BIO 112 Exam 2 [Study Guide]
Material from PREVIOUS EXAM:
1.) Describe and explain an organism's scientific name, including the proper format for writing and abbreviating scientific names. (find scientific names from other slides and google prefix meanings)
2.) Name the major levels of the Linnaean classification hierarchy.
Categorized based on overall similarity. Linnaean Classification System in Order:
Domain: The highest taxonomic rank, which categorizes life into three major groups: Archaea, Bacteria, and Eukarya.
Kingdom: The second highest rank, which further divides domains into major groups such as Animalia, Plantae, Fungi, and Protista.
Phylum: Groups organisms based on fundamental body plans and structural features.
Class: A more specific grouping within a phylum, categorizing organisms that share certain characteristics.
Order: Divides classes into smaller groups to reflect evolutionary relationships.
Family: A classification that includes closely related genera.
Genus: A group of species that are closely related and share a common ancestor.
Species: The most specific level of classification, representing individual organisms that can interbreed and produce fertile offspring.
*Genus and species names are italicized or underlined
*Abbreviating the genus is allowed after the full name is used once.
*All levels are capitalized except the species name
3.) On a phylogenetic tree, identify monophyletic groups, synapomorphy, reversal, & convergence.
Monophyletic Groups: An ancestor and all of its descendants. The group’s name is often listed next to its most recent common ancestor (CA). The group’s name can also be listed above the terminal taxa. Defined by synapomorphies.
Synapomorphy: Traits that are shared due to inheritance from a CA (homologous), and derived in that ancestor compared to more distant ancestors.
“syn-” = together; “apo” = away from; “morph” = form
Reversal: A process where a derived trait reverts back to a more ancestral state, potentially confusing interpretations of evolutionary relationships.
Convergence: The evolution of similar traits in unrelated lineages due to adaptation to similar environments or ecological niches, which can lead to misleading classifications if based solely on morphological characteristics.
Paraphyletic Groups: Leaves out some of the descendants of the most recent common ancestor (MRCA).
Polyphyletic Group: Leaves out the CA’s of the group.
Sister Taxon: Everything else that descended from the group’s MRCA.
Occam’s Razor: The simplest explanation is most likely.
Historical Geology - Ch. 25
4.) Explain Steno’s laws and other major principles of historical geology.
Steno’s Laws: Four principles of geology to interpret the history of rock layers (stratigraphy), establishing the foundation for relative dating. They describe how sediment is deposited, creating orderly, stacked layers that indicate which rock is oldest.
Steno’s Laws:
1.) Principle of Superposition: Older rock is on the bottom; younger rock is on top.
2.) Principle of Original Horizontality: Sediments are deposited in flat, horizontal layers. Any tilting, folding, or faulting come later.
3.) Principle of Original Lateral Continuity: Sediment deposited on the seafloor will be a layer that extends for a considerable distance in all directions.
4.) Principle of Intrusive Relationships: Sedimentary rocks are older that igneous rock that intrudes into them.
Three Kinds of Rock:
(1) Igneous Rock = volcanic
(2) Sedimentary Rock = deposited and accumulated in water; forms layers
(3) Metamorphic Rock = Rock transformed by heat and pressure.
Uniformitarianism:
Processes occurring in the present are the same processes that have operated in the past, over a very long time.
Instead of a young earth that was shaped by catastrophes, the earth is ancient and shaped by the slow and steady processes of volcanic activity, erosion, deposition of sediment, etc.
Principles of Fossil Succession:
Fossils occur in a consistent vertical order in sedimentary rocks all over the world.
**** Living fauna of an area are related to local recent fossils.
Geographic regions show distinct patterns of living and fossil organisms.
Ex: Australia’s native mammals (except bats) are all marsupials.
Prediction: Antartica and Australia separated from other continents before the evolution of placental mammals, so Antartica’s fossil mammals should all be marsupials.
5.) Use Steno’s laws and logic to interpret a stratigraphic diagram. (download PP and view answers to images)
6.) List the Eras of the geological time scale and the ages of the boundaries between them.
Precambrian “Era” (Group of Eons)
Precambrian Era: 4.6 billion to 541 million years ago, characterized by the formation of the Earth and the earliest life forms.
Major Eras of the Phanerozoic Eon [Phanerozoic Eon = spanning from 543 million years ago to the present] (In Order of Youngest to Oldest)
Cenozoic Era: 65 Ma (million years ago) to present. Known as the “Age of Mammals”.
Mesozoic Era: 251 Ma to 65 Ma. Known as the “Age of Reptiles” or dinosaurs.
Paleozoic Era: 543 Ma to 251 Ma. Known as the “Age of Fishes”.
*Explain how Pangea separated and into what land did it separate into? India first island because diversity?
Platonic Shifts:
Sea Floor Spreading:
Faulting:
Subduction and Orogeny (Mountain Building):
Sliding Plate Over Asthenosphere
Divergent Plate Boundary
Convergent Plate Boundary
Transform Plate Boundary
Mid Ocean Ridge Magnetic Striping
7.) List the Periods of the geological time scale associated with dinosaurs.
Periods of the Geological Time Scale of Dinosaurs: [In Order of Greatest to Least]
440 Million Years Ago: Late Ordovician; 85% Extinct
374 Million Years Ago: Late Devonian; 75% Extinct
250 Million Years Ago: Permian; 95% Extinct
200 Million Years Ago: Jurassic; 80% Extinct
65 Million Years Ago: Cretaceous; 76% Extinct
8.) Explain how C14 is formed, accumulates in organisms, and decays.
Living things have about 1 C14 for every trillion C12 atoms
C14 is constantly replaced in living things
Once and organism dies, C14 decay continues but replacement stops.
C14 can only be used to date organic samples that are a few thousand years old.
9.) Explain what sort of materials can be aged using C14.
Organic materials that were once part of a living organism include wood, bone, shell, and plant fibers. This method is particularly effective for dating ancient artifacts, archaeological findings, and biological specimens.
10.) State how many mass extinctions are known, and what evidence supports them.
The “Big Five”: Occurring over the last 500 million years and wiping out 70-95% of species. Evidence, primarily from the fossil record and geological strata, shows rapid, widespread biodiversity losses:
Ordovician- Silurian (approx. 440 Ma): Intense glaciation caused rapid sea-level drops.
Late Devonian (approx. 360 Ma): Likely caused by ocean oxygen depletion or global cooling.
Permian- Triassic (approx. 250 Ma): “The Great Dying” over 90% of species lost, triggered by massive volcanic activity (Siberian Traps).
Triassic- Jurassic (approx. 200 Ma): Caused by climate change and volcanic eruptions in the Central Atlantic Magmatic Province (CAMP).
Cretaceous- Paleogene (K-Pg) (approx. 65 Ma): Famous for asteroid impact, killing non-avian dinosaurs.
11.) State the best-supported hypothesis for the extinction of the dinosaurs. Identify evidence that supports this hypothesis.
Alvarez Hypothesis: Suggests a massive asteroid struck Earth 66 million years ago, causing catastrophic and abrupt climate change that dinosaurs could not adapt to. The Chicxulub crater in Mexico and a worldwide iridium layer provide primary evidence of this event.
**Index Fossils: Certain fossils that can be used to help find the relative age of rock layers.
To be an index fossil:
An organism must have lived only during a short path of earth’s history.
Many fossils of the organism must be found in rock layers.
The fossil must be found over a wide area of earth.
The organism must be unique.
The shorter time period the species lived the better the index fossil it is.
Fossils that are found in many rock layers, therefore living long periods of time, do not qualify/count as index fossils.
Fossil Transitions- Ch. 25
12.) Describe how a sequence of fossils can demonstrate evolutionary history, and describe an example that shows this.
Providing a chronological record of gradual morphological changes in species across sedimentary rock layers, revealing transitional forms that link ancestors to modern descendants.
These fossils explain how physical features adapt over time, such as the evolution of limbs and wings, skull shape, or overall size.
13.) Define adaptive radiation and list examples.
Adaptive Radiation is a rapid evolutionary process where a single ancestral species diversifies into a wide variety of new forms to exploit different ecological niches, typically driven by environmental changes, new habitat availability, or mass extinctions
Examples of adaptive radiation include:
Darwin's finches in the Galápagos Islands, which evolved distinct beak shapes based on their food sources.
The diversity of mammal species following the extinction of dinosaurs, leading to the emergence of various forms such as whales, bats, and primates.
The diversification of cichlid fish in African lakes, which adapted to different feeding strategies and habitat types.
Origin of cells and Multicellularity – Ch. 25
14.) Describe serial endosymbiosis
Hypothesis supposes that mitochondria evolved before plastids through a sequence of endosymbiotic events.
A hypothesis for the origin of eukaryotes consisting of a sequence of endosymbiotic events in which mitochondria, chloroplasts, and perhaps other cellular structures were derived from small prokaryotes that had been engulfed by larger cells.
Endosymbiotic Event occurs when one microorganism lives inside another, creating a stable, long-term, and intimate relationship that can lead to evolutionary merging (symbiogenesis).
15.) List evidence that supports the theory of endosymbiosis for eukaryotes
Double Membrane
DNA
Enzymes
Ribosomes
Multicellular Organisms – Ch. 25 (parts)
16.) Identify some characteristics of multicellular organisms vs. colonial vs. unicellular organisms.
Multicellular Organisms Characteristics:
Structure: Composed of many specialized cells (tissues, organs).
Interdependence: Cells cannot survive independently
Size/Complexity: Generally large; eukaryotes
Examples: Humans, animals, plants, most fungi.
Colonial Organisms:
Structure: Groups of identical, independent cells acting together
Independence: Individual cells can usually survive alone if separated
Organization” Minimal cell specialization; no true tissues (groups of cells working together for the same purpose)
Examples: Algae, sponges, some bacteria.
Unicellular Organisms:
Structure: A single cell handles all functions (metabolism, reproduction)
Size: Mostly microscopic
Examples: Bacteria, amoeba, yeast.
17.) Explain some of the ways that two cells of a multicellular organism might interact that are different from two cells of a colony.
In a multicellular organism, cells can communicate through chemical signals, such as hormones and neurotransmitters, leading to coordinated responses; they may also engage in direct contact through gap junctions or tight junctions to ensure proper function and synchronization within tissues. In contrast, cells of a colony primarily interact through shared resources and external signals, often relying on diffusion for communication instead of specialized connections.
Viruses and Vaccines – Ch. 19 (parts)
18.) Describe the structure of a typical virus.
A microscopic, acellular (non-cellular) agent composed of a core of genetic material - either DNA or RNA, but never both - surrounded by a protein coat called a capsid composed of subunits called capsomeres, which protect the genome.
Genome: DNA or RNA that can be single or double-stranded, linear or circular.
Capsid: Protein shell enclosing the genome.
Nucleoclapsid: Combination of genetic material and capsid.
Envelope (optional): Phospholipid membrane derived from the host cell that surrounds the capsid, often studded with glycoprotein spikes (peplomers) used for attachment to host cells.
Shapes: Varies.
19.) Identify which characteristics of living things viruses have, and which they lack.
Living Characteristics of a Virus:
Genetic Material: Contain Nucleic acids (DNA or RNA).
Reproduction/ Replication: Only after invading a living host cell and hijacking its machinery can viruses replicate rapidly.
Evolution/ Adaptation: Viruses can mutate and evolve through natural selection, adapting to their environment (e.g., developing strands resistant to drugs).
Structural Organization: Viruses have a defined, organized structure consisting of genetic material (either DNA or RNA) enclosed in a protein coat called a capsid.
Living Characteristics Viruses LACK:
Cellular Structure: Viruses are acellular and not made of cells. They therefore lack a cytoplasm, cell membrane, and organelles like ribosomes or mitochondria.
Independent Metabolism: Viruses do not carry out their own metabolic processes. They therefore can’t produce energy (ATP) on their own and depend completely on the host cell to synthesize proteins and replicate.
Independent Reproduction: Unlike living organisms, viruses cannot reproduce on their own. They must invade a host cell to produce new particles.
Homeostasis: Viruses cannot maintain a stable, constant internal state.
Growth and Development: Viruses do not increase in size or complexity; they are assembled in their final form within the host cell.
20.) Compare and contrast the lytic and lysogenic life cycles of viruses.
Lytic [“Break or Bust”]:
Host Fate: Kills the host cell immediately
Viral Genome: In the lytic cycle, the virus takes over cellular machinery to replicate DNA separately.
Replication Speed: Rapid and active
Outcome: Causes acute symptoms and spreads quickly
Lysogenic [“Birth of the Break”]:
Host Fate: Allows the host cell to survive
Viral Genome: The viral DNA merges with the host genome
Replication Speed: Dormant and long-term.
Outcome: Causes latent or chronic infections.
Switching: Lysogenic viruses can enter the lytic cycle in response to stressors like radiation.
Similarities of Lytic and Lysogenic:
Both are methods of viral reproduction used by bacteriophages.
Both involve attaching to and entering a host cell.
Both utilize the host’s machinery to express genes.
21.) Describe how viruses use host cells to reproduce.
Hijacking a host cell’s machinery. After attaching to a specific cell receptor, the virus enters, uncoats its genetic material, and forces the host to replicate the viral genome and translate proteins. These components assemble into new virions, which are then released, often destroying the host cell.
22.) Explain how phylogenetic systematics can be used to deduce the origin of emerging diseases.
Analyzing the genetic sequences (DNA/RNA) of pathogens to construct evolutionary trees, revealing their ancestor-descendant relationships, host origins, and transmission pathways. By comparing new strains with known samples, researchers can identify zoonotic spillover events (e.g., SARS from bats, HIV from primates) and pinpoint the geographic and temporal origins of outbreaks
Molecular Clock Analysis: Estimating the time of a host-switch or the most recent common ancestor.
Cladistic Analysis: Using outgroups to root phylogenies, establishing which species or population first harbored the pathogen.
Molecular Characterization: Mapping mutations and identifying the closest relatives in animal or environmental reservoirs.
Prokaryotes – Ch. 27
23.) Compare and contrast the structures of prokaryotic cells and eukaryotic cells.
Prokaryotic Cells: (bacteria and archaea)
No Nucleus
Circular DNA
No internal membranes
“Naked” loop of DNA
Small (70S) Ribosomes
Proteins
No membrane-bound organelles
Eukaryotic Cells: (animals, plants, fungi, protists)
Nucleus
Linear DNA and histones
Large (80S) R
Proteins
Internal membranes (Golgi, ER…)
Membrane-bound organelles
Prokaryotic Cells AND Eukaryotic Cells:
Plasma membrane
Cytoplasm
Double-stranded DNA
Ribosomes
24.) Define multicellularity and explain whether prokaryotes have it.
Multicellularity: An organism consisting of multiple, specialized cells that function together as a single unit, usually originating from a single ancestor cell.
Prokaryotes and Multicellularity:
Generally Unicellular: Prokaryotes (bacteria and archaea) are strictly single-celled organisms, lacking the complex organelles and genome regulation required for complex multicellularity seen in eukaryotes.
Simple Multicellularity/ Aggregation: Some bacteria exhibit “simple” multicellularity by forming colonies, filaments, or aggregating to share labor, such as cyanobacteria specializing in nitrogen fixation or biofilm formation.
Exceptions (MMPs): Multicellular magnetotactic prokaryotes (MMPs) are rare, complex bacteria that exist as obligate multicellular units, reproducing as a group rather than single cells.
While prokaryotes do not possess the complexity of multicellularity eukaryotes, they do exhibit functional, cooperative, and sometimes obligate multicellular behaviors.
25.) Explain why prokaryotes are so abundant.
Rapid Reproduction: They can reproduce quickly via binary fission, with some species dividing in a matter of minutes.
Metabolic Versatility: Prokaryotes can use various carbon and energy sources, allowing them to thrive in diverse, often inhospitable, environments.
Environmental Ubiquity: They are found on every imaginable surface, from oceans to extreme temperatures, making them the most populous organisms on Earth.
Evolutionary History & Adaptation: With a history spanning roughly 3.8 billion years, they have evolved to inhabit almost all environments, and they use horizontal gene transfer to rapidly adapt.
Small Size: Their tiny size (typically 0.5–5
m) allows them to occupy minimal space and consume fewer resources per individual.
26.) Describe the structure of prokaryotic cells.
Key Structural Components:
Nucleoid: A non-membrane-bound region holding the single, circular, double-stranded DNA chromosome.
Plasma Membrane: A phospholipid bilayer regulating transport, also serving as the site for energy reactions.
Cell Wall: A rigid outer layer (mostly peptidoglycan in bacteria) that maintains shape and prevents osmotic lysis.
Cytoplasm: Jelly-like cytosol filling the cell, containing ribosomes (protein synthesis) and inclusions.
Plasmids: Small, extra-chromosomal circular DNA molecules carrying advantageous genes.
External Structures (Optional/Variable):
Capsule/Slime Layer: Polysaccharide layer for protection and adherence.
Flagella: Whip-like appendages for locomotion.
Pili/Fimbriae: Hair-like appendages for attachment, surface adhesion, and DNA transfer (conjugation).
Types: Prokaryotes are divided into Bacteria (often peptidoglycan walls) and Archaea (distinct lipids, no peptidoglycan).
27.) Explain how prokaryotes differ in their sources of carbon.
Prokaryotes differ in carbon sources by acting as either autotrophs, which fix inorganic carbon dioxide () into organic molecules, or heterotrophs, which obtain carbon by consuming organic compounds from other organisms.
Autotrophic Prokaryotes: Utilize inorganic
as their primary carbon source, converting it into necessary organic compounds. These are often producers, such as cyanobacteria.
Heterotrophic Prokaryotes: Obtain carbon from organic compounds derived from other organisms (dead or alive), breaking them down for growth. They are common decomposers
28.) Explain how prokaryotes differ in their sources of energy.
Key Differences in Energy Sources:
Autotrophs (Self-feeders)
Photoautotrophs: Use light energy to convert carbon dioxide (CO2)
)into organic molecules (e.g., cyanobacteria).
Chemoautotrophs (Chemolithoautotrophs): Derive energy by oxidizing inorganic compounds (like hydrogen sulfide, iron, or ammonia) to fix CO2.
Heterotrophs (Other-feeders)
Chemoheterotrophs: Obtain both energy and carbon by consuming organic compounds produced by other organisms, acting as decomposers or pathogens.
Photoheterotrophs: A special class that uses light for energy but must consume organic carbon sources.
29.) Explain why some photosynthetic bacteria give off oxygen, and others do not.
Photosynthetic bacteria are divided into two groups—those that release oxygen (oxygenioic) and those that do not (anoxygenic)
Oxygen-Producing (Oxygenic) Bacteria: Cyanobacteria
Electron Donor: These bacteria use water as an electron donor to replace electrons in the chlorophyll molecule.
Mechanism: When water is oxidized, it splits into electrons, protons and oxygen
Photosystem Structure: They possess both Photosystem I (PSI) and Photosystem II (PSII). The presence of a PSII-like complex allows them to oxidize water.
Result: Oxygen is released as a byproduct.
Example: Cyanobacteria
Non-Oxygen-Producing (Anoxygenic) Bacteria: Purple and Green Bacteria
Electron Donor: These bacteria cannot use water as an electron donor because they cannot break it down. Instead, they use other reduced molecules.
Mechanism: Because they use different compounds they produce byproducts such as elemental sulfur or sulfate instead of oxygen.
Photosystem Structure: They possess only one type of reaction center (similar to either PS I or PS II, but not both). They lack the necessary enzymes to split water, specifically the oxygen-evolving complex.
Result: No oxygen is released; they often thrive in anaerobic (low/no oxygen) environments.
Examples: Purple sulfur bacteria, Green sulfur bacteria, and Green non-sulfur bacteria
30.) Discuss the evolution of antibiotic resistance and the proper use of antibiotics.
Evolution of Antibiotic Resistance
Mechanism: Resistance arises from random, spontaneous genetic mutations or the acquisition of resistance genes from other bacteria (horizontal gene transfer).
Natural Selection: The presence of antibiotics acts as a selective pressure, eliminating susceptible bacteria and allowing resistant bacteria to thrive and dominate the population.
Resistance Strategies: Bacteria employ several mechanisms to survive:
Inactivation: Producing enzymes (e.g.
-lactamases) that destroy the antibiotic.
Efflux Pumps: Actively expelling the drug from the bacterial cell.
Target Modification: Changing the structure of the antibiotic's target site.
Reduced Permeability: Decreasing the ability of the antibiotic to enter the cell.
Environmental Spread: Resistance genes are shared, even between different species, in the environment and human microbiome.
Proper Use of Antibiotics
Stewardship: Antibiotics should only be used when necessary, typically for bacterial infections, and avoided for viral infections like colds or flu.
Treatment Adherence: It is crucial to complete the full course of antibiotics as prescribed to ensure all bacteria are eliminated, preventing the selection of partially resistant strains.
Reducing Agriculture Usage: Minimizing the use of antibiotics as growth promoters in livestock is essential to reduce the spread of resistance through the food chain.
Infection Control: Improving hygiene, using vaccinations, and practicing good infection control in healthcare settings reduces the need for antibiotic treatment in the first place
31.) Compare and contrast the archaea and bacteria
Archaea AND Bacteria:
Circular Chromosome
No Nuclear Envelope
Membrane-enclosed Organelles
Archaea:
No peptidoglycan in cell wall
Some branched hydrocarbons
Several kinds of RNA polymerase
Methionine
Introns present in some genes
Growth not inhibited by antibiotics
Histones associated with DNA in some species
Growth at temperatures > 100C in some species
Bacteria:
Peptidoglycan in cell wall
Unbranched hydrocarbons
One kind of RNA polymerase
Formylmethionine
Introns are very RARE in genes
Growth inhibited by antibiotics
No histones associated with DNA
No growth at temperatures > 100C
32.) Describe the nutrition of heterotrophic bacteria and give examples of symbiosis in bacteria.
Heterotrophic bacteria depend on ready-made organic matter, utilizing enzymes to break down complex substances into simpler nutrients. They are divided into three main types based on their habitat and food source:
Saprophytic Bacteria: These obtain nutrition by decomposing dead organic matter, such as fallen leaves, animal feces, or corpses. They secrete enzymes to digest complex compounds outside their bodies, examples include Bacillus species.
Parasitic Bacteria: These live on or inside a host organism, stealing nutrients and often causing diseases. Examples include Salmonella typhi (typhoid fever) and Diplococcus pneumoniae (pneumonia).
Symbiotic Bacteria: These live in close association with other organisms, benefiting both parties
33.) Describe the anatomy & physiology of cyanobacteria and their historical significance.
Vital for global nitrogen fixation and carbon cycling.
Anatomy & Morphology
Structure: They can be unicellular, colonial, or filamentous (trichomes).
Cell Wall: Typical Gram-negative structure.
Photosynthetic Apparatus: Lack chloroplasts; instead, they possess thylakoid membranes within the cytoplasm for photosynthesis.
Pigments: Contain Chlorophyll
and phycobiliproteins (like phycocyanin), giving them their blue-green color.
Specialized Cells: Some filamentous types have heterocysts for nitrogen fixation and akinetes for survival in adverse conditions.
Buoyancy: Gas vesicles allow some planktonic forms to control their position in the water column
Physiology
Oxygenic Photosynthesis: They produce oxygen as a byproduct of photosynthesis, using light to convert
into nutrients.
Nitrogen Fixation: Many species can convert atmospheric nitrogen into ammonia, aiding nutrient cycling.
Metabolic Diversity: Adapted to various environments (aquatic, terrestrial, extreme temperatures) and can form mutualistic relationships with fungi (lichens) or plants.
Blooms: Under high nutrients, they form blooms, sometimes producing toxins (cyanotoxins)
34.) Discuss how bacterial infections can be controlled and how antibiotics work.
Antibody: Protein produced by lymphocytes (type of white blood cell) in response to presence of a specific antigen.
Antibodies: Bind to specific antigens and cause their destruction.
Antibiotics: Antibiotics are medications that target specific bacterial mechanisms without harming human cells
Protists – Ch. 28
35.) Explain why the kingdom “Protista” is no longer considered a proper taxonomic group.
It is paraphyletic and polyphyletic, meaning its members do not share a single common ancestor and are more closely related to plants, animals, or fungi than to each other
38.) Describe the evidence that supports the theory that mitochondria and plastids evolved by primary (and sometimes secondary) endosymbiosis. Of course, that means explaining the difference between primary and secondary endosymbiosis.
The endosymbiotic theory posits that mitochondria and plastids (such as chloroplasts) originated as free-living prokaryotic bacteria that were engulfed by ancestral eukaryotic cells, forming a symbiotic, and eventually, inseparable relationship.
Evidence:
Double Membrane Structure: Both organelles are surrounded by two membranes. The inner membrane is believed to be derived from the original plasma membrane of the prokaryote, while the outer membrane is derived from the host cell's vesicle membrane during engulfment.
Independent DNA and Genome Structure: Mitochondria and plastids contain their own DNA, which is circular and lacks histones, strongly resembling the chromosome structure of prokaryotes.
Replication by Binary Fission: These organelles replicate independently within the cell through a process similar to bacterial binary fission.
Prokaryotic Ribosomes: The ribosomes found inside mitochondria and plastids are smaller (resembling 70S ribosomes) and structurally closer to bacterial ribosomes than to the eukaryotic cytoplasmic ribosomes (80S).
Phylogenetic Analysis: DNA sequencing shows that mitochondria are closely related to
-proteobacteria, and chloroplasts are related to cyanobacteria.
Sensitivity to Antibiotics: Mitochondria and plastids are sensitive to antibiotics that inhibit bacterial protein synthesis (e.g., streptomycin, chloramphenicol).
Primary vs. Secondary Endosymbiosis:
Primary Endosymbiosis:
This is the initial engulfment of a free-living prokaryote by a heterotrophic eukaryotic host.
Mitochondria: Resulted from the engulfment of an aerobic bacterium.
Plastids: Resulted from the engulfment of a photosynthetic cyanobacterium by an early eukaryotic cell.
Result: The resulting organelle has a double membrane
Secondary Endosymbiosis:
This occurs when a eukaryotic cell engulfs a second eukaryotic cell that has already undergone primary endosymbiosis (i.e., a red or green alga).
Process: The engulfed alga is not digested but becomes a, complex"endosymbiont within a host".
Evidence: The resulting chloroplasts are often surrounded by three or four membranes, reflecting the multiple membranes of the original alga and the host’s food vacuole.
Example: Euglenids and Chlorarachniophytes acquired their chloroplasts via secondary endosymbiosis. Some secondary endosymbionts even retain a vestigial nucleus from the engulfed alga, known as a nucleomorph.
39.) Explain which living organisms are the closest relatives of the prokaryotes that gave rise to mitochondria and plastids.
Mitochondria and plastids originated from independent prokaryotic endosymbionts that were engulfed by a host cell. Mitochondria are most closely related to Alphaproteobacteria (particularly within the order Rickettsiales or marine Iodidimonas), while plastids (chloroplasts) are descended from cyanobacteria.
40.) Describe the evidence that suggests that mitochondria were acquired before plastids in eukaryotic evolution.
All eukaryotes possess mitochondria (or remnants of them), while only a subset (plants/algae) have plastids, indicating mitochondria were present in the common ancestor. Plastid acquisition (cyanobacteria) happened later in a lineage already possessing mitochondria.
41.) List examples of endosymbiosis in animals.
Key Examples of Endosymbiosis in Animals:
Buchnera in Aphids: Buchnera bacteria reside in specialized aphid cells (bacteriocytes) and provide essential amino acids that the aphid lacks in its plant sap diet.
Wigglesworthia in Tsetse Flies: These bacteria live in specialized cells and are essential for host nutrition and fertility.
Termite Gut Microbes: Diverse bacteria, archaea, and protists (e.g.Mixotricha paradoxa) live in the hindgut of termites to break down complex wood polysaccharides into nutrients.
Wolbachia in Insects/Nematodes: These common bacteria live inside reproductive tissues and can manipulate host reproduction (e.g., killing males or causing feminization).
Zooxanthellae in Corals: Photosynthetic algae live within the tissues of corals (cnidarians), providing energy from photosynthesis in exchange for protection and nutrients.
Mitochondria: All animals contain mitochondria, which are highly specialized organelles that originated from an ancient endosymbiotic bacterium that began living inside another cell.
42.) Explain why Plasmodium continues to pose a great risk to human health despite modern medical advances.
The persistence of malaria is driven by the parasite's high adaptability to drug and insecticide resistance, the complex nature of its lifecycle, and significant socio-economic barriers in affected regions
Plant Relationships & Characteristics – Ch. 29 & 30
43.) Describe four shared derived traits that link green algae and land plants.
Green algae contain the same carotenoids and chlorophyll a and b as land plants, whereas other algae have different accessory pigments and types of chlorophyll molecules in addition to chlorophyll a.
Both green algae and land plants also store carbohydrates as starch.
Cellulose in Cell Walls: Both groups have cell walls made of cellulose, providing structural support and protection.
Reproductive Strategies: Green algae generally reproduce asexually through spores, while land plants have evolved both sexual and asexual reproduction methods to adapt to terrestrial environments.
Habitat Preferences: Green algae are predominantly found in aquatic environments, whereas land plants have adapted to a wide range of terrestrial habitats, displaying varying adaptations for water conservation and nutrient acquisition.
44.) Describe plant characteristics that are adaptive for life on land.
waxy cuticle to reduce water loss
stomata for gas exchange
vascular tissue (xylem/phloem) for transport
roots for anchorage and water absorption
protected reproductive structures like pollen and seeds
45.) Define and distinguish among the stages of the alternation of generations in plant life cycles.
Alternates between a multicellular haploid (n) gametophyte stage and a multicellular diploid (2n) sporophyte stage.
Sporophyte Stage (Diploid, 2n): The multicellular, asexual phase that produces haploid spores through meiosis within sporangia. It develops from a fertilized zygote. In vascular plants (trees, flowers), this is the dominant, visible stage.
Gametophyte Stage (Haploid, n): The multicellular, sexual phase that develops from spores. It produces haploid gametes (sperm/egg) through mitosis. In nonvascular plants (mosses), this is the dominant, visible green mat.
46.) Describe vascular plant characteristics, including the functions of the major vascular tissue types.
Specialized Vascular Tissues: transport water, nutrients, and sugars, allowing them to grow tall and inhabit diverse environments
Xylem: Responsible for the conduction of water and dissolved minerals from the roots to the rest of the plant, providing structural support.
Phloem: Transports organic compounds, primarily sugars produced during photosynthesis, from the leaves to the other parts of the plant, facilitating growth and energy distribution.
Vascular tissues are crucial for the overall functioning of vascular plants, enabling them to efficiently manage resources and adapt to various ecological niches.
True Roots: Absorption/anchoring
Stems: Support/transport
Leaves: Photosynthesis
Dominant sporophyte generation
47.) Identify and name the major structures that are haploid vs. diploid in the life cycles of mosses, ferns, pine trees and flowering plants.
Summary Table
Structure Type | Mosses | Ferns | Pine Trees | Flowering Plants |
|---|---|---|---|---|
Dominant Stage | Gametophyte (n) | Sporophyte (2n) | Sporophyte (2n) | Sporophyte (2n) |
Haploid (n) | Gametophyte, Spores, Eggs, Sperm | Prothallus, Spores, Eggs, Sperm | Pollen, Female Gametophyte, Spores | Pollen, Embryo Sac, Spores |
Diploid (2n) | Sporophyte, Zygote | Sporophyte, Zygote, Sori | Tree, Embryo, Seed Coat | Tree/Plant, Embryo, Zygote |
Mosses (Bryophytes)
Ferns (Seedless Vascular Plants)
Pine Trees (Gymnosperms)
Flowering Plants (Angiosperms)
48.) Explain why pollen grains were an important adaptation for successful reproduction on land.
They protect male gametes (sperm) in a durable coat, preventing desiccation and eliminating the need for external water for fertilization
49.) Explain how a seed can be said to include contributions from three distinct generations.
A seed contains three distinct generations through the inclusion of maternal sporophyte tissue, a haploid gametophyte, and a new diploid embryo
Generation 1: The Parent Sporophyte (2n): The outer seed coat (testa/tegmen) originates from the ovule tissue of the mother plant, representing the parent generation.
Generation 2: The Female Gametophyte (n): This tissue (or the endosperm in many angiosperms) provides nutrition to the developing embryo, representing the intermediate gametophyte generation.
Generation 3: The Daughter Sporophyte (2n): The embryo, formed by the fertilization of an egg by sperm, is the new offspring generation that will grow into the next plant.
Photosynthesis – Ch. 10 (parts)
50). Explain the importance of photosynthesis to living things.
Energy Conversion: Plants, algae, and some bacteria convert light energy into glucose, a stable chemical energy source used by organisms for growth, reproduction, and daily functions.
Oxygen Production: Photosynthesis releases oxygen, which is essential for the survival of most organisms on Earth.
Food Chain Foundation: By producing organic compounds (biomass), it provides the base food source for herbivores, which in turn feed carnivores.
Atmospheric Balance: It regulates the atmosphere by consuming carbon dioxide, a greenhouse gas, and releasing oxygen.
Energy Storage: The energy trapped in fossil fuels (coal, oil, gas) is actually stored solar energy from photosynthesis that occurred millions of years ago.
51) Write a summary equation for photosynthesis.
The summary equation for photosynthesis is:
6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂.
Other Vocabulary:
Nonvascular Plants are Seedless Plants which are bryophytes.
Vascular plants are both seedless plants (lycophytes and monilophytes) and seeded plants called spermatophytes (gymnosperms and angiosperms)
Immunity: When our bodies encounter pathogens, our white blood
cells create antibodies against the pathogens. This
makes them easier for the immune system to destroy. After the first infection the
body remembers how to make the right antibodies, and can make them quickly if the same pathogen is encountered again.
Adaptive Immunity: Immunity which is acquired or developed by an individual only after a specific challenge is encountered.
The Father of Immunization: Edward Jenner. Created first vaccine.
Vaccines: contain either dead pathogens, live but weakened pathogens, or parts of the pathogen. The white blood cells respond to the vaccine as if it were a disease by creating antibodies.
MMR: Measles, Mumps and Rubella vaccine
Fimbriae and Pili: In some prokaryotes; allows them to stick to their substrate or other individuals in a colony
Capsule: cell wall of many prokaryotes is covered by a capsule, a sticky layer of polysaccharide or protein.
Radiometric Dating: Unstable isotopes decay to stable states
Isotopes: Decay at rates that are measurable and constant
Half-life: The time it takes for one-half of the parent atoms to decay to stable daughter elements (the half-life)
Endospores: microorganisms, exist in extreme environments, ability to shut off metabolism
Gymnosperms: naked seeds that are not enclosed in an ovary; they include conifers and are typically adapted to dry conditions.
Angiosperms: vesseled sperms, has a flower
Pollen: packaged plant sperm
Spermatophytes: not tied to water for reproduction
Conifers: cone
Bryophytes: tied to water for reproduction
Lycophyte: vascular plants that reproduce via spores, often characterized by their small, scale-like leaves.
Monilophyte: vascular plants that also reproduce through spores, typically featuring larger fronds and a more complex leaf structure than lycophytes.
Photosynthesis: process conducted by protists and plants and all primary producers, autotrophs and photoautotrophs.
Pillus: How some bacteria share information
Protozoa [“First Animals”]
Unicellular
Eukaryotic
Heterotrophic or autotrophic
>50,000 spp.
Aquatic or terrestrial habitat
Free-living or symbiotic
Locomotion:
pseudopodia, flagella, cilia, or direct movement of cell
sessile
Mostly microscopic
Endoskeleton / exoskeleton / most “naked”
No germ layer- have nucleus (single or multiple) and organelles
Reproduction
asexual (budding/fission/ cysts)
sexual (“conjugation”)
3 Protozoans to Know:
1.) Dinoflagelletes
Kingdom: Protista sometimes classified under Chromista in modern systems
Domain: Eukarya
Phylum: Dinoflagellata
Genus Name: Alexandrium
Symbiotic: No
Free-Living: Yes, they are free-living marine planktonic dinoflagellates
Unicellular: yes
Eukaryotic: yes they contain a tru nucleus and membrane-bound organelle
Heterotrophic or Autotrophic: primarily photoautotrophic, using sunlight and nutrients to grow, but many species are also mixotrophic, meaning they can supplement their diet by feeding on other microorganisms
Aquatic or terrestrial habitat: Aquatic and found in coastal, temperate, sub-polar, and tropical waters worldwide
Locomotion: Motile; utilize two dissimilar flagella (transverse and longitudinal) to produce a characteristic whirling, helical, or swimming motion. They are generally weak swimmers that inhabit the upper water column as plankton but can actively migrate vertically to locate nutrients or light
Reproduction (asexual- budding, fission, cysts- or sexual- cojugation): Asexual binary fission (simple cell division) in the water column, enabling harmful algal blooms. Asexual binary fission is how they normally reprodcue when in favorable and nutrient-rich contions, this called the Planktonic Phase. Under stress or nutrient limitations cells produce gametes that fuse to form a diploid planozygote. This matures into a dormant cyst (hypnozygote) that sinks to the sediment. This phase is the Benthic Phase.
Nucleus (single or multiple?): Single
Type of Skeleton: “armored” dinoflagellated, characterized by a cell covering made of cellulose plates known as theca (or shell/skeleton).
Microscopic?: Yes
Known for producing paralytic shellfish poisoning (PSP) in humans and marine life by red tides caused by their production of saxitoxins during rapid reproduction.
2.) Amoebae
Kingdom: Protista
Domain: Eukarya
Phylum: Amebozoa
Genus Name: Paramecium
Symbiotic:
Free-Living: yes
Unicellular:
Eukaryotic:
Heterotrophic or Autotrophic: Heterotrophic (feeds on bacteria and small microorganisms)
Aquatic or terrestrial habitat: Aquatic (mostly freshwater environments such as ponds and streams)
Locomotion: Moves using cilia (tiny hair- like structures covering the cell)
Reproduction (asexual- budding, fission, cysts- or sexual- cojugation): Primarily through transverse binary fission, where a single cell divides into two identical daughter cells under favorable conditions. In unfavorable conditions they engage in sexual reproducation, commonly conjugation, where two individuals exchange genetic material to rejuvenate and increase genetic diversity.
Nucleus (single or multiple?): Multiple nuclei (one polypoid macronucleus for cellular fuction and one or more diploid micronuclei for reproduction)
Type of Skeleton: No true skeleton; has a flexible outer covering called a pellicle that helps maintain shape
Microscopic?: Yes
3.) Euglena
Kingdom: Protista
Domain: Eukaryota
Phylum: Euglenozoa
Genus: Euglena
Symbiotic: Derived from ancient complex symbiotic events and can sometimes exist as intestinal commensals or with bacteria
Free-Living: Primarily free-living
Unicellular: Yes they are single-celled flagellate organisms
Eukaryotic: yes
Heterotrophic or Autotrophic: both heterotrophic and autotrophic (mixotrophic) capable or switching its nutrition mode based on environmental conditions. They act as autotrophs by using chloroplasts for photosynthesis in light, but become heterotrophs by absorbing or ingesting organic nutrients in the dark
Aquatic or terrestrial habitat: Primarily aquatic freshwater environments (ponds, lakes, ditches) and some marine habitats. They are occasionally found in moist soil and mud (terrestrial) and can form cysts to survive dry periods.
Locomotion: Primarily swim by using a long, whip- like flagellum that creates a spiral, rotating movement to propel them forward in freshwater. They also use a secondary, slower method called “euglenoid movement” or metaboly, which involves worm-like, peristaltic contractions of the flexible pellicle to crawl or wriggle.
Reproduction (asexual- budding, fission, cysts- or sexual- cojugation): longitudinal binary fission, an asexual process where the cell splits lengthwise into two daughter cells.
Nucleus (single or multiple?): One nucleus
Type of Skeleton: No true skeleton, have a flexible pellicle located beneath the plasma membrane, acting as a supportive ‘membrane skeleton’
Microscopic?: Yes