Name: _______________________________________
Unit 2B: Evolution
Review Sheet
Part I: Origin of Life
 biogenesis
 spontaneous generation
 Redi
 Spallanzani
 Pasteur
 radioactive dating
 first forms of life
 heterotroph hypothesis o anaerobic heterotroph o anaerobic autotroph o aerobic autotroph o aerobic heterotroph
Part II Evolution
 theories of evolution o Lamarck
 use & disuse
 acquired characteristics o Darwin
 natural selection
 survival
 overproduction
 competition
 variation
 reproduction
 speciation
 evidence of evolution o fossils
 Steno: Law of Superposition o comparative anatomy
 homologous structures
 analogous structures o vestigial organs o comparative embryology o comparative biochemistry
 patterns of evolution o coevolution o convergent evolution o divergent evolution
 adaptive radiation
 artificial selection
Per. _________
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= all living things come from other living things of the same kind
 now widely accepted
Spontaneous Generation
= idea that living things could “generate” from non-living things
= abiogenesis ex. van Helmont: dirty shirt/rags + few grains of wheat + 20 days= mice ex. frogs & fish from rain ex. flies from dead bodies
Several scientists performed controlled experiments to disprove abiogenesis:
Redi’s Experiment
 1668- proved that flies came from adult flies egg  larvae  pupa  adult
 flies were only present in the uncovered jars
 proved that the maggots came from adult flies that were able to come in contact with the meat jar sealed off no flies/ no maggots jar covered with gauze no flies/ yes maggots jar uncovered yes flies/ yes maggots
Spallanzani’s Experiment
 tested spontaneous generation of microorganisms
 boiled and sealed flask grew no microorganisms
 flask open to air did
 vital force destroyed in the air by sealing it off? boiled & uncovered: contamination boiled & covered: no contamination

Pasteur’s Experiment
 believed that microorganisms were present in air
 boiled broth in curve- necked flask did not grow microorganisms
 neck broken off, microorganisms flourished in flask
 Why? broth only became cloudy when air could get in easily… microorganisms exist in air
 the Principle of Biogenesis became a cornerstone of biological science; now a firmly established theory
1.1 Recap
1. (a) What is spontaneous generation?
Idea that life arose from non-living things
(b) Examples? flies from dead things; frogs & fish from rain; mice from dirty rags & wheat
2. (a) How did Redi disprove this idea? experimented using meat & flies
(b) What was the control in this experiment? meat in jar uncovered
(c) Describe the experimental groups.
1. meat in jar completely sealed off
2. meat in jar covered with gauze
3. (a) What did Spallanzani test? spontaneous generation of microorganisms
(b) What were the results of his experiment? broth open to air grew microorganisms broth sealed off from air had no microorganisms
4. (a) How did Pasteur separate microorganisms from the air? using a curve-necked flask
(b) What did this experiment prove? microorganisms are in air
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• Organic- Compound that contains a C-H bond (link)
• Inorganic- compound that does not contain a C-H bond (link)
• Respiration- Making ________________
• Aerobic- Using _________________ to make energy
• Anaerobic- Not using O
2
to make energy
• Heterotroph- gets _______________ from the environment
• Autotroph- makes own food
 earth formed 4.6 billion years ago.
 ways of estimating the age of materials on earth include radioactive dating
 ratio of radioisotope to regular isotope of an element can determine how old a specimen is
 rate of radioactive decay of an isotope is known as its half-life
 half-life = the amount of time it takes half the sample of a radioactive isotope to decay ex. carbon-14 5,730 years ex. thorium-230 75,000 years ex. potassium-40 1,300,000,000 years ex. uranium-238 4,500,000,000 years
 carbon-14 is useful only on organic samples less than 60,000 years old
 uranium-238 and thorium-230 have been used to estimate the age of the earth
The First Organic Compounds
 life first appeared on earth 4.2 to 3.5 billion years ago
Oparin’s Hypothesis (1923) aka heterotroph hypothesis
 atmosphere of primitive earth  NH
3
( ammonia ), CH
4
(methane), H
2
(hydrogen), H
2
O (water)
 addition of energy from lightening, volcanic eruptions, natural radiation, UV light from sun splits them into ions
 The energy allowed inorganic chemicals to bond and form organic chemicals.
 Simple sugars, amino acids (building block of proteins )
 formed “hot, thin soup” of organic molecules
 Clusters or aggregates absorbed organic compounds
 These clusters became more organized and complex
 They developed the ability to reproduce
 Once they reproduced they became the first living cells o these had to obtain organic compounds so they were heterotrophic
 Since there was no free oxygen the first cells were anaerobes o A waste of anaerobic respiration is CO
2

 Once CO
2
is present some cells gained the ability to use it to make food
 o these became the first autotroph
Autotrophs make food and as they do so they give off O
2
as a waste.
 Once O
2
is present in the atmosphere some organisms gained ability to use O
2
 These became the first aerobes
Miller-Urey Spark-Discharge Experiment (1953)
 actually produced amino acids!
NH
3
+ CH
4
+ H
2
+ H
2
0 + electric spark  amino acids
The First Cells- were prokaryotic, anaerobic, heterotrophs meaning: simple (no organelles), no oxygen needed, & had to go get food from environment
 competition for food resulted in evolution of autotrophs, including photosynthetic autotrophs
 CO
2
produced by heterotrophs and O
2
produced by autotroph changed atmosphere of earth drastically
Order of Appearance: anaerobic heterotroph 
Eukaryotic Cells anaerobic autotroph  aerobic heterotroph & aerobic autotroph
 appeared 1.5 billion years ago
 unclear as to how
 may explain mitochondria and chloroplasts as having been organisms that were incorporated into these cells
1.2 & 1.3 Recap
1. How do we estimate the age of materials on earth? radioactive dating
2. (a) Carbon-14 is used to age of what kind of samples? organic
(b) What two elements were used to estimate the age of the earth? U-238 & Th-230
3. According to the heterotroph hypothesis, the first cell-like structures were formed where? ocean
4. According to the heterotroph hypothesis, extended periods of fermentation produced what kind of gas in the earth’s environment? CO
2
5. According to the heterotroph hypothesis, the earliest heterotrophs carried out what type of respiration? anaerobic respiration
6. According to the heterotroph hypothesis, the order in which organisms evolved was: anaerobic anaerobic heterotroph  autotroph  aerobic heterotroph & aerobic autotroph
7. In an experiment by Miller & Urey, what were produced when gases present in the primitive earth were combined with an electrical spark? amino acids
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Regents Questions:
1. According to the heterotroph hypothesis, the first forms of life on Earth probably obtained energy by anaerobic respiration. What material is thought to have been added to early Earth’s atmosphere by this process?
1. methane
2. carbon dioxide
3. nitrogen
4. hydrogen
2. The heterotroph hypothesis is an attempt to explain
1. how the Earth was originally formed
2. why simple organisms usually evolved into complex organisms
3. why evolution occurs very slowly
4. how life originated on the Earth
3. One basic assumption of the heterotroph hypothesis is that the primitive Earth was exceptionally hot with a rich supply of
1. decomposers
2. atmospheric oxygen
3. producer organisms
4. energy
4. According to the heterotroph hypothesis, the earliest heterotrophs carried out what type of energyreleasing process?
1. protein synthesis
2. anaerobic respiration
3. photosynthesis
4. aerobic respiration
5. Which gas became more abundant in the Earth's primitive atmosphere as a result of long periods of fermentation by anaerobic organism?
1. hydrogen
2. carbon dioxide
3. ammonia
4. methane
6. According to the heterotroph hypothesis, the first life on Earth was able to
1. synthesize its food from inorganic compounds
2. feed upon carbohydrates produced by autotrophs
3. feed upon available nutrients in the environment
4. carry on photosynthesis instead of respiration
7. In an experiment by Stanley Miller, the chemicals methane, hydrogen, ammonia, and water vapor were subjected to a high-energy electrical sparking device at high temperatures. This experiment was an attempt to
1. produce organic compounds
2. produce elements
3. duplicate aerobic respiration
4. duplicate photosynthesis
8. According to the heterotroph hypothesis, extended periods of fermentation eventually changed Earth's environment. Which gas would have gradually increased in the atmosphere due to this activity?
1. ammonia
2. nitrogen
3. hydrogen
4. carbon dioxide
9. According to the heterotroph hypothesis, the order in which organisms evolved was
1. aerobic heterotroph  aerobic autotroph  anaerobic autotroph
2. anaerobic autotroph 
3. anaerobic heterotroph
4. anaerobic heterotroph anaerobic heterotroph

 aerobic autotroph  anaerobic autotroph
 aerobic and anaerobic autotroph anaerobic autotroph
 aerobic autotroph and heterotroph

 evolution = changes in organisms through time
 occurs in populations of organisms, not individuals
Lamarck’s Theory
 He believed in two principles: o Use and disuse o
Inheritance of acquired characteristics.
 Use and Disuse
1. New structures arise because they are needed .
2. Structures already present become better developed due to frequent use
3. Structures that are not used decrease in size and eventually disappear .
 Inheritance of acquired characteristics o Structures that were acquired or became more developed are passed on to the next generation.
Charles Darwin – The Beginning of Modern Evolutionary
Thought
 Darwin and Wallace proposed the theory of natural selection at about the same time (mid-1800s)
 Voyage of the Beagle and writing of The Origin of Species in 1859 made Darwin famous
What Darwin Saw:
 Many of the plants and animals seen on the islands were similar to those seen on mainland in South America
 How did they get out to the islands? Darwin had a theory… o Once the animals got on the islands they reproduced , and eventually their offspring became different than the original mainland animals o Even from island to island in the Galapagos animals were not the same (ex: turtles had different shells) o So what happened?
 Darwin is most famous for studying the beaks of finches o
He noticed that their beaks were different sizes and shapes o Each bird’s beak was suited to the type of life it led o If their beak was sharp and needle like  insects o If their beak was strong and wide  seeds o
These are all adaptations : a trait that helps an organism to survive and reproduce
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Darwin believed:
A. Descent with Modification
 newer species appearing in the fossil record are actually modified descendants of older species
B. Modification by Natural Selection
 Natural Selection o the environment acts as the selecting agent, determining which variations are helpful and which are harmful. Who will survive and who won’t.
 Fur for colder climates/ White fur for snowy areas etc. /Needles on cactus
 Survival of the Fittest o naturally occurring variations among the members of the population make some of them better adapted to the environment so they survive.
 Overpopulation o all organisms over-produce offspring (more offspring are produced within a population than can possibly survive)
 Competition o there must be competition between organisms for natural resources (food, water, space) o this is needed for survival o competition keeps the population under control
 Reproduction o individuals with helpful variations reproduce and pass the variations on to their offspring
 Speciation o eventually a new species develops as variations accumulate in a population over many generations.
 Environment determines which organisms, through natural selection, will survive!
 Darwin and Lamarck realized that organisms had to adapt in order to survive
 Darwin realized that variations within organisms made some better able to survive than others
 Lamarck’s mistake was that he tried to explain variations arose from a need
 The modern theory also expresses the idea that variations with a positive or high survival value increase within the population as more individuals with these traits survive
 variations with a negative or low survival value decrease within the populations as organisms with those traits die off
How variations can occur?
A.
Geographic Isolation
B.
Reproductive Isolation
 Geographic Isolation o separation of a small group from the main population due to natural barriers. o Ex: mountains, bodies of water, desert.
 isolation keeps the two populations from interbreeding and different traits may become favorable.
 3 factors which may be involved in the evolution of a new species o
Founder effect - differences in populations may have been present already o Different mutations occur in both populations o
Different environments exert different selection pressures on each population
 Ex: animals of Australia
 Reproductive Isolation o members of the same species become so different that they no longer interbreed and produce fertile offspring o they have now become a new species- speciation

2.1 Recap
1. Can evolution occur in individuals? No
2. (a) What is an example of an acquired characteristic? buff muscles; longer necks; tattoos; pierced ears
(b) Can it be passed on to offspring? No
3. According to the theory of Use and Disuse, what part of our bodies became smaller? tailbone; appendix
4. What were the 5 steps for modification to happen by natural selection according to Darwin? o survival of the fittest o overpopulations o competition o reproduction o speciation
5. What happened to the finches in Galapagos? evolved
Regents Questions:
_____1. The spotted touch-me-not, a flowering plant, has seed pods that burst open when touched and forcefully eject their seeds. Such an adaptation is favorable because it
1. aids in the dispersal of the species. 3. prevents germination within the seed pod.
2. attracts insects that aid in pollination. 4. can cause genetic changes to occur.
_____2. According to Darwin's theory of evolution, differences between species may be the result of
1.
the disuse of body structures
2.
the transmission of acquired characteristics
3.
natural selection
4.
mutagenic agents
_____3. The concept that species have changed over long periods of time is known as
1.
ecology 3. spontaneous generation
2. embryology 4. organic evolution
_____4. Which concept was not included in Charles Darwin’s theory of natural selection?
1.
survival of the fittest 3. overproduction of offspring
2. struggle for existence 4. punctuated equilibrium
_____5. Darwin's theory of evolution is based on the concept of
1.
use and disuse 3. natural selection
2.
mutations 4. hybridization
_____6. Even though the environment changes, a population that occupies a given geographic area will most likely continue to be found in this area if the
1.
variations in the population decrease over time
2.
members of the population decrease in number
3.
members of the population exceed the carrying capacity
4.
population passes on those genes that result in favorable adaptations
_____7. Which concept is not a part of the theory of evolution?
1. Present-day species developed from earlier species
2. Some species die out when environmental changes occur
3. Complex organisms develop from simple organisms over time
4. Change occurs according to the needs of an individual organism to survive
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The Fossil Record
 remains of organisms = fossils
 present in sedimentary rock
 formed by: a.
preservation of whole organism
 amber, ice, tar b.
preservation of hard parts
 shells, bones, stems, teeth c.
petrified
 mineral replacement d.
sedimentation
 buried, leaving imprint, mold, caste
 1668- Robert Hooke proposed that fossils are the remains of plants and animals
Distribution of Fossils
 1669- Nicolaus Steno proposed the Law of Superposition : layers of rock or soil are deposited on top of the one another by water or wind
 oldest undistributed layers are near the bottom ; youngest are at the top ; layer are about the same age
 this established the relative age of fossil evidence
 absolute (actual) age established using C-14 or other isotopes
fossils within the same
Grand Canyon
 sedimentary rocks from 200 million to 2 billion years old
 oldest sediments found at the bottom
 youngest found at the top
 fossils reveal: o changes in life over time o changes in climate over time
Homologous Structures: Comparative Anatomy
= body parts with same origin and structure but different functions o demonstrates common ancestry and genetic relationships ex. beaks of birds ex. forelimbs of penguin, alligator, bat and human o why different in function? different survival needs

 analogous structures
= similar structures with identical functions that have no anatomical or embryological similarities ex. bird wing and insect wing
 vestigial organs
= organs useful in an ancestor, but useless in a modern species
In humans: ex. coccyx ; nictitating membrane; appendix
 similarities in embryos: Comparative Embryology o
“ontogeny recapitulates phylogeny” o sign of common ancestry
 similarities in chemical makeup: Comparative Biochemistry o all have DNA/RNA similar organic compounds, organelles o closer the relationship, closer the protein structure o ex. similarity between hemoglobin molecules in various organisms
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2.2 Recap
1. How do scientists know evolution happened? fossils
2. The oldest sediments are found at which layer of soil? bottom
3. What do fossil records reveal? changes in organisms; change in climate
4. What are homologous structures? same basic structure, different functions
5. Similarities in the chemical makeup is called comparative biochemistry
Regents Questions:
_____1. Two nucleotide sequences found in two different species are almost exactly the same. This suggests that these species
1.
are evolving into the same species
2.
contain identical DNA
3.
may have similar evolutionary histories
4.
have the same number of mutations
_____2. The study of homologous structures in mature organisms provides evidence for the evolutionary relationships among certain groups of organisms. Which field of study includes this evidence of evolution?
1.
comparative cytology
2.
biochemistry
3.
geology
4.
comparative anatomy

_____3. The diagram below shows undisturbed sedimentary strata at the bottom of an ocean. The fossils found in layer B resemble the fossils found in layer A. This similarity suggests that
1.
the fossils in layer B were formed before the fossils in layer A
2.
modern forms of life may have evolved from earlier forms of life
3.
vertebrate fossils are only found in sediments
4.
the fossils in layer A must be more complex than those in layer B
_____4. The diagram below represents a section of undisturbed layers of sedimentary rock in New York
State and shows the location of fossils of several closely related species. According to currently accepted evolutionary theory, which is the most probable assumption about species A, B, and C?
1.
Species B is more abundant than species C.
2.
Species C existed before species B.
3.
Species A and B are genetically identical.
4.
Species B descended from species A.
_____5. The biochemical analysis of different chlorophyll pigments in plants would be most useful in determining
1.
how plants reproduce asexually
2.
how plants pass favorable traits to their offspring
3.
why some plants produce hemoglobin
4.
which plants might have a common ancestor
_____ 6. Characteristics of a species that make its members better able to live and reproduce in their environment are known as
1. favorable adaptations
2. abiotic factors
3. homologous structures
4. biotic factors
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 coevolution
= change of two or more species in close association with each other ex. plants and pollinators
 convergent evolution
= organisms in same environment adapt in a similar manner to that environment ex. shark and porpoise
 divergent evolution
= two related species become more and more different in response to differing habitats o adaptive radiation ex. evolution of marsupials of Australia from a common ancestor; Galapagos finches o artificial selection ex. selectively breeding dogs
Regents Questions:
_____1. Structures having a similar origin but adapted for different purposes, such as a flipper of a whale and arm of a human, are called
1. homozygous structures
2. homologous structures
3. identical structures
4. embryological structures
_____2. The constant change in the kinds and frequencies of genes in a population over a period of time is a modern definition of
1. a gene pool 2. evolution 3. Mendelian heredity 4. genetics
_____3. The fact that humans and sheep have similar hormones suggests that humans and sheep
1. are members of the same species 3. have similar nucleic acids
2. share the same environment 4. appeared on Earth at the same time
_____4. The leg structures of many different vertebrates are quite similar in number and location of bones.
Most scientists would probably explain this on the basis of
1. need of the organism
2. common ancestry
3. chance occurrence
4. inheritance of acquired traits
_____5. Some starfish larvae resemble some primitive chordate larvae. This similarity may be used to suggest that primitive chordates
1. share a common ancestor with starfish
2. evolved from modern-day starfish
3. evolved before starfish
4. belong to the same population as starfish
_____6. According to modern evolutionary theory, genes responsible for new traits that help a species survive in a particular environment will usually
1. not change in frequency
2. decrease gradually in frequency
3. decrease rapidly in frequency
4. increase in frequency
_____7. Differences between the members of a population will most likely be passed to future generations if they are
1. due to genetic changes and result in unfavorable variations
2. due to genetic changes and result in favorable variations
3. not due to genetic changes and result in unfavorable variations
4. not due to genetic changes and result in favorable variations
_____8. Although similar in many respects, two species of organisms exhibit differences that make each well adapted to the environment in which it lives. The process of change that may account for these differences is
1. evolution
2. germination
3. regenerating lost structures
4. transmitting homologous structures

_____9. According to the theory of natural selection, why are some individuals more likely than others to survive and reproduce?
1. Some individuals pass on their offspring new characteristics they have acquired during their lifetimes.
2. Some individuals are better adapted to exist in their environment than others are.
3. Some individuals do not pass on to their offspring new characteristics they have acquired during their lifetimes.
4. Some individuals tend to produce fewer offspring than others in the same environment.
_____11. The similarity among the blood proteins of all the mammals may be taken as evidence for evolutionary relationship based upon
1. comparative anatomy
2. geographic isolation
3. comparative embryology
4. comparative biochemistry
_____12. The presence of gill-like slits in a human embryo is considered to be evidence for the
1. theory that fish and mammals have a common ancestry
2. theory that the first organisms on earth were heterotrophs
3. close relationship between fish and mammalian reproductive patterns
4. close relationship between humans and annelids
______13. If a fossil mammoth were discovered frozen in ice, its cells could be analyzed to determine whether its proteins were similar to those of the modern elephant. This type of investigation is known as comparative
1. anatomy 2. embryology 3. biochemistry 4. ecology
_____14. Structural and physiological changes within a species occur over an extended period of time. These changes appear to be the product of the natural selection of favorable traits within that species. These statements best describe the concept of
1. spontaneous generation
2. reproductive isolations
3. homeostasis
4. evolution
_____15. A bird’s developmental stages resemble those of a reptile. This observation is often used to illustrate the probable common ancestry of those organisms through the study of
1. comparative biochemistry
2. comparative embryology
3. punctuated equilibrium
4. natural selection
_____16. Which is an example of evidence of evolution based on comparative biochemistry?
1. Sheep insulin can be substitute for human insulin.
2. The structure of a whale’s flipper is similar to that of a human hand.
3. Human embryos have a tail-like structure at one stage in their development.
4. Both birds and bats have wings.
_____17. Biochemical analysis has shown that hemoglobin molecules found in monkeys are very similar to those found in humans. Which concept is supported by this analysis?
1. Homologous structures exist in all vertebrates.
2. Embryonic development in humans and monkeys is identical.
3. Monkeys are humans have a common ancestor.
4. Invertebrates and vertebrates have a common ancestor.
_____18. A large population of cockroaches was sprayed with a newly developed, fast-acting insecticide. The appearance of some cockroaches that are resistant to this insecticide supports the concept that
1. species traits remain constant
2. insecticides cause mutations
3. variation exists within a species
4. the environment does not change
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_____19. The bones in the forelimbs of three mammals are shown below.
For these mammals, the number, position, and shape of the bones most likely indicates that they may have
1. developed in a common environment
2. developed from the same earlier species
3. identical genetic makeup
4. identical methods of obtaining food
_____20. A man lifts weights an develops large arm muscles. His son has larger muscles than his father had at the same age. According to Lamarck’s theory, this situation is due to
1. competition between father and son 3. inheritance of acquired characteristics
2. survival of the fittest 4. mutagenic agents
Base your answers to questions 21 through 23 on the information below.
Based on their analysis of the differences in amino acid sequences of one kind of protein, scientists prepared the evolutionary tree shown below.
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_____21. According to this diagram, the DNA of which pair of organisms would show the greatest similarity?
1. penguin and turtle 2. horse and donkey 3. snake and tuna 4. turtle and rabbit
22. Older systems of classification always placed penguins, chickens, ducks, and pigeons in the bird group and turtles and snakes in the reptile group. Does this diagram support the older system of classification? Explain your answer.
No, turtle is more related to birds than snakes... turtles are closer to birds on the tree.
23. According to this diagram, is the pig more closely related to the dog or the kangaroo?
Justify your answer.
Dog- closer together on the tree.

Short Answer Regents Questions:
Base your answers to questions 1 and 2 on the finch diversity chart below, which contains information concerning the finches found on the Galapagos Islands.
1. Identify one bird that would most likely compete for food with the large tree finch.
Support your answer. [1] small tree finch or wood pecker... same food source.
2. Identify one trait, other than beak characteristics, that would contribute to the survival of a finch species and state one way this trait contributes to the success of this species. [2] fast speed- get food faster.
Base your answers to questions 3 and 4 on the information below.
In birds, the ability to crush and eat seeds is related to the size, shape, and thickness of the beak. Birds with larger, thicker beaks are better adapted to crush and open seeds that are larger.
One species of bird found in the Galapagos Islands is the medium ground finch. It is easier for most of the medium ground finches to pick up and crack open smaller seeds rather than larger seeds. When food is scarce, some of the birds have been observed eating larger seeds.
3. Describe one change in beak characteristics that would most likely occur in the medium ground finch population after many generations when an environmental change results in a permanent shortage of small seeds. [1]
The finch will have large, thicker beaks.
4. Explain this long-term change in beak characteristics using the concepts of:
 competition [1]
 survival of the fittest [1]
 inheritance [1]
 Finches will start competing for the large seeds
 Finches with large beaks will be better adapted & survive (survival of the fittest)
 Offspring of these finches will inherit the large beak gene
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Base your answers to questions 5 through 8 on the passage below.
Evolution of Antibiotic-Resistant Bacteria
Some scientists are concerned about the overuse of antibiotic drugs. Since the discovery of the first antibiotic, these drugs have been widely used in the treatment of many types of bacterial infections, such as tuberculosis, gonorrhea, strep throat, and some types of pneumonia. Today, antibiotics are sometimes given to livestock in their food to help prevent certain infections. This widespread use of antibiotics is believed to have accelerated the occurrence of antibiotic-resistant forms of bacteria.
These resistant bacteria are increasing in number because of their adaptive advantage. In addition, non-resistant bacteria die due to the presence of antibiotics. The reduction in the number of nonresistant bacteria results in increased numbers of resistant bacteria, since they do not have to compete with the nonresistant bacteria.
Another factor that accounts for increasing numbers of antibiotic-resistant bacteria is the passing of genes for this resistance between resistant and nonresistant forms. This transfer of genes occurs when plasmids, round DNA fragments formed in the cytoplasm of bacteria, are exchanged when bacteria come in contact with one another.
_____5. An adaptive advantage that some types of bacteria have is their
1. ability to cause disease 3. ability to secrete antibiotics
2. resistance to certain antibiotics 4. resistance to certain infections
_____6. What usually happens when nonresistant bacteria die due to the presence of antibiotics?
1. resistant bacteria become nonresistant
2. treatment of bacterial infections becomes unnecessary
3. infections in livestock do not occur
4. resistant bacteria increase in number
_____7. Resistance to antibiotics may be genetically transmitted to nonresistant forms of bacteria by
1. infections such as tuberculosis 3. the exchange of plasmids
2. the overuse of antibiotics 4. food given to livestock
8. Using one or more complete sentences, state one bacterial trait that will increase in frequency when antibiotic use is widespread.
Resistance to antibiotics will increase in frequency.
_____9. When the antibiotic penicillin was first introduced, it was immediately effective in combating staphylococcus bacterial infections. After a number of years, there were outbreaks of staphylococcal infections that did not respond to treatment with penicillin. The best explanation for this situation is that
1. members of the original population of bacteria that were penicillin resistant survived and reproduced, creating a more resistant population
2. the bacteria that survived exposure to penicillin learned to avoid it
3. the bacteria that caused the new outbreaks were from populations that had never been exposed to penicillin
4. during each generation, the bacteria modified their own DNA to increase their ability to resist penicillin and passed this ability on to their descendants
_____10. When penicillin was first introduced, it was very effective in destroying most of the bacteria that cause gonorrhea. Today, certain varieties of this bacterium are resistant to penicillin. Which statement best explains the appearance of these resistant varieties?
1. Penicillin stimulated the bacteria to become resistant, and this resistance was passed to the offspring.
2. Penicillin killed the susceptible bacteria, while naturally resistant varieties survived and reproduced.
3. Penicillin used today is not as strong as the penicillin used when it was first introduced.
4. Penicillin stimulated the production of antigens in the resistant bacteria.

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