Midterm 2 Flashcards
What is the Geologic Time Scale (GTS) and how is it structured?
The GTS organizes significant events in Earths history into hierarchal units: eons, eras, periods, epochs, and ages. It allows scientists to study Earths history at varying levels of detail
what is unique about the Hadeon Eon?
the hadeon eon, the earliest eon (~4.6-4.0 bya), contains no fossils and was characterized by extreme conditions like volcanic activity and cosmic bombardements.
what characterizes the paleozoic era?
the paleozoic era (~5401-252 mya) began with the cambrian explosion, marked by the diversification of visible life, and ended with the permian mass extinction.
what is the fossil record, and why is it incomplete?
the fossil record provides evidence of evolutionary history but is incomplete because fossilization requires specific conditions (e.g., burial in sediment) and primarily preserves hard parts of organisms.
what is the difference between relative dating and absolute dating of fossils?
relative dating orders fossils based on their position in rock layers (stratigraphy), while absolute dating uses radioactive isotope decay rates to determine a fossils exact age.
what caused the permian mass extinction?
the permian mass extinction (~252 mya) was likely caused by massive volcanic eruptions in Siberia, leading to global warming and ocean acidification, wiping out ~90% of marine and ~70 of terrestrial species.
what caused the Cretaceous mass extinction?
the Cretaceous mass extinction (~66 mya) was primarily caused by an asteroid impact in Chicxulub, Mexico, leading to the extinction of non-avian dinosaurs and ~50% of marine species.
what is adaptive radiation, and what triggers it?
adaptive radiation is the rapid evolution of diverse species from a common ancestor, often triggered by mass extinctions, novel traits, or colonization of new environments (e.g., mammals after dinosaur extinction).
what did the Miller-Urey experiment deomstrate?
The Miller-Urey experiment demonstrated that organic molecules (e.g., amino acids) could form inorganic precursors under conditions simulating early earth.
What was the Great Oxygenation Event? (GOE)
the GOE (~2.7 bya) was a significant increase in atmospheric oxygen due to photosynthetic cyanobacteria, leading to the extinction of many anaerobic prokaryotes.
what are the key difference between prokaryotes and eukaryotes?
Prokaryotes lack a nucleus and membrane-bound organelles, while Eukaryotes have both. Prokaryotes include bacteria and archaea, while Eukaryotes include protists, plants, fungi, and animals.
How do Prokaryotes reproduce, and how do they achieve genetic diversity?
Prokaryotes reproduce asexually through binary fission. Genetic diversity arises from mutations and genetic recombination via transformation, transduction, and conjugation.
where are archaea commonly found, and what are extremophiles?
archaea often inhabit extreme environments (e.g., hot springs, acidic lakes). Extremophiles are archaea that thrive in extreme conditions like high salinity, low pH, or high temperatures.
what is the endosymbiotic theory, and what evidence supports it?
the endosymbiotic theory posits that mitochondria and chloroplast evolved from engulfed prokaryotic cells. Evidence includes their own DNA, binary fission, and structural similarities to bacteria.
what are protists, and how are they classified?
protists are mostly unicellular eukaryotes that don’t fit into plant, animal, or fungi kingdoms. They are classified into four supergroups: Excavata, SAR, Archaeplastida, and Unikonta.
what key adaptations allowed plants to colonize land?
key adaptations include sporopollenin (protects spores), cuticle (prevents water loss), stomata (regulates gas exchange), and vascular tissue (transports water and nutrients).
what is alernation of generations in plants?
alternation of generations is a life cycle with both haploid (gametophyte) and diploid (sporophyte) stages. in nonvascular plants, the gametophyte is dominant; in vascular plants, the sporophyte is dominant.
what are brophytes, and what are their characteristics?
brophytes (e.g., mosses, liverworts) are nonvascular plants lacking true vascular tissue. They have a dominant gametophyte generation and require water for fertilization.
what are seedless vascular plants, and how do they reproduce?
seedless vascular plants (e.g., ferns, horsetails) have vascular tissue but reproduce via spores. They require water for fertilization due to flagellated sperm.
what distinguishes gymnosperms from angiosperms?
gymnosperms have “naked seeds” not enclosed in fruit, while angiosperms are flowering plants with seeds enclosed in fruits.
what are the structural features of fungi?
fungi have hyphae that from a mycelium, chitinous cell walls, and reproduce via spores. They are absorptive heterotrophs, secreting enzymes to break down organic matter.
how do fungi reproduce sexually and asexually?
fungi reproduce asexually via fragmentation, budding, or spores, and sexually through hyphal fusion, plasmogamy, karygamy, and meiosis.
what is the RNA world hypothesis?
the RNA world hypothesis suggests that RNA was the first self-replicating molecule, capable of both storing genetic information and catalyzing reactions.
what are the causes and effects of mass extinctions?
mass extinctions are caused by events like climate change, volcanic activity, and asteroid impacts. Effects include biodiversity loss, ecological changes, and adaptive radiation of surviving species.
what are the four main nutritional modes of prokaryotes?
prokaryotes can be photoautotrophs, chemoautotrophs, photoheterotrophs, or chemoheterotrophs, depending on their energy and carbon sources.
what are the major fungal phyla?
major fungal phyla inclde Ascomycota (sac fungi), Basidiomycota (club fungi), Chrytridiomycota (flagellated spores), and Glomeromycota (mycorrhizal fungi).
how do seed plants disperse their seeds?
seed plants disperse seeds via wind (lightweight fruits) or animals (fleshy fruits).
how do prokaryotes achieve genetic variation?
prokaryotes achieve genetic variation through mutations, transformation (DNA uptake), transduction (DNA transfer via viruses), and conjugation (DNA transfer via pili).
what ecological roles do prokaryotes play?
prokaryotes play roles in decomposition, nutrient cycling, nitrogen fixation, and bioremediation. they also form symbiotic relationships (mutualism, commensalism, parasitism).
what are Dikarya Fungi?
dikarya fungi include Ascomycetes and Masidiomycetes, characterized by seperate hyphae and dikaryotic hyphae after plasmogamy.
what is the function of vascular tissue in plants?
vascular tissue (xylem and phloem) transports water, minerals, and sugars, enabling plants to grow taller and compete for sunlight.
what are the four supergroups of eukaryotes?
the four supergroups are Excavata, SAR, Archaeplastida, and Unikonta.
what is the haploid-dominant life cycle in fungi?
in the haploid-dominant life cycle, most of a fungus’s life is spent as a haploid mycelium. Sexual reproduction involves plasmogamy, karyogamy, and meiosis.
what is sporopollenin, and why is it important?
sporopollenin is a durable polymer that protects spores and pollen from desiccation and UV radiation, crucial for terrestrial life.
what is the difference between gram-positive and gram-negative bacteria?
gram-positive bacteria have a thick peptidoglycan layer, while gram-negative bacteria have a thin peptidoglycan layer and an outer membrane.
how do fungi use spores for reproduction and dispersal?
fungi produce vast numbers of spores that are resistant to drying and can be dispersed by wind, water, or animals, acting as the dispersal stage.
what are apical meristems, and what is their function?
apical meristems are regions of cell division at the tips of roots and shoots, enabling continuous growth and differentiation into various tissues.
what is the function of capsules in prokaryotes?
capsules are sticky outer layers that help prokaryotes attach to surfaces, protect against drying, and evade the host immune system.
what is an example of mutualism involving fungi?
mycorrhizae are mutualistic associations between fungi and plant roots, where fungi help plants absorb nutrients, and plants provide fungi with carbohydrates.
what is the function of the cuticle in plants?
the cuticle is a waxy layer that prevents water loss and protects against microbial threats in terrestrial environments.
what are endospores, and why are they important?
endospores are tough, dormant structures that allow bacteria to survive harsh conditions, such as extreme heat or lack of nutrients.
what is the function of fungal hyphae?
fungal hyphae form a mycelium, maximizing surface area for enzyme secretion and nutrient absorption.
what is the function of stomata in plants?
stomata are pores that regulate gas exchange (CO2 intake and O2 release) while minimizing water loss.
what is the function of flagella in prokaryotes?
flagella are whip-like appendages used for movement, enabling prokaryotes to move toward or away from stimuli (taxis)
how to fungi produce spores during sexual reproduction?
during sexual reproduction, fungi produce spores within multicellular fruiting bodies, which are specialized organs for spore production and dispersal.
when did vascular tissue evolve in plants?
vascular tissue evolved ~425 mya in seedless vascular plants, enabling them to grow taller and compete for sunlight.
what are the four main metabolic modes of prokaryotes?
prokaryotes can be photoautotrophs, chemoautotrophs, photoheterotrophs, or chemoheterotrophs, depending on their energy and carbon sources.
what are fungal walls made of?
fungal walls are made of chitin, a strong and flexible polysaccharide.
in which plants is the sporophyte generation dominant?
in vascular plants, the sporophyte generation is dominant, while in nonvascular plants (brophytes), the gametophyte is dominant.
what are the three methods of genetic recombination in prokaryotes?
the three methods are transformation (DNA uptake from the environment), transduction (DNA transfer via viruses), and conjugation (DNA transfer via pili)
what are the methods of asexual reproduction in fungi?
fungi can reproduce asexually through fragmentation, budding, or the production of asexual spores.
where are spores produced in plants?
spores are produced by the sporophyte within structures called sporangia, protected by sporopollenin.
what is nitrogen fixation, and why is it important?
nitrogen fixation is the process by which prokaryotes convert atmospheric nitrogen into a usable form (ammonia), essential for plant growth and ecosystem health.
what ecological roles do fungi play?
fungi act as decomposers, mutualists (e.g., mycorrhizae), and pathogens, playing critical roles in nutrient cycling and ecosystem balance
what is double fertilization in angiosperms?
double fertilization involves one sperm fertilizing the egg to form a zygote, and the other sperm joining with polar nuclei to form the endosperm, a food source for the developing plant.
why are archaea resistant to some antibiotics?
archaea lack peptidoglycan in their cell walls, making them resistant to antibiotics that target bacterial cell walls.
how do fungi communicate during sexual reproduction?
fungi use sexual signalling molecules (pheromones) to communicate their mating type during sexual reproduction.
when did plants first colonize land?
plants first colonized land at least 470 mya, evolving from freshwater green algae (charophytes).
what are plasmids, and what is their function?
plasmids are small, circular DNA molecules in prokaryotes that carry extra genes, enhancing genetic diversity and adaptability.
what are fruiting bodies in fungi?
fruiting bodies are specialized structures that produce and disperse spores during sexual reproduction in fungi
why is sporopollenin important for terrestrial plants?
sporopollenin protects spores and pollen from desiccation and UV radiation, enabling plants to survive and reproduce on land.
what does gram staining differentiate in bacteria?
gram staining differentiates bacteria based on cell wall thickness: gram-positive bacteria have thick peptidoglycan layers, while gram-negative bacteria have thin layers and an outer membrane.
what is plasmogamy in fungi?
plasmogamy is the fusion of cytoplasm from two parental mycelia during sexual reproduction, leading to the formation of a heterokaryon or dikaryotic mycelium.
what is the function of xylem and phloem in plants?
xylem transports water and minerals, while phloem distribute organic compounds like sugars throughout the plant.
why do some bacteria form endospores?
endospores form in response to harsh conditions, allowing bacteria to survive extreme heat, desiccation, or lack of nutrients.
how are fungal spores dispersed?
fungal spores are dispersed by wind, water, or animals, allowing fungi to colonize new environments.
how do stomata regulate water loss in plants?
stomata open to allow gas exchange (CO2 in, O2 out) and close to minimize water loss, regulated by guard cells.
what is the role of mycorrhizae in plant-fungal relationships?
mycorrhizae are mutualistic associations where fungi help plants absorb nutrients (e.g., phosphorus), and plants provide fungi with carbohydrates.
what is the sporophyte generation in plants?
the sporophyte is the diploid (2n) generation that produces spores through meiosis, dominant in vascular plants.
what is transformation in prokaryotes?
transformation is the uptake of DNA from the environment by a prokaryote, leading to genetic recombination.
why are fungal spores resistant to drying?
fungal spores have tough outer layers that protect them from desiccation, allowing them to survive in harsh conditions.
what is the gametophyte generation in plants?
the gametophyte is the haploid (1n) generation that produces gametes through mitosis, dominant in nonvascular plants.
