The natural limit to how large a population can grow within a specific habitat is referred to by ecologists as ______.

Scientists are analyzing DNA sequences for the same gene from three different species. Which cladogram most accurately reflects the relationship between the three species N, O, P? Species N: A A C T A G C G C G A T Species O: A A C T A G C G C C A T Species P: T T C T A G C G G T A T

Humans vary in their ability to taste the bitter chemical compound phenylthiocarbamide (PTC). The taster phenotype is dominant to the nontaster phenotype. Researchers tested the PTC taster phenotype of individuals from an isolated population. In the sample, 780 individuals were able to taste PTC and 70 individuals were not able to taste PTC. Assuming the population is in Hardy-Weinberg equilibrium, what is the frequency of the non-taster allele?

Students investigated the effect of light on the carbon cycle in aquatic ecosystems by performing the controlled experiment summarized below. The students placed equal amounts of water (pH 7.0)  from a large aquarium in glass beakers. The students transferred aquatic plants from the aquarium to several of the beakers, and then they placed equal numbers of the beakers in the light or the dark (Figure 1: Groups I and II). Similarly, the students transferred goldfish from the same aquarium to other beakers, and then they placed equal numbers of those beakers in the light or dark (Figure 1: groups III and IV). Finally, the students placed an equal number of beakers containing water only in the light or dark (Figure 1: Groups V and VI). After exposing the samples to light or dark for one hour, the students recorded the pH of the water in each beaker. Carbon dioxide dissolved in water will lower the pH of an aqueous solution. In the experiment, the students used changes in pH to monitor changes in the amount of carbon dioxide in the water.  For each treatment group, the students calculated the mean pH and standard error, as documented in the table below. The odd-numbered groups are marked Light, and the even-numbered groups are marked Dark. Each group contains a beaker with the same amount of water. From left to right, the beakers are as follows:1, plant. 2, plant. 3, fish. 4, fish. 5, empty. 6, empty. Figure 1. Treatment groups Mean pH of Treatment Groups After 1 Hour Treatment group (n = 10) I II III IV V VI Mean pH 8.2 6.4 5.9 5.6 7.3 6.8 Standard error of the mean 0.3 0.3 0.2 0.3 0.5 0.4 The results for treatment groups V and VI could suggest which of the following questions about the design of the experiment?

Which of the following best explains why there are seldom more than five trophic levels in a food chain?

All the following provide evidence and support for the theory of natural selection except ______.

Which of these organisms are most closely related? At the left is a branch point from which two lines extend. The upper line extends upward to the right, reaching a second branch point. From this second branch point, the upper line extends upward to the right, leading to Tuatara. The lower line from the second branch point extends to the right, then branches twice more, creating two upper lines that extend upward to the right and one lower line. A bracket to the right indicates that the two upper lines both represent Lizards. The lower line extends to the right, leading to Snakes. The lower line from the first branch point extends downward to the right, reaching a fourth branch point. From this fourth branch point, the upper line extends to the right, leading to Crocodiles, and the lower line extends downward to the right, leading to Birds.

Once the boundaries and number of individuals in a population are determined, populations are often described by their ______ and ______.

The lowest trophic level of a community is the level of ______.

Simpsons Diversity Index is a way to quantify the diversity of a community.  The equation can be written as: D = N(N-1) / ∑ n ( n– 1)  Where: D = Diversity index N = Total number of individuals of all species n = Number of individuals of a specific species   Community A has 3 species (A, B, C). There are 5 individuals of each species. (N=15) Community B has 6 species (A, B, C, D, E). There are 3 individuals each of species A, B, and C. There are 2 individuals each of species D, E, and F. (N=15) Community C has 5 species (A, B, C, D, E). There are 3 individuals each of species. (N=15)   What is the species diversity of Community C?