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Life 121 unit 2
| Question | Answer |
|---|---|
| What is the hypothesized order or events for the origin of a living cell? | 1. abiotic synthesis 2. small molecules join to create macromolecule polymers 3. protocells package molecules within a membrane 4. self-replicating molecules made inheritance possible |
| What evidence supports abiotic synthesis | reactions in early earth atmosphere discovered through lab experiments, and origins of space discovered in organic molecules in meteorites |
| What evidence supports small molecules joined to create molecule polymers? | lab-based synthesis of RNA nucleotides into nucleic acids and hydrothermal vents playing a role in environmental reactions |
| What evidence supports protocells packaging molecules into membranes? | lipids form vesicles in water due to being in volcanic clay particles, vesicles grow and divide spontaneously, and vesicles take in macromolecules |
| What evidence supports self-replicating molecules making inheritance possible? | lab experiments have shown that natural selection leads to improvements in RNA (first hypothesized genetic molecule) replication abilities |
| What is the evolutionary relationship among the three domains of life? | bacteria, archaea, and eukaryotes all originated from RNA |
| prokaryotes vs eukaryotes | prokaryotes- circular chromosomes, smaller, cell wall, eukaryotes- nucleus, linear chromosomes, larger, Golgi, rough and smooth ER, mitochondria |
| Are prokaryotes monophyletic, why or why not? | no, they are a non-monophyletic group |
| What are the important prokaryotic cell structures? | cell wall, plasma membrane, nucleoid, ribosomes, and cytoplasm |
| What are the important eukaryotic cell structures? | nucleus, ribosomes, cytoskeleton, rough ER, smooth ER, Golgi apparatus, lysosomes, vesicles, |
| What traits would our last universal common ancestor have? | DNA, ribosomes, plasma membrane |
| How would natural selection act in early earth? | natural selection could start acting on a population of protocells that have absorbed self-replicating RNA |
| According to the tree showing the 3 domains of life, which of the following are true? | we are more closely related to a species of Archaea than that Archaea species is to a species of Bacteria |
| How is prokaryotic fitness increased by the morphological adaptations to their functions? | adaptations for protection- cell wall, capsule, endospore adhesion movement- fimbriae, flagella metabolism- infoldings membranes reproduction- sex pili |
| How do prokaryotes reporduce? | binary fission--daughter cells are identical to parents; no reshuffling, only mutations can cause changes in offspring |
| How do eukaryotes reproduce? | sperm and egg fuse to form a zygote which allows for genetic recombination |
| Horizontal gene transfer | movement of genes from one species to another, contributes to genetic diversity in prokaryotes, happens before reproduction |
| What are the three mechanisms of HGT? | transformation, transduction, conjugation |
| transformation | prokaryote cells uptake free-floating DNA fragments or plasmids from the environment |
| transduction | phage virus transmits DNA between different prokaryote cells |
| conjugation | plasmids transferred directly from one prokaryote cell to another prokaryote cell |
| photoautotroph | use light energy and inorganic carbon to make organic food |
| chemoheterotroph | get energy and carbon by consuming organic foods |
| obligate | can only do metabolism in a certain way |
| facultative | can switch up metabolism depending on the environment condition |
| aerobic respiration | process by which cells break down glucose using oxygen to produce ATP, releasing CO2 and H2O as byproducts |
| anaerobic respiration | process by which cells break down glucose without using oxygen by using an alternative final electron acceptor or fermantaiton |
| nitrogen fixation | some bacteria can fix atmospheric nitrogen into ammonia |
| chemoautotroph | organisms that get its energy from inorganic chemicals and its carbon from CO2 |
| photoheterotroph | organisms that use light for energy but must obtain its carbon from organic molecules |
| adaptive radiation | rapid diversification of a lineage into many new species |
| What role do prokaryotes play in the ecosystem? | unique metabolic capabilities of some prokaryotes to facilitate evolution of other species that can rely on metabolic byproducts |
| How might horizontal gene transfer have facilitated prokaryotic adaptive radiation of metabolic diversity? | through transformation, transduction, and conjugation |
| What are some beneficial ecological impact of prokaryotes? | nutrient cycling, bioremediation, nitrogen fixation, producing oxygen via photosynthesis, producers for ecosystems that would otherwise be inhabitable, and live in gut to metabolize food that host cannot |
| cynobacteria | photosynthetic prokaryotes that use sunlight to make food and produce oxygen as a byproduct |
| How did evolution of cyanobacteria impact the ability of other organisms to evolve? | they released oxygen into atmosphere, the oxygen allowed for the evolution of eukaryotes, the cyanobacteria was then engulfed by eukaryotes and become chloroplasts which allowed for complex multicellular organisms to exist |
| How do prokaryotes impact humans? | they supply beneficial and harmful (pathogenic) bacteria |
| What percent of the cells in your body are bacteria? | 90% |
| What percent of your body weight is bacteria? | 10% |
| What do bacteria and other microbes in your gut create? | the microbiome |
| What are some beneficial aspects of bacteria in the body? | digestion of food, producing essential vitamins, protecting against pathogens, supporting immune systems, and regulating metabolism |
| Describe the evidence that multicellularity evolved independently multiple times | every major line of evidence shows that today's multicellular groups do not share a single multicellular ancestor, and each lineage invented key features of multicellularity on its own |
| unicellular colonial organisms | individual single-celled organisms that live together, but each cell still functions as an independent organism |
| multicellular organisms | organism made of many cells that work together as an integrated system |
| How did organelles evolve in the first eukaryotes? | through endosymbiosis |
| endosymbiosis | process in which one cell engulfs another cell, and instead of digesting it, the two cells form a long-term mutually beneficial relationship--the engulfed cell becomes an organelle |
| primary endosymbiosis | heterotrophic eukaryotes engulf cyanobacteria leading to evolution of chloroplast in agal ancestor |
| secondary endosymbiosis | some algal ancestors were engulfed by another eukaryotic organism leading to evolution of chloroplasts in other lineages |
| multicellularity hypothesis through generating new genes | hypothesis that multicellular organisms evolved when their ancestors acquired new genetic material |
| multicellularity hypothesis through co-opting existing genes | hypothesis that early organisms did not need to invest new genes, but rather repurposed genes they already had |
| What are some required aspects of being multicellular? | sticking together, communicating, and having differentiation of cell types that each have different functions |
| According to evidence, is generating new genes or co-opting genes the correct hypothesis? | evidence shows that both mechanisms occurred, but co-opting dominates the earliest steps when new gene evolution occurs later |
| What adaptive advantage is provided by multicellularity? | division of labor, increased size, improved internal regulation, damage tolerance, and greater complexity |
| What adaptive advantages are provided by tissue structure? | coordinated function, improved strength and support, faster communication, foundation for organs |
| What adaptive advantage is provided by digestion? | can eat food larger than its cells |
| What adaptive advantage is provided by nervous structures? | fast response to stimuli, coordinated movements, learning and memory |
| What adaptive advantage is provided by symmetry? | radial- sense stimuli from all directions bilateral- promotes directional movement, improves coordination |
| Cambrian explosion | apparent "explosion" of many new Bilaterian species evolving rapidly |
| How was the Cambrian explosion adaptive radiation? | because it was a rapid divergence of new species |
| What hypotheses explain the adaptive radiation of Bilaterians during the Cambrian explosion? | 1. predator-prey coevolution 2. increased oxygen levels 3. changes in genes that affect body plan |
| Why is it incorrect to say that some animal lineages are less evolved or less evolutionarily successful than others? | all living species are equally evolved, evolution is not goal-directed, and lineages are adapted and not ranked |
| predator-prey evolution | process of reciprocal evolutionary change that occurs b/w groups due to ecological interactions with each other |
| increased oxygen levels | oxygen levels steadily rose which allowed for larger body sizes which increased metabolism |
| changes in genes that affect body plan | genetic changes allowed for evolution of new body forms |
| What are the shared ancestral traits of land plants? | multicellularity, plasma membrane, ribosomes, DNA, nucleus, mitochondria, cell walls with cellulose, chloroplasts, flagellated sperm, and sporopollenin |
| What are the shared derived traits of land plants? | apical meristem, alternation of generations, dependent protected embryo, walled spores, waxy cuticle and stomata |
| apical meristem | allows top end of plant to grow upward and roots to grow downward |
| Describe and differentiate between the stages and ploidy changes within the alternation of generations plant life cycle | plants alternate b/w sporophytes and gametophytes producing generations |
| xylem | transport water and minerals over long distances and provides stuctural support |
| phloem | transports sugars over long distances and provides structural support |
| How did adaptations of vascular plants impact their ability to thrive on land and dominate terrestrial ecosystems? | adaptations allowed vascular plants to move water, support themselves, grow tall, colonize dry habitats, and outcompete earlier lineages |
| sporophyte generation (diploid) | zygote divides by mitosis to form sporophyte (2n) then specialized cells undergo meiosis to produce haploid spores (n) |
| gametophyte generation (haploid) | gametophyte produces gametes (n) by mitosis then gametes fuse during fertilization to form a zygote (2n) |
| What adaptations for dispersal made seedless plants successful? | spores are the primary mechanism for dispersal b/w they limit competition and maintain genetic diversity |
| What are adaptations within the bryophytes that helped them be successful? | water retention, reproduction on land, and protection from desiccation |
| sporophyte | most everything you can see on a gymnosperm is the sporophyte |
| gametophyte | female: inside cone, microscopic male: pollen |
| What are the advantages of pollen? | the sperm doesn't need water to travel can be carried by the wind |
| What are the advantages of seeds? | allows for widespread dispersal |
| Describe the four key shared derived traits of Chordates | dorsal hollow nerve cord, notochord, pharyngeal slits, and a muscular tail |
| Describe the order of adaptions that occurs across Chordates, Vertebrates, and Tetrapod's that allowed for colonization of land | vertebral column, jaws, mineralized skeleton, bony skeleton, lungs, lobed fins, limps with digits |
| amniotic egg | includes amniotic fluid protecting the embryo, a shell, and yolk sac |
| What are the shared derived traits that makes humans, human? | ability to communicate through speech and teaching through a specific language |
| communication vs language | many animals communicate but humans have a unique combination of brain structures that allow for complex language and speech |
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