Download CHAPTER 14, 15, 16 STUDY GUIDE Chapter 14: History of Life

CHAPTER 14, 15, 16 STUDY GUIDE
Chapter 14: History of Life
Section 1: Biogenesis
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Before the 1600s, it was generally thought that organisms could arise from nonliving material by spontaneous generation.
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Redi showed in 1668 that rotting meat kept away from flies would not produce new flies. Maggots appeared only on meat that had been
exposed to flies.
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Spallanzani showed in the 1700s that microorganisms would not grow in broth when its container was heated, and then sealed. He
inferred that microorganisms do not arise spontaneously but, rather, are carried in the air.
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Pasteur in the 1800s used a variation of Spallanzani’s design to prove that microorganisms are carried in the air and do not arise by
spontaneous generation.
Vocabulary
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Biogenesis: states that all living things come from other living things
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Spontaneous generation: living things could arise from nonliving things
Section 2: Earth’s History
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Scientists think that Earth formed by the gravitational accumulation of dust and debris moving through space.
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Isotopes are atoms with varying numbers of neutrons. The ages of rocks and other materials can be determined by measuring the amount
of radioactive decay that has occurred in radioactive isotopes found in samples of those materials. An isotope’s half-life is the time that
one-half of a sample of the isotope takes to decay.
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The first simple organic compounds on early Earth many have formed under conditions of high energy and in an atmosphere very different
from that of today’s Earth.
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Meteorites may have brought organic compounds to Earth.
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Further chemical reactions may have converted simple organic compounds into the macromolecules important to life. Lightning,
ultraviolet radiation, or heat from within the Earth could have provided the energy for these reactions. These conditions have been
experimentally modeled.
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Cell-like structures, including microspheres and coacervates, form spontaneously in certain kinds of solutions. These structures could have
been a step in the formation of modern cells but lack hereditary material.
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Scientists continue to investigate many hypotheses about the origins of organic molecules and cells in Earth’s history.
Vocabulary
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Radiometric dating: A method of establishing the age of materials include the techniques
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Isotope: atoms of the same element that differ in the number of neutrons they contain
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Mass number: of an isotope is the total number of protons and neutrons in the nucleus
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Radioactive decay: their nuclei release particles or radiant energy until the nuclei become stable.
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Radioactive isotope: isotopes that have unstable nuclei until the nuclei become stable
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Half-life: the length of time it takes for one-half of any size sample of an isotope to decay to a stable form
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Microsphere: spherical in shape and composed of many protein molecules that are organized as a membrane
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Coacervate: collections of droplets that are composed of molecules of different types, including lipids, amino acids and sugars
Section 3: The First-Life Forms
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In addition to serving as a template for protein assembly, some RNA molecules can act as enzymes. Like proteins, RNA molecules can
assume different shapes. These shapes depend on areas of attraction between the RNA nucleotides. For these reasons, the first molecule
that held hereditary information may have been RNA rather than DNA.
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The first cells that formed on Earth were probably heterotrophic prokaryotes.
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The first autotrophic cells probably used chemosynthesis to make food. Chemosynthesis produces energy through the oxidation of
inorganic substances.
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Most modern autotrophic cells use photosynthesis to make food. An important byproduct of photosynthesis is oxygen.
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Once oxygen began to accumulate on Earth, cells would need to bind oxygen to other compounds in order to prevent damage to cell
enzymes. This binding function may have been a first step toward aerobic respiration in cells.
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Eukaryotic cells may have evolved from large prokaryotic cells that engulfed smaller prokaryotic cells. The engulfed prokaryotic cells may
have become the ancestors of organelles such as mitochondria and chloroplasts.
Vocabulary
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Ribozyme: an RNA molecule that can act as a catalyst and promote a specific chemical reaction
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Archaea: related group of unicellular organisms, many of which thrive under extremely harsh environmental conditions
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Chemosynthesis: how many species of archaea that are autotrophs obtain energy, instead of using photosynthesis
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Cyanobacteria: a group of photosynthetic, unicellular prokaryotes
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Ozone: O3; poisonous to both plant and animal life, but in the upper atmosphere, a layer of ozone absorbs much of the ultraviolet radiation
from the sun
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Endosymbiosis: between 2 billion and 1.5 billion years ago, a type of small aerobic prokaryote was engulfed by and began to live and
reproduce inside a larger, anaerobic prokaryote
Chapter 15: Theory of Evolution
Section 1: History of Evolutionary Thought
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Evolution is the process of change in the inherited characteristics within populations over generations such that new types of organisms
develop from preexisting types.
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Scientific understanding of evolution began to develop in the 17 th and 18th centuries such as geologists and naturalists compared geologic
processes and living and fossil organisms around the world.
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Among geologists, Cuvier promoted the idea of catastrophism, and Lyell promoted uniformitarianism. Among naturalists, Lamarck
proposed the inheritance of acquired characteristic as a mechanism for evolution.
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After making many observations and considering ideas of other scientists, both Darwin and Wallace proposed the theory of natural
selection to explain evolution.
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Darwin wrote On the Origin of Species, in which he argued that descent with modification occurs, that all species descended from common
ancestors, and that natural selection is the mechanism for evolution.
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Organisms in a population adapt to their environment as the proportion of individuals with genes for favorable trait increases. Those
individuals that pass on more genes are considered to have greater fitness.
Vocabulary
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Evolution: the development of new types of organisms from preexisting types of organisms over time
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Natural selection: mechanism for descent with modification
o Overproduction: more offspring can be produced than can survive to maturity.
o Genetic Variation: within a population, individuals have different traits
o Struggle to Survive: individuals must compete with each other in what Darwin called “a struggle for existence.”
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Adaptation: a trait that makes an individual successful in its environment
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Fitness: measure of an individual’s hereditary contribution to the next generation
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Strata: rock layers
Section 2: Evidence of Evolution
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Evidence of evolution can be found by comparing several kinds of data, including the fossil record, biogeography, anatomy and
development, and biological molecules. Evolutionary theories are supported when several kinds of evidence support similar conclusions.
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Geologic evidence supports theories about the age and development of Earth. The fossil record shows that the types and distributions of
organisms on Earth have changed over time. Fossils of transitional species show evidence of descent with modification.
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Biogeography, the distribution of organisms, shows evidence of descent with modification.
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In organisms, analogous structures are similar in function but have different evolutionary origins. Homologous structures have a common
evolutionary origin. A species with a vestigial structure probably shares ancestry with a species that has a functional form of the structure.
Related species show similarities in embryological development.
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Similarity in the subunit sequences of biological molecules such as RNA, DNA and proteins indicates a common evolutionary history.
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Modern scientists integrate Darwin’s theory with other advances in biological knowledge. Theories and hypotheses about evolution
continue to be proposed and investigated.
Vocabulary
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Fossil: remains or traces of an organism that died long ago
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Superposition: principle states that if the rock strata at a location have not been disturbed., the lowest stratum was formed before the
strata above it.
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Relative age: its age compared to that of other fossils
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Absolute age: the time since formation
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Biogeography: study of the locations of organisms around the world
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Homologous structure: anatomical structures that occur in different species and originated by heredity from a structure in the most recent
common ancestor of the species
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Analogous structure: have closely related functions but do not derive from the same ancestral structure.
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Vestigial structure: seems to serve no function but resembles structures with functional roles in related organisms.
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Phylogeny: the relationships by ancestry among groups of organisms
Section 3: Evolution in Action
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Ongoing examples of evolution among living organisms can be observed, recorded, and tested.
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In divergent evolution, related populations become less similar as they respond to different environments. Adaptive radiation is the
divergent evolution of a single group of organisms in a new environment.
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In convergent evolution, organisms that are not closely related resemble each other because they have responded to similar environments.
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The great variety of dog breeds is an example of artificial selection.
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The increasing occurrence of antibiotic resistance among bacteria is an example of coevolution in progress.
Vocabulary
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Convergent evolution: the process by which different species evolve similar traits
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Divergent evolution: process in which the descendants of a single ancestor diversify into species that each fit different parts of the
environment
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Adaptive radiation: pattern of divergence – a new population in a new environment will undergo divergent evolution until the population
fills many parts of the environment
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Artificial selection: process occurs when a human breeder chooses individuals that will parent the next generation
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Coevolution: when two or more species have evolve adaptations to each other’s influence
Chapter 16: Populations Genetics and Speciation
Section 1: Genetic Equilibrium
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Population biologists study many different traits in populations, such as size and color.
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Traits vary and can be mapped along a bell curve, which shows that most individuals have average traits, whereas a few individuals have
extreme traits.
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Variations in genotype arise by mutation, recombination, and the random fusion of gametes.
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The total genetic information available in a population is called the gene pool.
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Allele frequencies in the gene pool do not change unless acted upon by certain forces.
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The principle of Hardy-Weinberg genetic equilibrium is a theoretical model of a population in which no evolution occurs and the gene pool
of the population is stable.
Vocabulary
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Microevolution: evolution at the genetic level
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Population genetics: study of evolution from a genetic point of view
Bell curve: a graph of the frequency of lengths in a population
Gene pool: used to describe the total genetic information available in a population
Allele frequency: determined by dividing the number of a certain allele
Phenotype frequency: equal to the number of individuals with a particular phenotype divided by the total number of individuals in the
population
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Hardy-Weinberg genetic equilibrium: showed that genotype frequencies in a population tend to remain the same from generation to
generation unless acted on by outside influences.
Section 2: Disruption of Genetic Equilibrium
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Evolution can take place when a population is not in a state of genetic equilibrium. Thus, evolution may take place when populations are
subject to genetic mutations, gene flow, genetic drift, nonrandom mating, or natural selection.
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Emigration and immigration cause gene flow between populations and can thus affect gene frequencies.
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Genetic drift is a change in allele frequencies due to random events. Genetic drift operates most strongly in small populations.
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Mating in nonrandom whenever individuals may choose partners. Sexual selection occurs when certain traits increase an individual’s
success at mating. Sexual selection explains the development of traits that improve reproductive success but that may harm the individual.
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Natural selection can influence evolution in one of three general patterns. Stabilizing selection favors the formation of average traits.
Disruptive selection favors extreme traits rather than average traits. Directional selection favors the formation of more-extreme traits.
Vocabulary
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Immigration: the movement of individuals into a population
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Emigration: the movement of individuals out of a population
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Gene flow: the process of genes moving from one population to another
o Can occur through various mechanisms, such as the migration of individuals
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Genetic drift: phenomenon by which allele frequency in a population change as a result of random events, or chance
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Sexual selection: tendency for females choosing the males they mate with based on certain traits
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Stabilizing selection: individuals with the average form a trait that have the highest fitness
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Disruptive selection: individuals with either extreme variation of a trait ave greater fitness than individuals with the average form of the
trait
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Directional selection: individuals that display a more extreme form of a trait have greater fitness than individuals with an average form of
the trait
Section 3: Formation of Species
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According to the biological species concept, a species is a population of organisms that can successfully interbreed but cannot breed with
other groups.
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Geographic isolation results from the separation of population subgroups by geographic barriers. Geographic isolation may lead to
allopatric speciation.
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Reproductive isolation results from the separation of population subgroups by barriers to successfully breeding. Reproductive isolation
may lead to sympatric speciation.
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In the gradual model of speciation, species undergo small changes at a constant rate. In the punctuated equilibrium model, new species
arise abruptly, differ greatly from their ancestors, and then change little over long periods.
Vocabulary
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Speciation: the process of species formation – results in closely related species
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Morphology: the internal and external structure and appearance of an organism
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Biological species concept: According to the biological species concept, as proposed by German-born, American biologist Ernst Mayr, a
species is a population of organisms that can successfully interbreed but cannot breed with other groups.
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Geographic isolation: the physical separation of members of a population
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Allopatric speciation: happens when species arise as a result of geographic isolation
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Reproductive isolation: results from barriers to successful breeding between population groups in the same area
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Prezygotic isolation: premating isolation that occurs before fertilization
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Postzygotic isolation: postmating isolation that occurs after fertilization
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Sympatric speciation: occurs when two subpopulations become reproductively isolated within the same geographic area
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Gradualism: the idea that speciation occurs at a regular, gradual rate
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Punctuated equilibrium: pattern of species formation that occurs in a few thousand years, rather than a million years
o Punctuated – sudden, rapid change
o Equilibrium – refers to periods of little change