bio unit 3
Gelatin is a protein that is derived from collagen which is found in the bones, skin, and connective tissue of animals. To investigate the ability of various enzymes to digest gelatin, a group of students set up an assay involving camera film. Camera film contains gelatin and appears black when exposed to light but turns clear as the gelatin gets broken down. The students incubated pieces of exposed camera film in test tubes, each containing one of three different enzyme solutions (trypsin, lipase, or amylase) as indicated in Figure 1. The students recorded the time it took for the enzymes to digest the gelatin in each test tube, turning the film from black to clear.
A test tube containing a piece of exposed camera film submerged in water
Which of the following correctly uses the data to justify the claim that the phosphagen system is an immediate, short-term source of ATPATP for muscle cells? Responses
ATP production by the phosphagen system increases and decreases rapidly following the start of the exercise period.
A researcher claims that the synthesis of ATP from ADP and inorganic phosphate (Pi) is essential to cellular function. Which of the following statements best helps justify the researcher's claim?
ATP hydrolysis is an energy-releasing reaction that is often coupled with reactions that require an input of energy.
A researcher claims that only a portion of the light energy captured by green plants is available for growth and repair. Which of the following observations best helps justify the researcher's claim?
As light energy is converted to chemical energy by metabolic processes, some of the energy is lost as heat.
A researcher claims that increased atmospheric carbon dioxide levels cause increased growth rates in plants. Which of the following statements best supports the researcher's claim?
Atmospheric carbon dioxide is the raw material for photosynthesis, which plants rely on for producing sugars and other organic compounds.
Alcohol dehydrogenase (ADH) is an enzyme that aids in the decomposition of ethyl alcohol (C2H5OH) into nontoxic substances. Methyl alcohol acts as a competitive inhibitor of ethyl alcohol by competing for the same active site on ADH. When attached to ADH, methyl alcohol is converted to formaldehyde, which is toxic in the body. Which of the following statements best predicts the effect of increasing the concentration of substrate (ethyl alcohol), while keeping the concentration of the inhibitor (methyl alcohol) constant?
Competitive inhibition will decrease because the proportion of the active sites occupied by substrate will increase.
In chloroplasts, ATP is synthesized from ADP plus inorganic phosphate (Pi) in a reaction catalyzed by ATP synthase molecules that are embedded in the thylakoid membrane. Which of the following statements provides evidence to support the claim that no ATP will be synthesized in the absence of a proton gradient across the thylakoid membrane?
No ATP is synthesized when channel proteins that allow the free passage of protons are inserted into the thylakoid membrane.
A researcher claims that different metabolic pathways allow bacteria to use different molecules as sources of matter and energy. Which of the following statements best helps justify the researcher's claim by providing a relevant example? Responses
E. coli bacteria reproduce in liquid media containing either glucose or galactose.
A scientist claims that Elysia chlorotica, a species of sea slug, is capable of photosynthesis. Which of the following observations provides the best evidence to support the claim?
Elysia chlorotica grows when exposed to light in the absence of other food sources.
Which of the following statements best helps explain the reaction specificity of hexokinase? Responses
Glucose has the right shape and charge to cause hexokinase to undergo a structural change needed for catalysis, whereas water does not.
Cyanobacteria contain a variety of pigment molecules, as shown in Table 1. As a result, the color of cyanobacteria cultures can vary significantly based on the relative amount of each pigment produced. A researcher placed a culture of cyanobacteria under green lights. Within a few weeks, the appearance of the cyanobacteria changed from green to red. The researcher claimed the color change in the culture was the result of an adaptation allowing greater photosynthesis. Which of the following provides the best reasoning to justify the researcher's claim?
In green light, more chlorophyll a molecules are produced, reflecting more light to other cyanobacteria to be used for photosynthesis. In green light, more phycoerythrin molecules are produced, allowing more green light to be absorbed, thus increasing photosynthesis.
A researcher claims that increasing the environmental temperature by 10°C10°C will double the rate of an enzyme-catalyzed reaction. To test the claim, the researcher designs an experiment that uses a particular enzyme isolated from plants. The design of the experiment is presented in Table 1. For each test tube in the experiment, the researcher will measure the rate of product formation. Which of the following statements best helps justify the inclusion of test tube 5 as a control in the experiment? Responses
It will provide a measurement of product formation in the presence of a denatured enzyme.
Protein digestion in humans is primarily carried out by three enzymes. Pepsin is found in the stomach (pH2)(pH2), where it aids in the breakdown of large proteins into smaller peptides, while trypsin and chymotrypsin are found in the small intestine (pH8)(pH8), where they aid in the further breakdown of the proteins into amino acids and dipeptides that can be absorbed into the bloodstream. Graph 1 shows the effect of pHpH on the activity levels of the three enzymes. Which of the following best predicts how the structure and function of pepsin will change as it enters the small intestine?
Pepsin will not change in shape but may not work due to the basic environment of the small intestine. Pepsin will change in shape because of the basic environment of the small intestine; therefore, its enzymatic activity will decrease.
In addition to the pigments commonly associated with photosynthesis, a certain photosynthetic species contains two additional pigment types. Which of the following best supports the claim that this species is better adapted to environmental changes than other photosynthetic species are?
The additional pigments allow the species containing them to harvest energy from wavelengths of light that the other photosynthetic species cannot use.
(a) Describe the effect on chlorophyll-containing photosystems when the chlorophyll molecules absorb photons of light.
The photon causes an electron in the chlorophyll to become "excited."
Question Which of the following statements best helps explain the reaction specificity of an enzyme?
The shape and charge of the substrates are compatible with the active site of the enzyme.
Which of the following statements best justifies the inclusion of test tubes 3 and 7 in the experiment?
They will show whether the isolated cellular contents have enzymatic activity.
If the experiment is repeated at pH 11, the observed activity level of the enzyme will most likely be
lower than the level at pH 9
A researcher claims that different enzymes exhibit maximal function over different pHpH ranges. To test the claim, the researcher carries out an experiment that includes three different enzymes: pepsin, salivary amylase, and arginase. The results of the experiment are represented in Figure 1. Figure 1. The effect of pHpH on three different enzymes Which of the following actions will provide the most appropriate negative control for the experiment?
repeating the experiment with denatured enzymes
A researcher designs an experiment to investigate the effect of environmental temperature on the function of an enzyme. For each trial included in the experiment, the researcher will add the enzyme and its substrate to an aqueous buffer solution and then measure the amount of product formed over 20 minutes. Which of the following must remain the same for all trials of this experiment?
the initial concentration of the substrate