Chemical reactions involve two main components, reactants and products. The reactants, often referred to as substrates, interact with each other and rearrange in order to be converted into products. The speeds of these reactions are often defined by substrate concentration and the presence of enzymes. Enzymes are referred to as catalysts. Peroxidase is traditionally derived from turnips; however, it is commonly found in many plant and animal cells. This enzyme helps plant cells by removing hydrogen peroxide from cells in the form of tetraguaiacol.

Study 1

     A scientist wants to observe the production of tetraguaiacol by observing a reaction between hydrogen peroxide and guaiacol. The product of this reaction is orange-brown in color. The scientist measures the intensity of color in each sample using a spectrophotometer. In the control experiment, the scientist mixed the substrates together and measured the reaction rate. In the test experiment, a peroxidase enzyme was added to a new set of substrates and rate of reaction was measured. The results of these reactions are plotted in Figure 1.

Figure 1

Study 2

     A research team decides to study the effects of the peroxidase facilitated reaction in the presence of heat. Reaction rates are known to speed up when heat is applied; however, at a certain point enzymes, such as peroxidase, denature and the reaction slows. The scientists perform a control trial at room temperature  and test trials at , , and . The results are plotted in Figure 2.

Figure 2

In Figure 2 of Study 2, the scientist observed the enzyme-facilitated reaction in the presence of heat. What could explain the results found in Test 3?

     Survivorship curves are constructed and used to compare population growth and survival between species. A Type I curve is characterized by a population whose individuals live to old age, indicating that there is high survivorship in the early and middle years. These individuals produce few offspring and have long periods of parental care. In a Type II curve, there is a constant survivorship across the individuals’ life spans. A Type III curve is characterized by a population of individuals that possess low survivorship early in age; however, this is followed by high survivorship of older individuals. These species produce large numbers of offspring with little or no parental care. Figure 1 is a graphical representation of these curves.

Which of the following organisms is likely to possess a type 1 curve?

Which of the following organisms is likely to possess a type 2 curve?

Survivorship curves are constructed and used to compare population growth and survival between species. A Type I curve is characterized by a population whose individuals live to old age, indicating that there is high survivorship in the early and middle years. These individuals produce few offspring and have long periods of parental care. In a Type II curve, there is a constant survivorship across the individuals’ life spans. A Type III curve is characterized by a population of individuals that possess low survivorship early in age; however, this is followed by high survivorship of older individuals. These species produce large numbers of offspring with little or no parental care. Figure 1 is a graphical representation of these curves.

Which of the following organisms is likely to possess a type 3 curve?

A scientist studies a new invasive species. It is a type of sea urchin that that produces many offspring. The offspring possess a very low mortality rate and grow exponentially through several generations. These organisms would follow which type of survivorship curve?

A spectrophotometer measures specific light wavelengths emitted by a sample. The readings of the samples are compared to those on a standard curve of known values. The standard curve creates a line and the equation of this line can be used to extrapolate the concentration of a given substance in samples whose spectrophotometric measurements fall within range of the curve.

A scientist measures a sample and plots it on the standard curve of known values. Estimate the concentration of substance in this sample.

A spectrophotometer measures specific light wavelengths emitted by a sample. The readings of the samples are compared to those on a standard curve of known values. The standard curve creates a line and the equation of this line can be used to extrapolate the concentration of a given substance in samples whose spectrophotometric measurements fall within range of the curve.

A scientist measures a sample and finds that it has an absorbance of . What is the concentration of substance in this sample?

A spectrophotometer measures specific light wavelengths emitted by a sample. The readings of the samples are compared to those on a standard curve of known values. The standard curve creates a line and the equation of this line can be used to extrapolate the concentration of a given substance in samples whose spectrophotometric measurements fall within range of the curve.

A scientist measures a sample and finds that it has an absorbance of . What is the concentration of substance in this sample?

Question Body

Which of the following best describes the species interaction that was observed when the researcher removed the Balanus species early in the study?

     Species competition is driven by a variety of factors. Resources such as water, food, sunlight, and suitable habitat are among the top contributors that influence interspecific and intraspecific competition. Interspecific is competition between different species and intraspecific competition is between members of the same species.

      One interesting example of interspecific completion is that of two barnacle species that inhabit intertidal zones. Balanus balanoides inhabits the lower intertidal zone and Chthamalus stellatus inhabits the lower intertidal zone. A researcher attempts to study this phenomenon.

     The researcher removes the Balanus species from the lower intertidal zone and observes that the Chthamalus species expands its range to inhabit the lower intertidal zone and the upper intertidal zone. The researcher then removes the Chthamalus species from the upper tidal zone of a different area and observes that the Balanus species does not extend its range. The researcher concludes that competition has allowed each species to exist simultaneously by forming specialized niches that promotes survivorship for each species.

Researchers suggest that the Balanus species disrupts the Chthamalus species' ability to inhabit the lower intertidal zones because it is much larger and can physically remove the smaller Chthamalus without much effort. Does this information agree witht the data observed in the barnacle study?