Exam 1 Module Flashcards
(25 cards)
What key observation inspired Darwin’s theory of evolution?
Variation among species on the Galápagos Islands during his voyage on the HMS Beagle.
What is natural selection?
The process where organisms with favorable traits survive and reproduce more successfully.
What are Darwin’s three major pieces of evidence for evolution?
1) Fossils, 2) Homologies between species, 3) Artificial selection.
What is the difference between natural and artificial selection?
Natural selection is environment-driven, artificial selection is human-directed.
What was Lamarck’s incorrect evolutionary theory?
Use and disuse & inheritance of acquired characteristics.
What experiment did Weismann use to disprove Lamarckism?
Cutting off rat tails for 20 generations—offspring were still born with tails.
What is the smallest biological unit that can evolve?
A population.
Define gene pool.
All alleles in all individuals in a population.
What is the Hardy-Weinberg principle?
Allele frequencies remain constant in a population unless disturbed by external factors.
What are the five conditions for Hardy-Weinberg equilibrium?
1) Large population, 2) No migration, 3) No mutation, 4) Random mating, 5) No natural selection.
What are causes of microevolution?
Mutation, genetic drift, gene flow, natural selection, and nonrandom mating.
Define genetic drift.
Random changes in allele frequencies, especially in small populations.
What is balanced polymorphism?
Maintaining multiple phenotypes in a population.
What is speciation?
The formation of new species.
Differentiate anagenesis and cladogenesis.
Anagenesis: species changes into a new one. Cladogenesis: branching off into multiple species.
What is sympatric speciation?
Speciation without geographic isolation, often through polyploidy.
Define polyploidy and its types.
More than two chromosome sets. Autopolyploidy: duplication in same species; allopolyploidy: hybrid of different species.
What are prezygotic isolating mechanisms?
Prevent mating or fertilization: habitat, temporal, behavioral, mechanical, gametic.
What are postzygotic isolating mechanisms?
Prevent viable offspring: hybrid inviability or sterility.
What are the two tempos of speciation?
Punctuated equilibrium (rapid bursts), and gradualism (slow continuous change).
What is a zygote?
A fertilized egg resulting from fusion of sperm and egg.
Difference between protostomes and deuterostomes?
Protostomes: blastopore becomes mouth; Deuterostomes: blastopore becomes anus.
What are the three types of eggs by yolk distribution?
Isolecithal (little yolk), mesolecithal (moderate yolk), telolecithal (large yolk).
What are the three germ layers and what do they form?
Ectoderm: skin/nervous, Mesoderm: muscle/bone, Endoderm: digestive/respiratory.
