Bio exam 1

Some human populations have the trait

"the ability for skin to change color" is due to (historic) selection, so that trait is an adaptation.

Evolution is a grand hypothesis

(a "theory") that explains many many patterns we observe.

natural selection needs variation

(a) heritable (b) variation that (c) affects reproductive success. Selection is an automatic consequence of (a) + (b) + (c) After time, variation fades over time

Special creation and evolution are different processes

, and lead to different patterns

to control

- control by keeping constant (including only a certain age group) - control by randomization (make groups and randomly place people in them and that way there would be little difference in the groups) - control by pair-matching (for each individual in group #1, put a similar individual in group #2)

Special creation:

-the process happened only once (that's why it's special creation) -there is NOT kinship between species -species do NOT change over time -a long time is NOT required

Evolution:

-the process is still happening today -there is kinship between species -species change over time -a long time is...sorta required. (Evolution can be quick, but to create the diversity of life today takes a long time.)

What is the difference between a hypothesis and a prediction? A hypothesis is an idea; a prediction is something that follows from a hypothesis and that you can measure Hypotheses are contingent (="truth with a little t") -- predictions are known facts Predictions can be tested; hypotheses cannot There is no difference -- the two terms are interchangeable Hypotheses can be tested; predictions cannot

A hypothesis is an idea; a prediction is something that follows from a hypothesis and that you can measure

What is a genetic locus? An allele of a gene. A gene with more than one allele. A particular position on a chromosome. A chromosome that contains genes.

A particular position on a chromosome.

In biology (and in science in general), what does the word theory mean? A computer simulation, mathematical model, or other abstraction (as opposed to experimental or other types of "hard data"). An idea that has been tested, but is still controversial--not yet considered an accepted fact. A conjecture or untested idea. A proposed explanation for a general phenomenon--a hypothesis relevant to a big question.

A proposed explanation for a general phenomenon--a hypothesis relevant to a big question.

What's a gamete? (Note that this term is used in the reading but not explicitly defined. If you need to, you can look it up in the glossary--the green-tipped pages in the back of the book.) A listing of the alleles present in an offspring (F1 or F2). A listing of the alleles inherited from a particular parent (mother or father). The genotype of a sperm or egg. A reproductive cell (sperm or egg).

A reproductive cell (sperm or egg).

What is a model organism? A species that is easy to work on (e.g. cheap to get and maintain, lots of offspring, etc). The organism that was first worked on in a particular field of biology. A simulated organism (experiments done via computer simulations). A species that is easy to work on. Also, results from this species are relevant to many other species.

A species that is easy to work on. Also, results from this species are relevant to many other species.

What is an autosomal trait? A continuous trait (one that takes many possible values). A discrete trait (one with distinct types only). A trait associated with a gene on a sex chromosome (either X or Y). A trait associated with a gene on a non-sex chromosome.

A trait associated with a gene on a non-sex chromosome.

How would you test whether the variation is heritable?

A trait is heritable if there is a correlation between the parent's trait and the offspring's trait. Eg, you could test whether height is heritably by graphing "parent height" vs "offspring height" and checking for a correlation.

In biology, what does the word adaptation mean? The ability to change in response to environmental change. A trait that is derived from an ancestor, analogous to a movie adapted from a book. A non-random trait that makes individuals stronger and more dominant. A trait that increases fitness in a certain environment.

A trait that increases fitness in a certain environment.

What's the difference between a chromosome and a chromatid? After replication, a chromosome consists of two chromatids. When a chromosome consists of two chromatids, chromosome number doubles. Sister chromatids are identical. The chromatids of homologous chromosomes may not be identical.

After replication, a chromosome consists of two chromatids.

What's the difference between a gene and an allele? An allele can be dominant or recessive; a gene can only be dominant. An allele is what the individual looks like; a gene is what the underlying genetic instructions are. Genes reside in parents; alleles are passed to offspring. An allele is a version of a gene.

An allele is a version of a gene.

What is cytokinesis? Correct! Cell division (usually follows mitosis and meiosis) "Cell-moving"--when cells change position during development. Another name for meiosis (refers to either meiosis I or meiosis II) Another name for mitosis

Cell division (usually follows mitosis and meiosis)

Which of the following happens during interphase, before mitosis or meiosis? The nuclear envelope breaks down (this has to happen so that spindle fibers can contact the chromosomes). Chromosomes replicate (each consists of two sister chromatids). The spindle apparatus forms. Chromosomes condense (so that they can move without getting tangled up).

Chromosomes replicate (each consists of two sister chromatids).

What does the process component of the theory of natural selection state? Evolution occurs because individuals with certain heritable characteristics produce the most offspring. Evolution occurs because individuals change in response to changes in the environment. Populations may change due to natural selection, but species do not. Evolution is random--not progressive.

Evolution occurs because individuals with certain heritable characteristics produce the most offspring.

Which of the following is always correct? F1s are heterozygous; F2s are homozygous recessive, homozygous dominant, and heterozygous There are more individuals in the F2 generation than the F1. F1s are the first generation in an experimental cross; F2s are the second. F1s have a 3:1 ratio of phenotypes; F2s have a 9:3:3:1 ratio.

F1s are the first generation in an experimental cross; F2s are the second.

What's the difference between a haploid cell and a diploid cell? Haploids are produced by meiosis; diploids are produced by mitosis. Haploids have one of each type of chromosome; diploids have two of each type. On average, haploids have half the fitness of diploids. Only sperm and eggs are haploid.

Haploids have one of each type of chromosome; diploids have two of each type.

What was important about the experimental design for Pasteur's flask experiment? He altered many variables at one time so he could learn the most from his experiment He compared results from two experimental setups which differed only in the type of flask in which the nutrient broth was placed He compared results from two experimental setups that were both designed to block exposure to pre-existing cells He compared results from two experimental setups that were both designed to allow exposure to pre-existing cells

He compared results from two experimental setups which differed only in the type of flask in which the nutrient broth was placed

Which of the following characterizes a recessive allele? If environmental conditions vary, its phenotype varies in response. It is the least common allele in the population. It is the allele that confers lower fitness. Heterozygotes don't show its phenotype.

Heterozygotes don't show its phenotype.

Which of the following characterizes a dominant allele? Heterozygotes show its phenotype. Even if environmental conditions vary, its phenotype does not. It is the allele that confers highest fitness. It is the most common allele in the population

Heterozygotes show its phenotype.

X and Y chromosomes follow the principle of segregation. What does this mean? They are physically separated (segregated). If an individual is XY, then each gamete gets one X or one Y. In mammals, females are XX and males are XY. At prophase of meiosis I, X and Y synapse and crossing over occurs.

If an individual is XY, then each gamete gets one X or one Y.

What does it mean to claim that an acquired character is passed on to offspring? The characteristics of species change when they need to, to ensure survival. If an individual's traits change during its lifetime, its offspring have the new version of trait. When giraffes stretch their necks to reach leaves high in trees, their necks get longer. Genetic characteristics don't change in response to changes in the environment.

If an individual's traits change during its lifetime, its offspring have the new version of trait.

What does it mean to say "an acquired character can be inherited"? Offspring tend to resemble their parents, because they usually experience an environment similar to their parents' environment. If an individual's traits change over the course of its lifetime, those changes will be passed on to offspring. Offspring tend to resemble their parents. An individual's phenotype can be transformed over time, in response to changes in the environment.

If an individual's traits change over the course of its lifetime, those changes will be passed on to offspring.

Why is it important that they assigned trees to the infected versus uninfected groups at random? Otherwise, it would not be possible to collect cones and determine the number of seeds being produced is the only way to make sure that the same number of individuals end up in the treatment and control groups It allowed them to collect data on a large number of individuals, resulting in a large sample size If assignment was not random, the result could be do to something other than the difference in infection

If assignment was not random, the result could be do to something other than the difference in infection

Which of the following is a prediction based on the cell theory that all organisms are made of cells, and all cells come from preexisting cells? Cells are produced only from pre-existing cells Cells arise spontaneously from nonliving material If you boil nutrient broth and place it in an air-tight flask, no cells will appear in the broth If you boil nutrient broth and place it in an air-tight flask, cells will appear in the broth

If you boil nutrient broth and place it in an air-tight flask, no cells will appear in the broth

"theory"

In biology, it means a grand hypothesis or group of hypotheses (eg: the theory of gravitation, germ theory, the heliocentric theory, the theory of evolution)

"adaptation"

In biology, it means a trait that is the result of evolution by natural selection.

"fitness"

In biology, it means the ability to survive and have many successful offspring.

Which of the following is the most important difference between the events of prophase in mitosis versus meiosis I? In mitosis, crossing over occurs between sister chromatids. In meiosis I, homologs synapse. In mitosis, sister chromatids separate. In mitosis, the nuclear envelope breaks down and the spindle fiber forms

In meiosis I, homologs synapse.

The top graph in Figure 22.13 (5th edition: 25.16) indicates that beak depth is variable in this population. What evidence did the researchers have that at least some of this variation was heritable? No evidence--the graph only indicates variation in observed size and nothing about the underlying genetics. In the next generation (in offspring of individuals who survived), average beak size was larger. Average beak size shifted within a generation (compare the top and bottom graphs). It is a general observation in biology: if traits vary among individuals, at least some of the variation is due to differences in their genetic make-up.

In the next generation (in offspring of individuals who survived), average beak size was larger.

What does it mean to say that something--like a gene--"segregates"? It is isolated or "pushed to one side." In the case of the gene, one of the alleles present in a parent goes into a gamete while the other is discarded. It divides into two identical halves. It separates. For a gene, it means the two alleles present in a parent separate and go into different gametes. They are ordered according to some criterion. In the case of a gene, the two alleles present in a parent have different fitnesses--one higher and one lower.

It separates. For a gene, it means the two alleles present in a parent separate and go into different gametes.

What's the pattern component of the chromosome theory of inheritance? The behavior of chromosomes during meiosis I. Mendel's rules: the principle of segregation and the principle of independent assortment, because genes are found on chromosomes. If genes are sex-linked, reciprocal crosses do not give identical results. Crossing over produces genetic recombination (new combinations of paternal and maternal alleles on the same chromosome). Linked genes may not follow the principle of independent assortment.

Mendel's rules: the principle of segregation and the principle of independent assortment, because genes are found on chromosomes.

What is "meta" about metaphase? Meta means "end"; metaphase is the final phase, when chromosomes move to the poles of the cell. Meta means "before"; metaphase is the initial phase. Meta means "between"; chromosomes move to the middle of the cell--between the two poles. The metaphase plate consists of densely-packed fibers.

Meta means "between"; chromosomes move to the middle of the cell--between the two poles.

What observations suggest that in environments containing antibiotics, M. tuberculosis individuals experience differential reproductive success based on their degree of resistance? Antibiotic resistance can only be detected in populations that have been exposed to antibiotics. People who are infected with resistant strains of M. tuberculosis do not respond to traditional therapies. Over time, the frequency of resistant individuals increases when patients take antibiotics. Over the course of their lifetime, individuals get increasingly better at resisting antibiotics.

Over time, the frequency of resistant individuals increases when patients take antibiotics.

If a parent's genotype is PpTtLl, what are the gamete genotypes it produces under the hypothesis of independent assortment? PTL, PTl, pTL, pTl, ptL, ptl, PtL, Ptl PP, Tt, Ll PTL, PTl, PtL, Ptl

PTL, PTl, pTL, pTl, ptL, ptl, PtL, Ptl

What does it mean to say that "homologs synapse?" Homologous chromosomes line up on the metaphase plate during metaphase of meiosis I. Pairs of homologous chromosomes physically come together. Homologous chromosomes pull apart during anaphase of meiosis I. When chromosomes replicate, the two sister chromatids are attached (synapsed).

Pairs of homologous chromosomes physically come together.

How do biologists test their ideas about the natural world? Scientists discuss different hypotheses and come to a consensus on the most likely explanation for an observation Scientists make observations about the natural world and generate theories based on these observations Biology is exclusively an observational science, since the high variability between different organisms would lead to irreproducible results Scientists make predictions based on hypotheses they have developed, and then design experiments to test those predictions

Scientists make predictions based on hypotheses they have developed, and then design experiments to test those predictions

How would you test whether the trait affects reproductive success?

See whether there's a correlation between the trait and reproductive success. Eg, if shorter parents tend to have more offspring, then "height" affects reproductive success.

Selection does not cause variation.

Selection acts on variation that already exists in a population.

What observations suggest that in M. tuberculosis, antibiotic resistance is a trait with heritable variation? The trait called antibiotic resistance did not exist until antibiotics came intro widespread use. Some individuals are more resistant to antibiotics than others, and pass this trait on to offspring. Antibiotic is an all-or-none phenomenon--an individual is either resistant or it isn't.

Some individuals are more resistant to antibiotics than others, and pass this trait on to offspring.

What is the pattern component of the theory of special creation? Species are recent, unrelated to each other, and do not change through time. Species change over time in response to changes in their environment. Species change in a progressive manner--meaning that they get larger and more complex over time.

Species are recent, unrelated to each other, and do not change through time.

What is the pattern component of Lamarckian evolution? Species change over time in response to changes in their environment. Species are recent, unrelated to each other, and do not change through time. Species change in a progressive manner--meaning that they get larger and more complex over time.

Species change in a progressive manner--meaning that they get larger and more complex over time.

What is the process component of the theory of special creation? Species were created, instantaneously and independently of each other, by God. Certain individiuals have heritable characteristics that allow them to produce more offspring than individuals without those traits. Individuals change in response to changes in their environment, and pass these changes on to offspring.

Species were created, instantaneously and independently of each other, by God.

In biology, what does the word fitness mean? The ability to survive and reproduce. Muscular tone and strength, ability to run or swim for long periods; overall "buffness" Survival of the fittest, because only the fittest survive. How well an organism matches the demands of its environment.

The ability to survive and reproduce.

What's the process component of the chromosome theory of inheritance? Linked genes may not follow the principle of independent assortment. If genes are sex-linked, reciprocal crosses do not give identical results. Crossing over produces genetic recombination (new combinations of paternal and maternal alleles on the same chromosome). Mendel's rules: the principle of segregation and the principle of independent assortment, because genes are found on chromosomes. The behavior of chromosomes during meiosis I.

The behavior of chromosomes during meiosis I.

What does the pattern component of the theory of evolution by natural selection state? The characterisitcs of populations change over time, in a progressive manner. The characteristics of populations change over time, in response to changes in the environment. Species are static--they change little, if at all, through time. The characteristics of populations may change over time, but the characteristics of species do not.

The characteristics of populations change over time, in response to changes in the environment.

Look at the middle graph in Figure 22.14 (5th edition: 25.17). Why didn't beak size continue to increase, after the 1978 drought? The environment changed, and large-beaked individuals no longer had highest fitness. It did--beak size is now much larger in this population. There was no more heritable variation, so evolutionary change was no longer possible. New mutations led to individuals with smaller beaks.

The environment changed, and large-beaked individuals no longer had highest fitness.

The remaining questions refer to this situation: Researchers do an experiment to test the hypothesis that Douglas fir trees put more resources into reproduction when they are infected with a fungus that causes a fatal disease. They establish study plots in a group of 50-year-old Douglas fir where the disease is not present. At random, they infect half the trees with the disease-causing fungus. Then they measure how many cones and seeds are produced by infected versus uninfected trees. What prediction follows from the hypothesis? The infected trees will produce more seeds than uninfected trees There will be no difference in the number of seeds produced by infected versus uninfected seeds More infected than uninfected trees will die The uninfected trees will produce more seeds then infected trees

The infected trees will produce more seeds than uninfected trees

Which of the following is the correct definition of haploid number? The number of each type of chromosome present. Having unreplicated chromosomes (one chromosome—not two chromatids) The total number of chromosomes present. The number of different types of chromosomes present.

The number of different types of chromosomes present.

Which of the following is the correct definition of ploidy? The total number of chromosomes present. The number of different types of chromosomes present. The number of each type of chromosome present. Having replicated chromosomes (two chromatids—not one chromosome)

The number of each type of chromosome present.

What was the central claim of the theory of blending inheritance? Correct! The physical matter responsible for traits blends within individuals, like pigments in paint. Alleles combine ("blend") at random to form offspring. If traits are modified during an individual's lifetime, they are passed on to offspring in the modified form. The physical matter responsible for traits stays inact, like particles.

The physical matter responsible for traits blends within individuals, like pigments in paint.

What does a ratio report? The relationship between dependent and independent datapoints (numbers) on a graph. A frequency or proportion of occurrence, often expressed as a percent. (Note that the frequencies have to sum to 1.) The relationship between numbers of the same kind (so it is unitless). The relationship between different treatment groups in an experiment.

The relationship between numbers of the same kind (so it is unitless).

Name one variable that is held constant between the two treatment groups. The number of cones and seeds produced The species of disease-causing fungus The species of tree

The species of tree

Darwin & Wallace thought the biological "coincidences" they saw demanded explanation.

Their explanation: the theory of evolution.

In response to studies on "evolution in action"--the observation that hundreds of populations have been observed to change in response to changes in their environments--proponents of the theory of special creation either 1) ignore the data, or 2) argue that they are irrelevant to the question of how large-scale differences among species arose (e.g. how bats came to have wings). As a scientist, how would you evaluate these objections? There is no logical reason to suspect that the process that lead to changes being observed today didn't operate in the past, and that they would not lead to large changes over long time periods. "The present is not a guide to the past"--there is no logical reason to suggest that natural events being observed today also occurred in the distant past. More studies need to be done--you can't draw a general conclusion from many independent studies on different species. It is acceptable to ignore data if they were not collected carefully (e.g. with good experimental controls or comparison groups).

There is no logical reason to suspect that the process that lead to changes being observed today didn't operate in the past, and that they would not lead to large changes over long time periods.

If the hypothesis is wrong, and being infected with the fungus has no impact at all on reproduction, what should they observe? More infected than uninfected trees will die The infected trees will produce more seeds than uninfected trees There will be no difference in the number of seeds produced by infected versus uninfected seeds The uninfected trees will produce more seeds then infected trees

There will be no difference in the number of seeds produced by infected versus uninfected seeds

If "dependent assortment" occurs, how do alleles of different genes behave? All gametes have the same genotype, no matter what the parent's genotype is. In this case, it's only possible for one allele to be present at each gene, instead of two. They segregate (separate) independently of each other. They "stick together" (they are transmitted together--as if they were a single gene).

They "stick together" (they are transmitted together--as if they were a single gene).

Why don't alleles from linked genes assort independently, if no crossing over occurs? They are involved in the same traits, so are transmitted together They are transmitted together (on the same chromosome), instead of being transmitted independently of each other. Crossing over is random, so the closer genes are on the chromosome, the less likely crossing over is to occur. They end up on different chromosomes, so are then transmitted independently of each other.

They are transmitted together (on the same chromosome), instead of being transmitted independently of each other.

Why do alleles from linked genes assort independently, if crossing over DOES occur? They end up on different chromosomes, so are then transmitted independently of each other. Crossing over is random, so the closer genes are on the chromosome, the less likely crossing over is to occur. They are involved in the same traits, so are transmitted together. They are transmitted together (on the same chromosome), instead of being transmitted independently of each other.

They end up on different chromosomes, so are then transmitted independently of each other.

The geologic record and radiometric dating are inconsistent with the theory of special creation. Why? Because radioactive atoms decay at a known rate, the percentage of radioactive atoms in a rock sample can be used to infer the age of the rock. They support the hypothesis that Earth itself and life on Earth are ancient. Geologic processes that are observed today (e.g. volcanoes, sedimentation, erosion) are responsible for landforms created in the past.

They support the hypothesis that Earth itself and life on Earth are ancient.

Genetic, developmental, and structural homologies are inconsistent with the theory of special creation. Why? They support the hypothesis that species are related by common ancestry--meaning that they were not created independently of each other. Developmental homologies are the result of genetic homologies. Genetic homologies can be observed at the level of DNA or proteins or other gene products. Structural homologies are the result of developmental homologies.

They support the hypothesis that species are related by common ancestry--meaning that they were not created independently of each other.

The "law of succession," the presence of vestigial traits, and the fact of extinction are all inconsistent with the theory of special creation. Why? The fossilized species present in an area tend to be similar to species that are still found living in that area. Some species have traits with reduced or no function that are similar to functioning traits in other species. Data in the fossil record indicate that more species have gone extinct than are present on Earth today. They support the hypothesis that the characteristics of species--and the collection of species present--has changed through time.

They support the hypothesis that the characteristics of species--and the collection of species present--has changed through time.

Why is it important to do the experiment in the same group of same-aged trees? So that there is a control treatment in the experiment To eliminate the possibility that the results are due to differences in age, soil, moisture, or other relevant variables Efficiency: they could get an extremely large sample size without a large expenditure of time and money The disease that they are studying is most common in same-aged groups of Douglas fir trees

To eliminate the possibility that the results are due to differences in age, soil, moisture, or other relevant variables

Why is it important to perform multiple trials in an experiment -- meaning that you include many test individuals or samples? To provide a large sample size To provide enough practice to ensure that the experiment was conducted correctly To make it more likely that physical conditions are alike in treatment and control groups To make it more likely that the results are not due to a few unusual individuals or circumstances

To make it more likely that the results are not due to a few unusual individuals or circumstances

What is the relationship between the Great Chain of Being and the process component of Lamarck's theory of evolution? Under Lamarkian evolution, species move up the Great Chain of Being over time. There is none--Plato and Aristotle made no claims about a process component of their theories. The Great Chain of Being is an ancient idea; Lamarck's is more recent. In both cases, the central claim is that species do not change through time.

Under Lamarkian evolution, species move up the Great Chain of Being over time.

When you look at a drawing or photograph of chromosomes, how can you tell if they are replicated or unreplicated? Unreplicated chromosomes consist of a single "thread"; replicated chromosomes have two "threads." Replicated chromosomes are condensed, unreplicated chromosomes are uncondensed. Replicated chromomes consist of two sister chromatids and are diploid. Chromosomes are unreplicated during interphase, but replicated during mitosis and meiosis.

Unreplicated chromosomes consist of a single "thread"; replicated chromosomes have two "threads."

We see if DEPENDENT variables depend on INDEPENDENT variables.

We see if OUTCOME variables depend on MANIPULATED variables.

Today, biologists boil Darwin's four postulates down to two conditions that result in evolution. What are these conditions? When 1) more offspring are produced than can survive, and 2) the offspring that survive best and reproduce most are a non-random sample of the population. When 1) variation observed in a population is 2) genetic--meaning that traits that appear in parents are passed on to offspring. When 1) certain heritable traits are associated with 2) higher numbers of offspring produced. When 1) organisms change in response to 2) changes in the environment.

When 1) certain heritable traits are associated with 2) higher numbers of offspring produced.

In many cases, the theory of evolution provides a logical explanation for observations that are puzzling under the theory of special creation. Under special creation, why is the presence of vestigial traits puzzling? Why would an intelligent designer create traits that have reduced or no function? Vestigial traits are reduced or functionless versions of traits observed in other organisms. Traits can be lost or reduced over time, if individuals without the traits in question produce more offspring than individuals with the traits. It is well known that trait loss or reduction results from lack of use (like unused muscles that atrophy).

Why would an intelligent designer create traits that have reduced or no function?

What is sex-linkage, X-linkage, and Y-linkage? Sex-linked traits are those that affect reproductive organs and other aspects of sexual reproduction. Very few genes are found on the Y chromosome. X-linked alleles are on the X chromosome; Y-linked alleles are on the Y chromosome; both are sex-linked. In mammals, females are XX and males are XY. They are different names for the same thing.

X-linked alleles are on the X chromosome; Y-linked alleles are on the Y chromosome; both are sex-linked.

In this class and other classes at the U, you'll write X-linked alleles as XR and Xr. If you're keeping track of more than one X-linked allele at a time, you'd write the chromosomes as XRB and Xrb (or whatever the genotype actually is for the Rand Bgenes). Suppose a male carries an X chromosome with the R allele and the b allele. How would you write his genotype? (Note: In the answer options, ^ means superscript) X^Rb Y X^R X^R X^b X^b X^Rb X^Rb X^RRbb

X^Rb Y

Why is it considered important that there is "internally consistent" support for the theory of evolution by natural selection? The consistent support proves that other explanations are wrong. Experimental evidence is the only valid type of data in science. As time goes by, we have more and more examples of vestigial traits. You can be more confident that an idea is correct if several different types of evidence support it.

You can be more confident that an idea is correct if several different types of evidence support it.

a. What is the main point (or what are the main points) of this graph? b. Give a hypothesis for any one observation you made in part a.

a. Higher income correlates with higher acceptance of evolution. The USA is an outlier. For its wealth (GDP per capita), it has low acceptance of evolution. (Alternately: for its acceptance of evolution, it has high GDP.) b. [A hypothesis is a guess at a reason for a phenomenon, so there are many possible hypotheses here. Two examples are shown below.] Wealthier countries have better education systems, and this leads to better acceptance of evolution. The USA 'should' be a poorer country (with an average wealth around $15,000) and is only wealthy because it has such bountiful natural resources.

For each diploid genotype, list all the gametes it produces, and in what ratios (without crossing over). a. AB/ab b. AaBb c. Ab/aB

a. 1 AB : 1 ab b. 1 AB : 1 Ab : 1 aB : 1 ab c. 1 Ab : 1 aB

Crest makes many kinds of toothpaste. Crest 3D White toothpaste promises "a noticeably whiter smile", while Crest Complete toothpaste makes no whitening claim. We run the following experiment: We get 400 volunteers, and randomly assign half of them to use Crest 3D White, and the other half Crest Complete. At the beginning of the experiment, we measure the whiteness of each person's teeth by comparing them to porcelain teeth of various shades of white. (This is actually how teeth whiteness is often measured.) After 3 months of using their assigned toothpaste, we measure the whiteness of each person's teeth again. a. What is the hypothesis being tested? b. People vary in their dental hygiene habits. Some brush after every meal, some never floss, etc. Do you think variation in dental hygiene habits will affect our results? Why or why not? c. Draw a graph of possible experimental results if the hypothesis is NOT correct.

a. Crest is making a truthful claim that Crest 3D White toothpaste whitens teeth more than a representative, "normal" toothpaste like Crest Complete. b. No, because we have randomly assigned a large number of individuals to each treatment group. While individual habits may vary, each group will probably have similar habits on average. (In other words, it's highly unlikely that one group gets all the people who floss, while the other group gets all the people who eat Oreos right before bed.)

Dr. Eggers studies Acyrthosiphon pisum (pea aphids), and is designing a selection experiment. To control for genetic variation between treatments, Dr. Eggers is using genetically identical aphids. a. Will selection cause genetic evolution (change over time) in this experiment? Explain why or why not. b. Is it possible, in studies on humans, to control for genetic variation by using genetically identical people?

a. No. Selection acts on existing variation, and the aphids are already genetically identical. So selection cannot cause a change the genetics of the aphids. b. Yes. Studies could use identical twins (which have effectively identical DNA), and "pair-match", meaning put one twin in Group A and one twin in Group B. [In practice, this is exceedingly rare.]

Recall from lecture that humans have a little fold of skin in the inside corner of each eye. This fold is called the 'plica semilunaris', and is a vestige of a 'third eyelid' (nictitating membrane). Last quarter, a student wrote "The 'third eyelid' (or nictitating membrane) is still with humans to show the related common ancestry [with] other species." a. Describe one error in this statement. Explain why it is incorrect. b. How would you explain why humans still have parts of a 'third eyelid'.

a. The third eyelid is not there "to show" anything. It was not designed as a clue to help us reconstruct species relationships. It is simply a vestige of our ancestry. b. Our ancestors had functional nictitating membranes. Ours are no longer functional, but we still have some genes responsible for their development.

Some males are XYY rather than XY; they have an extra Y chromosome. (This and XXX are the only trisomy in humans that, as far as we can tell, have no gross phenotypic consequence.) a. Does this trisomy originate in the sperm or egg? Explain your reasoning. b. The extra Y chromosome must come from Meiosis 2 rather than Meiosis 1. How do we know that?

a. The trisomy involves an extra y chromosome, and only males (and sperm) carry y chromosomes. b. Nondisjunction in Meiosis 1 results in an extra homologous chromosome in one of the gametes, but the homologue to Y is X. Nondisjunction in Meiosis 2 results in an extra sister chromatid (another Y) in one of the gametes.

a. Can a haploid cell undergo mitosis? If yes, draw a haploid cell in anaphase. If not, explain why not. b. Can a haploid cell undergo meiosis? If yes, draw a haploid cell in anaphase1. If not, explain why not. c. [This question, as written, is too vague for a test, but it's really cool to think about!] For humans, we don't think of the haploid phase (sperm, egg) as "human", only the diploid phase. Do you think it's possible to have creatures where we think of the haploid phase as "adult" and the diploid phase as "just little reproductive nothings"?

a. Yes. Mitosis anaphase in a haploid looks exactly like meiosis anaphase2 in a diploid. Check the "mitosis & meiosis cheat sheet" on Canvas and see for yourself! b. No. A haploid doesn't have homologous chromosomes to pair up and separate in meiosis1. c. Yes! It feels weird, but it's totally possible. In humans (and most sexual life), the diploid phase is multicellular and big, and the haploid phase is single-celled and brief-lived. But in some plants that's switched (look up "haplontic life cycle"). Heck, in some plants, both the diploid phase AND the haploid phase become multicellular and big (look up "diplohaplontic life cycle").

Suppose the "a gene" has alleles A1 and A2. This gene determines flower color:A1A1 = red flowersA1A2 = pink flowersA2A2 = white flowers a. Name a mating (eg: "red with pink") that distinguishes between the "blending inheritance" hypothesis and the "particulate inheritance" (Mendel) hypothesis, and explain your reasoning. If no such mating exists, explain why not. b. Name a mating that does NOT distinguish between the two hypotheses, and explain your reasoning. If no such mating exists, explain why not.

a. [any mating with pink will distinguish the two]Pink with pink. Under blending inheritance, all offspring will be pink. Under particulate inheritance, the offspring are 1 red : 2 pink : 1 white. b. [any mating without pink will fail to distinguish the two]Red with white. Under both kinds of inheritance, the offspring are all pink. So this test does not distinguish between the two hypotheses.

Since 1945, the USA has added fluoride to tap water. Fluoride is claimed to prevent dental cavities. Suppose you are designing an experiment to test whether fluoridated water prevents dental cavities. a. What is your manipulated (independent) variable? b. What is your outcome (dependent) variable? c. What is another factor (besides your manipulated variable) that might affect your outcome variable? d. How might you try to control for this variable?

a. fluoridation of water (or) "fluoridated vs unfluoridated water" b. # cavities recorded in 5 years (or) depth of cavities (or) [anything measurable and relevant] c. diet (or) dental hygiene (or) genetics (or) [anything reasonable] d. [Three main options, I think, listed below:] randomize it (randomly assign a large number of people to each group, so little average difference between them) control it directly (eg, only include people who report to brush regularly & visit dentists) pair-match (each person in group1 is matched to a similar person in group2)

An acclimation is a change that happens to a single individual due to

an environmental change

theory"

big hypothesis (or bunch of intertwined hypotheses). The germ theory of disease, the theory of gravitation, atomic theory, the heliocentric theory, etc.

evolutionary processes in action today

evolution in humans in the last few hundred years, evolution in many creatures in the last few decades, evolution of bacteria and viruses in a few years, evolution in lab experiments in a few weeks

Evolution provides explanations

for observed patterns

The threat of antibiotic resistance

has a lot to do with natural selection. So let's understand natural selection.

What is another name for a pure-breeding line or population? homozygous heterozygous high-fitness inbred

homozygous

What is the difference between "phenotype" and "genotype"? genotype is "nature;" phenotype is "nurture" phenotype can be measured; genotype cannot the genotype is a product of the phenotype phenotype is appearance; genotype is alleles

phenotype is appearance; genotype is alleles

Blending inheritance and particulate inheritance

predict different patterns.

kinship between species

similarity of body parts, similarity of genes, similarity of behaviors, biogeographic relationships, "transitional" fossils

The chromosome theory of inheritance is based on the claim that genes are found on chromosomes. If you were going to build a physical model of a chromosome from everyday materials to demonstrate meiosis (including crossing over), which of the following would work best? pipe cleaners (each pipe cleaner is one chromosome) string or twine (each length of string is one chromosome) strings of pop beads (each bead is a gene) a six-pack of soda with the cans held together by plastic rings

strings of pop beads (each bead is a gene)

special creation

the theory that all species were instantaneously and separately created by God.

If a trait has heritable variation... and the trait affects reproductive success...

then selection is an automatic consequence.

biological change over time

vestigial traits, fossils, reconstructed ancestry

Patterns match particulate inheritance

via genes and alleles.