus to the ribosomesin the cytosol
-ribosomal RNA (rRNA):
-part of the structure of ribosomes (organelles in the cell where protein synthesis occurs)
-transfer RNA (tRNA):
-transfers amino acids to the ribosome to make a protein
-where DNA acts as a template for the synthesis of RNA
-occurs in three steps:
1. RNA polymerase (catalyzes the formation of RNA on a DNA template) binds to the promoter (initiates transcription)
-the DNA strands unwind and separate
2. RNA polymerase adds complementary nucleotides, resulting in an RNA molecule
-as RNA polymerase moves past, the separated DNA strands rewind
3. RNA polymerase reaches a termination signal (marks the end of a gene)
-RNA polymerase releases both the DNA and the newly formed RNA
how to use the genetic code
-three adjacent nucleotides ("letters") in mRNA specify an amino acid ("word") in a polypeptide
-first, you must translate the DNA into RNA
-the codon AUG acts as a start codon
-cetain sequences in mRNA (UAA, UAG, or UGA) called stop codons, signal for translation to end
-where RNA directs the assembly of proteins
-each protein strand is made of polypeptides (chains of amino acids)
-occurs in five steps:
1. two ribosomal subunits, tRNA and mRNA join together
-enzymes attach a specific amino acid to one end of each tRNA according to the genetic code
-the other end of each tRNA contains three nucleotides on the RNA complementary to the sequence of codon in mRNA (anticodon)
2. a polypeptide chain is put together
-a tRNA with the appropriate amino acid pairs its anticodon with the second codon in mRNA
-ribosome detaches methionine from the 1st tRNA and a peptide bond forms between methionine and the second amino acid
-the first tRNA then exits the ribosome
3. the polypeptide chain continues to grow
4. the ribosome reaches the stop codon and the newly made polypeptide falls off
5. the ribosome complex falls apart, and the newly made polypeptide is released
spontaneous generation
-a process where living things could arise from nonliving things
-believed to be true before the 17th century
-it seemed to explain why maggots appeared on rotting meat and why fish appeared in ponds that were dry in the previous season
Redi's experiment
-Redi observed that tiny wormlike maggots turned into sturdy oval cases from which flies emerge
-he also observed that maggots seemed to appear where adult flies had previously landed
-his experimental group consisted of netting-covered jars that contained meat, to allow air to enter and prevent flies from landing on the meat
-the control group consisted of uncovered jars that also contained meat
-after a few days, maggots were living in the meat in the open jars, but the net-covered jars were maggot-free
-his experiment showed that flies come only from eggs laid by other flies
Pasteur's experiment
-Pasteur set out to clear up the issue of spontaneous generation
-he made a curve-necked flask that allowed the air inside the flask to mix with air outside, but it prevented solid parlicles (like microorganisms) from entering the flask
-he boiled broth in the flask, and the flasks remained clear for a year
-but when he broke the curved neck off, the flask became cloudy within a day
age of the earth
-the estimated age is more than 4 billion years
-to find it, scientists have explored Earth's surface and examined its many layers to establish a fairly complete picture of its geologic history
-early estimate's of Earth's age were made from studying layers of sedimentary rock in Earth's crust
-the age, however, couldn't be accurately estimated until the middle of the 20th century
atoms of the same element that differ in the number of neutrons they contain
-the length of time it takes for one-half of any size sample of an isotope to decay to a stable form
-how to find half-life:
-when an organism dies, decay of the existing carbon-14 continues
-after 5,730 years, half of the carbon-14 in a sample will have decayed
-after another 5,730 years, half of the remaining carbon-14 in the sample will have decayed
-but carbon-14 dating is limited to remains less than 60,000 years old
Miller-Urey experiment
-Miller and Urey used Oparin's hypothesis of how the Earth formed to set up their experiment
-their equipment had a chamber of gases (ammonia, hydrogen gas, water vapor, and compounds made of hydrogen and carbon, like methane)
-as the gases circulated in the chamber, electric sparks, substituting for lightning, supplied energy to drive chemical reactions
-the experiment produced a variety of organic compounds, including amino acids
-in this process, CO2 serves as a carbon source for the assembly of organic molecules
-energy is obtained from the oxidation of various inorganic substances, such as sulfur
-many species of archaea are autotrophs (or producers) that obtain energy this way, instead of photosynthesis
endosymbiotic theory
-the theory that between about 2.0 and 1.5 billion years ago, a type of small aerobic prokaryote was engulfed by and began to live and reproduce inside of a larger, anaerobic prokaryote
-the eukaryotes provided a beneficial environment and the prokaryotes provided a method of energy synthesis
-in a later case, photosynthetic cyanobacteria may have evolved into chloroplasts, which perform photosynthesis in modern eukaryotic plant and algae cells
catastrophism vs. uniforitarianism
-developed by Cuvier
-the idea that sudden geologic catastrophes caused the extinction of large groups of organisms at certain points in the past
-developed by Lyell
-the idea that geologic processes that have changed the shape of Earth's surface in the past continue to work in the same ways
-put forward a new idea to explain how evolution could happen (though it is no longer accepted)
-he thought that simple forms of life inevitably develop into more complex forms
-proposed that individuals could acquire traits during their lifetime as a result of experience or behavior, then pass on those traits to offspring
-his idea is called inheritance of acquired characteristics
natural selection
-a theory proposed by Darwin as the mechanism for descent with modification
-there was four main parts of Darwin's reasoning:
1. overproduction (more offspring are produced than can survive)
2. genetic variation (within a population, individuals have different traits)
3. struggle to survive (individuals compete for existence, and some variations improve an individual's chance to survive)
4. differential reproduction (through inheritance, successful adaptations will become more frequent in the population)
-a measure of an individual's hereditary contribution to the next generation
-"survival of the fittest" is a kind of fitness that is more than simply living a long time: a fit individual is one that has offspring that also live long enough to reproduce in a given environment
homologous structure
-anatomical structures that occur in different species and that originated by hereditary from a structure in the most recent common ancestor of the species
-have a related structure even if their functions differ between species
analogous structure
-have closely related functions but do not derive from the same ancestral structure
-ex: even though birds, bats, and moths have wings, they all have different structures
vestigial structures
-structures that seem to serve no function but resemble structures with functional roles in related organisms
-ex: the human tailbone resembles bones in an animal's tail, but the human one serves no purpose
divergent evolution
-a process in which the descendants of a single ancestor diversify into species that each fit different parts of the environment
-ex: a wolf has diversified into many types of dogs
convergent evolution
-the process by which different species evolve similar traits
-ex: a bat (mammal) and bug (insect) can both fly, even though they are different species
artificial selection
-a process when a human breeder chooses individuals that will parent the next generation
-ex: dogs, horses, cats, birds, flower, vegetables
-when two or more species have evolved adaptations to each other's influence
-ex: humans have used antibiotics to kill disease-causing bacteria, but populations of bacteria have evolved to resist the effects of antibiotics
-through coevolution, some species have evolved strategies to avoid being eaten, while the animals that eat them have evolved strategies to keep eating them
causes of genetic variation (5)
(1) mutation
(2) recombination (reshuffling of genes)
(3) random pairing of gametes
(4) environmental factors
(5) heredity
mutation in equilibrium
-the first requirement for genetic equilibrium is that the allele frequencies not change overall because of mutations
-can affect genetic equilibrium by producing totally new alleles for a trait
-many are harmful, though some have no effect
-because natural selection operates only on genes that are expressed, it is very slow to eliminate harmful recessive mutations
-the movement of individuals out of a population
-the movement of individuals into a population
gene flow
-the process of genes moving from one population to another
-can occur through various mechanisms, such as the migration of individuals or the dispersal of seeds or spores
-one of the requirements for genetic equilibrium is that there cannot be gene flow
random mating
-another requirement of genetic equilibrium is random mating, without regard to genetic makeup
-however, many species do not mate randomly
sexual selection
-a tendency for females to choose males they mate with based on certain traits
-extreme traits, such as heavy, brightly colored plumage, may give the female an indication of the quality of the male's genes or his fitness in the environment
genetic drift
-the phenomenon by which allele frequencies in a population change as a result of random events
-in small populations, the failure of even a single organism to reproduce can significantly disrupt the allele frequency of the population
-because it can result in significant changes, genetic drift is thought to be another possible mechanism for the evolution of new species
-so you would need large population sizes to get genetic equilibrium to prevent big changes
natural selection
-a requirement of genetic equilibrium is the absence of natural selection
-it means that some members of a population are more likely than others to survive and reproduce
-operates on variations of traits within a population
-when natural selection is at work over time, the distribution of traits in a population may change
stabilizing selection
-in this, individuals with the average form of a trait have the highest fitness
-it is a shift toward the center of the original bell curve in a graph
disruptive selection
-individuals with either extreme variation of a trait have greater fitness than individuals with the average form of the trait
-there is a shift in both directions away from the center on a graph
directional selection
-individuals that display a more extreme form of a trait have greater fitness than individuals with an average form of the trait
-there is a shift in one direction only on a graph
allopatric speciation
-happens when species arise as a result of geographic isolation
-populations separated by a geographic barrier no longer experience gene flower between them
-so, gene pools of each separate population begin to differ due to genetic drift, mutations, and natural selection
-is more likely to occur in small populations because a smaller gene pool will be changed more significantly
sympatric speciation
-occurs when two subpopulations become reproductively isolated in the same geographic area
-ex: a population of insects might live on a single type of plant; if some of the individuals from this population began to live on another type of plant, they might no longer interbreed w/ the original; the two groups of insects would evolve independently
the science of describing, naming, and classifying organisms
-Carolus Linnaeus devised a system of grouping organisms into hierarchical categories according to their form and structure
-each category represents a level of grouping
-his original system had seven levels, but there are eight now
levels of classification
-phylum (replaced by division in plants)
-King Phillip Chases Old Fat Girl Scouts
binomial nomenclature
-two-part name system for scientific names, consisting of genus and species
-both names are italicized
-the genus is capitalized, but the species is lowercased
-a system of phylogenetic analysis that uses shared (a feature that all members of a group have) and derived (a feature that evolved only within the group under consideration) characteristics as the only criteria for grouping taxa
-developed by Willi Hennig
-categories above the kingdom level
-only three: Archaea, Bacteria, and Eukarya
-not in Linnaeus's original system, but was added later by scientists
3 characteristics of ALL animals
-eukaryotic cells
-the outer germ layer of an embryo
-forms the outer layer of the gastrula
-becomes the SKIN and NERVOUS SYSTEM
-the inner germ layer of an embryo
-becomes the MUSCLES and BONES
-a third layer that forms between the endoderm and the ectoderm as development progresses in the embryo
patterns of symmetry
-radial symmetry
-the parts are organization in a circle around an axis
-bilateral symmetry
-two similar halves on either side of a central plane
-not displaying symmetry
-the concentration of sensory and brain structures in the anterior (toward the head) region of the animal
-typically shown in bilaterally symmetrical animals
-as a cephalized animal moves through its environment, the anterior end precedes the rest of the body, sensing the environment
-the series of cell divisions that occurs immediately following fertilization
-steps 1., 2., 3.: the number of cells increases from 2 to 4 to 8 and so on
-step 4. it produces a mass of 16-64 cells
-step 5. the mass becomes a blastula
-during cleavage, mitotic divisions rapidly increase the number of cells, but the cells don't grow in size
-increases the surface area-to-volume ratio of each cell, which enhances gas exchange and other environmental interactions
-a hollow ball of cells
-happens in step 5 of cleavage
-the central cavity is called the blastocoel
-during gastrulation, the blastula collapses inward and the blastula is transformed into a gastrula
-the process of transforming the blastula into a multilayered embryo
-the cells at one end of the blastula moves inward
-gastrulation is marked by changes in the shape of cells and the way cells interact with each other
a multilayered embryo
blastopore fate
-in the embryos of mollusks, arthropods, and annelids, the blastopore develops into a mouth, and a second opening forms at the other end, forming an anus (protostomes)
-in the embryos of echinoderms and chordates, the blastopore develops into an anus, and a second opening becomes the mouth (deuterostomes)
-the blastopore develops into a mouth, and a second opening forms at the other end of the archenteron, forming an anus
-in embryos of mollusks, arthropods, and annelids
-means "first mouth"
-many undergo spiral cleavage
-the blastopore develops into an anus, and a second opening at the other end of the archenteron becomes the mouth
-in embryos of echinoderms and chordates
-means "second mouth"
-many undergo radial cleavage
-animals that don't have a body cavity
-the interior is solid
-the endodermic gut and the outer covering of the animal are connected by a solid tissue of mesoderm
-ex: flatworms
-a cavity that is not completely lined by mesoderm
-in pseudocoelomates, mesoderm lines the fluid-filled body cavity, and the endodermic gut is suspended in this fluid
-ex: roundworms
-a cavity completely lined by mesoderm
-in coelomates, mesoderm lines the body cavity and surrounds and supports the endodermic gut
-the mesoderm also forms the tissues of attachment for the organs located in the coelom, such as the liver and the lungs
-ex: mollusks, annelids, chordates, arthropods, and echinoderms
Phylum Porifera
made up of sponges
-when an animal attaches themselves firmly to a surface and doesn't move
-adult sponges are sessile
-flagellated cells that draw water into the sponge through numerous pores by beating their flagella
-lines the interior of the body wall cylinder of a sponge
-the opening at the top of the sponge
-the water that is pumped into the interior of the sponge leaves through here
-some sponges have skeletons consisting of these
-they are tiny, hard particles of calcium carbonate or silicon dioxide that are often shaped like spikes
filter feeding
-when the flagella of choanocytes beat, drawing water through the osculum, and the choanocytes trap plankton and other tiny organisms in their small, hair-like projections
-used in sponges because they cannot pursue food since they are sessile
-cells that crawl within the body wall of a sponge (after receiving nutrients from the choanocytes) and deliver the nutrients to the rest of the body
-called amoebocyte because they resemble amoebas
sponge reproduction
-can reproduce asexually by forming small buds that break off and live separately
-they can also reproduce sexually, by releasing sperm into the water from one sponge and entering the pores of a second sponge
-are hermaphrodites
-a vase-shaped cnidarian
-specialized for a sessile existence
-bell-shaped cnidarian
-specialized for swimming
cnidarian cell layers
-there are two layers:
-an outer epidermis
-an inner gastrodermis
-between these layers is a jelly-like material called mesoglea
-a jelly-like material in between cell layers in a cnidarian
gastrovascular cavity
-a hollow gut in the center of a cnidarian
-has a single opening, or mouth, which is surrounded by tentacles
-specialized cells used for defense and capturing prey
-in some cnidarians, the cnidocytes are concentrated in the epidermis, especially on the tentacles
-inside it is the organelle, the nemotocyst
-when an object brushes against the "trigger" on a cnidocyte, the nematocyst inside it pushes the filament out of the cell with great force
-a cnidocyte organelle with a long filament coiled up inside it
-when an object brushes against the "trigger" on a cnidocyte, the nematocyst inside it pushes the filament out of the cell with great force
-some nematocysts have filaments with sharp tips and spines that puncture the object and inject poison
-others have filaments that hold on to the object by wrapping around it
nerve net
-a scattered web of interconnected nerve cells that controls nervous responses in cnidarians
-in many cnidarians, the nerve net is distributed uniformly throughout the entire body
-there is no brain or similar structure that controls the rest of the nerve net
-it enables cnidarians to respond to specific stimuli in their environment
Class Hydrozoa
-most in class Hydrozoa live as colonial organisms
-ex: Portuguese man-of-war, hydra
-hydra can either move by floating in water or tumbling
-hydras generally reproduce asexually during warm weather and sexually in the fall
Class Scyphozoa
-"cup animals" which describes the medusa, the dominant form of the life cycle of this class
-known commonly as jellyfish
-move through pulsating motions of the cup
-the common jellyfish is a scyphozoan whose life cycle includes medusa and polyp forms
Class Anthozoa
-"flower animals"
-ex: sea anemones and corals
-sea anemones are polyps commonly found in coastal areas, where they attach themselves to rocks and other submerged objects
-anemones have symbiotic relationship with clownfish
-corals are polyps; when they die, their skeletons serve as the foundation for new polyps
-over thousands of years, they build coral reefs
Class Cubozoa
-"box jellies"
-have cube-shaped medusae
-a tentacle or group of tentacles is found at each corner of the "box"
-the cnidocytes of some can inflict severe pain, or death, among humans
-ex: sea wasp
reproduction in jellyfish
1. adult medusae release sperm and eggs into the water, where fertilization occurs
2. the resulting zygote divides many times to form a blastula
3. the blastula develops into a ciliated larva called a planula
4. the planula attaches to the ocean bottom
5. the planula becomes a polyp by developing a mouth and tentacles as the unattached end
6. the polyp grows and forms a stack of medusae
7. the medusae detach and develop into free-swimming jellyfish
Phylum Platyhelminthes
-ex: flatworms
-the classes are divided into Tuberllaria, Trematoda, Monogenea, and Cestoda
excretion in planaria
-eliminate excess water through a network of excretory tubules that run the length of the body
-each tubule is connected to several flame cells, which are so named because they enclose tufts of beating cilia that resemble candle flames
-the beating of cilia in flame cells draws in the excess water
-the water is then transported through the tubules and excreted from numerous pores scattered over the body surface
planaria reproduction
-planarians are hermaphrodites and can sexually reproduce by simultaneously fertilizing each other
-they can also reproduce sexually, through a process called fission
-fission is when the body constricts just behind the pharynx, and while the posterior part of the worm is attached to a solid surface, the anterior part moves forward until the worm splits in two
-planaria regenerate to produce 2 complete planaria
tapeworm anatomy
-tapeworms are surrounded by a tegument that protects them from their host's defenses
-at the anterior end is a knob-shaped organ called the scolex which has hooks and suckers that enable the worm to attach to its host
-a short neck connects the scolex with a long series of body sections called proglottids
-have no mouth, gastrovascular cavity, or other digestive organs
-absorb nutrients directly through their tegument
Phylum Nematoda
-they are pseudocoelomates
-ex: roundworms
Mollusca means...
-"soft body"
are Mollusks coelomates?
yes, they are coelomates
-the larval stage of development in mollusks and annelids
-it is a free-swimming larva, propelled by cilia on the surface
visceral mass
-region that contains the heart and the organs of digestion, excretion, and reproduction
-located above the head-foot
-produces the shell
-covers the visceral mass
-the space between the mantle and visceral mass is the mantle cavity, which protects the gills
ganglia of mollusk
-paired clusters of nerve cells that make up the nervous system of a mollusk
-situated in the head-foot and visceral mass, and connected by two pairs of long nerve cords
-nerve cells in the ganglia...
-control the muscles for locomotion
-control the muscles for feeding
-process sensory information
-a flexible, tonguelike strip of tissue covered with teeth that point backward
-has a variety of functions in different mollusks
Class Gastropoda
-snail, slug, conch, abalone, nudibranchs
-undergo torsion during development
-the visceral mass twists and the mantle cavity, gills, and anus is brought to the front of the animal
-because of this, a gastropod can withdraw its head when threatened
-have an open circulatory system
Class Bivalvia
-clams, oysters, scallops
-their shell is divided into two halves connected by a hinge
-most are sessile
-lack a distinct head, but their nervous system has three pairs of ganglia, connected by nerve cords
Class Cephalopoda
-octopus, squid, cuttlefish, chamber nautilus
-specialized for free-swimming, predatory existence
-the cephalopod brain, which is the largest of any invertebrate brain, is divided into several lobes and contains millions of nerve cells
-have a closed circulatory system
-also have separate sexes
-have pigment cells called chromatophores which can produce a sudden change in the animal's color
phylum Annelida
-means "little rings"
-bilaterally symmetrical, segmented worms
-have a true coelom, but it is divided into several compartments, which is an advantage
-external bristles on most annelids
-use their setae for movement
-it grips the ground as the longitudinal muscles contract
-setae project from parapodia, some of which function in gas exchange
-has many setae to help it move
-have no setae
fleshy protrusions that some annelids have
Class Oligochaeta
-means "few bristles"
-generally live in soil or fresh water and have no parapodia
-ex: earthworm
Class Polychaeta
-means "many bristles"
-have antennae and specialized mouthparts
-are also the only annelids with a trochophore stage
-most polychaetes live in marine habitats
Class Hirudinea
-ex: leeches
-leeches have no setae or parapodia
-at each end of a leech's body is a sucker that can attach to surfaces
-many are carnivores, but some are parasites
earthworm digestive tract
-food is sucked into the mouth by the muscular pharynx
-next, it goes to the esophagus (tube that soil is passed through)
-then moved into the temporary storage area called the crop
-the gizzard grinds the soil
-as the soil goes through the intestine, digested organic compounds and nutrients are absorbed by the blood
-undigested material goes out through the anus
circulation in earthworms
-have a closed circulatory system
-blood travels toward the posterior end through a ventral blood vessel then returns to the anterior end through a dorsal blood vessel
-five pairs of muscular tubes, the aortic arches, link the dorsal and ventral blood vessels
-contractions of the dorsal blood vessel and aortic arches force blood through the circulatory system
respiration in earthworms
-oxygen and carbon dioxide diffuse directly through the skin, which contains many small blood vessels
-BUT this can only happen if the skin is moist!
-therefore, earthworms avoid dry ground and extreme heat
excretion in earthworms
-eliminate cellular wastes and excess water through nephridia (like a kidney)
-each segment, except the first three and last one, contains a pair of nephridia
-as coelomic fluid passes through the nephridia, some of the water is reabsorbed by blood vessels
-remaining fluid/wastes dissolved in it are released from the body through pores on the ventral surface
nervous system in earthworms
-consists of a chain of ganglia connected by a ventral nerve cord
-they are cephalized and have a brain
-one of the main functions of the brain is to process information from sensory structures, which are concentrated at the anterior end
-a thickened section of the body in earthworms
-when earthworms mate, they press their ventral surfaces together with the anterior ends pointing in opposite directions
-they are held together by their setae and by a film of mucus secreted by each worm's clitellum
Phylum Arthropoda
-segmented with jointed appendages
-their protection is in their exoskeleton
-have a high degree of cephalization
-have a compound eye
-open circulatory system
-go through the process of molting
compound eye
-eyes made of many individual light detectors, each with its own lens
-useful for:
-detecting movement
-NOT good at detecting images
-seen in arthropods
-process of an arthropod shedding its exoskeleton and making a new one
-the cycle begins with the tissues of an arthropod swelling
-when the pressure inside the exoskeleton is strong, a hormone that triggers molting is produced
-the epidermis begins to make a new exoskeleton by using the digested material
-eventually, the outer layer of the old exoskeleton is shed, and a new, flexible one stretches to fit
-while the new exoskeleton is becoming hard, the animal is vulnerable to predators
-a tough polysaccharide
-makes up the middle layer (which provides the primary protection) of the exoskeleton of an arthropod
arthropods evolved how many years ago?
appeared 545 million years ago
phylogeny in arthropods
-very little is understood
-because all arthropods have a true coelom, an exoskeleton, and jointed appendages, biologists infer that all arthropods evolved from a common ancestor
-the order in which subgroups evolved are unclear
-a larger structure that is made of fused segments
-plural is tagmata
-the tagmata tend to be specialized for functions such as feeding, locomotion, and reproduction
-in arthropods, the cephalothorax consists of two tagmata
a jaw-like major type of mouthpart
pincher-like major type of mouthpart
single defining feature of a crustacean
two pairs of antennae
crayfish order
Decapoda, which means "10 feet"
parts of the crayfish
-a major section of the body
-consists of two tagmata:
-the head
-the thorax, which has eight segments and is behind the head
-the tagma behind the cephalothorax
-divided into six segments
-feelers that respond to touch and taste
-serve as feelers sensitive to touch, taste, and balance
-also used to catch/grasp food
-used for grasping food
-used to manipulate food
-involved in respiration
-used for capturing food
-also used for defense
-walking legs
-used for movement on surfaces
-create water currents
-function in reproduction
-the free-swimming larva in many crustaceans
-has three pairs of appendages and a single eye in the middle of its head
respiration in crayfish
-have featherlike gills for respiration
-the gills extend from the base of each walking leg into a chamber under the carapace
-as the crayfish walks, its legs circulate water across its gills
-feathery branches on the posterior pair of maxillae also help direct water over the gills
excretion in crayfish
-excess water and wastes is eliminated by excretory organs called green glands
-the dilute fluid collected by the green glands leaves the body through a pore at the base of the antennae
nervous system in crayfish
-the brain consists of a pair of ganglia above the esophagus that receive nerve impulses from the eyes, antennules, and antennae
-two bundles of nerve fibers extend from the brain and pass around each side of esophagus to ganglion that controls mandibles, maxillae, and maxillipeds
-the ventral nerve cord runs posteriorly from this ganglion, connecting a series of ganglia that control the appendages and muscles in the segments of the thorax and abdomen
Subphylum Chelicerata
-spiders, scorpions, mites, sea spiders, horseshoe crabs
-lack antennae
-have six pairs of appendages
-the first pair of appendages, chelicerae, are modified into pincers or fangs
spider respiration
-in some spiders, respiration occurs in the book lungs (paired sacs in the abdomen with many parallel folds that resemble the pages of a book)
-the folds in the book lung provide a large surface area for gas exchange
-other spiders have a system of tubes called tracheae that carry air directly to the tissues from openings in the exoskeleton, known as spiracles
-some spiders have both
arachnid body parts
-chelicerae (modified as fangs and used to inject venom into prey)
-pedipalps (handle food/prey, deposit sperm)
-four walking legs
-abdomen (no appendages)
-eight simple eyes
-produces silk threads using spinnerets
-respires through spiracles (like a pore) connected to book lungs or tracheae
-uses Malpighian tubules to excrete
spider eyes
-most have 8 simple eyes at front of cephalothorax
-each simple eye has a single lens
-composed of hundreds of microscopic tubes that connect to silk glands in the abdomen
-a protein-containing fluid produced in silk glands hardens into threads as it is secreted from spinnerets
-on the tip of the abdomen
spider excretion
-main excretory organs, called Malpighian tubules, are hollow projections of digestive tract that collect body fluids and wastes that carry them to intestine
-after most of the water is reabsorbed, the wastes leave the body in a nearly solid form with the feces
-thus, Malpighian tubules help spiders conserve water in earthly environments
sexual dimorphism in spiders
the female spider is usually bigger than the male
Class Diplopoda
-ex: millipedes
-rounded body
-four legs per segment (two pairs of legs per segment)
-eat decaying vegetation
-in Subphylum Myriapoda
Class Chilopoda
-ex: centipedes
-flat body
-one pair of joined legs per each body segment (except first and last two)
-eat bugs
-in Subphylum Myriapoda
Class Insecta
-have a segmented body
-have jointed appendages
-have an exoskeleton
-in Subphylum Hexapoda
parts of an insect body
-have mandibles
-have one pair of antennae
-three pairs of jointed legs
-many times, 1-2 pairs of wings
-9-11 segments
-in adults, has no wings or legs
grasshopper anatomy
-anterior tagma (the head):
-has the mouthparts
-also has a pair of unbranched antennae
-simple and compound eyes
-middle tagma (thorax):
-attaches to head
-has first pair of walking legs
-second pair of walking legs
-attaches to abdomen
-jumping legs
-composed of upper and lower plates
circulation in insects
-open circulatory system
-blood flows through a large dorsal blood vessel called the aorta
-muscular heart (located in the abdomen and thorax) pumps the blood forward through the aorta and into the part of the coelom nearest the head
-the blood then percolates through the coelom toward the abdomen and reenters the heart through small pores along its length
respiration in insects
-insects exchange oxygen and carbon dioxide with the environment through a complex network of air tubes called trachea
-in grasshoppers, air enters the trachea through the spiracles on the sides of the thorax and abdomen
-ends of the tracheae branch near the cells of the body and are filled with fluid
-oxygen diffuses into the cells from this fluid while carbon dioxide diffuses in the reverse direction
-air can be pumped in and out of the tracheae by the movements of the abdomen and wings
excretion in insects
-have Malpighian tubules that collect water and cellular wastes from the blood
-attached to the digestive tract between the midgut and the hindgut
-a sound-sensing organ
-it is a large, oval membrane that covers an air-filled cavity on each side of the first abdominal segment
-sounds cause the tympanum to vibrate and the vibrations are detected by many other insects that use sound in communication
-a pointed organ in the last segment of the female's abdomen in the grasshopper
-the female grasshopper uses it to dig a hole in the soil, where she lays the fertilized eggs
incomplete metamorphosis
-a nymph hatches from an egg and gradually develops into an adult
-a nymph is smaller than an adult and has no wings
-ex: grasshopper, dragonfly
complete metamorphosis
-an insect undergoes two stages of development between the egg and the adult
-in both of these stages, the insect looks different from its adult form
-ex: butterfly, moth, fly
-a chemical released by an animal that affects the behavior or development of other members of the same species through the sense of smell or taste
-play a major role in behavior patterns of insects
-the aiding of other individuals at one's own risk or expense
-ex: the stinging of honeybees
bee societies
-worker bees
-non-reproductive females that make up the vast majority of the hive population
-perform all the duties of the hive except reproduction
-feed royal jelly to the queen and larvae
-queen bee
-the only reproductive female in the hive
-uses the queen factor to prevent others from developing into queens
-males whose only function is to deliver sperm to the queen
are echinoderms deuterostomes?
-yes, they are deuterostomes
echinoderm symmetry
radial symmetry (penta)
5 classes of echinoderms
Class Crinoidea
-ex: sea lilies, feather stars
-sea lilies are sessile as adults, and feather stars can swim or crawl as adults
-in both types, five arms extend from the body and branch to form more arms
Class Ophiuridea
-means "snake-tail"
-ex: basket star, brittle star
-largest echinoderm class
-have long, narrow arms, which allow them to move quickly
Class Asteroidea
-means "star-like"
-ex: sea stars (starfish)
-bad for humans because they prey on oysters, clams, and other organisms that humans use as food
Class Holothuroidea
-means "water polyp"
-most live on the sea bottom, where they crawl or burrow into soft sediment by using their tube feet
-have soft bodies
-ex: sea cucumber
Class Echinoidea
-means "spine-like"
-ex: sea urchin, sand dollar
-the internal organs are enclosed within a fused, rigid endoskeleton called a test
sea star anatomy
- side of the body with the mouth is the oral surface
-the side opposite the mouth is the aboral surface
-the body is usually covered with short spines
-surrounding each spider are numerous tiny pincers called pedicellariae
-water enters the body through small pores in the madreporite, then the radial canal carries water around the animal
-no circulatory, excretory, or respitory system
-no cephalization either
-the larva stage is called a bipinnaria
-cardiac stomach (leaves body to feed)
-pyloric stomach (connects digestive gland)
Phylum Chordata
-named because they have a notochord (a stiff but flexible rod of cells that runs the length of the body near the dorsal surface)
-includes all animals with backbones (vertebrates) and two groups of invertebrates
characteristics of all chordates
(1) a dorsal nerve cord
(2) pharyngeal pouches (outpockets in the pharynx)
(3) a post-anal tail
three subphyla of chordates
-Vertebrata (the largest subphyla, vertebrates)
-Cephalochordata (live only in ocean)
-Urochordata (live only in ocean)
characteristics of vertebrates
-have vertebrae (bones or cartilage that surround the dorsal nerve cord and form the spine)
-have a cranium (or skull), that protects the brain
-have endoskeleton composed of bone or cartilage
Class Chondrichthyes
-predatory fishes with jaws and paired fins
-their skeleton is made of cartilage, not bone
-many have skin covered by a unique kind of scale
-ex: sharks, rays, skates, ratfishes
Class Osteichthyes
-bony fishes
-characterized by three features:
-lungs or swim bladder
-there are two main groups of bony fishes:
-lobe-finned fishes
-ray-finned fishes
Class Amphibia
-ex: frogs, toads, salamanders
-they have thin skin and it is permeable to gases and water
-most species lay their eggs in water and pass through an aquatic larval stage
Class Reptilia
-ex: turtles, crocodiles, alligator, lizards, snakes
-the skin is dry and scaly
-the eggs of reptiles protect the embryo from draying out and can be laid on land
Class Aves
-characterized by adaptations that enable flight, including:
-hollow bones
-unique respiratory system
-ex: birds
Class Mammalia
-ex: humans, cats, mice, horses
-all mammals have hair and nurse their young with milk
-a hard plate that opens at the rear and covers and protects the gills in a yellow perch fish
-it is on each side of the head
digestive system of bony fish
-commonly are carnivores
-digestive tract:
-pharynx (or throat cavity)
-moves through the esophagus
-goes to the stomach, which secretes acid and digestive enzymes that begin to break down food
-passes into intestine, where digestion is completed and nutrients are absorbed
circulatory system of bony fish
-consists of a heart, blood vessels, and blood
-a closed circulatory system
-path of blood:
-deoxygenated blood from the body empties into a collecting chamber called the sinus venosus
-next, blood moves into the larger atrium
-contraction of the atrium drives the blood to the muscular ventricle (the main pumping chamber of the heart)
-contraction of ventricle provides most of force that drives blood through the system
-the conus arteriosus is part of the main artery leaving the heart
respiration of bony fish
-its respiratory organ is gills
-in most bony fishes, water is taken into the mouth and pumped over the gills, where it flows across the gill filaments before exiting behind the operculum
-water and blood flower across the gill filaments in opposite directions (countercurrent flow)
-countercurrent flow causes more oxygen to diffuse into the blood
excretion in bony fish
-a fish's kidneys filter dissolved chemical wastes from the blood, creating urine
-urine is carried from kidneys to the urinary bladder, which later expels it
-kidneys and gills regulate water balance
-gills also regulate the concentration of ions in the body, and transport the ions out
function of swim bladder
-adjust their overall density by regulating the amount of gas in the swim bladder, enabling them to move up or down in the water
-in some fishes, the swim bladder is known to amplify sound by vibrating and transmitting sound to the inner ear
function of lateral line
allows fish to sense vibration in the water
reproduction in bony fish
-using a modified anal fin, the male inserts sperm into the female, and fertilization is INTERNAL
-the female carries the eggs in her body until the young are born
-the reproductive, or spawning, behavior of bony fishes varies widely
-some species build crude nests from plants, sticks, and shells, and many migrate to warm, protected shallow water to spawn
Order Anura
-live in a variety of habitats
-ex: frogs and toads
-characteristic of frog:
-has smooth, moist skin
-characteristic of toad:
-has rough, bumpy skin
Order Caudata
-have elongated bodies, long tails, and moist skin
-most have four limbs
-lay their eggs in water, and the eggs hatch into swimming larval forms
-ex: salamanders
Order Gymnophonia
-highly specialized group of legless amphibians that resemble small snakes
-often are blind
-most burrow in the soil, but some are aquatic
-eat worms and other invertebrates
-ex: caecilians
-the process of a tadpole growing and changing from an aquatic larva into an adult frog
-legs grow from the tadpole body, and the tail and gills disappear; the mouth broadens, developing teeth and jaws, and the lungs become functional
skin characteristics of amphibian
-thin and moist
-no scales
feet of amphibians
-law claws
-are often webbed
respiration of amphibians
use gills, lungs, and skin
eggs of anurans
-in nearly all species, eggs are fertilized externally
-the fertilized eggs hatch into swimming, tailed larvae called tadpoles
skin of amphibians
-the skin serves two important functions: respiration and protection
-skin is moist and permeable to gases and water
-mucous glands supply a lubricant that keeps the skin moist in air, making it feel slimy
-also contains glands that secrete foul-tasting or poisonous substances that provide protection
skeleton of amphibians
-the vertebrate of the spine interlock and form a rigid structure that can bear the weight of the body
-strong limbs support the body during walking or standing
-the forelimbs attach to the pectoral girdle (shoulder and supporting bones) while the hind limbs attach to the pelvic girdle (the "hips")
-cervical vertebra at the anterior end of the spine allows neck movement
-in frogs:
-the bones of the lower forelimb are fused into a single bone, the radio-ulna
-bones of the lower hind limb are fused into the tibiofibula
-pectoral girdle has thick bones to absorb the impact of landing
circulation in amphibians
-divided into two separate loops:
-the pulmonary circulation carries deoxygenated blood from the heart to the lungs and back to the heart
-the systemic circulation carries oxygenated blood from the heart to the body and back to the heart
-they have a three-chambered heart
-have a fast, "single-loop" circulation
respiration in amphibians
-larval amphibians respire through gills and skin
-most adult amphibians can respire through their LUNGS and skin
-respiration through the lungs is called pulmonary respiration, and use a mechanism to pump air into the lungs called positive-pressure breathing
-because amphibians have a small surface area in the lungs for gas exchange, respiration through the skin, or cutaneous respiration, is important to most aquatic and terrestrial amphibians
also called buccal cavity
the passage from the mouth to the larynx and esophagus
passage from pharynx to stomach
stomach in amphibians
once food reaches the stomach, tiny glands in the stomach walls secrete gastric juices that help break down, or digest the food
liver in amphibians
-produces bile
-bile helps break down fat into tiny globules that can be further digested and absorbed
gallbladder in amphibians
-stores bile
-bile helps break down fat into tiny globules that can be further digested and absorbed
small intestine in amphibians
-digestion is completed and the released nutrients pass through capillary walls into the bloodstream, which carries them to all parts of the body
-the upper portion is called the duodenum
-the coiled middle portion is the ileum
-a membrane resembling plastic wrap, called the mesentery, holds the small intestine in place
large intenstine in amphibians
indigestible wastes are collected and pushed by muscle action into the cloaca
a cavity for wastes from the kidneys and urinary bladder, and sperm or eggs
the upper portion of the small intestine in amphibians
a membrane resembling plastic wrap that holds the small intestine in place in amphibians
-where waste materials exit the body in amphibians
-a gland that secretes enzymes that enter the small intestine
-also helps break down food into products that can by absorbed by the blood
-located near the stomach
-makes insulin
kidney in amphibians
-the primary excretory organs
-lies on either side of the spine against the dorsal body wall
-filter nitrogenous wastes from the blood (urine)
olfactory lobe
-the center of the sense of smell in amphibians
-are larger in amphibians than in fish
-the area of the brain that integrates behavior and is responsible for learning in amphibians
-they are long lobes
-behind the olfactory lobes
-the center of muscular coordination in amphibians
-not as well developed in amphibians as it is in other tetrapods
-a small band of tissue that lies at a right angle to the long axis of the brain
optic lobes
-processes information from the eyes in amphibians
-lies behind the cerebrum
medula oblongata
-controls some organ functions, such as heart rate and respiration rate in amphibians
-lies at the back of brain and joins the spinal cord
nicitating membrane
a transparent, movable membrane that covers the eyes in an amphibian
tympanic membrane
eardrum in amphibians
mating calls in amphibians
-males call to attract females of their own species and to warn off other males
-each species has its own mating call
-the frog's croak is produced by air that is driven back and forth between the mouth and the lungs, vibrating the vocal folds
-male frogs have vocal sacs that amplify their calls
-the female responds only to the call from a male of the same species
Avery's experiment
-wanted to test whether the transforming agent in Griffith's experiment was protein, RNA, or DNA
-used enzymes to separately destroy each of the three molecules in heat-killed S cells
-used protease to destroy protein, RNase for RNA, and DNase for DNA
-then, they separately mixed the three experimental batches of heat-killed S cells with live R cells and injected mice with the mixtures
-the cells missing protein and RNA were able to transform R cells into S cells and kill the mice
-but the cells missing DNA didn't transform, and the mice survived, concluding that DNA is responsible for transformation in bacteria
-an embrace used in mating in amphibians
-when a female approaches, the male frog climbs onto her back and uses an amplexus
-he clings to her until she lays her eggs
-when she releases them into the water, the male discharges his sperm over them and direct external fertilization takes place
fertilization in amphibians
-the male uses the amplexus until the female lays her eggs
-when she releases them into the water, the male discharges his sperm over them and direct external fertilization takes place
-after that, the frogs separate and resume their lives
reproduction in amphibians
-in males:
-two bean-shaped testes near the kidneys
-during breeding, sperm cells develop in the testes and pass through tubes to the kidneys and urinary ducts
-during mating, sperm leave the body through a cloacal opening
-in females:
-a pair of large, lobed ovaries containing thousands of tiny immature eggs lie near the kidneys
-during the breeding season, the eggs enlarge, mature, and burst through the thin ovarian walls into the body cavity
-as the eggs pass down the oviducts, they are coated with a protective jelly-like material
-the eggs exit by cloaca to the external environment, where they are fertilized
-a hormone that circulates throughout the bloodstream to stimulate metamorphosis
-produced by the thyroid gland
purines and pyrimidines
-nitrogenous bases that have a double ring of carbon and nitrogen atoms (like adenine and guanine)
-nitrogenous bases that have a single ring of carbon and nitrogen atoms (like cytosine and thymine)