BIO 181 Exam 4 Homework Questions

In a population with two alleles, the frequency of the two alleles in the gene pool is 0.19 (A) and 0.81 (a). Assume that the population is in Hardy-Weinberg equilibrium. (a) What percentage of heterozygous individuals are present and (b) what percentage of homozygous recessives are in the population?

- 31% - 66%

From module 7.1 of Cogbooks: Why is it that for many animal lineages, we don't see many transitional fossils?

- Fossilization is chancy and usually only preserves hard skeletons or exoskeletons. - While it has taken a while, science is gradually filling in the blanks and more transitional fossils are being discovered. - It may be that evolution is not always quite so gradual an affair as Charles Darwin imagined it to be.

Why might females (in such species as peacocks) choose males with big displays - that obviously make them a target for predators?

- Such gaudy displays may be an 'honest signal' of health and fitness - By mating with a 'sexy' male, the female may also have 'sexy' sons that will have good prospects in mating

From Cogbooks module 7.1: How could something as complex as the behavior of ant-parasitizing Lomechusa (staphylinid beetles) have evolved? These are beetles with special glands, behavior, and body-shape that trick ants into taking them into their nests. Inside the ant-nest, these beetles act as parasites, feeding on ant brood and being fed by the ants.

- These complex behaviors may have arisen gradually through natural selection. - Many Lomechusa beetles already have pre-existing glands and behaviors that could potentially be co-opted and modified through time.

Evolutionarily conserved molecules:

- are similar in sequence among distantly related organisms - were likely present in the most recent common ancestor of the organisms possessing them - likely changed little over time because they serve a vital function - are molecules in which most mutations are likely to be harmful.

From module 7.1 in Cogbooks: Which of the following were modified through artificial selection by humans?

- dogs - cabbages - chickens

In animals, homeotic genes:

- encode transcription factors. - specify the identities of individual body parts or segments during development. - are controlled by segment-polarity genes expressed earlier in development - are found in a wide variety of animals with bilateral symmetry, from fruit flies to vertebrates.

In Drosophila, bicoid and nanos are examples of:

- genes whose products are needed in the oocyte. - genes whose products are needed early in development. - maternal-effect genes

Which of the following is a key assumption of Hardy-Weinberg equilibrium?

- no migration - random mating - no mutation - an infinite population (or at least very large)

An allele W, for white eggs, is dominant over allele w, for black eggs. In a sample of 300 birds, 297 are white egg layers and 3 are black egg layers. Calculate the allelic frequencies within this population, assuming that the population is in H-W equilibrium.

- p = 0.9 - q = 0.1

A good example of evolution through natural selection affecting human health would be:

- the spread of antibiotic resistant bacteria in hospitals - The progression of metastatic cancer and increasing resistance to chemotherapy

What is one reason why many mutations may be deleterious?

Because if a mutation changes the primary structure of a protein, the protein may no longer work.

Why do your chromosomes come in pairs?

Because one member of each pair came from my mother and the other from my father.

Examine the figure and statements below. Which of the statements is INCORRECT?

Bicoid protein promotes the transcription of the hunchback gene in the anterior region of the embryo.

An example of a Hox mutant in Drosophila. The mutant phenotype has two pairs of wings rather than the usual one pair.

Bithorax

There are two varietes of spotted skunk found in North America, the eastern spotted skunk and the western spotted skunk. Even while being physically similar, they cannot mate due to the fact that eastern spotted skunks breed in the spring while the western variety breeds in the fall. This is an example of....

Both a prezygotic barrier and a temporal barrier to reproduction

What would a female genotype have to be for her to have the genetic disease hemophilia?

Both her X chromosomes would have to have the recessive hemophilia gene.

When natural events (such as an earthquake) kills off a large portion of the population - leaving only a small number of survivors - and resulting loss of genetic diversity.

Bottleneck effect

The allele underlying sickle-cell disease affects the structure of the _____ molecule inside _____ blood cells.

Hemoglobin; red

A form of speciation in which there are physical barriers between two sub-species (such as being on different islands) that prevents reproduction long enough for two new species form.

allopatricspeciation

The sum of all alleles in a population.

gene pool

Cells differentiate through:

gene regulation

The changing of a population's allele and genotype frequencies - strictly by chance. Small populations are more vulnerable than large ones.

genetic drift

Calculate the percentage of heterozygotes The frequency of two alleles in a gene pool is 0.24 (A) and 0.76(a). Assume that the population is in Hardy-Weinberg equilibrium. Calculate the percentage of heterozygous individuals in the population.

0.36

If the frequency of allele A is 0.7, using the Hardy-Weinberg formula, what would the frequency of the heterozygous Aa genotype be?

0.42

In a hypothetical population of 1000 frogs there exists a gene with two alleles. 280 of the frogs are homozygous dominant (DD), and 220 are homozygous recessive (dd). What is the frequency of heterozygotes in the population?

0.50

When pink sweet peas were self-pollinated and the seeds were collected and sown, the following flower colors were obtained: Red 34 Pink 76 White 40 Use a chi-squared test to determine whether these results are consistent with the hypothesis that pink flowers are heterozygous for a single pair of color alleles, showing incomplete dominance. What will the chi-square statistic calculation be for this problem?

0.506

Calculate the percentage of homozygotes The frequency of two alleles in a gene pool is 0.24 (A) and 0.76(a). Assume that the population is in Hardy-Weinberg equilibrium. Calculate the percentage of homozygous recessive individuals in the population.

0.58

If the allele frequency for the recessive single allele that causes a particular rare hair color is 0.02, how frequently would you expect the hair color to be present in humans?

1 in every 50 individuals

You have a six-sided die and you roll it four times in row. What is the probability of the following outcomes? 1st roll: 1, 2nd roll: 2, 3rd roll: 3, 4th roll: 4

1/1296 (0.00077)

You have a six-sided die and you roll it four times, what is the probability of the following outcome: Roll1: 1; Roll 2: Greater than 3; Roll 3; Less than 4; Roll 4: 6

1/144

A woman who has five children (all boys) is planning to have another child. What is the probability that this child will be a boy?

1/2

A woman you know has five children - all of whom are boys. What is the probability for a woman to have five boys out of five children?

1/32

A dihybrid cross is arranged for two plants with the following genotype: AaGg x aa gg A = Almond seed shape a = round seed shape G = Green seed color g = yellow seed color What proportion of the offspring will be Almond-shaped and yellow?

1/4

When pink sweet peas were self-pollinated and the seeds were collected and sown, the following flower colors were obtained: Red 34 Pink 76 White 40 Use a chi-squared test to determine whether these results are consistent with the hypothesis that pink flowers are heterozygous for a single pair of color alleles, showing incomplete dominance. If this is indeed a case of incomplete dominance, what ratio of red: pink: white flowers should we predict for our null hypothesis?

1: 2: 1

When pink sweet peas were self-pollinated and the seeds were collected and sown, the following flower colors were obtained: Red 34 Pink 76 White 40 Use a chi-squared test to determine whether these results are consistent with the hypothesis that pink flowers are heterozygous for a single pair of color alleles, showing incomplete dominance. How many degrees of freedom should we use when calculating our chi-square statistic?

2

A rare genetic disease which is due to a recessive allele (a) that is lethal when homozygous, occurs within a specific population at a frequency of one in a million. How many individuals in a town with a population of 16,000 can be expected to carry this allele?

32

Human ABO blood groups are determined by a single gene with 3 alleles: A, B, and O. In a sample of 300 individuals, 100 are blood type A and genotype AA, 100 are blood type B and genotype BO, and 100 are blood type O and genotype OO. What are the allele frequencies?

33.3% A, 16.6% B, 50% O

Calculate the percentage of heterozygotes Allele T, for the ability to taste a particular chemical, is dominant over allele t, for the inability to taste the chemical. Four hundred university students were surveyed and 84 were found to be non-tasters. Calculate the percentage of heterozygous students. Assume that the population is in H-W equilibrium.

50%

Hemophilia has an X-linked recessive pattern. It is carried on the 'X' chromosome. It is only expressed phenotypically as homozygous recessive in women but men that inherit the affected chromosome will suffer from the disorder. A carrier female (one with an affected X chromosome) married a man with hemophilia, and they have children. What percent of their male children will be affected by hemophilia?

50% of the male children

The diagram below represents a protein electrophoresis gel with samples from six individuals tested for variants (alleles A and B) of a single protein. The darkness of the band is a reflection of the intensity of staining in the gel and corresponds to the amount of enzyme present at that band. What are the allele frequencies?

66.6% A, 33.3% B

Consider the following cross involving five independently assorting genes: Aa Bb Cc Dd Ee ´ Aa bb cc DD Ee What proportion of the progeny will have the same phenotype as the first parent?

9/64

You are given the following information about a population: • There are two alleles: C and c. • C codes for green hair and c codes for white hair. • C is dominant over c. • The frequency of the c allele is 0.3. • The population is comprised of 100 individuals. Assuming the population is in Hardy-Weinberg equilibrium, how many individuals have green hair?

91% of the population will have green hair

A particular gene in a given population of individuals has two alleles, A and a. The frequency of the A allele equals the frequency of the aallele. What are the expected genotype frequencies, assuming the population is in Hardy-Weinberg equilibrium?

AA = 0.25, Aa = 0.50, aa = 0.25

What are the types of gametes that can be produced by an individual with the genotype AaBb?

AB, Ab, aB, ab

With independent assortment, the ratio of genotypes in the F2 generation of a cross between true-breeding strains (AA bb × aa BB) can be described as 1:2:1:2:4:2:1:2:1. To what genotype does the "4" in the ratio refer?

AaBb

When pink sweet peas were self-pollinated and the seeds were collected and sown, the following flower colors were obtained: Red 34 Pink 76 White 40 Use a chi-squared test to determine whether these results are consistent with the hypothesis that pink flowers are heterozygous for a single pair of color alleles, showing incomplete dominance. How many degrees of freedom should we use when calculating our chi-square statistic? Do we accept or reject the null hypothesis that this is a case of incomplete dominance?

Accept

The co-discoverer of the theory of evolution by natural selection - who traveled to Malaysia (as well as Brazil). It was his letter which prompted the writing of the 'Origin of Species'.

Alfred Russel Wallace

From Cogbooks module 7.1: Did Charles Darwin take advantage of Alfred Russel Wallace by 'co-publishing' with him (unbeknownst to Wallace - who was in the far east at the time)? What do you think?

All of the above could be reasonable conclusions one could make from this episode in history.

The author of the book, 'The Origin of Species...' He was the co-discoverer of the theory of evolution by natural selection.

Charles Darwin

Which researcher was the first to propose the concept of 'sexual selection'?

Charles Darwin

If one isolated cells at random from an organism at different times in its development and measured developmental potential as the average number of distinct cell types that the cells could differentiate into, which of the curves shown here would MOST likely result?

Curve K

In New Mexico, large expanses of black lava create patches of unique habitat. If, in every generation, selection favors the darkest colored pocket mice in those habitats because they are best hidden from predators, this would be an example of:

Directional Selection

(From Cogbooks module 1.1 and module 7.1): When Richard Dawkins describes a 'Blind Watchmaker' he is referring to what?

Evolution through natural selection

Endangered species with very small populations are especially at risk of loss of genetic diversity due to:

Genetic Drift

You have a small population of beetles. One day a large rainstorm causes flooding and wipes out 87% of the population. The remaining individuals have much lower genetic variation than the original population. Which of the following would explain the lack of Hardy-Weinberg equilibrium seen after the flood?

Genetic Drift

The theory posed by two mathematicians that a population's allele and genotype frequencies are inherently stable - with no migration, genetic drift, mutation, or other forces of change.

Hardy-Weinberg equilibrium

How did Mendel get the peas to cross-fertilize?

He kept them apart and pollinated them by hand

The method of regulation of developmental genes where genes that are expressed early in an organism's development regulate the expression of other groups of genes later in development.

Hierarchal control

The Bithorax mutation in Drosophila results in a pair of wings developing from what would normally develop as halters. Bithorax is an example of a _____ mutation.

Homeotic (Hox)

A recessive trait will be observed in individuals that are _____________ for that trait.

Homozygous

In an experiment a researcher identifies a mutant invertebrate with an extra pair of antennae where legs ought to be. A mutation of what type of gene is most likely responsible for this change?

Hox gene

A group of homeotic genes that controls the development of specific segments of an embryo (including insect larvae): deciding if a segment should be an antenna or a leg or a claw, etc...

Hox genes

The result of a cross between two related subspecies or between related varieties. When distantly related animal species are crossed, the result is usually sterile.

Hybrid

What does it mean to say that an allele is "fixed" in the population?

It is an indication of no genetic variation at that locus in the population.

In which group of organisms is it possible to see a whole range of eyes developing in increasing complexity? (from lecture)

Molluscs

The processes that give rise to large-scale evolutionary changes: new species and higher taxonomic groups with widely diverging characteres.

Macroevolution

The processes of small-scale population change over time.

Microevolution

In a population of birds, it is found that females begin to prefer mating with males who have bright feathers (a recessive trait) over males with dull feathers (the dominant trait). Given this preference of the females, is the population in Hardy-Weinberg equilibrium?

No

A developmental gene that is a transcription factor that directs eye development across a wide range of metazoan animals.

Pax-6

The observable traits expressed by an organism are described as its ___________________

Phenotype

What is the theory called that suggests that new species can evolve and appear quite rapidly (in geological time)?

Punctuated equilibrium

Genetic variation has two sources-mutation and:

Recombination

The differential success of alleles is called:

Selection

___________ selection is where individuals choose mates based upon the quality of their appearance and/or their decorative ornaments

Sexual

What kind of selection would it be? For human females, very small babies are more likely to perish due to a lack of body fat and inadequate neurological development. Very large babies, however, have a difficult time making it through the narrow birth canal of the mother (potentially putting the mother and baby's life at risk). What kind of selection may be at work?

Stabilizing

A behavioral isolating mechanism where sub-species are prevented from mating by differences in the timing of their mating behavior.

Temporal isolation

From Cogbooks module 7.1 using the natural selection simulator: As you played each round, what happened to the average speed of the bugs? Does it get easier or harder over time to catch the bugs?

The average speed got faster. It was more difficult to catch the bugs later on in the simulation.

'Intelligent design' critics of the theory of evolution make the claim that some organs (and organisms) are too complex to have arisen without a designer (of divine nature). What human organ do they present as one instance of this 'irreducible complexity'? (from lecture)...

The human eye

Imagine two neighboring populations, one on a small island with only 100 individuals, the other on a larger island with 10,000 individuals. For a particular trait both populations begin with five different alleles of the gene. After 500 generations, which population is most likely to have lost alleles due to genetic drift (that is, chance)?

The smaller population will most likely have lost more alleles due to genetic drift.

From Cogbooks module 7.1: According to Professor Rutowski in the video, 'Interview with Ron Rutowski', what information do the spots and colors on the butterfly wings convey (Pipevine swallowtail)?

The spots and colors can convey bad-taste in some cases and convey mate quality in others.

Which of the following is true about genes that are located on different chromosomes?

These genes are inherited independently of each other

The allele frequency of all the alleles of a gene present in the population must add up to 1.

True

A gene, that when expressed as a protein, acts to regulate the expression of other genes.

Transcription Factor

From Cogbooks module 7.1: In the video, 'Aposematic trials', what was the function of the bright coloration in the Grape Leaf Skeletonizer caterpillar.

Warning coloration: a means to warn potential predators that they taste bad.

From Cogbooks module 7.1 the natural selection simulator: In the simulation, is there any evidence to assume that one color of bug is less fit than another?

Yes, the purple and blue bugs were the slowest and easiest to pick off with the 'hawk' - resulting in lower survival (and thus lower fitness) for bugs of those colors.

A heritable trait that helps an organism's survival and reproduction in its environment.

adaptation

When a species disperses to a new and uninhabited area and over time that the species develops into many new species to fill the many lifestyles now available in this new region.

adaptive radiation

In a cross between a homozygous red-eyed female fruit fly and a white-eyed male fruit fly, what is the expected outcome?

all offspring with red eyes

In a cross between a white-eyed female fruit fly and a red-eyed male fruit fly, what is the expected outcome?

all offspring with white eyes

The rate at which a particular allele occurs in the population.

allele frequency

Alternate forms of a gene are called_______.

alleles

A type of natural selection that has been mediated by humans. Examples include corn from teosinte, dogs from wolves, peaches, and cabbages.

artificial selection

Differentiation refers to the process by which:

cells become progressively more specialized during development.

A term used to describe the great deal of similarity between many developmental genes (including Hox genes and Pax-6) in a multitude of animals.

deep homology

The finding that induced pluripotent stem cells (iPS cells) can be created by activation of a small number of genes implies that:

developmental restriction of cell fate is reversible.

The muscle cells and nerve cells in a mouse look very different and serve very different functions in the mouse's body. These differences are because the muscle cells and nerve cells in the mouse:

express different genes

Differentiating cells delete the DNA for genes they do not need.

false

Which of the following cells, or cell types, has the GREATEST developmental potential?

fertilized egg

Which of the following CORRECTLY lists the stages of human development in order?

fertilized egg, morula, blastocyst, gastrula

If you crossed a true-breeding yellow-seed plant (AA) with a heterozygous yellow-seed plant (Aa), offspring what would you expect? (aa) individuals would be green.

genotypes would be 1 AA: 1 Aa

Synonymous parts of different organisms that, while having different shapes, were derived from the same structures in ancestors. Example: human limbs, versus dogs, birds, and whales.

homologous structures

A testcross involves crossing with a(n) _____ individual and is used to determine the _____ of the tested parent.

homozygous recessive; genotype

When the Pax6 transcription factor is transferred from a donor individual of one species into the genome of a recipient individual of a different species, it:

induces the development of eyes similar to those in the recipient species

In Drosophila, absence of Bicoid protein results in larvae missing anterior segments and absence of Nanos protein results in larvae missing posterior segments. Suppose you inject Nanos protein into the anterior region of early embryos lacking Bicoid. The expected result would be:

larvae with two posterior regions

Half of the gametes produced by an organism with the genotype Aa will receive the A allele, while half will receive the a allele. This is a demonstration of ______________.

law of segregation

Developmental genes that act to establish early gradients in embryos and larvae. These proteins are deposited by the mother to establish basic orientation during development: top to bottom, front to back.

maternal effect genes

Observing crabs at the beach while you are on vacation, you notice a funny looking juvenile crab where instead of having the usual 10 legs, this individual is missing the entire anterior portion of its body (its tail end). What kind of gene likely contributed to this mutant phenotype?

maternal effect genes

Which of the following CORRECTLY orders the sequence in which genes controlling the development of the anterior-posterior axis of Drosophila larvae are expressed?

maternal-effect genes, gap genes, pair-rule genes, segment-polarity genes

The combining of the concepts of natural selection with genetics (in the 1940's) that gave us our current view of evolution in populations.

modern synthesis

In John Gurdon's nuclear-transfer experiments, do you think he would have had more or less success if he had taken cells from a blastula? From an adult frog?

more; less

In animals with sex chromosomes, males inherit their X chromosome from their _____ and transmit it to their _____.

mothers; daughters

Also known as 'survival of the fittest' - this is the mechanism by which evolution takes place in living organisms.

natural selection

If a researcher knocked out the normal Pax-6 gene for eye development in a crab and replaced it with a homologous Pax-6 gene for eye development from fruit flies, what would the likely effect be to the development of eyes in the crab?

normal crab eyes would develop

Congenital generalized hypertrichosis is an X-linked dominant disease. If an affected male marries an unaffected female, what is the probability of passing the hypertrichosis gene to his offspring?

p = 0.5, all daughters will be affected

Developmental genes that establish alternative segments in the developing larvae or embryo. Regulated by Gap genes and Maternal effect genes among others.

pair-rule genes

Describing a person as having hemophilia is to indicate his or her_________________

phenotype

An example of a reproductive barrier where two sub-species are able to sexually reproduce - but the offspring is infertile due to genetic incompatability. Examples include: ligers and mules.

post zygotic barrier

An example of a reproductive barrier where some factor (which could be behavioral or anatomical) prevents two sub-species from successfully reproducing.

prezygotic barrier

When the Pax6 gene from a mouse is introduced into a Drosophila genome, it induces eye development. The eyes appear to be normal fly eyes, not mouse eyes. This supports the hypothesis that the Pax6 gene:

produces a product that switches on the genes for eye formation in a wide range of organisms

Mendel's principle of independent assortment corresponds to which part of meiosis?

random alignment of homologs on the metaphase plate during metaphase I

When two sub-species are prevented from sexually reproducing together. The barrier can be behavioral or physical in nature.

reproductive isolation

A form of natural selection in which animals choose their mates based upon desirable qualities such as bright plumage in birds or symmetric design in sand by pufferfish.

sexual selection

From an evolutionary perspective, germ-line mutations are more significant than somatic mutations. This is because:

somatic mutations affect only one or a few cells and only germ-line mutations will appear in an individual's descendants.

The process by which a new species of animal originates.

speciation

Female starlings (a species of bird) that lay clutches of four or five eggs have more surviving young than those with either larger or smaller clutches. This is an example:

stabilizing selection acting on clutch size.

Cichlid fish in the great lakes of Africa have undergone an explosive adaptive radiation of species in the last three hundred thousand years. What kind of speciation would this be?

sympatric speciation

An example of speciation where the new species form even while the related animals are living in the same environment. Usually, behavioral and ecological factors help to isolate the sub-species and encourage speciation.

sympatricspeciation

Each answer option below lists terms that classify cell types according to their developmental potential. Which of the options lists the terms from those capable of differentiating into the greatest number of different specialized cells to those capable of differentiating into the least number of different specialized cells?

totipotent, pluripotent, multipotent