Study your flashcards anywhere!

Download the official Cram app for free >

  • Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key


Play button


Play button




Click to flip

115 Cards in this Set

  • Front
  • Back
Difference between heterochromatin and euchromatin both in appearance and gene expression?
Heterochromatin is the portion of the chromosome that is always condensed, thus the genes are never expressed. Euchromatin is the chromosomal material condensed only during cell division; at other times the genes are expressible.
What defines whether or not a collection of individuals of a single type is truly multicellular? How many times did multicellularity arise during evolution, and what advantages do multicellular organisms have over unicellular ones?
Multicellular organisms possess significant degree of coordination & integration among individual cells of group. Multicellularity arose many times in the evolutionary process. advantages are: ability to carry out activities, including self-protection, movement, & search for food and mates, with a complexity not possible by unicellular organisms.
How did the writings of Lyell and Malthus help Darwin develop his theory of evolution?
Lyell's writings in geology suggest that earth and organisms in "constant state of flux," influencing Darwin to seek explanations for the disappearance of some species and the appearance of others. Malthus' observation on the differential growth of animal populations and their food supplies also led Darwin to investigate limiting factors in population growth.
How are prokaryotes different than eukaryotes?
Prokaryotes=peptidoglycan in cell walls, eukaryotes do not; eukaryotic = membrane-bounded organelles, prokaryotes do not; prokaryotes flagella composed of a simple fibrous protein, while eukaryotic flagella have complicated structure w/ doublets and triplets of microtubules.
What mechanism ensures that each daughter cell receives one of the replicated genomes? (bacteria cell)
copies of DNA attached to cell membrane, when cell undergoes binary fission new cell membrane and cell wall materials are laid down between the replicated genomes, ensuring that each daughter cell has one copy of DNA.
Which is more likely to become extinct: a small or a large population? why? how does inbreeding effect possibility of extinction?
small population more likely to become extinct -random events more likely to adversely affect population of few individuals. Inbreeding = loss of genetic vigor, loss of variability affects ability to adjust to changing conditions, increasing possibility of extinction.
Four *general * characteristics of living things? (hint: not defining factors of life.)
1. Highly organized structures
2. can respond to stimuli
3. can grow, develop, reproduce w/ hereditary sys.
4. possess regulatory mechanisms that control life processes
How does rough ER differ from smooth ER?
Rough ER has ribosomes and synthesizes proteins; smooth ER does not have ribosomes and is involved in lipid synthesis and detoxification.
what events signals initiation and ending of metaphase?
Metaphase begins when chromosome pairs align along a central plane of the cell, the metaphase plane. It ends with the splitting of the chromosomes into sister chromatids.
Define the biotic potential of a population. What is the definition for the actual rate of population increase and what two factors effect it?
biotic potential = rate at which given population will increase with no limits placed on it. actual rate of population increase is the difference between birth rate and death rate per individuals per time. emigration & immigration affect it.
Homologous vs. analogous structures? examples?
homologous: develops same way embryologically but two homologous structures may not resemble each other in two separate species. Bat wing, porpoise flipper.

Analogous structures: look similar, same function, but unrelated embryologically. Eg: bat wing, butterfly wing.
What is the endoplasmic reticulum? What does it's function?
The endoplasmic reticulum is a bilayer lipid membrane. It compartmentalizes the cell interior and channels transport of molecules throughout the cell.
which phase is the longest in cells of mature eukaryotes?
most mature tissues remain in G0 most of the time
three types of dispersion in a population, which most frequent in nature and why?
random spacing, even spacing, and clumping. most frequent in nature = clumping - specific environmental conditions are neither randomly nor evenly distributed. Animals congregate for various reasons, and species young likely to be near the parents.
What further evidence since theory of evolution published has lent further support ?
- expanded fossil record
- more accurate estimation of the age of the earth
- mechanisms of heredity
- examination of comparative anatomy
- advances in molecular biology.
How does the surface to volume ratio of cells limit the size that cells can attain?
There is an optimal surface-to-volume ratio; a big cell does not have enough surface area to interact properly for all its volume.
which phases of the cell cycle are longest in embryo cells?
Embryonic tissue cells spend most of their time in the S and M phases
What is the function of the Golgi complex? How do the substances released by golgi make their way to other cell locations?
Golgi bodies collect, package, and distribute cell-synthesized molecules. They are closely associated with the ER, which transports material to the Golgi.
Describe evidence that led Darwin to propose that evolution occurs by means of natural selection.
Darwin observed: organisms better adapted to environment and that left more offspring - more successful. These lived, reproduced, and passed the "successful genes" to offspring. Gradual accumulations of changes from generation to generation could give rise to new species under the right conditions.
What are ribosomes? Where are they assembled?
Ribosomes are aggregates of protein and ribosomal RNA instrumental in protein synthesis. They are manufactured as subunits in the nucleolus and assembled in the cytoplasm.
Which phases of the cell cycle are specifically associated with cell division?
The mitotic, or M, phase of the cell cycle is associated with microtubular assembly for cell division. C phase is cytokinesis, when the cell is actually physically pulling apart.
How do cilia compare with eukaryotic flagella? What does the term 9+2 structure refer to?
Cilia and flagella have the same structure but cilia are shorter and more numerous. The term "9 + 2 structure" means a circle of 9 pairs of microtubules surrounding 2 central microtubules. This is characteristic of eukaryotes.
what are the major points of Darwin's theory of evolution by natural selection?
organisms reproduce excessively, those better able to survive reproduce more, ability to survive is passed on to offspring, favored characteristics will thus increase in the population.
What is the nuclear envelope? What types of materials move through nuclear pores?
The nuclear membrane is bilayered. Proteins move in, and RNA and ribosomal subunits move out through nuclear pores.
what molecular mechanism is responsible for movement of the poles during anaphase? what mechanism is responsible for the movement of centromeres during anaphase?
Anaphase is characterized by movement of the chromatids to opposite poles. The two microtubular movements are (1) sliding of adjacent pole to pole microtubules, which pushes poles apart as the cell elongates and (2) microtubules attached to centrioles shorten by actual loss of tubulin subunits pulling centromeres toward the organizing center at each pole.
What types of eukaryotic cells contain mitochondrion? what does a mitochondrion do?
It functions in oxidative metabolism. Almost all eukaryotic cells contain mitochondria. In general, the more metabolically active the cell, the more mitochondria it will contain.
what is the difference between deductive and inductive reasoning?
Deductive reasoning = data analysis to reach conclusions and to test the validity of ideas or hypotheses. Inductive reasoning = from careful observation of specific phenomena, upon which certain conclusions are made.
What are the three principles of cell theory?
All organisms are composed of one or more cells. (2) Cells are the smallest living things. (3) Cells arise only from the division of other pre-existing cells.
How is the genome replicated prior to binary fission in a bacterial cell?
Several enzymes in prokaryotic DNA initiate duplication at the replication origin, whereupon replication proceeds around the entire loop of DNA until two full copies are made
How do some types of microbodies protect cells from the effects of hydrogen peroxide?
Microbodies such as peroxisomes contain enzymes that degrade hydrogen peroxide, a dangerous intracellular waste product, into water and oxygen.
three events of telophase?
The spindle disassembles, the nuclear envelope reforms around a group of chromatids at each pole, chromatids begin to uncoil to permit gene expression, and rRNA begins to be synthesized, making the nucleolus reappear
What three kinds of fibres make up the cytoskeleton? which of the fibres are stable and which are changeable?
The cytoskeleton is composed of actin protein filaments, tubulin microtubules, and intermediate fibers. The first two are changeable and the last is stable.
What are nucleosomes composed of? How do they participate in the coiling of DNA?
nucleosome = eight arginine/lysine histone polypeptides. DNA duplex wraps around the histone core of the nucleosome. Supercoiling is further coiling of the DNA/nucleosome string.
What types of eukaryotic cells contain chloroplasts? What unique metabolic activity takes place in chloroplasts?
Chloroplasts are encountered in some bacteria, some protists, and plants, and are the site of photosynthesis.
What happens to chromosomes during S phase?
Chromosomes in the S phase are dispersed, and DNA is replicating
Describe the basic structure of a mitochondrion.
. A mitochondrion has an outer membrane, an outer compartment, an inner folded membrane or cristae, and an inner matrix.
what changes occur during prophase, to ribosomal RNA? what characteristic structure of hte nucleus does this effect?
At the beginning of prophase rRNA synthesis stops. At this point the nucleolus disappears
What is the endosymbiont theory and what is the evidence supporting it?
endosymbiont theory suggests eukaryotes arose as a result of specific kinds prokaryotic organisms living in association with one another: a photosynthetic organism perhaps invaded and started living within a non-photosynthetic organism. Evidence = chloroplasts and mitochondria have their own DNA.
how is cytokinesis different in animal cells versus plant cells?
In animals the cell pinches in two via a constricting belt of microfilaments around the cleavage furrow. In plants the cell wall prevents constriction, membrane components are assembled perpendicular to the orientation of the spindle apparatus, the cell plate grows outward to the edge of the cell, and cellulose is then laid down.
What cellular functions do centrioles participate in?
Centrioles form the mitotic spindle between them during cell division (mitosis).
what aspects of cell cycle are controlled by the g1, g2, & M checkpoints?
Cell growth is controlled at the G1 check point, DNA replication is controlled at the G2 check point, and mitosis is controlled at the M check point
How many chromatids are present for each type of chromosome at the completion of crossing over? What two mechanisms hold the chromatids together at this stage?
Four chromatids are present. They are still held together at their common centromeres and at the synaptonemal complex.
Two unique differentiating features between meiosis and mitosis?
Meiosis consists of two divisions, one of which is a reduction division. Mitosis is characterized by one division and no reduction division
what types of organisms are capable of asexual reproduction? How do asexual vs. sexual progeny differ from their parents?
Asexual reproduction has been documented in all kingdoms of life. Any organism produced asexually is genetically identical to its parent
what are the cellular products of meiosis called? Are they haploid or diploid?
Meiosis produces haploid gametes (egg or sperm).
what molecules were present in the atmosphere of the early earth? what was absent that is now a major component, and what process was responsible for the change?
The atmosphere of early earth contained N2, CO2, H2O, H2S, NH3, CH4, and maybe H2. O2 was absent. Then the atmosphere was reducing, now it is oxidizing as a result of several millions years of photosynthesis.
what is the cellular product of syngamy and is it haploid or diploid?
Syngamy produces a diploid zygote
how does the force of selectioon correlate with population divergence?
Forces that differ greatly produce rapid divergence. If forces are similar, there is slow divergence.
what are synaptonemal complexes? How do they participate in crossing over? What two mechanisms hold the chromatids together at this stage?
Synaptonemal complexes hold homologous chromosome arms together which facilitates crossing over. They are formed during Prophase I
what are epistasis and pleiotropy and how can they make interpreting patterns of inheritance difficult?
Epistasis is the effect of one gene on another such that expression becomes altered. Pleiotropy is an allele having more than one effect on an organism (i.e., height and color). Both interfere with interpreting inheritance because they interfere with typical Mendelian ratios
What is a karyotype? How are chromosomes distinguished from one another in a karyotype?
A karyotype is the particular array of chromosomes in an organism. Differentiation is accomplished by comparing length of arms, size, staining properties, and location of arm constrictions.
what is a niche and how many species can occupy it?
A niche is the distinctive role an organism plays in nature, habitat, behavior, feeding, etc. Only one species can occupy any given niche at a time.
What happens to chromosomes in G2 phase? What other event nec. for cell div also occurs in G2?
chromosomes start to condense in preparation for mitosis. During G2, cellular organelles are also duplicated, including assembly of the microtubular apparatus necessary for cell division
what is parthenogenesis and how is it different from other forms of asexual reproduction?
Parthenogenesis is the development of an adult organism from an unfertilized egg. It differs from asexual reproduction per se in that it involves at least one gamete
what is genetic drift and why is it dependent on the size of the population?
Genetic drift is loss of an allele from a population. This is more likely to occur if a population is small because the loss of a single breeding individual will greatly affect gene frequencies.
why did the frequency of light coloured moths decrease while dark colored moths increased during industrialism? What is industrial melanism?
Soot-darkened trees and pollution killed light-colored lichens, so light-colored moths stood out on the dark background and were eaten. Therefore, fewer light-colored moths survived to reproduce and a greater number of dark-colored moths reproduced and passed on their dark-color genes. Industrial melanism refers to the increase of melanin production by organisms to blend into the sootier atmosphere generated by industry.
what is primary non-disjunction? how is it related to downs syndrome and how are age and sex related to likelihood of producing gametes affected by non-disjunction?
Primary nondisjunction is the failure of chromosomes to separate from one another in meiosis. Down syndrome is usually caused by primary nondisjunction. Women who are more than 35 years old are more prone to produce these gametes because gametes in women are held in prophase I from birth to whenever the egg is released to develop further (ovulation), and the chance for damage increases if this holding pattern is lengthy. In men, sperm are produced continuously from puberty and are not stored for long periods.
How does meiosis II compare with mitosis? What is the chromosomal complement of the nuclei resulting from meiosis II?
Meiosis II and mitosis are identical except that meiosis II divisions yield haploid cells (gametes) while mitotic divisions yield diploid cells
How do the chromosomes present at either pole of the cell during telophase I compare with the chromosomes present in the cell before the start of meiosis? what is responsible for the differences?
Both cells are diploid, although changes to the chromatids of the individual chromosomes will have occurred through crossing over
define the terms polyploidy and parthenogenesis.
Polyploidy is an amount of genetic material greater than 2N. Parthenogenesis is asexual reproduction wherein the egg develops directly into the embryo or wherein somatic cells fuse to produce the embryo.
what is the current scientific explanation for the evolution of sexual reproduction?
developed as a means to repair double-strand damage to DNA
How did Koelreuters experiments on tobacco plants conflict with ideas about heredity at the time? Why weren't the implications of his results recognized for so long?
The hybridization showed that breeding between species produced fertile offspring and that traits were masked through one generation and not blended as expected. The progeny were all different from one another, exhibiting different forms of a trait. Recognition of the significance of Koelreuter's theories was delayed because subsequent workers for almost a century did not quantify their results.
Is huntingtons disease dominant or recessive, why is it maintained at its frequency in humans?
Huntington's disease is dominant. Its frequency is maintained because the physiological effects are not evident until relatively late in life, generally after some offspring have already been produced.
define allele. How are homozygous and heterozygous individuals different?
An allele is one expressible version of a gene. A homozygous individual has two of the same alleles, an individual who is heterozygous possess two different alleles (typically one dominant and one recessive)
how did darwins studies of island populations provide evidence for evolution?
Darwin showed that an isolated population of organisms rapidly adapts and evolves to fit their habitat-with their closest relatives being those encountered in the closest continental region.
what barriers exist to the formation of hybrids? which are prezygotic and which are post zygotic isolating mechanisms?
Geographical, ecological, temporal, behavioral, and mechanical isolations exist to the formation of hybrids. Prezygotic mechanisms prevent gamete fusion; postzygotic mechanisms involve embryo developmental failure or abnormalities.
How did Mendel produce self-fertilization & cross fertilization in the peas?
He isolated single plants to allow them to self-fertilize; to cross-fertilize he cut the anthers off of one plant and applied it to the stigma of another
how does the concept of punctuated equilibria differ from gradualism as they both concern evolutionary process?
The gradualists believe that all change was gradual, with many transitional forms. The punctuated view is that little change occurred over long periods of time with occasional sudden large evolutionary changes.
what environmental conditions foster rapid evolution?
Varied habitats in close proximity to one another and rapid changes in climate foster rapid evolution.
define selection. How does it alter allele frequencies, what are three types of selection? give an example of each.
Selection is the ultimate success of an organism so that it survives to leave more offspring and hence pass on more of its genetic material. The ``successful'' organisms will leave more offspring and hence more of their own genes, skewing the allele frequencies, even if only slightly. Directional selection eliminates one extreme from a range of phenotypes, such as the elimination of Drosophila individuals in a population that move toward light. Stabilizing selection eliminates both extremes from a range of phenotypes, such as reduced survival values in duck eggs at the higher and lower extremes of weight. Disruptive selection actually eliminates some of the intermediate forms instead of extremes, as seen in increased predation on nonmimic butterflies in Africa.
why is the allele for sickle cell anemia maintained at high levels in some african poulations? What are the advantages or disadvantages to being homozygous or heterozygous for this allele?
The allele is maintained at high levels because the incidence of malaria is high in these regions, against which the sickle cell allele confers resistance. An individual homozygous for sickle cell anemia will die of sickle cell anemia; an individual homozygous for no sickle cell anemia at all runs the risk of dying of malaria. The heterozygote, while perhaps exhibiting some traits of sickle cell anemia, isn't likely to die of sickle cell anemia or malaria.
describe morgans experiments that indicated that mendelian trait factors are actually on chromosomes
Morgan noticed that some mutant flies had white eyes. In an effort to see if the eye color assorted in a Mendelian fashion, he noticed that eye color was strongly associated with sex, leading him to conclude that those chromosomes that designate sex must also designate eye color.
what is gene flow? How does it take place and what factors determine the degree to which it takes place?
Gene flow is the movement of genes from one population to another through migration or hybridization. Gene flow is affected by the distance between populations, how much individuals move during or before they reach reproductive age, and the distance over which mating takes place
In mendels cross of white and purple peas, which color is shown by the offspring, which trait is dominant, which is recessive, and what is the ratio of dom:rec in F2?
All the F1 offspring were purple, which was dominant over the recessive white color. F1 crosses yielded a 3:1, purple:white (dominant:recessive) F2 ratio
how do proto-oncogenes differ from tumor suppressor genes in the mechanisms by which they lead to excessive cell proliferation and cancer?
Proto-oncogenes are normal genes that code for frequent cell division and as such, if mutated, could become overexpressed and code unchecked for cellular duplication leading to cancer. Tumor-suppressor genes are also normal genes that code for suppression of cell division. Should a tumor-supressor gene become mutated, unchecked cellular division may result.
to determine whether a purple flowered pea plant of unknown genotype is homo or heterozygous, what type of plant should it be crossed with, what would offspring be like if it was homozygous, vs. heterozygous?
To determine an unknown genotype, cross the plant with a homozygous recessive (white) plant. If the unknown plant was homozygous (WW) for the purple color, 100% of the offspring will also be purple. If the genotype of the unknown plant was, on the other hand, heterozygous (Ww) for purple color, the offspring of this cross would be half white (ww) and half purple (Ww).
what is convergent evolution - examples?
Convergent evolution is seen in organisms which are vastly different yet seem to have evolved the same mechanisms to deal with specific environmental pressures (such as albinism and blindness in cave organisms).
what are coacervates, what characteristics do they have in common with organisms, are they alive and why or why not?
Coacervates are protein/lipid aggregations, have a quasi-lipid bilayer membrane, accumulate more organic materials inside themselves, and divide by "budding." They are not alive because they possess no known genetic material.
define micro and macroevolution. How are they related?
Macroevolution refers to changes in populations of plants and animals so that new species develop from old ones. Microevolution refers to changes in allele frequencies within a species
how did stern demonstrate that exchange of genetic traits occurs by crossing over? how can this be used to map genetic loci on chromosomes?
Stern noticed that if an exchange of genetic material occurred resulting in a change in eye color, "abnormal ends" of chromosomes also seemed to have exchanged, indicating the phenomenon of crossing over. Relative position of genes on a chromosome (a genetic map) can be determined by how frequently they do or do not cross over: genes farther apart on chromosomes cross over more frequently than those that are closer together.
why is the frequency of sickle cell anemia lower among african americans than it is among natives of central africa?
The frequency is lower among African Americans because malaria does not exist as a selective pressure in North America.
why do scientists think that whales still have pelvic bones even though they serve no useful function - what term is used to describe these apparently useless structures?
Whales are mammals, which have pelvic bones. Despite no apparent function, homology would dictate the presence of the structures somewhere in some form. "Useless" structures such as these are referred to as vestigial structures
what is adaptation and how does it fit into evolution?
Adaptation results from the possession of features that promote the chance of an organism's survival and reproduction. The natural selection of Darwin's concept of evolution is the process, and adaptation is the result
how is the attachment of spindle microtubules to centromeres in metaphase I of meiosis different from that which occurs in metaphase of mitosis? What effect does this difference have on the movement of chromosomes during anaphase?
Microtubules form the spindle but attach to only one face of each centromere at the kinetochore. The kinetochore of each homologue attaches to the pole toward its outer side, and the sides of the centromeres facing one another are not attached to a spindle fiber from either pole. In mitosis each centromere region attaches to spindle fibers from both poles. In meiosis, then, an entire chromosome is pulled to a pole in anaphase, whereas in mitosis only a single chromatid is pulled to a pole.
when are species hybrids at a fitness disadvantage? what can be the result of this disadvantage?
Species hybrids are at a fitness disadvantage when the hybrids are sterile, are nearly sterile, or are less well-adapted to survive in the environment. The disadvantage to the hybrid is that they often do not survive, and if they do, they do not pass their genes on to following generations.
why are there limits to the success of selection?
Few traits are completely independent of others, and their interactions increase with successive matings; selection can only act on traits in which the homozygotes and heterozygotes are clearly phenotypically distinguishable.
what is the definition of a species?
Species refers to groups that differ in one or more characteristics and do not naturally intergrade to any great extent.
Based on the definition of scientific process, is creationism scientific? why or why not?
Scientific creationism is not truly scientific because it is based on beliefs rather than observations and it does not infer its principles from observations
if two populations of the same species are geographically close to one another and are under similar selective forces, will they retain similar characteristics over time? why or why not?
If populations are reproductively isolated, there may be subtle selective forces that cause one population to diverge more strongly from another, despite geographic proximity
what characteristics of the garden pea made it a good choice for Mendel's experiments?
1) many people had already done research on it and many hybrids were available; (2) a large number of fine-breeding varieties were available; (3) pea plants are small, easy to grow, and have a short generation time, and (4) the sexual organs of the pea were enclosed in the flower.
what mechanism is responsible for the independent assortment of chromosomes?
The chromosomes move to the poles in a random fashion, and some paternal and some maternal chromosomes move to each pole without regard to the movement of all other chromosomes.
What is the difference between the genotype and the phenotype of an individual?
phenotype is what is expressed by the combination of the two alleles (what one would see, such as a purple color). The genotype is the actual genetic make-up of the individual (for example, either a WW or Ww genotype would be expressed as the same purple phenotype).
how is sexual selection different from natural selection?
Sexual selection is differential reproduction resulting from variable success in obtaining mates due to combat or courtship. Natural selection is the natural predominance of certain phenotypes over others in nature; the more favorable survive to leave more offspring and therefore perhaps alter gene frequencies.
how did Urey and miller simulate the process in which organic compounds are thought to have been produced on the earths surface? What types of compounds were produced in their simulation and in similar experiments later?
These experiments took compounds assumed present in the early atmosphere, bombarded them with electricity, and observed the formation of simple organic molecules-formic acid, urea, and the amino acids glycine and alanine.
3 mechanisms by which sexual reproduction increases genetic variability? how does this effect evolution?
Sexual reproduction increases genetic variability through crossing over, independent assortment, and random fertilization. Genetic variability provides the raw material for natural selection and thus, evolution
what evidence supports the argument that RNA evolved first on early earth? What evidence supports the argument that proteins evolved first?
RNA-worlders claim that without molecules capable of transmitting genetic information, proteins and other complex molecules could not have evolved successfully. Protein-firsters maintain that enzymes (proteins) would have had to exist for anything to replicate at all. The discovery of ribozymes and their apparently autocatalytic properties has therefore been very attractive to many theoreticians.
why do populations of organisms change?
They adapt according to environmental demands and changes.
what are the characteristics of living things? which are the necessary characteristics for all living things and which are sufficient characteristics possessed only by living things?
Cellular organization, growth and metabolism, reproduction, and heredity are necessary. Most living things also exhibit sufficient characteristics such as movement, sensitivity, and complexity.
what is the primary mechanism that maintains the integrity of the species clusters of Drosophila in the hawaiian islands?
Behavioral isolation maintains the integrity of the species clusters of Drosophila in the Hawaiian Islands.
what is adaptive radiation, what types of habitats encourage adaptive radiation and why?
Adaptive radiation refers to groups of closely related species which evolved from a common ancestor. An example would be Darwin's finches or Hawaiian Drosophila. Isolated discontinuous habitats (such as islands or lakes) encourage adaptive radiation, because they are subject to a unique combination of selective pressures in a small place, often leading to rapid divergence among small subpopulations, leading to the development of new species.
when did eukaryotes first appear, how did they differ from earlier prokaryotes, and by what mechanism did they evolve from the earlier prokaryotes?
The first eukaryotes known are fossils 1.3 to 1.5 billion years old. Eukaryotes differ from earlier prokaryotes in that they have a nucleus. Eukaryotes are thought to have evolved through the phenomenon of endosymbiosis.
What is homology and how does it give evidence to support evolution?
Homology is the development of seemingly different structures from the same ancestral source (wings in birds and fins on fish). It shows that change has taken place slowly and very demonstrably from earlier forms.
what were the earliest known organisms like, when did they appear, what present day organisms do they resemble?
Prokaryotic organisms were probably the earliest known organisms, appearing about 3.5 billion years ago. They are most closely related to cyanobacteria.
how do archaebacteria differ from eubacteria and which group contains bacteria capable of photosynthesis?
Archaebacteria are similar to the eubacteria except in a few key areas: their cell walls lack peptidoglycan, they possess a lipid in their cell membranes unique to that group, their genetics are surprisingly similar to eukaryotic genetics (eubacterial genetics are very different), and their biochemistry is unique, permitting them to survive in extreme environments (such as high temperature or salt content). Methanogens are characteristic archaebacteria. Photosynthetic prokaryotes are limited to the eubacteria.
what are the six kindoms of life and what sorts of organisms do they contain?
The six kingdoms of life are the Archaebacteria (methanogens); Eubacteria (true bacteria); Protista (single-celled eukaryotes), Fungi (multicellular saprophytes such as mushrooms), Plantae (multicellular eukaryotic autotrophs such as trees, bushes, and flowers); and Animalia (multicellular eukaryotic heterotrophs such as jellyfish, spiders, sea cucumbers, fish, and birds).
How does the molecular record indicate evolutionary change?
More closely related species have a greater number of DNA sequences in common and more distant relations have a greater number of differences, based on a progressive accumulation of DNA change.
What direct and indirect evidence exists to support macroevolution?
The fossil record, molecular record, homology, development, vestigial structures, parallel adaptation, and patterns of distribution support macroevolution.
how likely is it that life has evolved on other planets, and what characteristics must a planet have to be conducive to evolution of carbon-based life forms?
sheer mathematical probability = some form of life elsewhere. With so many stars and planets, life should have evolved somewhere out there. For carbon-based life forms to evolve, a planet must have temperature and atmospheric characteristics similar to those on earth.
why did Mendels research succeed in clarifying the features of gene segregation among offspring where others had failed? (4 reasons)
(1) He used previous researchers' success to direct his work, (2) he picked seven clearly distinguishable traits to examine closely, (3) peas are small, are easy to grow, and have short generation times, and (4) peas are self-fertile but can be easily cross-fertilized as well.
why does the founder principle have such a profound effect on the genetic makeup of a population and how does it differ from the founder principle?
The only alleles the subsequent population can build on are those few present in the population originators (the "founders"). If a population should become catastrophically reduced in size (through earthquakes, etc.), subsequent alleles in the population will only be those of the survivors, a phenomenon called the bottleneck effect.
why does nonrandom mating adversely affect hardy weinberg prediction, what effect does inbreeding have on allele frequency and why is a marriage between close relatives discouraged?
Nonrandom mating increases the proportion of homozygotes. Inbreeding has no effect on allele frequencies. Inbreeding tends to throw deleterious recessive alleles together, which is typically not favored by natural selection. Marriage between close relatives contributes to inbreeding.
How did scientists date fossils in Darwins time and why is it possible to date rocks more accurately now?
In Darwin's day they age-dated rocks by the position of various strata and could only give ages in relation to one another. Now radioactive dating is based on the half-life decay of certain radioisotopes, a definite quantity.
What is the apparent origin of at least two organelles found in eukaryotes and which is possessed by nearly all eukaryotic organisms? To what type of organism is this organelle most similar, how many ancestors have given rise to the organelle and why?
Mitochondria and chloroplasts are apparently of symbiotic origin. Mitochondria are possessed by nearly all eukaryotic organisms, and are most closely related to nonsulfur purple bacteria. Three ancestors appear to have given rise to the other organelle because there are three distinct biochemical categories of chloroplasts.
what are the five factors that can alter the proportions of Hardy-Weinberg allele values? Which produce adaptive evolutionary change and why?
Genetic Drift,
Mutation, Migration, Non random mating, selection. Selection produces adaptive change, the rest are independent of environmental pressure.
what is the sex chromosome genotype of an individual with Klinefelter syndrome, are they genetically male or female, what characteristics do they have?
The genotype of a person with Klinefelter syndrome is XXY, which makes him genetically male, since the presence of the Y chromosome determines maleness. The individual appears female.