Biology 1821 final 3
Organisms that are only distantly related can resemble each other. Explain convergent evolution, and describe how analogous structures can arise.
Convergent evolution: the independent evolution of similar features in different lineage. Analogous traits arise when groups independently adapt to similar environments in similar ways.
Why do some scientist believe that RNA, rather than DNA, was the first genetic material?
RNA has both information storage and catalytic properties
Explain the evidence for an early RNA world
RNA was probably the first molecule to replicate because it has both information storage and catalytic properties. RNA is also single stranded so it can form into different shapes and formations. These properties could have played a huge role in the formation of DNA.
How does the large amount of genetic variation observed in prokaryotes arise?
- They have extremely short generation times and large populations. - They can exchange DNA with many types of prokaryotes by way of horizontal gene transfer.
What was Darwin's argument?
evolution was the cause of population changing and evolving over time. He explained three broad observations: the unity of life, the diversity of life, and the match between organisms and their environment
a swim bladder is a gas-filled sac that helps fish maintain buoyancy. The evolution of the swim bladder from lungs of an ancestral fish is an example of
exaptation
Consider natural selection, genetic drift and gene flow. Which of the factors results in a random, nonadaptive change in allelic frequencies?
genetic drift
describes how allele frequencies fluctuate unpredictably from one generation to the next
genetic drift
Which of the following characteristics, structures, or processes is common to both bacteria and viruses?
genetic material composed of nucleic acid
the combining of DNA from two sources, contributes to diversity; prokaryotic DNA from different individuals can be brought together by transformation, transduction, and conjugation
genetic recombination
Explain transduction
movement of genes between bacteria and results from accidents that occur during phage replicative cycle
Genetic variation ____.
must be present in a population before natural selection can act upon the population
natural selection ultimately depends on favorable what?
mutations
increases the frequencies of alleles that enhance survival and reproduction. EX: an allele that confers resistance to DDT in fruit flies increased in frequency after DDT was used widely in agriculture
natural selection
what is the only evolutionary mechanism that consistently leads to adaptive evolution?
natural selection
The upper forelimbs of humans and bats have fairly similar skeletal structures, whereas the corresponding bones in whales have very different shapes and proportions. However, genetic data suggest that all three kinds of organisms diverged from a common ancestor at about the same time. Which of the following is the most likely explanation for these data? - Natural selection in an aquatic environment resulted in significant changes to whale forelimb anatomy. - Genes mutate faster in whales than in humans or bats. - Whales are not properly classified as mammals. - Forelimb evolution was adaptive in people and bats, but not in whales. - Humans and bats evolved by natural selection, and whales evolved by Lamarckian mechanisms.
natural selection in an aquatic environment resulted in significant changes to whale forelimb anatomy
bony fish evolved during the ____.
paleozoic
most modern animal phyla evolved during the ____ era.
paleozoic
seed plants first appeared during the ___.
paleozoic
What do we call a virus that attacks a bacterium?
phage
Prokaryotes can be placed in four groups according to their mode of nutrition, which is how they take in carbon and how they obtain energy. List each group in the following chart, and summarize how each of them obtain energy.
photoautotrophy: use light to make food chemoautotrophy: use chemicals to make food and other organic molecules photoheterotrophy: use light energy and get carbon from organic compounds chemoheterotrophy: energy and carbon from organic compounds
longer than fimbriae and allow prokaryotes to exchange DNA
pili
Several sources of genetic variation are available. What is the ultimate source of new alleles?
sexual reproduction
behavioral isolation is
sexual selection based on behavior Ex: blue foot booby male showing off his blue foot, if he cannot do this his chances of breeding are smaller.
Small Aristelliger lizards have difficulty defending territories, but large lizards are more likely to be preyed upon by owls. Which kind of selection acts on the adult body size of these lizards?
stabilizing selection
Women often have complications during labor while giving birth to very large babies, whereas very small babies tend to be underdeveloped. Which kind of selection is most likely at work regarding the birth weight of babies?
stabilizing selection
phages that use both lytic and lysogenic cycles are called
temperate phages (because it has the choice to go in either direction)
The virus genome and viral proteins are assembled into virions (virus particles) during _____.
the lytic cycle only
harmless derivatives of pathogenic microbes that stimulate the immune system to mount defenses against the harmful pathogen
vaccines
the Mesozoic era began approximately ___ million years ago.
251
What does Dr. Carroll mean when he says, "while mutation is random, natural selection is not"?
- Natural selection favors some mutations. - Natural selection acts on traits. - Mutations for advantageous traits are more likely to be passed on to the next generation.
Differences among individuals show two common patterns. One type of variation is between "either-or" characters, and the other is when the character varies along continuum. Explain the underlying genetic differences that contribute to each pattern.
"either-or": characters like this are typically determined by a single gene locus, with different alleles producing distinct phenotypes Continuum: usually results from the influence of two or more genes on a single phenotypic character
You perform a bacteriophage transduction experiment. The donor bacteria strain has the genotype a+ b+ c+ d+. The recipient bacteria strain has the genotype a- b- c- d-. When you analyze the recipients, you obtain the results shown in this data table. Genotype Number of cotransduced cells a+ and b+ 0 a+ and c+ 10 a+ and d+ 0 b+ and c+ 2 b+ and d+ 10 c+ and d+ 0 Fill in the gene map below based on these data. Drag the genes to the correct locations on this gene map.
---a--c------------b--d---
In a hypothetical situation, a bacterium lives on the surface of a leaf, where it obtains nutrition from the leaf's nonliving, waxy covering while inhibiting the growth of other microbes that are plant pathogens. If this bacterium gains access to the inside of a leaf, however, it causes a fatal disease in the plant. Once the plant dies, the bacterium and its offspring decompose the plant. What is the correct sequence of ecological roles played by the bacterium in the situation described here? 1. nutrient recycler 2. mutualist 3. commensal 4. pathogen 5. primary producer
2,4,1
Why can't natural selection fashion perfect organisms?
1. selection can act only on existing variations 2. evolution is limited by historical constrains 3. adaptations are often compromises 4. chance, natural selection, and the environment interact
To date fossils outside the range of carbon-14 dating, researchers use indirect methods of establishing absolute fossil age. Explain how this could be done using radioisotopes with longer half-lives.
1.) could use things with longer half-lives (methane) 2.) An indirect method can be used on fossils sandwiched between two layers of volcanic rock. As the volcanic rock cools, radioisotopes from the surrounding environment became trapped in this new rock. Some of these radioisotopes have longer half-lives. So if two volcanic layers surround a fossil in a certain time frame, then the age of the fossil can be approximated.
The primary headings of this concept list four areas of important evidence for evolution. List the four, and give an example that supports each.
1.) direct observation: Souther FL soap berry bugs feed on the native balloon vide with larger fruits -> they will have longer beaks; Central FL they feed on the introduced golden rain tree with smaller fruit -> they have shorter beaks 2.) homology: mammalion forelimbs, even though they've become adaptive for different functions, they have basic skeletal structures. This represents variation on a structural theme that was present in their common ancestor 3.) the fossil record: pelvic bones in fossil stickleback fish became reduced over time in size. This suggest that the reduction in size may have been driven by natural selection. Shows evolutionary change over time. 4.) biogeography: trees and age of horse fossils suggest that horses originated 5 million years ago in N. Am at this time N and S Am were not connected. So we can predict that the oldest equus fossil should only be found where the group originated - N. Am.
The current theory of the origin of life suggest that chemical and physical process could have produced simple cells through a sequence of four main stages. Summarize them
1st: includes the nonliving synthesis of organic molecules such as amino acids and nitrogen bases, which are small 2nd: the joining of the small molecules into molecule such as proteins and nucleic acids, also called macromolecules 3rd: packaging in which molecules are packaged into protocells (droplets with membranes that contain a different atmosphere than the outside surroundings) 4th: the origin of self-replicating molecules and this eventually made inheritance possible
What is thought to be the correct sequence of these events, from earliest to most recent, in the evolution of life on earth: 1. origin of mitochondria 2. origin of multicellular eukaryotes 3. origin of chloroplasts 4. origin of cyanobacteria 5. origin of fungal-plant symbioses
4,1,3,2,5
the precambrian time began at least ____ million years ago.
4,600
the Cenozoic era began approximately ___ million years ago.
65
which of the following is an orphan gene?
A gene found only in the two-toed sloth
How is carbon dating used for dating fossils?
All living organisms have a proportional set of carbon. When they die carbon-14 slowly becomes carbon-12 because the carbon-14 decays. As it decays over a period of time there will be more carbon-12 and this can be measured to the original amount to determine how long ago the fossil existed.
Besides the Miller-Urey type experiments that have demonstrated one was organic compounds may have been generated, what are some other hypotheses that show alternative situations?
Another possible situation that could have occurred is the abiotic synthesis of macromolecules. The abiotic synthesis of RNA monomers could occur spontaneously from simple precursor molecules. Also, if solutions of amino acids or RNA nucleotides are dripped onto hot sand, clay, or rock, polymers have been produced. So it is possible that such polymers acted as weak catalysts for chemical for chemical reactions on early Earth.
Why is it ineffective to treat viral disease with antibiotics?
Antibiotics inhibit enzymes specific to bacteria and have no effect on virally encoded enzymes.
what are bacteriophages? Differentiate the lytic and lysogenic cycle?
Bacteriophages: virus that parasitizes a bacterium by infecting it and reproducing inside it lytic: the host cell dies lysogenic: the host cell survives
We are living during the ____ era.
Cenozoic
which of the following is true? - Once a de novo gene is in a species' DNA, it will remain there. - De novo genes can be lost. - Mutations do not affect de novo genes. - De novo genes are found only in humans.
De novo genes can be lost
Black-bellied seedcrackers have either small beaks (better for eating soft seeds) or large beaks (better for hard seeds). There are no seeds of intermediate hardness; therefore, which kind of selection acts on beak size in seedcrackers?
Disruptive selection
Mutation are any change in the nucleotide sequence of an organism's DNA. These mutations provide the raw material from which new traits may arise and be selected. What occurs in a point mutation? Do point mutations always result in a change of phenotype?
During a point mutation one base in a gene is changed, usually (most likely) resulting in a harmful change in phenotype.
Sexual reproduction in eukaryotes increases genetic variation. In prokaryotes, transformation, transduction, and conjugation are mechanisms that increase genetic variation. A fundamental difference between the generations of genetic variation in the two domains is:
Eukaryotic genetic variation occurs with vertical gene transfer while prokaryotic genetic variation occurs with horizontal gene transfer.
Convergent evolution might be summarized like this: similar problem, similar solution. Can you give two example of convergent evolution?
Ex 1: flippers Seals (mammal) and penguins (bird) both have them -> flippers evolved in these different species because it was the best feature for the environment (not from an ancestor) Ex 2: wings of bats, birds, insects. These forelimbs morphed over time but did so independently.
Explain what happens in each of these examples of genetic drift (founder effect and bottle neck)
Founder effect: few individuals become isolated from a larger population, such is if a very strong gust of wind from a storm blows a group of organisms away from their population. bottleneck effect: severe, random, drop in population (fire)
What are plasmids? What kind of genes do plasmids usually carry and transfer from one bacteria to another through conjugation? How does this relate to evolution of antibiotic resistant bacterial strains?
Genetic structure that can replicate independently of the chromosomes. Carries the F+ cell through the mating bridge. Plasmids also carry R plasmids which are resistant to antibiotics.
caused by differences in genes or other DNA segments
Genetic variation
Distinguish Gram postive and gram negatie bacteria. If you were to develop antibiotics to both, which one of those two would be more resistant to antibiotics and why?
Gram positive: have a thinner cell wall gram negative: has an outer membrane over the cell wall which acts as more defense more resistance to antibiotics because has more defense
Several scientific laboratories across the globe are involved in research concerning the origin of life on earth. Which of these questions is currently the most problematic and would have the greatest impact on our surroundings if we were able to answer it?
How did RNA sequences come to carry the code for amino acid sequences?
James Hutton and Charles Lyell were geologists whose ideas strongly influenced Darwin's thinking. What were the ideas each of them contributed?
Hutton contributed the proposed principle of gradualism, in which over time he observed that fossils gradually looked different. For example, he proposed that Earth's geologic features, such as rivers being formed happened gradually. Lyell furthered Hutton's proposal and he proposed that these same geologic processes are happening today, just like the past, and at the same rate.
Which of the following is the correct sequence of events in the origin of life? I. formation of protobionts II. synthesis of organic monomers II. synthesis of organic polymers IV. formation of DNA-based genetic systems
II, III, I, IV
When dark-colored fur gives mice a 1% competitive advantage and 1% of the population begins with dark fur, in about 1000 years, 95% of the population will have dark fur. Which of the following statements is true?
If dark-colored rock pocket mice had a competitive advantage of 0.1%, it would take longer for 95% of the population to have dark fur.
Which factor most likely caused animals and plants in India to differ greatly from species in nearby Asia?
India was a separated continent until 45 million years ago.
Although Lamarck's mechanism of evolution does not explain the changes in species over time, his thinking has been influential. What is considered to be the great importance of his ideas?
Lamarck is known for the incorrect mechanisms that he proposed. He is known for use and disuse. Basically, the traits we use a lot we pass onto generations. For example, a giraffe having a long neck is passed on because this is a desired trait (false because acquired traits don't get passed on). But, the importance of this idea was the evolutionary process that organisms adapt to changes in the environment.
Which of the following is not true about bacteria? - short generation time - presence of peptidoglycan - circular DNA - live in extreme environments
Live in extreme environments
Dinosaurs went extinct during the ____.
Mesozoic
animals first appeared during the ____.
Precambrian
Reptiles first appear during the ____ era.
Paleozoic
Which of the following observations helped Darwin shape his concept of descent with modification? - Fewer species live on islands than on the nearest continents. - Birds can be found on islands located farther from the mainland than the birds' maximum nonstop flight distance. - Earthquakes reshape life by causing mass extinctions. - Species diversity declines farther from the equator. - South American temperate plants are more similar to the tropical plants of South America than to the temperate plants of Europe.
South American temperature plants are more similar to the tropical plants of South American than to the temperate plants of Europe
The first eukaryotes did not appear until approximately 1.8 billion years ago. Using Figure 25.10 label and explain the evolution of eukaryotes by endosymbiosis.
The ancestral prokaryote started with DNA, cytoplasm, and plasma membrane. From there it developed an endoplasmic reticulum and a cell with a nucleus. The engulfed aerobic bacterium became the mitochondria of the cell. Additionally, the engulfed photosynthetic bacterium became the plastid. This formation became the ancestral photosynthetic eukaryote.
What is the com potion of the typical bacterial cell wall?
The cell wall is composed of cellulose or chitin. They also contain peptidoglycan (network of sugar polymers cross-linked by polypeptides).
What unique ability was originated with cyanobacteria? How did this alter life on Earth and lead to a wave of mass extinction?
The cynabacteria and other photosynthetic prokaryotes coated damp terrestrial surfaces billions of years ago. This evolution out of the water was associated with the adoption that made it possible to reproduce on land.
What was the earliest form of life on the planet? How long ago did this life-form first occur?
The earliest form of life on the planet was stromatolites occurring 1.5 billion years ago. These are layered rocks that from when certain prokaryotes bind thin films of sediment together.
What adaption of bacteria help them survive harsh conditions?
The fimbriae, which allows them to stick to their substrate or to other individuals in a colony which helps them survive harsh conditions.
The first stage is the synthesis of organic molecules. Consider the early planet, probably thick with water vapor and stinky with methane, ammonia, and hydrogen sulfide. What gas was missing from this early mix? Why?
The gas that was missing was oxygen. It was hard for oxygen to exist because there was nothing to produce this oxygen. Lakes and seas were not formed, and oxygen producing organisms did not exist either. The first atmosphere was thick with water vapor and once the Earth cooled, this water vapor condensed into oceans. These became viable for the creation of life and further photosynthesis which created oxygen.
Which of the following is characteristic of the lytic cycle?
a large number of phage are released at a time
Summarize three lines of evidence that support the model endosymbiosis.
The inner membranes of both are similar, containing enzymes and transport system. The mitochondria and plastids replicate by a splitting process and also contain circular DNA molecules. The mitochondria and plat ids have the machinery needed to transcribe and translate DNA into proteins. Lastly, the ribosomes of mitochondria and plastids are similar to prokaryotic ribosomes.
Which of the following observations about flagella is true and is consistent with the scientific conclusion that the flagella from protists and bacteria evolved independently?
The protein structure and the mechanism of movement in protist flagella are different from those of bacteria flagella.
Explain how retroviruses are different from influenza virus?
They can transcribe a DNA copt from a RNA template. Retroviruses contain the enzyme reverse transcriptase, which transcribes DNA from RNA, which is opposite of the usual direction of information flow.
As you read in the overview to this chapter, many arches live on the edge and so are termed extremophiles. Where would you find these types of archaea?
They would live in environments that are so extreme that few other organisms can survive there. (hot water of yellowstone)
It is important to remember that difference in heritable traits can lead to differential reproductive success. This means that the individuals who have the necessary traits to promote survival in the current environment will leave the most offspring. How can this differential reproductive success affect the match between organisms and their environment?
This differential reproductive success increases the likelihood that organisms will better match the environment they are born into.
As you see, all viruses consist of a nucleic acid enclosed in a protein coat. Some viruses also have a membranous envelope. What are the components of a viral envelope? Which component is derived from the host cell, and which is of viral origin?
Viral envelopes: contain a combo of viral and host cell molecules Envelopes are derived from host cell capsids are from the viral origin
What are other small pathogenic agents that are as small simple as viruses?
Viroids: small circular RNA molecules that infect plants and sirupy their growth prions: slow-acting, virtually indestructible infectious proteins that cause brain disease in mammals (can both go on to infect animals)
You are an oncologist working in the field of gene therapy. You are researching way to alter the NCYM gene in humans. Who is your research most likely benefit?
a 6 year old boy with a brain tumor
mutations are always ___.
a change in an individual's DNA
What genetic material has not been found in any virus?
a combination of DNA and RNA (single - or double-stranded)
which of the following is a defining characteristic that all protocols had in common?
a surrounding membrane or membrane-like structure
Current evidence shows that flagella of prokaryotes and eukaryotes perform similar functions but are not related by common descent. They can be best described as?
analogous, because of similar environmental pressures (convergent evolution)
What is important within a population for natural selection to happen?
adaption to new environment, this can be called mutations, or genetic diversity. The diversity among a population can allow individuals to adapt to an environment. And this causes the rise to new species.
post zygotic means
after fertilization has taken place
Which statement about variation is true?
all new alleles are the result of nucleotide variability
____ were the dominant vertebrate life form during the paleozoic era.
amphibians
All of the statements below are true. Select the statement that best supports the view of most biologists that viruses are nonliving. - An isolated virus is unable to replicate its genes or regenerate ATP. - The viral genome may be single-stranded or double-stranded RNA or DNA. - Viruses are obligate intracellular parasites.
an isolated virus is unable to replicate its genes or regenerate ATP
two divisions of prokaryotes
bacteria and archaea
Figure 23.13 is important because it helps explain the three modes of selection. Label each type of selection, and fill in the chart to explain what is occurring.
balancing selection: acts against extreme phenotypes and favors intermediate varieties directional selection: occurs when conditions favor individuals exhibiting one extreme of a phenotypic trait disruptive selection: conditions favor individuals at both extremes.
Why do you need to get a flu shot every year?
because there are different strands of the virus that become immune to the vaccine so you get a shot every year to target that strand of the virus
pre zygotic means
before fertilization has taken place
Which of the following involves metabolic cooperation among prokaryotic cells? - binary fission - photoautotrophy - biofilms - endotoxin release - endospore formation
biofilms
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 members of other populations
biological species concept
a sudden reduction in population size due to a change in the environment
bottleneck effect
How do we measure Genetic Variation?
can be measured as gene variability or nucleotide variability. Nucleotide variability is measured by comparing the DNA sequences of pairs of individuals. For gene variability, average percent of loci that are heterozygous in a population is measured.
The nucleic acid of a virus particle is enclosed in a protein coat. What is it called?
capsid
protein shell that encloses the viral genome
capsid
compare the three domains in this chart by filling in either present or absent
characteristic-->bacteria-->archae-->eukaryotes membrane bound organelles-->A-->A-->P peptidoglycans-->P-->A-->A circular DNA-->P-->P-->A introns-->Very rare-->Present in some genes-->Present in many genes
During a study session about evolution, one of your fellow students remarks, "The giraffe stretched its neck while reaching for higher leaves; its offspring inherited longer necks as a result." Which statement is most likely to be helpful in correcting this student's misconception? - Disuse of an organ may lead to its eventual disappearance. - Spontaneous mutations can result in the appearance of new traits. - Only favorable adaptations have survival value. - Characteristics acquired during an organism's life are generally not passed on through genes.
characteristics acquired during an organism's life are generally not passed on through genes
process where genetic material is transferred between prokaryotic cells
conjugation
in evolutionary terms, an organism's fitness is measured by its ___.
contribution to the gene pool of the next generation
the evolution of similar, or analogous features in distantly related groups
convergent evolution
which of the following is true? - Current research indicates that medians are not similar to islands when comparing the diversity of animals or plants. - Current research indicates that medians are similar to islands when comparing the diversity of plants, but not of animals. - Current research indicates that medians are similar to islands when comparing the diversity of animals, but not of plants. - Current research indicates that medians are similar to islands when comparing the diversity of animals and plants.
current research indicated that medians are not similar to islands when comparing the diversity of animals or plants
What type of bacteria was the first creation of oxygen?
cyanobacteria; oxygen is a byproduct of their metabolism
Bacteria perform the following ecological roles. Which role typically does not involve symbiosis?
decomposer
Which of the following is the most predictable outcome of increased gene flow between two populations? - decreased genetic difference between the two populations - increased genetic difference between the two populations - higher average fitness in both populations - lower average fitness in both populations
decreased genetic differences between the two populations
What is the best modern definition of evolution?
descent with modification
What is the meaning of Darwin's expression "descent with modification?"
descent with modification refers to evolutionary change over time.
temporal isolation is
different breeding seasons
____ were the dominant vertebrate life form during the Mesozoic era.
dinosaurs
Long necks make it easier for giraffes to reach leaves high on trees, while also making them better fighters in "neck wrestling" contests. In both cases, which kind of selection appears to have made giraffes the long-necked creatures they are today?
directional selection
Darwin and Wallace's theory of evolution by natural selection was revolutionary because it _____.
dismissed the idea that species are constant and emphasized the importance of variation and change in populations
Which type of selection tends to increase genetic variation?
disruptive selection
Mutation is the only evolutionary mechanism that ___.
does little to change allele frequencies (it is natural selection that changes the frequencies)
viral genomes may consist of either...
double or single stranded DNA or double or single stranded RNA
mitochondria and plastids (chloroplasts and related organelles) were formerly small prokaryotes living within larger hose cells
endosymbiont theory (endosymbiont is a cell living within a host cell)
Which statement about endotoxins is true? - An example of a prokaryote that produces endotoxins is Clostridium botulinum. - Endotoxins are proteins secreted by prokaryotes. - Endotoxins are components of the cell wall of gram-positive bacteria. - The source of endotoxins is endospores. - Endotoxins are released only when bacteria die and their cell walls break down.
endotoxins are released only when bacteria die and their cell walls break down
T or F? Heterozygote advantage refers to the tendency for heterozygous individuals to have better fitness than homozygous individuals. This higher fitness results in less genetic variation in the population.
false; heterozygous results in more genetic variation in the population
allow prokaryotes to stick to their substrate or other individuals in a colony
fimbriae
You discover that a company illegally dumbed old vats of PCBs into a nearby river. What do you expect to see?
fish with deformities
help prokaryotes move towards or away from substances they want to get to or get away from
flagellum
Four sources of Genetic Variation?
formation of new alleles, altering gene number or position, rapid reproduction, sexual reproduction
What situation most likely explains the occasional high frequency of certain inherited disorders among human populations established by a small population?
founder effect
when a few individuals become isolated from a larger population
founder effect
Only mutations in a cell that produce ____ can be passed to offspring.
gametes
What was the order in which life on earth was formed?
gases in early earth, simple organic molecules (monomers), polymers (DNA, RNA, Proteins), packaged protocols, self-replicating molecules
Which of the following results in the creation of gene families?
gene duplication
Consider natural selection, genetic drift and gene flow. Which tends to reduce the genetic difference between populations and make populations more similar over a period of time?
gene flow
Over time, the movement of people on Earth has steadily increased. This has altered the course of human evolution by increasing _____.
gene flow
consists of the movement of alleles among populations. EX can be transferred through pollen. reduces variation among population over time
gene flow
Allele frequencies in a gene pool may shift randomly and by chance. What is this random shift called?
genetic drift
Use of synthetic fertilizers often leads to the contamination of groundwater with nitrates. Nitrate pollution is also a suspected cause of anoxic "dead zones" in the ocean. Which of the following might help reduce nitrate pollution?
growing improved crop plants that have nitrogen-fixing enzymes
How were conditions on the early earth of more than three billion years ago different from those on today's earth? Unlike Earth today, early Earth ____.
had an atmosphere rich in gases released from volcanic eruptions
Which organisms are more favored in a changing environment? Homozygous or heterozygous?
heterozygous depending on the changing environment and chance of survival
What is meant by each of the following terms (homologous, analogous)? Give an explanation and example of each.
homologous: share common ancestry, but not necessarily similar functions. Ex are of human, wing of bird, leg of dog, flipper of dolphin -> they all have a different purpose but share a common descent analogous: species share features because of convergent evolution. (similar function but not ancestry). Ex sugar gliders similar to flying squirrels. They have a need to fly (not common ancestry) that makes them alike.
you are infected with an antibiotic-resistant strain of klebsiella pneumoniae. where did you most likely contract it?
hospital
offspring doesn't live in a certain condition or they live and they aren't fertile and produce offspring, so therefore the generations won't be carried on
hybrid viability
the offspring of crosses between different species
hybrids
After the drought of 1977, researchers hypothesized that on the Galápagos island Daphne Major, medium ground finches with large, deep beaks survived better than those with smaller beaks because they could more easily crack and eat the tough Tribulus cistoides fruits. A tourist company sets up reliable feeding stations with a variety of bird seeds (different types and sizes) so that tourists can get a better look at the finches. Which of these events is now most likely to occur to finch beaks on this island?
increased variation in beak size and shape over time
What is true of microevolution?
it is the kind of evolution that can change the relative abundance of a particular allele in a gene pool over the course of generations.
What was the significance of Milly and Urey's experiment?
it showed that organic molecules such as amino acids could be produced from inorganic molecules. (under the conditions of early earth it was possible to spontaneously form essential organic molecules.)
What is the function of reverse transcriptase in retroviruses?
it uses viral RNA as a template for DNA synthesis
What conditions on early Earth made the origin of life possible?
it was a reducing environment (gases were in the most reduced form) and this reduced atmosphere may have led to the formation of organic molecules (miller and urey)
genetic variation in bacterial populations cannot result from
meiosis
flowering plants first appeared during the ___.
mesozoic
a change in allele frequencies in a population over generations
microevolution
Why would the mitochondria be produced first? Why wouldn't we need photosynthesis at this time?
mitochondria was needed for the metabolism function, and organisms could've gotten food from oxygen or other organisms
photoautotrophs use
light as an energy source and CO2 as a carbon source
What happens first when a phage infects a bacterial cell and is going to enter a lysogenic cycle?
linear DNA circularizes
identify the pair of homologous structures.
maple leaf and oak leaf
Explain the process of natural selection in your own words.
natural selection is a process in which individuals with more desirable traits, for the environment they are in, tend to have a better change of survival and reproduce at a higher rate. Natural selection can lead to the rise of new species over time.
three major factors that alter allele frequencies and bring about most evolutionary change are?
natural selection, genetic drift, gene flow
Consider natural selection, genetic drift and gene flow; only one results in individuals that are better suited to their environment. Which is it?
natural selection.
which of the following is true: - once it is established in population, a new mutation will always disappear rapidly. - once it is established in a population, a new mutation may increase or decrease in frequency depending on the environment - once it is established in a population, a new mutation will always decrease in frequency over time - once it is established in a population, a new mutation will always increase in frequency over time.
once it is established in a population, a new mutation may increase or decrease in frequency depending on the environment
a change in one base in a gene
point mutation
life arose during the ___.
precambrian
the first prokaryotic cells appeared during the ____.
precambrian
In prokaryotes new mutations accumulate quickly in populations, while in eukaryotes new mutations accumulate much more slowly. The primary reasons for this are
prokaryotes have short generation times and large population sizes
How do internal function (prokaryotes and eukaryotes) differ?
prokaryotes lack complex compartments but they do have membranes that perform metabolic function
Explain transformation
prokaryotic cell takes and incorporates DNA from the surrounding environment
the earliest organisms were most likely ___.
prokaryotic; after Earth's crust cooled and solidified
Which of the following is true? - Protein-coding genes make up far more of the human genome than noncoding DNA. - Noncoding DNA has not been found in humans. - Protein-coding genes and noncoding DNA make up about the same amount of the human genome. - Protein-coding genes make up far less of the human genome than noncoding DNA.
protein-coding genes make up far less of the human genome than noncoding DNA
What are protocols? What properties of life do they demonstrate? What conditions contribute to their formation?
protocols are droplets with membranes that maintain internal chemistry different from the surroundings. They demonstrate the ability to self-replicate and appear to have a metabolism-like source of building blocks needed for this replication.
the absolute ages of fossils can be determine by
radiometric dating
Three factors that contribute to genetic diversity in prokaryotes?
rapid reproduction, mutation, genetic recombination
What are the properties of a living cell?
reproduce (self-replicating molecules), metabolize, response to stimuli, grow and develop, ability to adapt to environment.
the existence of biological factors (barriers) that impede two species from producing viable, fertile offspring
reproductive isolation
What are restriction enzymes? How do they help prevent viral infections of bacteria?
restriction enzymes are defense mechanisms bacteria uses against phage, that recognizes and cuts up certain phage DNA.
a virus consisting of a single strand of RNA, which is transcribed into complementary DNA, is a ___.
retrovirus
Which viruses have single-stranded RNA that acts as a template for DNA synthesis?
retroviruses
the first genetic material on earth was probably ____.
self-replicating RNA molecules
Which of the following is a property of life shared by prokaryotic cells and eukaryotic cells, but not viruses?
the ability to process energy through metabolic reactions
Which of the following is true of generalized bacteriophage transduction? - The bacteriophage must enter the lysogenic cycle. - The bacteriophage packages fragments of bacterial DNA into new phage particles. - The bacteriophage chromosome has a region homologous to the bacterial chromosome.
the bacteriophage packages fragments of bacterial DNA into new phage particles
the oxygen revolution changed Earth's environment dramatically. Which of the following 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
The theory that the earth was reducing was not convincing enough, what was then hypothesized?
the first organic compound may have been synthesized near volcanoes, deep-sea hydrothermal vents or deep-sea alkaline vents.
Catastrophism was Cuvier's attempt to explain the existence of ___.
the fossil record
Soon after the island of Hawaii rose above the sea surface (somewhat less than one million years ago), the evolution of life on this new island should have been most strongly influenced by _____.
the founder effect
mechanical isolation is
the genitals don't meet to mate, so mechanically they cannot mate
the evolutionary effect of genetic drift are greatest when ___.
the population size is small
explain conjugation
the process where genetic material is transferred between prokaryotic cells
What are some ways bacteria may win the battle against the phages?
the receptors and proteins on the outside of the membrane can change and not allow the T4 virus to inject its DNA. (restriction enzymes of the bacteria cut up foreign DNA at specific sites so it can't inhabit the bacteria).
If all prokaryotes on Earth suddenly vanished, which of the following would be the most likely and most direct result?
the recycling of nutrient would be greatly reduced, at least initially
Members of two different species possess a similar-looking structure that they use in a similar way to perform about the same function. Which of the following would suggest that the relationship more likely represents homology instead of convergent evolution?
the two species share many proteins in common, and the nucleotide sequences that code for these proteins are almost identical
When a virus infects a bacterial cell, often new viruses are assembled and released when the host bacterial cell is lysed. If these new viruses go on to infect new bacterial cells the host cells may not be lysed. What is the most plausible explanation for this?
the virus has entered the genome of the bacterial cell and is in the lysongenic stage
Which of the following supports the argument that viruses are nonliving?
they are not cellular
Which statement is true about obligate anaerobes? - They will use O2 if it is present, but can obtain energy by fermentation if needed. - They use O2 for cellular respiration and cannot grow without it. - They obtain energy by oxidizing ferrous ions. - They live exclusively by cellular respiration or by anaerobic respiration. - They are poisoned by O2.
they are poisoned by O2
Key features of prokaryotic reproduction (3)
they are small, they reproduce by binary fusion, they have short generation times
gametic isolation is
they can mate but the sperm cells cannot get together. mechanically they'd fit but gameticaly they can't
Miller and Urey's experiments that attempted to recreate conditions on early Earth were significant because _____.
they showed that organic molecules such as amino acids could be produced from inorganic molecules
Why are retroviruses considered a special class of viruses?
they transcribe RNA to DNA using reverse transcriptase
Why are viruses referred to as obligate parasites?
they use the host cell to reproduce
Perhaps because we tend to focus on mutations that cause changes in phenotypes, it is easy to think that every mutation will lead to a phenotypic change. Why is this notion incorrect?
this notion is wrong because a large portion of DNA has no function, so a mutation there will have no effect. A mutation on a certain part of the chromosome may have no direct impact on the phenotype. (introns)
Which of the following processes contributes to genetic recombination in prokaryotes? - Mutation - Meiosis - Transduction
transduction
the movement of genes between bacteria by bacteriophages
transduction
a prokaryotic cell can take up and incorporate foreign DNA from the surrounding environment in a process called
transformation
Which of the following is a fitness trade-off (compromise)? - Turtle shells provide protection but are heavy and burdensome when moving. - The strong, thick beak of a woodpecker helps it find insects in trees. - Hummingbirds are the best pollinators of certain flowers, but bees are the best pollinators for orchids. - In some hornbill species, the male helps seal the female in a tree with her nest until the young are ready to fledge.
turtle shells provide protection but are heavy and burdensome when moving.
the atmosphere of early Earth probably contained no O2 until the emergence of organisms that ___.
used water as an electron source for photosynthesis.
What is the most effective way to stop viral infections?
vaccines
in the lysogenic cycle ___.
viral DNA is replicated along with host DNA
surround the capsids of viruses such as influenza and many animal viruses; contain combination of viral and host cell molecules
viral envelopes
What is the role of an envelope in animal viruses?
viral glycoproteins on the envelope bind to specific receptor molecules on the surface of the host cell.
an infectious particle consisting of genes packaged in a protein coat; much simpler than prokaryotic cells, cannot reproduce or carry out metabolism outside of the hose cell
virus
If you were authorized to classify viruses as either living or non-living, how would you classify them and explain the features that support your classification?
viruses are non-living because they cannot carry out metabolic processes without taking over the host cell and they lack the necessary organic molecules to live. They also cannot reproduce on their own.
Which is not accepted theory about the evolution of viruses?
viruses are the descendants of pre-cellular life
How does a virus differ from a bacterium?
viruses, unlike bacteria, lack metabolic enzymes
