Bio II - Test I
Advocated catastrophism, speculating that each boundary between strata represents a catastrophe
The theory that changes in the earth's crust during geological history have resulted chiefly from sudden violent and unusual events
Lyell's principle that states that the mechanisms of change are constant over time
Proposed by Hutton and Lyell, this theory states that changes in Earth’s surface can result from slow continuous actions still operating today
The geographic distribution of species
Perceived age of Earth before Darwin and Lyell
Few thousand years old
Descent with modification by natural selection explains the adaptations of organisms and the unity and diversity of life
Mechanism of evolution
Evolution is supported by
1. Direct observations of evolutionary change
3. Fossil record
What did Darwin learn from the writings of Malthus?
Species are capable of overpopulation, but are kept in check by mechanisms such as disease, which causes certain organisms to struggle to survive - many don't
What are the conditions that promote natural selection on a population?
1. Overproduction of species
2. Variability of characteristics
3. Variation is inherited
4. Differences in reproduction and survival are due to variations among organisms
Similarity resulting from common ancestry
Anatomical resemblances that represent variations on a structural theme present in a common ancestor
What inference would you draw from an observation that two modern organisms share very few homologous structures?
Their shared common ancestor occurred long ago
If all organisms use essentially the same genetic code what does that suggests to you about the origin of all life on earth?
All organisms share a common ancestor
A change in allele frequencies in a population over generations
Three mechanisms cause allele frequency change:
1. Natural selection
2. Genetic drift
3. Gene flow
Occurs when the probability that two individuals in a population will mate is not the same for all possible pairs of individuals
Variation in the relative frequency of different genotypes in a small population, owing to the chance disappearance of particular genes as individuals die or do not reproduce
Three sources of genetic variation
2. gene flow
A change in one base in a gene
A change in nucleotide sequence of DNA
Consists of the movement of alleles among populations; tends to reduce variation over time
The proportion of a particular allele (variant of a gene) among all allele copies being considered
Number of alleles present
Five conditions for Hardy-Weinberg Theory to prove a population is non-evolving
1. No mutations
2. Random mating
3. No natural selection
4. Large population
5. No gene flow
Why is the 2 in the term 2pq necessary in the formula for determining a population's genotype frequencies?
It represents both "Aa" and "aA"
The broad pattern of evolution over time
Defines a species in terms of its ecological niche, the set of environmental resources that a species uses, and its role in a biological community
Ecological species concept
The oldest and still most practical, defines a species by body shape, size, and other structural features
Morphological species concept
Defines a species as the smallest group of individuals that share a common ancestor and form one branch on the tree of life
Phylogenetic species concept
States that a species is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring; they do not breed successfully with other populations
Biological species concept
First-generation hybrids are viable and fertile. When first-generation hybrids mate with either parent species or with each other, however, the next generation is feeble or sterile
Closely related species may attempt to mate but fail because they are anatomically incompatible and transfer of sperm is not possible
Species use unique and elaborate courtship behaviors to attract mates
The gametes of two species do not form a zygote because of incompatibilities preventing fertilization
Two species that breed during different times of day, different seasons, or different years cannot mix gametes
Two organisms that use different habitats (even in the same geographic area) are unlikely to encounter each other to even attempt mating
Genetic incompatibility between the two species may abort the development of the hybrid at some embryonic stage or produce frail offspring
Reduced hybrid viability
Even if the hybrid offspring are vigorous, the hybrids may be infertile, and the hybrid cannot backbreed with either parental species. This infertility may be due to problems in meiosis because of differences in chromosome number or structure
Reduced hybrid fertility
Sympatric speciation scheme in which mutations in a population allow individuals to exploit different conditions within the same environment
Geographic separation of populations restricts gene flow
Speciation occurs in geographically overlapping populations when biological factors, such as chromosomal changes and nonrandom mating, reduce gene flow
The process by which one species splits into two or more species
Among known plant species, which have been the two most commonly occurring phenomena leading to the origin of new species?
Sympatric speciation & Polyploidy
A mutant condition stemming from accidents during cell division that result in extra sets of chromosomes
An individual that has more than two chromosome sets, all derived from a single species
The difference between geographic isolation and habitat differentiation is:
the relative locations of two populations as speciation occurs
The hypothesis that evolutionary development is marked by isolated episodes of rapid speciation between long periods of little or no change
How were conditions on the early Earth of more than 3 billion years ago different from those on today's Earth?
Only early Earth was bombarded with large space debris
What is true of the amino acids that might have been delivered to Earth within carbonaceous chondrites?
There were more kinds of amino acids on the chondrites than are found in living organisms today
What defining characteristics did all protobionts (protocells) have in common?
a surrounding membrane or membrane-like structure
The first genes on Earth were probably …
Why do we suspect the first genes on Earth were RNA?
- RNA molecules called ribozymes have been found to catalyze many different reactions
- Natural selection has produced self-replicating RNA molecules
- RNA molecules that were more stable or replicated more quickly would have left the most descendent RNA molecules
- The early genetic material might have formed an “RNA world” Vesicles with RNA capable of replication would have been protocells
- RNA could have provided the template for DNA, a more stable genetic material
Which measurement(s) would help determine absolute dates by radiometric means?
The accumulation of daughter isotopes and loss of parent isotopes
Approximately how far back in time does the fossil record extend?
3.5 billion years
Characteristics of the fossil record of mammalian origins
It includes transitional forms with progressively specialized teeth
What are the early consequences of the release of oxygen gas by plant and bacterial photosynthesis?
Cause iron in ocean water and terrestrial rocks to rust (oxidize)
What is/are the strongest evidence that prokaryotes evolved before eukaryotes?
The oldest fossilized cells resemble prokaryotes
Oldest known fossils made of rocks formed by the accumulation of sedimentary layers on bacterial mats; resemble structures formed by bacterial communities that are found today in some warm, shallow, salty bays
The oxygen revolution changed Earth's environment dramatically. Which events took advantage of the presence of free oxygen in the oceans and atmosphere?
The evolution of cellular respiration, which used oxygen to help harvest energy from organic molecules
A shift in the function of a trait during evolution. For example, a trait can evolve because it served one particular function, but subsequently it may come to serve another