Cumulative Ex2 Flashcards
From study guide
What are ribozymes?
Enzyme-like RNA molecules that catalyze many different reactions
Ribozymes provide insight into the origins of life and the role of RNA.
What is the Phanerozoic?
The eon that encompasses multicellular eukaryotic life
It is divided into three eras: Paleozoic, Mesozoic, and Cenozoic.
What are stromatolites?
Oldest known fossils; rock-like structures formed by microbial mats
They provide evidence for early life on Earth.
When did prokaryotes originate?
Around 3.5 billion years ago
Prokaryotes are the earliest known forms of life on Earth.
How did the oxygenation of Earth occur?
Through oxygenic photosynthesis by prokaryotes, primarily cyanobacteria
This process began around 2.4 billion years ago.
What is the Serial Endosymbiosis theory?
The theory that mitochondria and plastids originated from small prokaryotes living within larger host cells
It explains the origin of eukaryotic cells.
What is the origin of multicellular eukaryotes?
Multicellular eukaryotes likely evolved from simple unicellular ancestors
This process allowed for increased complexity and diversity.
What is the Ediacaran biota?
An assemblage of larger and more diverse soft-bodied organisms that lived from 635 to 541 million years ago
Represents some of the earliest complex life forms.
What is plate tectonics?
The theory explaining the movement of Earth’s lithospheric plates
It influences geological processes, including continental drift.
What is the Cambrian explosion?
The rapid appearance of fossils resembling modern phyla during the Cambrian period
It marks a significant increase in biodiversity.
What is the Permian extinction?
The largest mass extinction event, resulting in 84% of species disappearing
Occurred around 252 million years ago.
What is the Cretaceous mass extinction?
A mass extinction event that led to the demise of the dinosaurs
It occurred approximately 66 million years ago.
What is systematics?
The discipline that classifies organisms and determines their evolutionary relationships
It uses various data types, including fossil and genetic data.
What is taxonomy?
The ordered division and naming of organisms
It includes hierarchical classification.
What is phylogeny?
The evolutionary history of a species or group of related species
It is often depicted through phylogenetic trees.
What is maximum parsimony?
An approach that assumes the tree requiring the fewest evolutionary events is the most likely
It is used in constructing phylogenetic trees.
What is the difference between homology and analogy?
Homology refers to shared ancestry, while analogy refers to similar function without common ancestry
Example: bat wings and bird wings.
What are monophyletic, paraphyletic, and polyphyletic groups?
Monophyletic: includes an ancestor and all descendants; paraphyletic: includes an ancestor and some descendants; polyphyletic: includes species from different ancestors
These classifications are important in systematics.
What are shared derived and shared ancestral characters?
Shared derived: evolutionary novelties unique to a clade; shared ancestral: characters that originated in an ancestor of the taxon
They help differentiate between groups.
What is horizontal gene transfer?
The transfer of genes between organisms in a manner other than traditional reproduction
It plays a significant role in bacterial evolution.
What are the three domains of life?
- Bacteria
- Archaea
- Eukarya
This classification reflects the fundamental differences in cellular organization.
What is peptidoglycan?
A polymer that forms the cell wall of many bacteria
It provides structural support and protection.
What are the characteristics of gram stain?
Gram-positive: thick peptidoglycan layer; Gram-negative: thin peptidoglycan layer and outer membrane
This classification helps in identifying bacterial types.
What are fimbriae, sex pili, and capsules?
- Fimbriae: hair-like structures for adhesion
- Sex pili: structures for conjugation
- Capsule: protective layer around some bacteria
These features enhance bacterial survival and reproduction.
What are plasmids?
Small, circular DNA molecules found in bacteria
They can carry genes for antibiotic resistance.
What is transformation in bacteria?
The uptake of foreign DNA from the environment by a bacterial cell
It contributes to genetic diversity.
What is transduction?
The process by which bacteriophages transfer genetic material between bacteria
It is another mechanism of horizontal gene transfer.
What is conjugation in bacteria?
The direct transfer of DNA between two bacterial cells through a physical connection
It often involves the F factor.
What is a phototroph?
An organism that obtains energy from light
Examples include plants and some bacteria.
What is a chemotroph?
An organism that obtains energy from chemical compounds
Examples include many bacteria and archaea.
What is an autotroph?
An organism that can produce its own food from inorganic substances
Includes plants, algae, and some bacteria.
What is a heterotroph?
An organism that obtains food by consuming other organisms
Includes animals, fungi, and many bacteria.
What is symbiosis?
A close ecological relationship between two or more different species
Includes mutualism, commensalism, and parasitism.
What is mutualism?
A symbiotic relationship where both species benefit
Example: bees and flowering plants.
What is commensalism?
A symbiotic relationship where one species benefits and the other is neither helped nor harmed
Example: barnacles on whales.
What is parasitism?
A symbiotic relationship where one species benefits at the expense of another
Example: tapeworms in the intestines of animals.
What is a pathogen?
An organism that causes disease
Examples include bacteria, viruses, and fungi.
What is an exotoxin?
A toxic substance secreted by bacteria into their surroundings
It can cause damage to host cells.
What is an endotoxin?
A component of the outer membrane of Gram-negative bacteria that can trigger strong immune responses
It is released when bacteria die.
What is a mixotroph?
An organism that can use both photosynthesis and heterotrophy to obtain energy
Example: some protists and plants.
What is secondary endosymbiosis?
The process where a eukaryotic cell engulfs another eukaryotic cell that has already undergone primary endosymbiosis
This is how some algae acquired chloroplasts.
What are the four supergroups of protists?
- Excavata
- SAR
- Archaeplastida
- Unikonta
Each supergroup has distinct characteristics and examples.
What are alveolates?
A group of protists characterized by the presence of alveoli, small membrane-bound sacs beneath the plasma membrane
Includes ciliates, dinoflagellates, and apicomplexans.
What is an apical complex?
A specialized structure found in apicomplexans that helps them invade host cells
It is crucial for their parasitic lifestyle.
What are apicomplexans?
A group of parasitic protists, including Plasmodium, which causes malaria
They have complex life cycles involving multiple hosts.
What is biofilm?
A community of microorganisms that attach to surfaces and encase themselves in a protective matrix
Biofilms can form on natural and artificial surfaces.
What are brown algae?
A group of multicellular protists that are primarily marine and include species like kelp
They are important in marine ecosystems.
What is a cellular slime mold?
A type of protist that can exist as single cells but can aggregate to form multicellular structures when food is scarce
Example: Dictyostelium.
What are charophyte green algae?
A group of green algae closely related to land plants
They share derived characteristics with land plants.
What is chlorophyta?
A division of green algae that includes both unicellular and multicellular species
They are important photosynthetic organisms in aquatic environments.
What are ciliates?
A group of protists characterized by the presence of cilia used for movement and feeding
Example: Paramecium.
What is cladistics?
An approach to systematics that classifies organisms based on common ancestry
It emphasizes measurable characteristics.
What is a clade?
A group of species that includes an ancestral species and all its descendants
Clades can be nested within larger clades.
What is a crystalline rod?
A structure found in some protists that helps in light perception
It is associated with photosensitivity.
What are diatoms?
A group of unicellular algae with silica cell walls
They are important primary producers in aquatic ecosystems.
What are dinoflagellates?
A group of protists known for their two flagella and often responsible for harmful algal blooms
They can produce toxins, leading to red tides.
What is an endospore?
A thick-walled protective spore that can survive harsh conditions
Produced by some bacteria to ensure survival.
What is Entamoeba?
A genus of protozoan parasites that can cause dysentery in humans
Example: Entamoeba histolytica.
What are euglenids?
A group of protists that have both plant-like and animal-like characteristics
They can photosynthesize and also consume organic matter.
What are forams?
A group of protists with porous shells made of calcium carbonate
They are important in geological studies and as indicators of environmental change.
What are holdfasts?
Structures that anchor multicellular algae to substrates
They are essential for stability in aquatic environments.
What is a kinetoplast?
A large, organized mass of DNA found in the mitochondria of kinetoplastids
It is involved in cellular functions.
What are kinetoplastids?
A group of protists characterized by the presence of a kinetoplast
Example: Trypanosoma, the causative agent of sleeping sickness.
What are macronuclei?
Large nuclei found in ciliates that control non-reproductive cell functions
They are distinct from micronuclei.
What are micronuclei?
Small nuclei found in ciliates that are involved in reproduction
They play a role in genetic exchange.
What are mitosomes?
Reduced mitochondria found in some anaerobic eukaryotes
They are involved in iron-sulfur cluster assembly.
What are nucleomorphs?
Remnants of a nucleus from a eukaryotic algal endosymbiont found in some protists
They provide evidence for secondary endosymbiosis.
What are obligate aerobes?
Organisms that require oxygen for survival
They rely on aerobic respiration.
What are obligate anaerobes?
Organisms that cannot survive in the presence of oxygen
They rely on anaerobic respiration.
What is phycoerythrin?
A red pigment found in red algae that allows them to photosynthesize in deep water
It absorbs blue light.
What is a plasmodial slime mold?
A type of slime mold that consists of a single cell with multiple nuclei
It can move and grow as a giant cell.
What is Plasmodium?
A genus of parasitic protists that cause malaria in humans
It is transmitted by Anopheles mosquitoes.
What is plasmolysis?
The process in which cells lose water in a hypertonic solution, causing the cell membrane to pull away from the cell wall
It can lead to cell death.
What is a polytomy?
A branch point in a phylogenetic tree where more than two descendant groups emerge
It indicates uncertainty in evolutionary relationships.
What are pseudopodia?
Temporary, foot-like extensions of a cell used for movement and feeding
Common in amoebas and some protists.
What are radiolarians?
A group of protists with intricate silica skeletons
They are important in marine ecosystems and sediment formation.
What are red algae?
A group of marine algae that contain phycoerythrin, giving them a red color
They are important for coral reefs and have commercial uses.
What is a red tide?
A harmful algal bloom caused by dinoflagellates that can produce toxins
It can harm marine life and human health.
What is a stipe?
The stalk-like structure of a seaweed or mushroom
It supports the fronds or cap.
What are tests?
Shells or protective coverings of certain protists, such as foraminifera
They can provide insights into past environments.
What is thallus?
The vegetative body of a fungus or algae
It is not differentiated into roots, stems, or leaves.
What is Trichomonas?
A genus of parasitic protists known for causing sexually transmitted infections
Example: Trichomonas vaginalis.
What is Trypanosoma?
A genus of parasitic protists that cause diseases such as sleeping sickness
Transmitted by tsetse flies.
What are tubulinids?
A group of amoeboid protists characterized by their use of pseudopodia for movement
Example: Amoeba proteus.
What is sporopollenin?
A durable polymer that protects the spores and pollen of plants
It is resistant to decay and environmental stress.
What is lignin?
A complex organic polymer found in the cell walls of many plants
It provides structural support and rigidity.
What is a phragmoplast?
A structure that forms during cell division in plants, guiding the formation of the cell plate
It is crucial for cytokinesis.
What is alternation of generations?
The life cycle of plants involving both multicellular diploid (sporophyte) and multicellular haploid (gametophyte) stages
This cycle alternates between the two forms.
What are gametophyte and sporophyte?
- Gametophyte: the haploid stage producing gametes
- Sporophyte: the diploid stage producing spores
Both stages are crucial for plant reproduction.
What are embryophytes?
Land plants that develop from embryos
They include all groups of terrestrial plants.
What are archegonia and antheridia?
- Archegonia: female reproductive structures in plants
- Antheridia: male reproductive structures in plants
They produce gametes for fertilization.
What is an apical meristem?
A region of actively dividing cells at the tips of roots and shoots in plants
It is responsible for primary growth.
What are bryophytes?
Non-vascular plants, such as mosses, that reproduce via spores
They have a dominant gametophyte stage.
What are xylem and phloem?
- Xylem: vascular tissue that transports water and minerals
- Phloem: vascular tissue that transports sugars and nutrients
Both are essential for plant nutrition and growth.
What are seeds?
Structures that contain the embryo and provide nourishment for the developing plant
They are crucial for reproduction in seed plants.
What is endosperm?
A tissue in seeds that provides nourishment to the developing embryo
It results from double fertilization in angiosperms.
What is pollen?
The male gametophyte in seed plants, responsible for fertilization
It is carried by wind or animals to female structures.
What are the differences between gymnosperms and angiosperms?
- Gymnosperms: seed plants with exposed seeds (e.g., conifers)
- Angiosperms: seed plants with enclosed seeds (e.g., flowering plants)
Angiosperms are more diverse and dominate most terrestrial ecosystems.
What is flower anatomy?
The structure of flowers includes sepals, petals, stamens, and carpels
Each part has specific functions in reproduction.
What is an ovule?
The structure in seed plants that develops into a seed after fertilization
It contains the female gamete.
What are fruits?
Mature ovaries that contain seeds and aid in their dispersal
Fruits can be fleshy or dry.
What does the fossil record show?
Macro-evolutionary changes over large time scales
It provides evidence for the history of life on Earth.
What is the significance of mass extinctions?
They have long-term impacts on biodiversity and ecosystem structure
Mass extinctions create opportunities for adaptive radiations.
What are the stages of abiotic synthesis of small organic molecules?
- Abiotic synthesis of small organic molecules
- Joining of these into macromolecules
- Packaging of molecules into protocells
- Maintaining internal chemicals different from surroundings
These stages are theorized to lead to the origin of life.
What energy sources may have contributed to early organic compound synthesis?
- Lightning
- UV radiation
- Deep sea hydrothermal vents
- Alkaline vents
- Carbonaceous meteorites
These sources could have facilitated the formation of life.
What is the significance of the Miller-Urey experiment?
It demonstrated the abiotic synthesis of organic molecules under conditions thought to resemble early Earth
The experiment produced amino acids, supporting the hypothesis of life’s origin.
What is the geologic record divided into?
- Archaean Eon
- Proterozoic Eon
- Phanerozoic Eon
Each eon represents significant milestones in Earth’s history.
What is the oxygen revolution?
The period when oxygen produced by photosynthetic prokaryotes began to accumulate in Earth’s atmosphere
This led to significant changes in Earth’s environment and life forms.
What is the Endosymbiotic Theory?
The theory that mitochondria and plastids originated from free-living prokaryotes that were engulfed by ancestral eukaryotic cells
It explains the evolution of complex cells.
What is the Cambrian period known for?
The sudden appearance of fossils resembling modern phyla and the first evidence of predator-prey interactions
It marks a pivotal point in the history of life.
What role did tectonic events play in mass extinctions?
They altered habitats, driving some species to extinction while providing new opportunities for others
Plate tectonics can reshape ecosystems dramatically.
What is the K-T boundary event?
The mass extinction event between the Cretaceous and Tertiary periods, believed to be caused by a meteor impact
It led to the extinction of the dinosaurs.
What is phylogenetic nomenclature?
A formal set of rules governing the naming of clades, including the common ancestor and all descendants
It is distinct from traditional rank-based nomenclature.
What does Maximum Likelihood assume?
Given certain rules about how DNA changes over time, it finds the tree that reflects the most likely sequence of evolutionary events
It is used in constructing phylogenetic trees.
What is the significance of age in building a phylogenetic tree?
It refers to the age of individuals within the group that you’re comparing.
What are the two methods that can narrow down the best tree in a large data set?
Maximum Parsimony & Maximum Likelihood.
What does Maximum Parsimony assume?
The tree that requires the fewest evolutionary events is the most likely.
What are evolutionary events defined as?
Appearances of shared derived characters.
What does Maximum Likelihood reflect?
The most likely sequence of evolutionary events based on certain rules about how DNA changes over time.
What classification system did early taxonomists develop?
They classified all species as plants or animals, then into kingdoms, and then developed the 3 domain system.
What are the three domains of life?
Bacteria, Archaea, Eukarya.
What is horizontal gene transfer?
Movement of genes from one genome to another.
What is a genome?
A complete set of DNA in an organism, including all of its genes.
How do prokaryotes differ from eukaryotes?
Most prokaryotes are unicellular or colonial and much smaller than eukaryotic cells.
What is the size range of prokaryotic cells?
.5-5μm.
What is the size range of eukaryotic cells?
10-100μm.
What is a microbiome?
Any number of existing organisms that exist within that environment.
What is the function of the prokaryotic cell wall?
Maintains cell shape, protects the cell, and prevents bursting in hypotonic environments.
What is peptidoglycan?
A network of sugar polymers cross-linked by polypeptides found in bacterial cell walls.
What are eukaryotic cell walls made of?
Cellulose or chitin.
What do Archaea lack in their cell walls?
Peptidoglycan.
What is the purpose of a gram stain?
To classify species into gram-positive and gram-negative groups based on cell wall composition.
What characterizes Gram-negative bacteria?
Less peptidoglycan and an outer membrane that can be toxic; more likely to be antibiotic resistant.
What is a capsule in prokaryotes?
A polysaccharide/protein layer that covers many prokaryotes.
What are endospores?
Structures found in some species to endure harsh conditions, can be dormant for centuries.
What are fimbriae?
Short protein appendages that extend from the bacterial cell surface, allowing adherence to surfaces.
What is taxis in prokaryotes?
The ability to move toward or away from certain stimuli.
What are the two types of taxis?
Chemotaxis and phototaxis.
How do most motile bacteria move?
Using flagella that are structurally and functionally different from eukaryotic flagella.
What does prokaryotic genome typically consist of?
A circular chromosome located in the nucleoid region.
What are plasmids?
Smaller rings of DNA found in some prokaryotic species.
What contributes to genetic variability in prokaryotes?
Rapid reproduction, mutation, and genetic recombination.
What is the typical reproduction method of prokaryotes?
Binary fission.
What is transformation in prokaryotes?
The process where a cell takes up and incorporates foreign DNA from the environment.
What is transduction?
Movement of genes between bacteria by bacteriophages.
What is conjugation?
A process where genetic material is transferred between bacterial cells, usually one-way.
What is the F factor?
A circular plasmid required for the production of sex pili.
What are R plasmids?
Plasmids that carry genes for antibiotic resistance.
What are the two categories of prokaryotic nutrition?
Energy and carbon sources.
What is a prototroph?
An organism that obtains energy from light.
What is a chemoautotroph?
An organism that obtains energy from inorganic chemicals and carbon from CO2.
What is nitrogen fixation?
The conversion of atmospheric nitrogen to ammonia.
What is cooperation in prokaryotes?
Allows them to use environmental resources they couldn’t use as individuals.
What is a biofilm?
Surface-coating colonies of multiple prokaryotic species.
What role do prokaryotes play in recycling chemical elements?
Chemoheterotrophic prokaryotes function as decomposers.
What is symbiosis?
An ecological relationship between organisms.
What is mutualism?
A type of symbiosis where both organisms benefit.
What is commensalism?
A type of symbiosis where one organism benefits while the other is neither helped nor harmed significantly.
What is parasitism?
A type of symbiosis where one organism harms but does not kill its host.
What are pathogens?
Parasites that cause diseases.
What are exotoxins?
Toxins released by living cells, causing disease even if the producing prokaryotes are not present.
What are endotoxins?
Toxins released only when bacteria die and their cell walls break down.
What is bioremediation?
The use of organisms to remove pollutants from the environment.
What is a protist?
An informal name for a group of mostly unicellular eukaryotes.
Why are protists not classified as a valid kingdom?
They are not monophyletic but paraphyletic.
What are photoautotrophs?
Protists that contain chloroplasts and obtain energy from light.
What is the endosymbiotic theory?
Mitochondria evolved by endosymbiosis of an aerobic prokaryote.
What are the four supergroups of eukaryotes?
Excavate, SAR, Archaeplastida, Unikonta.
What characterizes the Excavata supergroup?
Members have a ventral feeding groove and flagella.
What are diplomonads?
Protists with reduced mitochondria, anaerobic metabolism, and often two equal-sized nuclei.
What are parabasalids?
Protists with reduced mitochondria that generate energy anaerobically.
What defines the Euglenozoa clade?
Diversity including predatory heterotrophs, photosynthetic autotrophs, and pathogenic parasites.
What are kinetoplastids?
Euglenozoa with a single mitochondrion containing a kinetoplast.
What is the significance of stramenopiles?
Includes several groups of heterotrophs and certain algae with hairy flagella.
What are diatoms?
Unicellular algae with a unique two-part, glass-like wall of hydrated silica.
What are brown algae?
The largest and most complex algae, all multicellular, commonly called ‘seaweeds’.
What are alveolates?
Protists characterized by membrane-bound sacs (alveoli) under their plasma membrane.
What are dinoflagellates?
Aquatic mixotrophs/heterotrophs important for marine and freshwater phytoplankton.
What are apicomplexans?
Parasites of animals, some causing serious human diseases.
What are ciliates?
A large, varied group of protists named for their use of cilia to move/feed.
What defines the Rhizarians group?
Defined by DNA similarities, includes forams and radiolarians.
What are radiolarians?
Protists with intricate tests usually made of silica.
What are foraminiferans (forams)?
Named for porous, multi-chambered shells made of CaCO3.
What is Archaeplastida?
A monophyletic group that includes red & green algae, as well as land plants.
What gives red algae its reddish color?
Accessory pigment called phycoerythrin.
What are chlorophytes?
A group of green algae that are large and complex, most live in freshwater.
What are charophyceans?
Multicellular freshwater organisms that are the closest relatives of land plants.
What is alternation of generations in plants?
A reproductive cycle where plants alternate between two multicellular stages.
What is a gametophyte?
The haploid stage in plants that produces haploid gametes by mitosis.
What is a sporophyte?
The diploid stage in plants that produces haploid spores by meiosis.
What is the role of placental transfer cells in plants?
They transfer nutrients from parent to embryo.
What type of sporophyte do plants give rise to?
Diploid sporophyte
What process produces haploid spores in plants?
Meiosis
What occurs after fertilization in relation to ploidy level?
Doubling the ploidy level
What is the cellular process that reduces ploidy level by half?
Meiosis
What type of spores do plants produce?
Haploid spores
What are multicellular, dependent embryos retained within?
Tissue of female gametophyte
What type of cells transfer nutrients from parent to embryo?
Placental Transfer Cells
What term refers to plants that have a dependency of the embryo on the parent?
Embryophytes
What are walled spores produced in?
Sporangia
What are diploid cells that undergo meiosis to generate haploid spores called?
Sporocytes
What polymer makes cells resistant to harsh environments?
Sporopollenin
What are organs in which gametes are produced called?
Gametangia
What are the female gametangia that produce nonmotile eggs called?
Archegonia
What are the male gametangia that are the site of sperm production called?
Antheridia
Where are apical meristems located?
At shoots and roots
What is the function of stomata in plants?
Allows exchange of gases with the environment
What type of association may have helped early land plants obtain nutrients?
Symbiotic Association between fungi & first land plants
What type of plants have life cycles dominated by gametophytes?
Bryophytes
What is the name of the teeth-like structure that surrounds the opening of a sporangium?
Perisome
What type of vascular plants include ferns?
Seedless vascular plants
What are the two main types of vascular tissue?
Xylem and phloem
What does xylem conduct?
Water and minerals
What does phloem distribute?
Sugars, amino acids, and other organic products
What are the two types of leaves based on vascular structure?
- Microphylls
- Megaphylls
What are clusters of sporangia on the undersides of sporophylls called?
Sori
What is the difference between homosporous and heterosporous plants?
- Homosporous: single type of spore
- Heterosporous: produces megaspores and microspores
What does a seed consist of?
- An embryo
- Nutrients
- Protective coat
What is the purpose of pollen in seeded vascular plants?
Protect male gametophytes and facilitate transport
What two structures develop from fertilized ovules?
- Seeds
- Endosperm
What are the four phyla of gymnosperms?
- Cycadophyta
- Ginkgophyta
- Gnetophyta
- Coniferophyta
What type of angiosperms have one cotyledon?
Monocots
What is double fertilization?
Occurs when the pollen tube discharges two sperm into the female gametophyte
What is the name of the tissue in seeds that provides nourishment to the embryo?
Endosperm
What are the two groups of angiosperms?
- Monocots
- Eudicots
What type of root system do monocots usually have?
Fibrous root system
What is the typical floral organ arrangement in eudicots?
Multiples of four or five
