Diapause is the interruption of an organism’s life cycle in response to the environmental cues. The soil nematode Caenorhabditis elegans is capable of entering entering adult reproductive diapause (ARD) when food is scarce. In C. elegans, individuals normally become reproductively mature 2 days after hatching and remain fertile for 18 days. They reproduce either by self-fertilization or by mating with another individual. In an investigation, researchers examined the survival and reproductive success of female C. elegans who were without food for 0-30 days. Groups of C. elegans were held in ARD for different numbers of days before reintroduction of food. Average brood sizes (average number of offspring per adult) were determined following either self fertilization or mating with a well-fed males. The results are shown in Figure 1. There are tick marks on the horizontal axis labeled from left to right: 0, 3 through 15 in increments of 2, and 30, with a break indicated between 15 and 30. The vertical axis has evenly spaced tick marks labeled from 0 to 450 in increments of 50. There are two bars on each of the tick marks on the horizontal axis. In each pair, the unshaded bar represents self-fertilized and the shaded bar represents mated. Each bar also shows an error bar. From left toright, the data are as follows. All numbers are approximate. 0 days: self-fertilized, 260, error bar from 255 to 265; mated, 375, error bar from 325 to 420. 3 days: self-fertilized, 190, error bar from 185 to 200; mated, 245, error bar from 240 to 250. 5 days: self-fertilized, 120, error bar from 115 to 125; mated, 150, error bar from 140 to 170. 7 days: self-fertilized, 75, error bar from 70 to 80; mated, 125, error bar from 120 to 130. 9 days: self-fertilized, 50, error bar from 49 to 51; mated, 110, error bar from 95 to 115. 11 days: self-fertilized,40, error bar from 38 to 41; mated, 120, error bar from 110 to 130. 13 days: self-fertilized, 25, error bar from 24 to 26; mated, 100, error bar from 90 to 110.15 days: self-fertilized, 10, error bar from 9 to 11; mated, 125, error bar from 120 to 130. 30 days: self-fertilized, 5, error bar from 3 to 7; mated, 45, error bar from 35 to 50. The caption on the figure reads: Figure 1. Mean brood sizes plus or minus two times the standard error of the mean after different times in A R D. Individual C. elegans were held in A R D and subsequently allowed to reproduce either via self-fertilization (unshaded bars) or by mating with well-fed males (shaded bars). Figure 1. Mean brood sizes ± SEg after different times in ARD. Individual C. elegans were held in ARD and subsequently allowed to reproduce either via self-fertilization (unshaded bars) or by mating with well-fed males (shaded bars). In a second experiment, individuals were held in ARD without food for 0-30 days and monitored for average survival times following reintroduction of food (Figure 2). There are tick marks on the horizontal axis labeled from left to right: 0, 3 through 15 in increments of 2, and 30, with a break indicated between 15 and 30. The vertical axis has evenly spaced tick marks labeled 0 to 30 in increments of 5. Each bar shows an error bar. From left to right, the data are as follows. All numbers are approximate. 0 days: 18, error bar from 15 to 21. 3 days: 15, error bar from 12 to 18. 5 days: 18, error bar from 15 to 22. 7 days: 19, error bar from 17 to 23. 9 days: 19, error bar from 16 to 23. 11 days: 17, error bar from 14 to 20. 13 days: 16, error bar from 12 to 20. 15 days: 19, error bar from 16 to 23. 30 days: 22, error bar from 18 to 24. The caption on the figure reads: Figure 2. Mean survival plus or minus two times the standard error of the mean following different times in A R D. Individual C. elegans were held in A R D and subsequently given access to food, whereupon their survival times were determined. Figure 2. Mean survival ± SEg following different times in ARD. Individual C. elegans were held in ARD and subsequently given access to food, whereupon their survival times were determined. Which of the following best describes the reproductive ability of C. elegans following the ARD induced in the first experiment?

Female European corn borer moths (Ostrinia nubilalis) produce the sex pheromone 11−tetradecenyl acetate (11−TDA), which attracts males of their species. 11−TDA can be produced in two forms, E and Z, each with a different three-dimensional shape. Researchers have discovered two different strains of the European corn borer moth living in the same area. Females of the E strain produce primarily the E form of 11−TDA and females of the Z strain produce primarily the Z form of 11−TDA. Males of both strains are more attracted to the form of 11−TDA produced by the females of the same strain. Which of the following best predicts a long-term effect of the differences between the E and Z strains?

In a long‑term study of a population of gray squirrels, researchers observed that most of the squirrels had gray fur. However, there were some individuals in the population with white fur (albino). Genetic analysis revealed that the albino condition is expressed by individuals who are homozygous recessive (gg). Over a ten-year period, the average frequency of albino squirrels in the population was 0.18. If the population is assumed to be in Hardy-Weinberg equilibrium, the average frequency of the dominant allele is closest to which of the following?

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

A small number of lizards from a mainland population have been deposited on four isolated islands because of the effects of a rare strong storm. Which of the following best predicts the outcome of these lizards reproducing for many generations on the islands?

Some scientists claim that amphibians are currently experiencing a period of mass extinction. Which of the following should be included in an alternative hypothesis that would best support this claim?

______ is the enzyme used in the synthesis of mRNA.

_______ is the process in which naked DNA is taken up by a bacterial or yeast cell.

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?

The three-spined stickleback (Gasterosteus aculeatus) is a small fish found in both marine and freshwater environments. Marine stickleback populations consist mainly of individuals with armor-like plates covering most of their body surface (completely plated). Approximately 10,000 years ago, some marine sticklebacks colonized freshwater environments. After many generations in the freshwater environments, the freshwater stickleback populations lacked the armor plating (low plated) typical of marine stickleback populations. Over the period between 1957 and 2005, one freshwater population, in Lake Washington, a lake in a coastal region of the northwestern United States, changed from having a majority of individuals of the low-plated phenotype to having more individuals of the completely-plated phenotype than of the low-plated phenotype. Figure 1 shows the distribution of plated phenotypes in Lake Washington sticklebacks at four time points between 1957 and 2005. There are 5 tick marks along the horizontal axis. Centered between each tick mark, from left to right, are the numbers 1957, 1968, 1976, and 2005. The vertical axis is label Percentage of Fish, and the numbers appearing on it, from bottom to top, are zero,20, 40, 60, 80, and 100. The graph shows 11 bars and a key indicates black bars are completely plated, shaded bars are partially plated, and white bars are low plated. From left to right, the data reads as approximately:1957: completely plated,no bar; partially plated, 10; low plated, 90.1968: completely plated, 7; partially plated, 24; low plated 70. 1976: completely plated, 40; partially plated, 35; low plated 24. 2005: completely plated, 50; partially plated, 35; low plated 15. A single gene, ectodysplasin (EDA), is thought to be responsible for the variation in the number of armor plates in sticklebacks. Figure 2 shows a phylogenetic tree constructed by comparing DNA sequences of the EDA gene from a number of stickleback populations with low-plated or completely plated phenotypes. Figure 3 shows a phylogenetic tree constructed by comparing the sequences of 25 genes that were randomly selected from the same populations as shown in Figure 2. In both figures, shaded populations display the completely plated phenotype. The figures show two phylogenetic trees titled Figure 2, Phylogeny based on EDA gene only, and Figure 3, Phylogeny based on 25 random genes. Shaded populations indicated completely plated phenotypes. Figure 2 on the left divides Populations 1 through 8 as low plated, and Populations 9 through 15 as completely plated.A large branch connects all low plated phenotypes to all completely plated phenotypes. On the top branch, a tree connects Populations 1 and 2 only, and a branch then connects them to Population 3. A branch then connects Populations 1 through 3 to Population 4. A tree connects Populations 5 and 6 only, and a branch is then connected from Populations 5 and 6 to Populations 1 through 4. This tree is then connected to Population 7.On the bottom branch, a tree connects Populations 8 and 9, and a tree connects Populations 10 and 11. A branch then connects Populations 8 and 9 to Populations 10 and 11. This branch is then connected to Population 12. A tree connects Populations 8 through 12 to Population 13, a branch connects Population 14 to Populations 8 through 13, and a branch connects Population 15 to Populations 8 through 14. Figure 3 on the right has a tree that connects Population 15 to Populations one through 14. A tree connects Populations 4 and 6 and a single branch extends to the tree connecting Population 15 to Populations one through 14. A tree connects Populations 14 and 7, and a branch connects this set to Population 5. A branch then connects this set to Population 12, another branch connects this set to Population 13, and another branch connects this set to Population 8. A tree connects Populations 11 and 9, a branch connects this set to Population 10, another branch connects this set to Population 1, another branch connects this set to Population 3, and another branch connects this set to Population 2. A tree connects Populations 14, 7, 5, 12, 13, and 8 to Populations 11, 9, 10, 1, 3 and 2. Evolution of a new trait typically takes many generations. Yet a dramatic shift in the extent of armor plating in the Lake Washington stickleback population occurred in the 50 years following the cleanup of the lake. Which of the following best describes the mechanism of the rapid evolution of the armor phenotype in the Lake Washington sticklebacks?