biology questions

A moth's color is controlled by two alleles, G and g, at a single locus. G (gray) is dominant to g (white). A large population of moths was studied, and the frequency of the G allele in the population over time was documented, as shown in the figure below. In 1980 a random sample of 2,000 pupae was collected and moths were allowed to emerge. Assuming that the population was in Hardy-Weinberg equilibrium for the G locus, what percentage of the gray moths that emerged in 1980 was heterozygous? https://assets.learnosity.com/organisations/537/36a6c356-dba0-46c7-997f-1bdb7a0e301d.png THIS LINK IS THE LINK TO THE IMAGE

A. 0% B.25% C. 33% D. 67% E. 100%

Some strains of the bacterium Streptococcus pyogenes secrete poisonous substances called exotoxins. The genes encoding the exotoxins are thought to have originated in bacteriophages, which are viruses that infect bacteria. Which of the following is the most likely mechanism by which the S. pyogenes acquired the ability to produce the exotoxins?

A. Bacteriophages engulfed cellular debris from dead bacteria. B. Bacteriophages in the environment activated bacterial cell division. C. Bacteriophage DNA became integrated in the bacterial chromosome. D. Bacteriophage proteins were absorbed into bacteria cells by endocytosis.

Which of the following correctly compares the two processes shown above? https://assets.learnosity.com/organisations/537/media.academicmerit.com/ed04026affe2d9472789f49327578f3c/original.png THIS IS THE LINK TO THE IMAGE

A. Both processes increase genetic variation. B. Both processes represent aspects of sexual reproduction. C. Both processes require partitioning of genetic material and organelles. D. The amount of genetic material per cell remains constant in both processes.

https://assets.learnosity.com/organisations/537/VR595725.g02.svg THIS LINK IS THE LINK TO THE IMAGE Portions of the amino acid sequences of some dehydrogenase enzymes found in bacteria, yeast, corn, horses, and sheep are shown in Figure 1. Each letter represents a different amino acid in the sequence. Based on Figure 1, which of the following conclusions about the enzymes is most likely correct?

A. Corn and horse dehydrogenase enzymes arose separately during each organism's evolution and now exhibit strong sequence similarity as a result of their similar catalytic roles. B. These enzymes all evolved from a common prokaryotic dehydrogenase enzyme, so they exhibit regions of sequence similarity. C. Any evolutionary relationship is unlikely, because there is little sequence similarity between these enzymes. D. No conclusion can be drawn based on amino acid sequence, because there are twenty amino acids and only four nucleotides.

This group of questions consists of five lettered headings followed by a list of phrases or sentences. For each phrase or sentence, select the one heading to which it is most closely related. Each heading may be used once, more than once, or not at all. This group of questions refers to the following enzymes. (A) DNA ligase(B) DNA polymerase(C) RNA polymerase(D) Restriction enzyme(E) Reverse transcriptase Question Enzyme used in the synthesis of mRNA

A. DNA ligase B. DNA polymerase C. RNA polymerase D. Restriction enzyme E. Reverse transcriptase

Mutations in the MYO6 and POU4F3 genes have been associated with a form of hereditary hearing loss in humans. Researchers studying the genes have proposed that POU4F3 encodes a transcription factor that influences the regulation of MYO6. Which of the following questions will best help guide the researchers toward a direct test of their proposal?

A. Have mutations in other genes also been associated with hearing loss? B. cells are the mutant forms of the POU4F3 gene expressed? C. Are mutations in the MYO6 and POU4F3 genes also found in mice? D. Do mutations in the POU4F3 gene affect MYO6 mRNA levels in cells?

Methicillin-resistant Staphylococcus aureus (MRSA) can be a serious threat to human health. There is evidence that S. aureus infections are common in hospitals and that MRSA have become resistant to other antibiotics besides methicillin. This suggests that the rapid evolution of resistance in the bacteria poses a serious public-health challenge. Which of the following best explains the ability of MRSA to evade existing drug therapies?

A. MRSA have very long generation times and very large population sizes. B. MRSA develop new alleles by intentionally introducing specific mutations that will give them a selective advantage over other bacteria C. MRSA metabolize many drugs in their lysosomes and therefore evolve resistance at a high rate. D. MRSA exchange genetic material with other antibiotic-resistant bacteria, which can spread resistance in the S. aureus population.

Ciprofloxacin is given as an antibiotic to healthy livestock to promote efficient weight gain. Strains of the bacterium Campylobacter jejuni naturally colonize the digestive tracts of livestock, and the C. jejuni can be transferred to people through the handling and consumption of contaminated meat. People infected with C. jejuni also are treated with ciprofloxacin. Which of the following is the most likely consequence of adding ciprofloxacin to animal feed?

A. Naturally occurring strains of C. jejuni will reproduce more rapidly in the digestive tracts of livestock, reducing the risk of food-borne illnesses in people. B. Ciprofloxacin-resistant strains of C. jejuni will have a selective advantage in the digestive tracts of livestock, increasing the risk of serious infections in people. C. Ciprofloxacin-sensitive strains of C. jejuni will be consumed in meat that contains a chemical that inhibits bacterial growth, reducing the risk of food poisoning in people. D. Actively growing strains of C. jejuni will metabolize the nutrients in meat produced by livestock operations, increasing the risk of protein deficiencies in people.

A new mutation that arose in one copy of gene X in a somatic cell resulted in the formation of a tumor. Which of the following pieces of evidence best describes how the new mutation directly caused the tumor?

A. Protein X normally stimulates cell division, and the mutation created an overactive version of protein X. B. Protein X normally activates a growth hormone receptor, and the mutation decreased the stability of protein X. C. Protein X normally prevents passage through the cell cycle, and the mutation created an overactive version of protein X. D. Protein X normally regulates gene expression, and the mutation created an underactive version of protein X that blocked the cell cycle.

Which of the following is most likely to create genetic variation in a population?

A. RNA polymerase errors during transcription B. Helicase failure to unwind DNA during DNA replication C. DNA polymerase errors during replication D. Misincorporation of amino acids by tRNA during translation

Freshwater bony fish secrete large volumes of very dilute urine. Many marine bony fish secrete small volumes of concentrated urine. Which of the following best explains the differences in nitrogenous-waste excretion between freshwater and marine bony fish?

A. The differences arose during divergence, as fish from a common ancestor faced different selective pressures in environments of different osmolarity. B. The differences resulted from the evolution of kidneys in independent evolutionary lineages that were adapted to different environmental conditions. C. The differences are accidents of evolutionary divergence and are unrelated to the osmotic differences in freshwater and marine environments. D. The differences arise in each generation because of the physiological adjustment of individual fish to fluctuating salt concentrations in the environments in which they live.

The apple maggot fly, Rhagoletis pomonella, is native to North America and originally fed on fruit of the wild hawthorn. Since the mid-1800s, a population of flies has emerged that instead feed on domesticated apples. Apple maggot flies typically mate on or near the fruit of their host plants. Many varieties of apples ripen three to four weeks before the hawthorn fruits do. The different fruit preferences of the two fly populations will most likely have which of the following effects?

A. The flies that eat hawthorn fruit will increase in number, while the flies that eat apples will decrease in number because of the use of insecticides on apple trees. B. The single fly species will evolve into two distinct species because of the lack of gene flow between the two populations. C. The ability to survive on a diet of two different fruits will help the flies learn to eat many more types of fruit. D. The flies that eat hawthorn fruit will lay some of their eggs on the earlier-ripening apples to minimize competition among the larvae.

While there is only one species of Galápagos Island tortoise, there are several subspecies. Larger islands with more wet highlands have lush vegetation near the ground. Tortoises there tend to have high-domed shells and shorter necks, which restrict upward head movement. They also have shorter limbs. They are the heaviest and largest of the subspecies. Smaller, drier islands are inhabited by tortoises with longer necks and limbs and with shells that are elevated above the neck, which allow them to browse taller vegetation. Based on the information given, which of the following is a plausible explanation for the ancestry of the tortoise subspecies?

A. The subspecies share a recent common ancestor whose neck length, shell shape, and leg length were intermediate between the two subspecies. B. The tortoises with shorter legs and necks were most easily preyed on as young animals by the rats that were introduced, so they survived only on a few islands. C. Random mutations coupled with the inheritance of acquired characteristics resulted in distinct subspecies. D. Individuals with different adaptations in shell shape and leg length best exploited the food resources and left more surviving offspring on each island.

For following group of questions first study the description of the situation and then choose the one best answer to each question following it and fill in the corresponding oval on the answer sheet. A survey reveals that 25 percent of a population of 1,000 individuals have attached earlobes (are homozygous recessivefor the trait). For the following questions, assume that the population fits the parameters of the Hardy-Weinberg law. Question If p equals the frequency of the dominant allele and q equals the frequency of the recessive allele, which of the following terms represents the frequency of the individuals who show the dominant phenotype?

A. p2 B. q2 C. 2pq D. p2 + 2pq E. p2 + q2

Evolutionary fitness is measured by

A. physical strength B. reproductive success C. length of life D. resistance to disease E. competitiveness