Questions and Answers
What is the difference between gradualism and punctuated equilibrium?
Gradualism states that evolution occurred slowly over a long period of time, while punctuated equilibrium occurs when there are periods of apparent stasis interrupted by sudden change.
The prezygotic barriers that would prevent reproductive success between 2 organisms include habitat, temporal, behavioral, mechanical, and ___ barriers.
gametic
What are the prezygotic barriers that would prevent reproductive success between 2 organisms?
Habitat barriers, temporal barriers, behavioral barriers, mechanical barriers, and gametic barriers.
What are the postzygotic barriers that distinguish between different species?
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What is sympatry and how might it occur?
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What is allopatry?
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What is the hierarchy of classification?
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What is the hierarchy of classification for humans?
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What is a homologous structure?
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What is an analogous structure?
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What is the concept of parsimony?
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What is the difference between mono-, para-, and polyphyletic?
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What were some of the constraints organisms had to face when moving onto land?
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What adaptations evolved to address constraints when moving onto land?
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What were the main advantages for plants becoming terrestrial?
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What are two main differences in the lifecycles of mosses and ferns?
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What advantages do seed plants have?
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What is the advantage of having seeds as a means for reproduction?
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What is the endosperm?
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What two main principles guide the development of plants?
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What roles does auxin play in a plant?
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What role do cytokinins play in a plant?
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What role does gibberellin play in a plant?
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What role does abscisic acid play in a plant?
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What role does ethylene play in a plant?
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What is tropism?
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What is the difference between the apoplastic and symplastic routes?
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What is the name of the barrier blocking the apoplastic route?
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Study Notes
Evolutionary Concepts
- Gradualism involves slow evolutionary changes over long periods while punctuated equilibrium indicates long periods of stasis interrupted by sudden changes.
Reproductive Barriers
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Prezygotic barriers include:
- Habitat: Different living environments prevent mating.
- Temporal: Mating occurs at different times.
- Behavioral: Distinct courtship behaviors hinder mating.
- Mechanical: Structural differences in genitalia prevent reproduction.
- Gametic: Sperm fails to survive in the female reproductive system.
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Postzygotic barriers distinguish different species by:
- Reduced Hybrid Viability: Hybrids fail to survive development.
- Reduced Hybrid Fertility: Hybrids are sterile.
- Hybrid Breakdown: Offspring of hybrids are sterile.
Sympatry and Allopatry
- Sympatry refers to species evolution without physical barriers, often through mechanisms like sexual selection and polyploidy.
- Allopatry involves species evolution due to geographical barriers.
Classification Hierarchy
- The classification hierarchy is arranged as: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.
- For humans, the hierarchy is Eukarya, Animalia, Chordata, Mammalia, Primates, Hominidae, Homo, Sapiens.
Structural Comparisons
- Homologous structures are similar due to shared ancestry, while analogous structures share function due to convergent evolution.
Parsimony in Evolution
- Parsimony refers to the simplest explanation being the most likely for the evolution of species, commonly used in constructing cladograms.
Phylogenetic Terms
- Monophyletic: Contains an ancestor and all its descendants.
- Paraphyletic: Includes an ancestor and some of its descendants.
- Polyphyletic: Group containing organisms from multiple clades.
Organisms on Land
- Constraints faced by land organisms included surface area to volume ratio, gravity, aridity, nutrient uptake, and salinity.
- Adaptations that evolved included transport systems for nutrients, structural support, water conservation strategies, nutrient exchange systems, and filtering systems for salinity.
Advantages of Terrestrial Life for Plants
- Advantages included access to unfiltered sunlight, nutrient-rich soils, abundant atmospheric CO₂, and initially fewer herbivores/pathogens.
Lifecycles of Mosses vs. Ferns
- In mosses, the gametophyte is dominant and dependent on the sporophyte, while ferns have a dominant and independent sporophyte.
Seed Plant Advantages
- Seed development includes gametophytes in protective sporangia, seeds that survive harsh conditions and can remain dormant, airborne pollen for fertilization, and dispersal aided by fruits and flowers.
Seed Reproduction Benefits
- Seeds offer protection via a seed coat, food supply, dormancy capability, and resilience to harsh conditions.
Endosperm
- Endosperm is a nutrient-rich tissue resulting from double fertilization, characterized by a 3n chromosome number.
Plant Development Principles
- Positional Information: Cell location determines its function, often influenced by polarity.
- Pattern Formation: Specific structures develop at defined locations.
Plant Hormones
- Auxin: Promotes cell elongation, apical dominance, and leaf abscission.
- Cytokinins: Induce cell division and regulate apical dominance.
- Gibberellin: Plays a role in fruit development and seed germination.
- Abscisic Acid: Encompasses seed dormancy and drought response.
- Ethylene: Manages plant stress responses, leaf abscission, and programmed cell death.
Tropism
- Tropism describes the plant's growth response to stimuli, directing growth toward or away from factors.
Water Movement Routes in Plants
- Apoplastic Route: Moves water and nutrients along cell walls.
- Symplastic Route: Transports substances through the cytoplasm.
- Casparian Strip: A barrier that blocks the apoplastic route, enhancing selective filtration entering the xylem.
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Test your knowledge with these flashcards covering key concepts for Biology Exam 2. This quiz includes important definitions and differences in evolutionary theories such as gradualism and punctuated equilibrium, along with reproductive barriers. Perfect for revising before your exam!