Blog

The horizontal axis is labeled “Egg Incubation Temperature, in degrees Celsius,” and the numbers 20 and 40 are indicated. The vertical axis is labeled “Proportion of Hatchlings That Are Male,” and the numbers 0 through 1, in increments of 0 point 5, are indicated. The three curves are labeled “Green Turtles”, “Crocodilians”, and “Lizards”. The curve labeled “Green Turtles” begins at 20 degrees Celsius and 1 male hatchling. It moves slightly downward and to the right at first until it reaches approximately 27 degrees Celsius and 0 point 9 5 male hatchling. It then descends steeply until it reaches approximately 33 degrees and 0 point 0 5 male hatchling. At this point it moves slightly downward and to the right until it ends at approximately 40 degrees Celsius and 0 male hatchlings. The curve labeled “Lizards” begins at 20 degrees Celsius and 0 male hatchlings. It moves slightly upward and to the right at first until it reaches approximately 27 degrees Celsius and 0 point 0 5 male hatchling. It then rises steeply until it reaches approximately 33 degrees and 0 point 9 5 male hatchling. At this point it moves slightly upward and to the right until it ends at approximately 40 degrees Celsius and 1 male hatchling. The curve labeled “Crocodilians” begins at 20 degrees Celsius and 0 male hatchling. It moves horizontally to the right at first until it reaches approximately 23 degrees Celsius and 0 point 0 male hatchlings. It then curves steeply upward and to the right until it reaches approximately 30 degrees and 1 male hatchling. At his point it curves steeply downward and to the right until it reaches approximately 37 degrees Celsius and 1 male hatchling. It continues horizontally until it ends. The Green Turtles curve intersects the Lizards curve at 30 degrees Celsius and 0 point 5 male hatchling. The Crocodilians curve intersects the Green Turtles curve at approximately 27 degrees and 0 point 9 male hatchling, and it intersects the Lizards curve at approximately 37 degrees and 0 point 9 male hatchling. The graph above represents the proportions of hatchlings of certain types of reptiles that are male at different egg incubation temperatures. Which of the following claims is best supported by the data?

Stickleback fish are found in both marine and freshwater habitats. The marine fish have no scales but have hardened, armorlike plates along their sides. The plates are thought to protect sticklebacks from certain predators. In the late 1980s, sticklebacks from a marine population colonized Loberg Lake, a freshwater lake in Alaska. Starting in 1990, researchers sampled fish from the lake every four years and recorded the armor-plate phenotypes of the male sticklebacks in each sample. The armor-plate phenotypes were categorized as either complete (plates extending from head to tail), partial (plates extending from head to abdomen), or low (a few plates near the head only). The results are shown in the table below. ARMOR-PLATE VARIATION IN THE STICKLEBACK POPULATION OF LOBERG LAKE Percent of Males in the Sample with Each Armor-Plate Phenotype Year Low Partial Complete 1990 1% 2% 97% 1994 45% 14% 41% 1998 58% 16% 26% 2002 76% 15% 9% 2006 90% 6% 4% To evaluate the reliability of the results, it would be best to know which of the following?

Genetic engineering techniques can be used when analyzing and manipulating DNA and RNA. Scientists used gel electrophoresis to study transcription of gene L and discovered that mRNA strands of three different lengths are consistently produced. Which of the following explanations best accounts for this experimental result?

A group of students summarized information on five great extinction events. Five Great Extinction Events Mass Extinction Time of Extinction Organisms Greatly Reduced or Made Extinct End of the Ordovician period 443 million years ago Trilobites, brachiopods, echinoderms, and corals End of the Devonian period 354 million years ago Marine families on tropical reefs, corals, brachiopods, and bivalves End of the Permian period 248 million years ago Trilobites, mollusks, brachiopods, and many vertebrates End of the Triassic period 206 million years ago Mollusks, sponges, marine vertebrates, and large amphibians End of the Cretaceous period 65 million years Ammonites, dinosaurs, brachiopods, bivalves, and echinoderms The students are sampling a site in search of fossils from the Devonian period. Based on the chart, which of the following would be the most reasonable plan for the students to follow?

Competition for food would probably be most severe between two

Which of the following is not a potential problem posed by non-native species?

Stickleback fish are found in both marine and freshwater habitats. The marine fish have no scales but have hardened, armorlike plates along their sides. The plates are thought to protect sticklebacks from certain predators. In the late 1980s, sticklebacks from a marine population colonized Loberg Lake, a freshwater lake in Alaska. Starting in 1990, researchers sampled fish from the lake every four years and recorded the armor-plate phenotypes of the male sticklebacks in each sample. The armor-plate phenotypes were categorized as either complete (plates extending from head to tail), partial (plates extending from head to abdomen), or low (a few plates near the head only). The results are shown in the table below. ARMOR-PLATE VARIATION IN THE STICKLEBACK POPULATION OF LOBERG LAKE Percent of Males in the Sample with Each Armor-Plate Phenotype Year Low Partial Complete 1990 1% 2% 97% 1994 45% 14% 41% 1998 58% 16% 26% 2002 76% 15% 9% 2006 90% 6% 4% Which of the following graphs best represents the type of selection most likely operating in the stickleback population of Loberg Lake? The key indicates that a solid line represents Before selection, a dashed line represents After selection, and a downward pointing arrow indicates selection against.

True or false? Disturbance events must be naturally occurring to be considered true ecological disturbances.

Which nutrient cycle is most affected by human overuse of fertilizers?

Data regarding the presence (+) or absence (-) of five derived traits in several different species are shown in the table below. Presence (+) or absense (-) of five derived traits. Species Traits 1 2 3 4 5 V + + + – – W + + – – – X + – – + + Y – – – – – Z + – – – + Which of the following cladograms provides the simplest and most accurate representation of the data in the table?