In order for a hypothesis to be able to be used in science, which of the following must be true?- It is testable and falsifiableIn the 1950s, when Watson and Crick were working on their model of DNA, which concepts were well accepted by the scientific community?o Chromosomes are made up of protein and nucleic acido Chromosomes are found in the nucleuso Genes are located on chromosomes (Morgan)In the early 1950s, many researchers were racing to describe the structure of DNA using different approaches. Which of the following statements is true?o Jim Watson and Francis Crick built theoretical models, incorporating current knowledge about chemical bonding and X-ray data.o Wilkins and Franklin collected data using X-ray diffraction.o Oswald Avery and colleagues were the scientists who conducted experiments in 1944 demonstrating that DNA could carry genetic information.o Rosalind Franklin and Maurice Wilkins were the scientists collecting X-ray diffraction data about DNA.Early, flawed DNA models proposed by Watson and Crick and by Linus Pauling correctly described which property of DNA?o DNA is composed of sugars, phosphates, and bases.What did Rosalind Franklin’s famous photo 51 show?o DNA is a helixErwin Chargaff observed that the proportions of adenine (A) and thymine (T) bases were always equal, as were the proportion of guanine (G) and cytosine (C). Chargaff’s observation suggests which of the following statements?o The data suggest that A would always pair with T and G would always pair with C in a DNA molecule.How does a scientific theory differ from a scientific hypothesis?(Theories are usually an explanation for a more general phenomenon; hypotheses typically address more specific issues.)Modern travel along with migration reduces the probability of _____ having an effect on the evolution of humans. (genetic drift)Crossing over, resulting in an increase in genetic variation, occurs between _____. (non-sister chromatids of homologous chromosomes)The original source of all genetic variation is _____. (mutation)Genetic variation _____. (must be present in a population before natural selection can act upon the population)Cystic fibrosis is a genetic disorder in homozygous recessives that causes death during the teenage years. If 9 in 10,000 newborn babies have the disease, what are the expected frequencies of the dominant (A1) and recessive (A2) alleles according to the Hardy-Weinberg model?When imbalances occur in the sex ratio of sexual species that have two sexes (that is, other than a 50:50 ratio), the members of the minority sex often receive a greater proportion of care and resources from parents than do the offspring of the majority sex. This is most clearly an example of _____.- Frequency-dependent selectionAccording to the Hardy-Weinberg theorem, the frequencies of alleles in a population will remain constant if _____ is the onlyprocess that affects the gene pool.- Sexual reproductionFor a biologist studying a small fish population in the lab, which Hardy-Weinberg condition is easiest to meet?- No gene flowA man who carries an allele of an X-linked gene will pass it on to _____.- all of his daughtersHow would one explain a testcross involving F1 dihybrid flies in which more parental-type offspring than recombinant-type offspring are produced?- The two genes are closely linked on the same chromosome.The Dunkers are a religious group that moved from Germany to Pennsylvania in the mid-1700s. They do not marry with members outside their own immediate community. Today, the Dunkers are genetically unique and differ in gene frequencies,at many loci, from all other populations including those in their original homeland. Which of the following likely explains the genetic uniqueness of this population?- founder effect and genetic driftIn those parts of equatorial Africa where the malaria parasite is most common, the sickle-cell allele constitutes 20% of the β hemoglobin alleles in the human gene pool. In the United States, the parasite that causes malaria is not present, but African-Americans whose ancestors were from equatorial Africa are present. What should be happening to the sickle-cell allele in the United States, and what should be happening to it in equatorial Africa?- Directional selection, stabilizing selection The restriction enzymes of bacteria protect the bacteria from successful attack by bacteriophages, whose genomes can be degraded by the restriction enzymes. The bacterial genomes are not vulnerable to these restriction enzymes because bacterial DNA is methylated. This situation selects for bacteriophages whose genomes are also methylated. As new strains of resistant bacteriophages become more prevalent, this in turn selects for bacteria whose genomes are not methylated andwhose restriction enzymes instead degrade methylated DNA. The outcome of the conflict between bacteria and bacteriophage at any point in time results from _____.- frequency-dependent selectionWhat is the most important factor that holds a gene pool of a species together and prevents speciation?- Gene flow (Gene flow refers to the transfer of alleles among populations. As long as populations are exchanging alleles, speciation is unlikely.)A narrow hybrid zone separates the toad species Bombina bombina and Bombina variegata. What is true of those alleles that are unique to the parental species?- The alleles' heterozygosity should be higher among the hybrid toads than in toad populations distant from the hybrid