AP Bio Unit 1 Study Gudie

7/29/2019 AP Bio Unit 1 Study Gudie

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AP Biology Unit 1 Study Guide

Chapter 22

1) What did Darwin mean by decent of modification?

Darwin meant that todays species are descendants of ancestral species which were different from the present-day species.

2) List and describe some types of evidence that are used to support the theory of evolution.

The fossil record shows that past organisms differed from present day organism and that may species have become extinct over

time. Georges Curvier, a French scientist, discovered that the deeper the layer in which the fossils are buried the more different

they were from present fossils.

Color patterns of male guppies correspond to the intensity of predation. For example, in pools with few predators, male guppies

tend to be brightly colored. However in pools with many predators, male guppies tend to be less brightly colored. This shows

that selection can cause rapid evolution in wild populations.

The drug-resistance of pathogens, bacteria, and viruses is another example. Scientists have developed drugs to combat HIV.

However some viruses may survive, reproduce, and pass on the alleles that enable them to resist the drug.

The forelimbs of all mammals show the same arrangement of bones from the shoulders to the tips of the digits although they

have different functions for different mammals. These homologous structures suggest that all organisms have a common

ancestor.

3) Briefly explain how natural selection works. Give one example.

Natural selection is a process in which individuals with more favorable inherited traits leave more offspring than individuals with

other traits. The finches in the Galapogos Islands serve as an excellent example. Whenever the environment became arid,

finches that had bigger beaks could eat the hard seeds which were the only food available. As a result, they were able to survive

and reproduce. This proves that over time, nature selects the best adapted individuals because they have more favorable

characteristics are more likely to survive, to reproduce, and to pass on their traits.

4) Using an example, define microevolution.

Microevolution is the change of allele frequencies over generations. An example would be the change in color of the pepperedmoths over generations due to environmental changes.

5) In your own words, define Hardy-Weinberg equilibrium.

Hardy-Weinberg equilibrium is the state when the allele and genotype frequencies of a population remain constant over

generations.

6) What are the conditions a population must meet in order to maintain Hardy-Weinberg equilibrium.

There can be no mutations in the population because they modify the gene pool.

There can be no natural selection because the differences in reproductive success and genotypes can alter allele frequencies.

There can be no gene flow because it also alters allele frequencies.Random mating must occur to ensure that genotype frequencies dont change.

There must also be a large population to decrease the chance of having fluctuating allele frequencies.

7) What five factors can cause microevolutionary change in a population? Describe the effect of each one.

Mutations in the population modify the gene pool.

Natural selection causes differences in the reproductive success of individuals with different genotypes can alter allele

frequencies.

Gene flow also alters allele frequencies.

Random mating must occur to ensure that genotype frequencies dont change. IfIf individuals keep on interbreeding, the

gametes will not randomly mix and the genotype frequency will change.

The size of the population determines whether or not the allele frequencies are going to fluctuate.

8) How is variation within a population related to natural selection?

Natural selection selects the species with the more favorable traits from the variations within a population. An example would

be the peppered moths with the variation of color. Before the Industrial Revolution, most moths were white and were hidden by


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the light-colored trees, while the dark moths were easily seen by predators. However after the pollution from the Industrial

Revolution swept over the trees, the white moths were exposed under the dark-colored trees. Hence, the black moths were

more successful in reproducing in the end because less black moths were eaten.

9) What are three modes of natural selection? How are they distinguished from each other?

Directional selection occurs when conditions favor individuals exhibiting one extreme of a phenotypic range and therefore

shifting the curve and overall make-up of the distribution.

Disruptive selection occurs when conditions favor individuals at both extremes of the distribution.

Stabilizing selection acts against both extreme phenotypes from the population and favors intermediate variants.

Chapter 23

10) What is the most commonly used definition of a species?

A species is a population or group of populations whose members are able to interbreed and have fertile offspring.

11) What is meant by speciation?

Speciation is the biological process by which new species arrive for other existing species. Speciation is responsible for the huge

diversity of life on earth.

12) What are five prezygotic isolating mechanisms? Give an example of each.

The five prezygotic isolating mecahnisms are habitat, temporal, behavioral, and mechanical isolation. Habitat isolation occurs

when two different species live in the same area but in different habitats. An example would be two species of garter snakes,

one living in the water, the other living on land.

Temporal isolation occurs when species have different times of breeding and therefore cannot mix their gametes. An example

would be the skunks in North America, which one species mate in the winter and the other in the summer.

Behavioral isolation occurs when courtship rituals are only unique to a species. This means that individuals of a certain species

would only mate other from the same species.

Mechanical isolation occurs when mating is attempted but is not successful because the reproductive organs cant come

together. An example would be two species of snails with different spiral directions and the genital openings cannot be aligned.

Gametic isolation occurs when the sperm of one species cannot fertilize the eggs of another species. An example would be two

species of sea urchins failure to reproduce because the surfaces of the eggs and sperm cannot bind to each other.

13) What are three postzygotic isolating mechanisms? Give an example of each.

The three postzygotic isolating mechanisms are reduced hybrid viability, reduced hybrid fertility, and hybrid breakdown.

Reduced hybrid viability occurs when genes of different parent species interact in ways that impair the hybrids development or

survival in its environment. An example would be a liger because they are more prone to predation due the color of its coat.

Reduced hybrid fertility occurs when the two parent species produce an infertile hybrid. An example would a horse and a

donkey producing a mule. Hybrid breakdown occurs when the first generation of hybrid is fertile, but the second generation is

infertile. An example would be cultivated rice strains.

14) What is the difference between sympatric speciation and allopatric speciation?

Sympatric speciation occurs in populations of different species that live in the same geographic area, while allopatric speciation

occurs when a population is divided into geographically isolated subpopulations.

15) Give a definition of adaptive radiation.

Adaptive radiation is a period of evolutionary change in which groups of organisms form many new species which are adapted to

fill different ecological roles in their communities.

16) What are the major differences between the two schools of thought about the tempo of speciation, gradualism, and

punctuated equilibrium?


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Gradualism is the view that speciation proceeds by small cumulative steps over long periods of time rather than abrupt major

changes. However, punctuated equilibrium is the view that speciation occurs suddenly over short periods of time followed by

long periods of inactivity.

Chapter 24

17) In your own words, define macroevolution.

Macroevolution is a large-scaled evolution that happens a long period of time. An example would be the evolution from apes to

humans.

18) Describe the most common method for absolute dating of rocks and fossils.

One of the most common methods for absolute dating is radiometric dating, which is based on the decay of radioactive isotopes.

An original radioactive isotope decays the stable product. The rate of decay is expressed by the half-life which is the time for 50%

of the parent isotope to decay.

19) Describe how each of the following could be a mechanism of macroevolution: allometric growth (delayed maturity),

continental drift, tectonic trauma, mass extinction, and impact hypothesis.

Allometric growth is the differences in relative rates of growth of various body parts. This results is that an adult structure isshaped differently that its juvenile state. It involves the timing of genes. A single mutation in the genes may result in a new

species. For example, different allometric patterns contribute to the contrast of adult skull shapes of humans and chimpanzees.

Continental drift is the slow movement of Earths continents over time. Continental drift can be used to predict where fossils of

different groups of organisms from millions of years ago might be found Since macroevolution is concerned with the major

events of life in history from the fossil record, continental drift can be a mechanism of macroevolution. Tectonic trauma is

associated with volcanoes and earthquakes. It can influence the distribution of organism and greatly affect the history of life by

possibly triggering extinctions and diversification of organisms. Mass extinction is the period of time when global environmental

changes lead to the elimination a large number of species. Mass extinction shapes the overall pattern of macroevolution as

shown in the history of life where many mass extinctions have occurred. The impact hypothesis refers to the theory that a

meteorite hit the earth millions of year ago and brought the dinosaurs to extinction. This explains the mass extinction of

dinosaurs and also macroevolution in the history of life.

20) How are systematics and phylogenies related?

Systematics is the discipline focused on classifying organism and determining their evolutionary relationships. Phylogeny is the

evolutionary history of a species or a group of species. After studying phylogeny, systematics can be used to show how the

species are related according to the history of the species.

21) What is the difference between homologous and analogous structures?

Homologous structures are structures in different species that are similar, which suggests that they have common ancestors.

However analogous structures are structures that are similar in appearance and function but are not the result of common

ancestry.

22) What is convergent evolution?

Convergent evolution is the evolution of similar features in different lineages.

23) Briefly explain how is molecular biology is used in the development of phylogenies.

By comparing nucleic acids or molecules in molecular biology, scientists have discovered phylogenetic relationships that cannot

be determined by nonmolecular methods. Molecular biology has also helped in reconstructing phylogenies among groups of

present day prokaryotes and microorganism that have no fossil record.

Chapter 25

24) Describe Miller and Ureys experiment. Why is it considered so important?


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The Miller and Urey Experiment attempted to create the early Earths atmosphere to test whether organic molecules could arise

under conditions thought to have existed on the early Earth. Miller and Urey simulated conditions that were thought to have

existed on the early Earth, such as an atmosphere of no oxygen and lightning. After sparks were discharged amino acids and

nucleotides were form, which suggests that this may be how life on earth started.

25) What other steps must be explained if life (living cells) did evolve from non-life?

The abiotic synthesis of small organic molecules, such as amino acids and nucleotides, and the joining of these molecules must

occur in order for life to evolve from nonliving material. The packaging of these molecules into protobionts or droplets withmembranes that maintained themselves must be formed. The origin of self-replicating molecules must then occur to make

inheritance eventually possible.

26) What unique characteristics disthinguish the archaebacteria from the eubacteria?

Archaebacteria are one of the oldest organism found on earth. They are prokaryotes and are found under extreme conditions.

Eubacteria are the ones we refer to as bacteria. They are more complex in structure and are found in neutral conditions. They

also have a peptidoglycan layer which is unique to only eubacteria.

27) How are the hypotheses of membrane infolding and endosymbiosis related to the evolution of eukaryotic cells?

These two hypotheses explain how eukaryotic cells were first formed. The infolding of the membrane possibly formed the

endoplasmic reticulum and golgi apparatus of the eukaryotic cell. The endosymbiosis theory suggests that mitochondria and

chloroplast were originally small prokaryotes that were taken in into eukaryotic cells.

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AP Bio Unit 1 Study Gudie