bio 150 homework

Select the correct statement about gene flow.

Gene flow makes allele frequencies more similar between populations.

Which discovery supports the hypothesis that evolution of the lactase-persistence trait was driven by the use of milk in pastoralist cultures?

Ancient pots used to hold milk are about the same age as the lactase-persistence mutations.

These phylogenetic trees represent two interpretations of the origin of hair in humans and dogs in which hair is or is not homologous in humans and dogs. For each interpretation, did the most recent common ancestor of humans and dogs have hair? Which tree is correct?

If hair is homologous in humans and dogs (left tree), their most recent common ancestor did have hair. If hair is not homologous in humans and dogs (right tree), their most recent common ancestor did not have hair. The left tree is correct.

In which country would you most likely find a higher incidence of lactase persistence?

In a Scandinavian country where people historically raised dairy cattle and made cheese

What did researchers discover about the genetic mutation causing lactase persistence?

It is found in a regulatory region (a "switch") upstream of the lactase gene.

which of the situations below describes vicariance?

The Grand Canyon forms, separating two populations of squirrels on the North Rim and the South Rim.

How do autopolyploidy and allopolyploidy differ?

The chromosomes of an autopolyploid individual come from the same species, while an allopolyploid individual has sets of chromosomes from different species.

how do lactase supplements help people who are lactose intolerant?

The supplements provide the enzyme that breaks down the lactose in dairy products.

Lactose intolerance in infants is more common in the population today than it was a hundred years ago. Why?

Today there are alternatives to breast milk, such as lactose-free formula and soy milk, so lactose intolerant infants can survive.

stop codon

UAA UAG UGA

Suppose that a mutation for lactase-persistence occurred in each of the populations described below. In which populations would the mutation be more likely to increase in frequency over time because of natural selection?

a population that raises wheat and sheep

Review the video to determine which statement(s) correctly describe the origin of antibiotic resistance. (select true or false)

a random mutation enabled resistance prior to exposure to the drug treatment. - true a random mutation enabled resistance after exposure to the drug treatment. - false some of the bacterial cells mutated their genes on purpose because they wanted to survive the drug treatment. - false the drug caused some of the bacterial cells to mutate and become resistant. - false

When should a lactase supplement be taken in order to be most effective, and why?

at the same time the dairy product is consumed, so that the lactase will be in contact with the lactose

_____ is the process by which haploid gametes form a diploid zygote.

fertilization

The enzyme lactase breaks the sugar lactose into which compound(s)?

glucose and galactose

In 1949, Dr. Tony Allison observed a high frequency of Kenyans carrying the sickle cell allele in coastal areas and near Lake Victoria, but a lower frequency in the highlands. What did he hypothesize?

he hypothesized that there was a connection between malaria and sickle cell disease.

Which mechanism of reproductive isolation causes postzygotic isolation?

hybrid sterility

Most polyploid plants arise as a result of _____.

hybridization - Most polyploid plants are the result of the hybridization of two different parental species.

How did the sunflower species Helianthus anomalus originate?

hybridization - Rieseberg et al. concluded that H. anomalus formed as a hybrid between two other Helianthus species. Return to Assignment

which is the first step in allopatric speciation?

physical isolation of two populations

Which of these terms applies to an organism with extra sets of chromosomes?

polyploid

How did Dr. Allison test his hypothesis that sickle cell disease was connected to malaria?

- He expanded his study area beyond Kenya to the rest of East Africa to see if malaria and sickle disease were connected. - He evaluated blood samples for malaria parasites and the presence of sickle cells.

How does Dr. Allison's work provide an example of natural selection in humans?

- In areas without malaria, individuals with two sickle cell alleles reproduced at lower rates than those without sickle cell disease. - in areas with malaria, individuals with one sickle cell allele reproduced at higher rates than those with no sickle cell alleles.

How could milk-drinking have provided strong favorable selection for lactase persistence?

- Milk may have been a critical food source during times of famine. - Milk was safer to drink than water and reduced exposure to pathogens. - Milk is protein and fat-rich and therefore could have been an important, high-quality food source.

If a person has two normal copies of the hemoglobin allele, which statements are true?

- The person is homozygous at the hemoglobin locus. - The person is susceptible to malaria.

Humans are diploid and have 46 chromosomes (or two sets). How many sets of chromosomes are found in each human gamete?

1 - meiosis cuts the number of chromosomal sets in half

Humans are diploid and have 46 chromosomes (or two sets). How many chromosomes are found in each human gamete?

23 - 23 is one half of 46

In the Hershey-Chase experiment, the material that entered cells upon infection by T2 virus was labeled with which radioactive isotope?

32P - phosphorus is present in DNA as part of the phosphate group on a nucleotide but not in viral proteins or in proteins in general.

A particular diploid plant species has 48 chromosomes, or two sets. A mutation occurs and gametes with 48 chromosomes are produced. If self-fertilization occurs, the zygote will have _____ set(s) of chromosomes.

4 - if self-fertilization occurs, and two gametes (each having 48 chromosomes) unite, the zygote will have 96 chromosomes (or 4 sets).

Amino Acid

ACU UGC AAA CAC GCA AUC

start codon

AUG

Why should we not view lactose intolerance as a disease in adult humans?

Adult humans did not consume dairy products until fairly recently in our evolutionary history.

Predict how prickles ("thorns") originated in roses.

By chance, a mutation occurred in some roses that resulted in sharp bumps on the stems. Individuals with these early prickles survived herbivore attacks and produced more offspring than roses without the mutation, increasing the frequency of the prickled roses in the population over time.

Why does natural selection not produce populations that are perfectly adapted to their environment?

Changing environments may change the nature of adaptive traits in a population.

Scientific evidence documents the pattern of evolution. The evidence exists in a variety of categories, including direct observation of evolutionary change, the fossil record, homology, and biogeography. Sort the following examples into the correct categories.

Direct Observation of Evolutionary Change: - development of drug resistance in bacteria Fossil Record: - discovery of transitional forms of horses - discovery of shells of extinct species Homology: - vestigial pelvis in right whales - similarities in mammalian forelimbs - same genetic code in fireflies and tobacco plants biogeography: - similarity of endemic island species to nearby mainland species - the high concentration of marsupial species in Australia

Which statement about inbreeding is correct?

Inbreeding increases the rate of purifying selection.

In some populations, 1 in 500 people have sickle cell disease. What reason does the film give for why a potentially deadly, inherited disease is found at such high frequencies?

Individuals with one sickle cell allele are protected from malaria and do not have sickle cell disease, thus keeping the allele in the population.

How did the 1977 drought on Daphne Major cause evolutionary change in the medium ground finch population?

Medium ground finches with large and deep beaks had higher survival rates during the drought.

translation of mRNA: 5' - AUGGCAAGAAAA - 3'

Met-Ala-Arg-Lys

3′−TACAGAACGGTA−5′

Met-Ser-Cys-His

Which assumption must be met for a population to be in Hardy-Weinberg equilibrium for a specific gene?

No genetic drift can affect allele frequencies for the gene.

A population at Time 1 consists of 20 AA, 5 Aa, and 2 aa individuals. After a genetic bottleneck, at Time 2, there is 1 AA, 1 Aa, and 1 aa. Compare the frequencies of the a allele at Time 1 and Time 2.

Original population at Time 1: freq(a) = q = (5 + 2 + 2)/54 = 0.17; new population at Time 2: freq(a) = q

Why do related species share homologous traits?

Related species inherited homologous traits from a common ancestor.

Four individuals measured their baseline blood glucose, then drank a litre of milk. They then measured their blood glucose levels at regular 15 minute intervals for 60 minutes. The results are shown in the graph below. Which individuals are lactase-persistent?

Sarah and Peter

Compare sickle cell disease and malaria.

Sickle cell disease and malaria are both potentially lethal diseases.

which statement shows population thinking?

Variation among individuals in a species is real and important.

what is a gene pool?

a hypothetical collection of all the possible alleles in a population

How does the term "lactase persistent" relate to the term "lactose tolerant"?

a lactase-persistent person is lactose tolerant.

Genes contain the information for making what classes of proteins?

all proteins (enzymes, structural proteins, membrane proteins)

Mutant tetraploid plants _____.

are unable to interbreed with a diploid plant - this is why polyploidy is a mechanism of plant speciation

Why is the enzyme lactase necessary to digest dairy products?

lactase breaks down lactose into smaller molecules that can be absorbed by the cells that line the small intestine.

Most people are lactose intolerant as adults, but nearly everyone produces sufficient lactase as an infant. However, in some cases, genetic mutations can occur that make an infant lactose intolerant. From an evolutionary perspective -- over thousands of years -- why would lactose intolerance in infants be very rare in the population?

lactose intolerant infants could not digest breast milk and therefore usually died, never having the chance to pass the mutation on to their children.

Which evolutionary mechanism increases genetic variation in a population?

mutation

Examine this Punnett square. What does the number 0.6 refer to?

the gamete allele frequency p

Review the video to determine what evolved in this drug-resistance scenario. (choose true or false)

the human population evolved. - false individual bacterial cells within the patient's lungs evolved. - false the patient with TB (bob) evolved. - false the population of bacterial cells within the patient's lungs evolved. - true the lung cells within the patient evolved. - false

Predict what will happen to the frequency of the sickle cell allele in areas where malaria has been eradicated.

the sickle cell allele will decrease in frequency