Biology Exam 2 Flashcards

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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?

Reduced hybrid viability, reduced hybrid fertility, and hybrid breakdown. Signup and view all the answers

What is sympatry and how might it occur?

Sympatry is the evolution of species without a physical barrier, which can occur through sexual selection, polyploidy, and habitat differentiation. Signup and view all the answers

What is allopatry?

The evolution of a species due to a physical barrier. Signup and view all the answers

What is the hierarchy of classification?

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species. Signup and view all the answers

What is the hierarchy of classification for humans?

Eukarya, Animalia, Chordata, Mammalia, Primates, Hominidae, Homo, Sapiens. Signup and view all the answers

What is a homologous structure?

A homologous structure is shared among multiple species because of common ancestry. Signup and view all the answers

What is an analogous structure?

An analogous structure is the same basic structure found in various species because of convergent evolution. Signup and view all the answers

What is the concept of parsimony?

The simplest possible explanation for the evolution of a species or group of species. Signup and view all the answers

What is the difference between mono-, para-, and polyphyletic?

Monophyletic refers to a clade, paraphyletic refers to part of a clade, and polyphyletic refers to more than one clade. Signup and view all the answers

What were some of the constraints organisms had to face when moving onto land?

Surface area to volume ratio, gravity, aridity, nutrient uptake, and salinity. Signup and view all the answers

What adaptations evolved to address constraints when moving onto land?

Transport systems for nutrients, structural support of cells, water conservation, systems of nutrient exchange, and a filtering system. Signup and view all the answers

What were the main advantages for plants becoming terrestrial?

Unfiltered sunlight, nutrient-rich soil, abundant CO₂ in the atmosphere, and relatively few herbivores/pathogens at first. Signup and view all the answers

What are two main differences in the lifecycles of mosses and ferns?

The sporophyte is dominant in ferns, while the gametophyte is dominant in mosses; the sporophyte of a moss is nutritionally dependent on the gametophyte, whereas the sporophyte and gametophyte of a fern are independent. Signup and view all the answers

What advantages do seed plants have?

The gametophyte develops in the sporangia providing protection and nutrients, seeds can survive harsh conditions, pollen allows for airborne transport for fertilization, and fruits and flowers aid in seed dispersal. Signup and view all the answers

What is the advantage of having seeds as a means for reproduction?

Seed coat provides protection, provides a supply of food, can remain dormant, and can withstand harsh conditions and far transport. Signup and view all the answers

What is the endosperm?

A tissue rich in nutrients that nourishes the gametophyte, with a 3n chromosome number due to double fertilization. Signup and view all the answers

What two main principles guide the development of plants?

Positional information and pattern formation. Signup and view all the answers

What roles does auxin play in a plant?

Cell elongation, apical dominance, and leaf abscission. Signup and view all the answers

What role do cytokinins play in a plant?

Induce cell division and growth, control apical dominance. Signup and view all the answers

What role does gibberellin play in a plant?

Fruit development and seed germination. Signup and view all the answers

What role does abscisic acid play in a plant?

Seed dormancy and drought tolerance. Signup and view all the answers

What role does ethylene play in a plant?

Monitors all plant stresses, promotes programmed cell death, and leaf abscission. Signup and view all the answers

What is tropism?

Any growth response that causes a plant to grow towards or away from stimuli. Signup and view all the answers

What is the difference between the apoplastic and symplastic routes?

The apoplastic route allows water and nutrients to move along cell walls, while the symplastic route moves through the cytoplasm. Signup and view all the answers

What is the name of the barrier blocking the apoplastic route?

Casparian strip. Signup and view all the answers

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

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.
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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Description

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!