Chapter 28 — Prokaryotes, Viruses, Prions, Origins of Life
Leeuwenhoek & Pasteur
Leeuwenhoek: First to observe and describe microbes through microscope observations of “animalcules”.
Pasteur:
Showed that spontaneous generation does not occur through swan-neck flask experiments.
Developed pasteurization techniques.
Linked microbes to fermentation and disease processes.
Microbiota
Definition: Community of microorganisms (bacteria, archaea, fungi, viruses) that live on/in an organism.
Roles:
Beneficial: Aid in digestion, immune system development.
Pathogenic: Can cause disease.
Beneficial effects of microbes
Nutrient cycling: e.g., nitrogen fixation.
Digestion: Gut microbes facilitate nutrient absorption.
Production of vitamins: Includes vitamins K and some B vitamins.
Decomposition: Breakdown of organic material for nutrient recycling.
Bioremediation: Use of microbes to clean up environmental pollutants.
Fermentation: Used in food production processes.
Antibiotic producers: Certain bacteria/fungi produce antibiotics.
Chemical vs. Biological evolution
Chemical evolution:
Abiotic formation of organic molecules leading to prebiotic chemistry.
Biological evolution:
Descent with modification of living organisms via natural selection and genetic changes.
Four stages leading to cell formation:
Abiotic synthesis of small organic molecules (e.g., amino acids, nucleotides).
Polymerization into macromolecules (e.g., proteins, nucleic acids).
Formation of protocells (lipid membranes, compartmentalization).
Origin of self-replicating molecules (the RNA world hypothesis leading to genetic inheritance).
Miller–Urey experiment:
Simulated early Earth atmosphere with electrical sparks; resulted in the production of amino acids from simple gases, indicating abiotic synthesis of organic molecules.
Distinguishing Archaea, Bacteria, Eukaryotes:
Bacteria:
Peptidoglycan cell walls (some), typically possess membrane lipids (ester), contain 70S ribosomes, exhibit diverse metabolic types.
Archaea:
Lack of peptidoglycan, unique membrane lipids (ether-linked), rRNA sequences distinct, and many are extremophiles.
Eukaryotes:
Contain membrane-bound organelles (e.g., nucleus, mitochondria), consist of larger cells, and possess linear chromosomes.
Types of Archaea:
Halophiles: Thrive in high salt conditions (e.g., Halobacterium).
Thermoacidophiles: Thrive in hot, acidic environments (e.g., Sulfolobus).
Methanogens: Produce methane anaerobically (found in guts, wetlands).
Bacterial structural features:
Cell wall (peptidoglycan in some bacteria), plasma membrane, nucleoid region (circular DNA), plasmids (extra-chromosomal DNA), ribosomes (70S), flagella (for motility), pili (for attachment), capsule (protective layer).
Bacterial reproduction:
Binary fission: A single bacterial cell divides into two genetically similar cells.
Three ways bacteria increase genetic variation:
Transformation: Uptake of free DNA from the environment.
Transduction: Bacteriophage-mediated DNA transfer between bacteria.
Conjugation: Direct transfer of plasmid or DNA via a pilus from one cell to another.
Cyanobacteria metabolism & ecological function:
Engage in oxygenic photosynthesis (producing O₂), some can fix nitrogen (through specialized cells called heterocysts), serve as primary producers in many aquatic ecosystems, and are responsible for the Great Oxygenation Event.
Diseases caused by Streptococcus pyogenes and Staphylococcus aureus:
S. pyogenes causes strep throat, scarlet fever, rheumatic fever (as a post-infectious reaction), and impetigo.
S. aureus leads to skin infections, MRSA (methicillin-resistant Staphylococcus aureus), food poisoning, and toxic shock syndrome.
Food poisoning types & example species:
Intoxication (caused by preformed toxins):
E.g., Staphylococcus aureus enterotoxin; Bacillus cereus (emetic toxin).
Infection (pathogen ingested and replicates):
E.g., Salmonella spp., Clostridium perfringens.
Function of most antibiotics:
Target bacterial structures and processes such as cell wall synthesis (e.g., penicillins), protein synthesis (e.g., tetracyclines), and DNA replication (e.g., fluoroquinolones) to inhibit growth or kill bacteria.
Viruses vs. prions:
Viruses: Consist of genetic material (DNA or RNA) enclosed in a protein coat; some have an envelope; replicate inside host cells using the host machinery.
Prions: Misfolded proteins that induce misfolding of normal proteins; do not contain nucleic acid; cause neurodegenerative diseases (e.g., Creutzfeldt-Jakob disease).
Stages of viral reproduction (example: rubella):
Attachment: Virus binds to host receptor.
Entry: Virus penetrates the cell via fusion or endocytosis.
Uncoating: Release of the viral genome into the host cell.
Replication: Viral genome replication and production of viral proteins.
Assembly: Newly formed virions are assembled.
Release: New virions are released through budding or lysis of the host cell.
Antigenic drift and shift:
Drift: Small mutations in viral surface proteins (e.g., influenza HA/NA) occur over time, leading to seasonal variations in the flu.
Shift: Major reassortment of genome segments in segmented viruses (like influenza), creating drastically different antigenic types—can lead to pandemics.
Prions & species infected:
Examples include:
Scrapie (sheep),
Bovine spongiform encephalopathy (BSE, cattle),
Creutzfeldt-Jakob disease (humans),
Chronic wasting disease (deer and elk).
Definitions and Questions:
Microbiology is the study of microbes, which include all but which of the following?
A. Archaea
B. Bacteria
C. viruses
D. plants (Correct Answer)What general feature is necessary to consider an organism a microbe?
A. Small enough that a microscope is required to see them (Correct Answer)
D. Use aerobic respiration for metabolismMiller's laboratory experiments demonstrated that:
A. It is possible to form protocells.
B. The primitive gases can react to produce small organic molecules. (Correct Answer)
C. Atmospheric pressure is required for life to begin.
D. The Earth is approximately 4.5 billion years old.Which of the following molecules is thought to have been absent from the primitive reducing atmosphere?
A. Water vapor (H₂O)
B. Methane (CH₄)
C. Hydrogen (H₂)
D. Oxygen (O₂) (Correct Answer)Considering the various theories, the energy used to form organic molecules in the primitive atmosphere could have come from all EXCEPT:
A. Lightning
B. Ultraviolet radiation
C. Heat from volcanoes
D. Sound (Correct Answer)What is the evolutionary relationship among Archaea, Bacteria, and Eukarya?
A. Archaea are the most primitive; they gave rise to Bacteria which in turn gave rise to Eukaryotes.
B. All three domains are equally distant from the most primitive common ancestor, a protocell.
C. Archaea and Eukarya share nucleic acid similarities; Eukarya split off from Archaea. (Correct Answer)
D. Bacterial ancestors gave rise to both Archaea and Eukarya as separate lineages.One bacterial cell passes DNA to a second cell through a sex pilus in the process called:
A. Transformation.
B. Transduction.
C. Conjugation. (Correct Answer)
D. Replication.Bacterial cells pick up free pieces of DNA from the medium released from dead bacteria in a process called:
A. Transformation. (Correct Answer)
B. Transduction.The capsid of a virus is composed of:
A. RNA.
B. Protein. (Correct Answer)
C. DNA.
D. Cellulose.
E. Lipid.Which of these describes a form of horizontal gene transfer in bacteria?
A. Crossing-over between paired chromosomes during meiosis.
B. Conjugation occurs when a cell passes DNA to another cell via a sex pilus. (Correct Answer)
C. Transformation occurs when a bacteriophage carries a bit of DNA from a previous host cell to a new host cell.
D. Transduction occurs when a live bacterium picks up DNA from dead bacteria that shed it into the environment.Which type of genetic exchange occurs among bacteria where DNA is carried by a virus?
A. Conjugation
B. Transformation
C. Transduction (Correct Answer)
D. Budding.Which statement is true about bacteria?
A. They contain a nucleus.
B. They lack ribosomes.
C. They usually lack a cell wall.
D. They contain a single, circular DNA molecule as the genetic material. (Correct Answer)Which statement is NOT true about bacteria?
A. They lack mitochondria.
B. They lack a nucleus but contain DNA.
C. They reproduce sexually. (Correct Answer)
D. They have a single circular chromosome.Which of the following is NOT true about viruses?
A. The genome may be DNA or RNA.
B. They contain nucleic acid, protein, and mitochondria. (Correct Answer)
C. They exhibit host specificity.
D. They are obligate intracellular parasites.The innermost core of a virus's structure is made up of:
A. A membranous envelope.
B. Either DNA or RNA. (Correct Answer)
C. A protein capsid.
D. A protein spore coat.A viral envelope describes:
A. The outer layer of some viruses composed of the host's plasma membrane. (Correct Answer)
B. Viral DNA.
C. A prion.
D. A protein capsid.Which is the most accurate description of a virus?
A. A noncellular living organism.
B. One of the smallest bacteria known.
C. A cell at the boundary between living and nonliving things.
D. Chemical complexes of RNA or DNA protected by protein. (Correct Answer)Which of the following is considered to be acellular?
A. Bacteria
B. Fungi
C. Algae
D. Protozoans
E. Viruses (Correct Answer)The life cycle stage of an animal virus during which a mature capsid forms around copies of the viral RNA genome is:
A. Budding.
B. Biosynthesis.
C. Uncoating.
D. Assembly. (Correct Answer)Which stage of viral reproduction takes place when the spikes of the virus bind to a specific receptor molecule on the surface of a host cell?
A. Attachment stage (Correct Answer)
B. Penetration stage
C. Biosynthesis stage
D. Release stage.When an enveloped animal virus enters a cell during the entry stage:
A. The next thing it does is assemble a new virus.
B. The envelope is removed after the virus is inside the cell's nucleus.
C. The protein capsid is removed through uncoating to expose the viral genome. (Correct Answer)
D. It immediately integrates its nucleic acid genome into the host chromosomes.Bovine spongiform encephalopathy (BSE), or "mad cow disease," is caused by a(n):
A. Archeon.
B. Bacterium.
C. Cyanobacterium.
D. Prion. (Correct Answer)
E. Virus.Some human diseases are attributed to protein agents that may cause normal proteins in the cell to also misfold. This new disease-causing protein agent is called a(n):
A. Prion. (Correct Answer)
B. Cyanobacterium.
C. Phage.
D. Retrovirus.The term "virus" was invented by:
A. Louis Pasteur. (Correct Answer)
B. Anton van Leeuwenhoek.
C. Stanley Miller.
D. Harold Urey.Cyanobacteria:
Do photosynthesis in a way similar to green plants. (Correct Answer)
Are heterotrophs.
Have a nucleus and chloroplasts.
Chapter 29 — Protists & Fungi (Summary)
Bacterial reproduction is referred to as:
Binary fission. (Correct Answer)
The first membranes that formed before full cells were likely made of:
Fatty acids. (Correct Answer)
Which type of archaean is likely to be found in the intestines of animals?
Methanogen. (Correct Answer)
Evolution & characteristics of first eukaryotic cells:
Eukaryotes likely arose via endosymbiosis, where mitochondria originated from α-proteobacteria, and chloroplasts derived from cyanobacteria in photosynthetic lineages.
Key features of eukaryotes include a nucleus, membrane-bound organelles, and a cytoskeleton.
General characteristics of protists:
Mostly unicellular eukaryotes (some are multicellular or colonial).
Nutritional diversity: include photoautotrophs, heterotrophs, and mixotrophs.
Varied life cycles: many are aquatic.
Protist nutritional modes:
Photosynthesis: Carried out by algae.
Phagotrophy: Involves engulfing particles.
Osmotrophy: Absorption of dissolved nutrients.
Mixotrophy: A combination of photosynthesis and ingestion of organic matter.
Protist supergroups (basic features):
Archaeplastida: Includes red and green algae and land plants; primary plastids derived from cyanobacteria.
Chromalveolates: Comprises diatoms, brown algae, dinoflagellates, and ciliates; many possess secondary plastids.
Excavates: Some with modified mitochondria (e.g., diplomonads), includes Euglena relatives.
Amoebozoans: Characterized by amoeboid movement via pseudopodia and includes slime molds.
Opisthokonts: Includes animals, fungi, and related protists.
Specific protists and characteristics:
Spirogyra: Filamentous green algae with spiral chloroplasts; reproduces sexually via conjugation tubes.
Diatoms: Unicellular algae featuring silica cell walls (frustules); play a significant role as primary producers and are planktonic.
Dinoflagellates: Characterized by two flagella and cellulose plates; can be photosynthetic or mixotrophic; certain species cause red tides (harmful algal blooms) and some are bioluminescent.
Ciliates: Possess numerous cilia for movement and feeding; have both a macronucleus and micronucleus (example: Paramecium).
Brown algae (kelp): Large multicellular chromalveolates that form kelp forests; possess holdfasts, stipes, and blades, illustrating complex multicellularity.
Euglena: Flagellated protist that displays mixotrophy; photosynthetic in light but heterotrophic in the absence of light, equipped with an eyespot for sensing light.
Amoeba & plasmodial slime molds:
Amoeba: Utilize pseudopodia for movement and phagocytosis.
Plasmodial slime molds: Characterized by a large multinucleate plasmodium that feeds on microbes by phagocytosis. Possesses a complex life cycle with stages including fruiting bodies.
Fungi covered in class:
Ascomycetes: Known as sac fungi; produce ascospores within asci (examples include yeast, morels).
Basidiomycetes: Recognized as club fungi; generate basidiospores on basidia (examples include mushrooms).
Lichens: Formed through symbiosis between a fungus (typically an ascomycete) and a photosynthetic partner (alga or cyanobacterium).
Mycorrhizae: Mutualistic associations between fungal hyphae and plant roots that enhance nutrient and water uptake.
Questions:
Single-celled eukaryotes are:
A. Protists. (Correct Answer)
B. Archaea.
C. Land plants.
D. Animals.Distinguishing features of protists:
A. Unicellular and microscopic. (Correct Answer)
B. Multicellular and microscopic.
C. Photosynthetic and unicellular.
D. None of the answer choices are correct.The algae closely related to the first plants are:
A. Brown
B. Red
C. Green. (Correct Answer)
D. Pink.Which genus of algae found in ponds has spiral chloroplasts?
A. Spirogyra. (Correct Answer)
B. Euglena.
C. Chlamydomonas.
D. Volvox.An example of an alga is:
A. Amoebae.
B. Slime molds.
C. Diatoms. (Correct Answer)
D. Ciliates.Which protist is incorrectly linked with its movement type?
A. Amoeboids - pseudopodia.
B. Ciliates - cilia.
C. Euglena - pseudopod. (Correct Answer)
D. Paramecium - cilia.Which organisms use pseudopodia for movement?
A. Trypanosome.
B. Amoeba proteus. (Correct Answer)
C. Chlamydomonas.
D. Paramecium caudatum.The kingdom characteristic of having filaments called hyphae is:
A. Archaea.
B. Protista.
C. Fungi. (Correct Answer)
D. Animalia.
E. Plantae.Molds (excluding slime and water molds) and mushrooms belong to the kingdom:
A. Protists.
B. Fungi. (Correct Answer)
C. Plantae.
D. Animalia.An organism that feeds on dead plants, animals, and microbes is termed:
A. Autotrophic.
B. Heterotrophic.
C. Saprotrophs. (Correct Answer)
D. Parasitic.Organisms breaking down dead organic matter to absorb nutrients are:
A. Eukaryotes.
B. Parasites.
C. Saprotrophs. (Correct Answer)
D. Heterotrophs.Fungi are mostly saprotrophic decomposers playing key roles in nutrient recycling. (Correct Answer)
Fungi and heterotrophic bacteria share that:
A. They both produce gametes.
B. Both are heterotrophic and important for ecosystems. (Correct Answer)
C. Both have cell walls made of the same material.
D. Both are photosynthetic and thus producers.
E. Both are eukaryotic.The theory that fungi were once plants without chlorophyll has been dismissed because:
A. Fungal cell walls contain chitin, not cellulose. (Correct Answer)
B. Fungi engulf and digest food internally.
C. Fungi develop flagella at some life stages, providing mobility lacking in plants.
D. Plants are multicellular while fungi can be unicellular or multinucleate noncellular plasmodia.
E. Plants store glycogen while fungi store starch.Fungi are not photosynthetic due to lacking:
A. Xylem.
B. Cell walls.
C. Chloroplasts. (Correct Answer)
D. Cell membranes.A chain of asexual spores produced by a sac fungus is called:
A. A mycelium.
B. A conidia. (Correct Answer)
C. An ascospore.
D. A basidiospore.
Chapter 30 — Plants
Challenges moving to land & adaptations:
Challenges: Desiccation, UV radiation, support against gravity, nutrient uptake, reproduction without water.
Adaptations: Waxy cuticle, stomata for gas exchange, vascular tissues (xylem for water/nutrient transport, phloem for food transport), lignin for structural support, developed root systems, seeds for reproduction and protection, pollen for reproduction and dispersal, alternation of generations with protected embryos.
Plants & green algae shared traits:
Chlorophylls a and b, cellulose in cell walls, starch storage, similar photosynthetic pigments and chloroplast structures, indicating common ancestry.
Five major evolutionary stages of land plants:
Nonvascular plants (bryophytes, e.g., mosses and liverworts).
Seedless vascular plants (ferns and lycophytes).
Gymnosperms (naked seeds, e.g., conifers and Ginkgo).
Angiosperms (flowering plants).
Alternation of generations:
Describes two multicellular stages:
Haploid gametophyte, which produces gametes by mitosis.
Fertilization occurs, resulting in a diploid zygote.
Zygote develops into a diploid sporophyte, which produces haploid spores by meiosis.
Spores then grow into the gametophyte stage.
Nonvascular plants & mosses:
Nonvascular plants lack true xylem and phloem, are small in size, and rely on moist aquatic habitats.
In mosses, the dominant gametophyte stage (visible as a green carpet) is dependent on the sporophyte, which produces flagellated sperm requiring water to reach archegonia for fertilization.
Seedless vascular plants: ferns (fern life cycle):
Ferns exhibit dominant sporophyte; during their lifecycle, the sporophyte produces sori (clusters of sporangia) leading to meiosis, resulting in haploid spores.
Spores develop into gametophytes (prothallus) that produce gametes; fertilization leads to a new sporophyte.
Gymnosperms (including conifers and Ginkgo biloba):
Produce seeds that are not enclosed in fruit and often develop in cones; adaptations enable them to thrive in dry and cold environments.
Ginkgo features unique fan-shaped leaves and is a deciduous species considered a living fossil.
Angiosperms:
Known as flowering plants; characterized by flowers (containing male stamens and female carpels).
Double fertilization occurs, producing both a zygote and endosperm; seeds are enclosed within fruits, for improved seed dispersal.
Flower parts and relationship to fruit/pollination:
Sepals and petals: Attract pollinators.
Stamens: Comprising anthers and filaments, produce pollen.
Carpels/Pistils: Include stigma, style, and ovary; receive pollen and house ovules.
The mode of pollination often relates to flower structure (e.g., color, odor, and nectar for animal pollinators; reduced petals and dangling stamens in wind-pollinated species).
Fruit development originates from ovaries to facilitate seed dispersal (fleshy fruits aid animal dispersal while pods, wings, and wind dispersal adaptations aid in other means).
Seed parts & advantages over spores:
Seeds consist of a seed coat for protection, an embryo, and stored food (endosperm or cotyledons).
Advantages include improved protection, dormancy capability, nutrient support for seedlings, and enhanced dispersal adaptations; spores, being unicellular, offer less protection.
Chapter 31 — Animal Diversity & Body Plans
Characteristics shared by all animals:
Multicellular, heterotrophic organisms lacking cell walls; they typically exhibit specialized tissues (except sponges), develop from a blastula, and most possess complex intercellular signaling and an extracellular matrix characterized by collagen.
Body symmetry, cephalization, levels of organization:
Symmetry:
Asymmetrical (e.g., sponges), radial (e.g., cnidarians), bilateral (most animals).
Cephalization: Concentration of sensory structures at the anterior end (head).
Levels of organization:
Cell (e.g., Porifera), tissue (e.g., Cnidaria), and organ/organ-system organization (typical in most bilaterians).
Protostome vs. Deuterostome:
Protostome: Mouth develops from blastopore, exhibits spiral and determinate cleavage (e.g., molluscs, annelids, arthropods).
Deuterostome: Anus develops from blastopore, exhibits radial and indeterminate cleavage (e.g., echinoderms, chordates).
Sponges (Phylum Porifera):
Composed of a simple body structure with pore openings (ostia); possess choanocytes (flagellated cells) for feeding.
Largely composed of choanocytes and amoebocytes, sponges do not exhibit true tissues and primarily function as sessile filter feeders.
Cnidarians (e.g., corals, sea anemones, jellyfish):
Exhibit radial symmetry, diploblastic organization (ectoderm & endoderm with mesoglea), and cnidocytes (stinging cells) containing nematocysts.
Present in two body forms: polyp (sessile) and medusa (free-swimming).
Corals are vital as they build calcium carbonate skeletons, while sea anemones act as sessile predators.
Flatworms (Phylum Platyhelminthes):
Planarians: Free-living, bilateral, acoelomate organisms that exhibit cephalization and can regenerate.
Tapeworms: Endoparasitic organisms featuring a segmented body (proglottids), and they lack a digestive tract, absorbing nutrients through a specialized tegument.
Molluscs (three main classes):
General features include a muscular foot, visceral mass, and mantle (may secrete a shell).
Gastropods: E.g., snails and slugs; exhibit torsion (twisting of body); primarily herbivores or detritivores.
Bivalves: E.g., clams and oysters; characterized by two shells and act as filter feeders with a reduced head.
Cephalopods: E.g., octopuses and squids; recognized as active predators with a complex nervous system, tentacles, and reduced or absent external shells (i.e., squid pen and cuttlefish bone).
Annelids (e.g., earthworms):
Segmented worms exhibiting metamerism, employ a closed circulatory system, and utilize setae for locomotion (in many species).
Earthworms play critical roles in soil aeration and nutrient cycling.
Arthropods (Ecdysozoans):
Defined by three key characteristics: segmented body, chitinous exoskeleton, and jointed appendages requiring molting (ecdysis).
Crustaceans: Typically aquatic, possessing two pairs of antennae and biramous appendages (e.g., crabs and shrimp).
Insects: Characterized by three body regions (head, thorax, abdomen), three pairs of legs, and often wings, making them the largest terrestrial group.
Arachnids: Exhibit four pairs of legs and two body segments (cephalothorax and abdomen) without antennae (e.g., spiders and scorpions).
Echinoderms (Deuterostomes):
Exhibit radial symmetry in adults (pentamerous), possess a water vascular system with tube feet, and consist of a calcareous endoskeleton.
Examples include sea stars, which are predators that utilize an eversible stomach, and sea urchins, which graze on algae.
Chordates characteristics (present at some life stage):
Features include a notochord, dorsal hollow nerve cord, pharyngeal slits or clefts, and a muscular post-anal tail. Present in lancelets and tunicates while vertebrates exhibit further advancements.
Chapter 32 — Vertebrates & Tetrapods
Lancelets: Small, fishlike chordates that retain all chordate features throughout their lives; filter feeders and crucial for understanding primitive chordate anatomy.
Jawless fishes:
Comprising hagfish and lampreys; lack true jaws and feature cartilaginous skeletons; lampreys exhibit parasitic behavior in particular life stages.
Cartilaginous fishes:
Include sharks and rays characterized by cartilaginous skeletons, placoid scales, and often internal fertilization; many species have heterocercal tails.
Ray-finned fishes (Actinopterygii):
Represent most contemporary fish species, featuring a bony skeleton and fins supported by rays; adaptions include swim bladders for buoyancy along with diverse respiratory and feeding strategies.
Lobe-finned fishes:
Possess robust internal bone structures in fins (e.g., coelacanths and lungfishes) and are considered evolutionary forerunners to tetrapods.
Major evolutionary innovations in fish → amphibians:
Development of limbs with digits stemming from lobe-finned fishes, adaptation of lungs or lung-like structures, stronger limb girdles, and modifications to hearing and vision to accommodate terrestrial life.
Life cycles typically involve metamorphosis.
Amphibians (comprising three living groups):
Orders:
Anura: Frogs and toads.
Caudata/Urodela: Salamanders.
Gymnophiona/Apoda: Caecilians.
Amphibians generally maintain moist skin, which is permeable to gases, and many undergo an aquatic larval stage that undergoes metamorphosis.
Amniotic egg:
Consists of key parts:
Amnion (protective membrane creating a fluid-filled sac), chorion (gas exchange), allantois (waste storage and gas exchange), yolk sac (nutrient storage).
This adaptation allows for reproduction away from water, marking a significant evolution in land-based life forms.
Reptiles vs. mammals innovations:
Reptiles: Characterized by scaly skin primarily containing keratin, exhibiting ectothermy (most species), featuring amniotic eggs with leathery or calcified shells, and have a single occipital condyle.
Mammals: Distinguished by hair, mammary glands, endothermy, containing three middle ear bones (malleus, incus, stapes), heterodont dentition, and specialized jaw articulation (dentary-squamosal).
Birds:
Distinguished from other reptiles by feathers (modified scales), a lightweight skeleton often featuring fused bones and ay keel for muscle attachment related to flying; exhibit high metabolic rates and endothermy, and possess beaks (lacking teeth) alongside unique air sac respiratory systems.
Three major groups of living mammals:
Monotremes: Egg-laying mammals (e.g., platypus, echidna).
Marsupials: Pouched mammals characterized by short gestation periods; young complete development within the pouch (e.g., kangaroo).
Eutherians (placental mammals): Feature extended gestation with placenta; young develop within the uterus.
Primate characteristics:
Defined by grasping hands/feet with opposable thumbs (in many species), forward-facing eyes facilitating stereoscopic vision, a larger brain relative to body size, the use of nails rather than claws, and complex social structures alongside prolonged parental care.
From Chapter 27 — Phylogenetics & Classification
Relation among phylogenetics, evolution, classification:
Phylogenetics employs evolutionary relationships (including common ancestry, descent with modification) to infer tree-like relationships, while classification (taxonomy) aims to reflect evolutionary history (clades).
A phylogenetic tree serves as a hypothesis depicting these evolutionary relationships.
Interpreting a phylogenetic tree:
Closely related organisms internode share more recent common ancestors (nodes).
Taxa joined at more recent nodes are closer evolutionarily.
Relatedness is assessed by tracing back to the most recent common ancestor rather than merely by proximity of tips on the tree.
Focused lists for species/groups (quick facts / what to remember)
Chapter 28 species:
Halophiles: Live in high salt, archaeal.
Thermoacidophiles: Thrive in hot, acidic environments.
Methanogens: Anaerobic methane producers (Archaea).
Cyanobacteria: Photosynthetic organisms and oxygen producers.
Clostridium botulinum: Obligate anaerobe producing botulinum toxin causing botulism.
Streptococcus pyogenes: Causes strep throat and other infections.
Staphylococcus aureus: Leads to skin infections, MRSA, toxins.
Salmonella: Causes gastroenteritis and foodborne illness.
Rhinovirus: Causes the common cold; classified as a picornavirus.
Influenza virus: A segmented RNA virus associated with antigenic drift and shift.
Prions: Proteinaceous infectious particles causing spongiform encephalopathies.
Chapter 29 species/groups:
Spirogyra: Filamentous green alga using conjugation for sexual reproduction.
Kelp: Large brown algae (multicellular).
Diatoms: Characterized by silica walls; serve as primary producers.
Dinoflagellates: Feature two flagella; known for red tides.
Ciliates: Notable for numerous cilia and dual nuclei.
Euglena: A mixotrophic organism equipped with an eyespot.
Amoeba: Exhibits amoeboid movement and phagocytosis capabilities.
Plasmodial slime mold life cycle: Plasmodium forms → sporangia → spores → swarm cells → fusion → plasmodium.
Ascomycetes and Basidiomycetes: Fungi identified by sexual spore production; ichens and mycorrhizae as notable symbiotic relationships.
Chapter 30:
Mosses: Dominated by gametophyte stage, dependent on water for sperm movement.
Ferns: Dominated by sporophyte stage; include lifecycle stages of spores → gametophyte → gametes → sporophyte.
Gymnosperms: Characterized by naked seeds and conifer qualities; Ginkgo is unique among them.
Angiosperms: Noted for flowering structures, double fertilization, and fruit formation.
Chapter 31:
Porifera: Filter feeders utilizing choanocytes.
Cnidaria: Characterized by cnidocytes; exist in polyp and medusa forms.
Mollusca: Include gastropods, cephalopods, and bivalves, with differences in locomotion, feeding, and nervous systems.
Annelids: Segmented worms like earthworms.
Platyhelminthes: Flatworms, which include planarians as free-living and tapeworms as parasitic.
Arthropods: Comprising crustaceans, insects, and arachnids; defined by body plan and lifecycle.
Echinoderms: Including sea stars, characterized by water vascular systems.
Chapter 32:
Lancelets: Seen as primitive chordates.
Jawless fishes: Including lampreys and hagfish.
Cartilaginous fishes: Incorporating sharks and rays that possess cartilaginous structures.
Ray-finned fishes: Represent typical bony fish that exhibit diversity.
Lobe-finned fishes: Considered ancestors to tetrapods.
Amphibians: Their life cycle is interconnected with aquatic habitats, with three main groups defined.
Reptiles and mammals: Adaptations as amniotes diverge further, with distinct characteristics for mammals (hair, mammary glands).