Unit 2 - Cellular Energetics (Chs 8-10)

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?

• Rhizobia bacteria form close associations with the roots of bean plants.

• E. coli bacteria reproduce in liquid media containing either glucose or galactose.

• The antibiotic rifampicin inhibits the growth of some bacterial strains but not of others.

• Some viruses that infect bacteria reproduce by either the lysogenic cycle or the lytic cycle.

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NGSS.HS-LS2-3

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?

• Light-capturing pigment molecules in green plants absorb red, blue, and violet light but reflect green light.

• The energy of a photon of light is proportional to its frequency and inversely proportional to its wavelength.

• As light energy is converted to chemical energy by metabolic processes, some of the energy is lost as heat.

• Captured energy is stored in the molecular bonds of organic molecules, including simple sugars and starch.

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NGSS.HS-LS1-5

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

• The final concentration of the product

• The three-dimensional structure of the enzyme

• The temperature of the aqueous buffer solution

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NGSS.HS-PS1-5

Which of the following best describes the function of the coenzymes NAD+ and FAD in eukaryotic cellular respiration?

• They participate in hydrolysis reactions by accepting protons from water molecules.

• They participate directly in the phosphorylation of ADP to ATP.

• They serve as final electron acceptors in the electron transport chain.

• They aid vitamins such as niacin in the breakdown of glucose.

• They accept electrons during oxidation-reduction reactions.

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NGSS.HS-LS1-7

Chemical equilibrium is relatively rare in living cells because metabolic pathways are interconnected. Which of the following statements describes an example of a reaction that may be at chemical equilibrium in a cell?

• an exergonic reaction in which the entropy change in the cell is precisely balanced by an opposite entropy change in the cell's surroundings

• an endergonic reaction in an active metabolic pathway where the energy for that reaction is supplied only by heat from the environment

• a chemical reaction in which neither the reactants nor the products are being produced or consumed in any metabolic pathway at that time in the cell

• an exergonic reaction in which the free energy at equilibrium is higher than the energy content of the reaction at any point away from equilibrium

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NGSS.HS-PS1-4

NGSS.HS-PS1-6

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.

Which of the following would be the most appropriate control for this experiment?

• A test tube containing no camera film

• A test tube containing only a piece of exposed camera film

• A test tube containing a piece of exposed camera film submerged in water

• A test tube containing a piece of exposed camera film and all three enzyme solutions

Tags

NGSS.HS-PS1-5

A respirometer is a container used to measure the amount of oxygen consumed by an organism. A respirometer was used to determine how environmental temperature affects the uptake of oxygen in one 300-gram rat and one 50-gram mouse. The results of this experiment are shown on the graph below.

Which of the following hypotheses is best supported by the results of this experiment?

• Metabolic rate per gram of tissue is higher in smaller mammals.

• Metabolic rate per gram of tissue is not related to body mass.

• Mice produce less CO₂ per gram of tissue than do rats.

• Rats consume more food per gram of tissue than do mice.

• Rats lose more heat per gram of tissue than do mice.

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NGSS.HS-LS1-7

A respirometer is a container used to measure the amount of oxygen consumed by an organism. A respirometer was used to determine how environmental temperature affects the uptake of oxygen in one 300-gram rat and one 50-gram mouse. The results of this experiment are shown on the graph below.

Which of the following would most adversely affect the validity of this experiment?

• Large variation in metabolic rates between individuals of a species

• Repeating the experiment several times

• Using a brown rat and a white mouse

• Using a thermometer that consistently read 2°C too low

• Using a scale that consistently indicated 2 grams too much

Tags

NGSS.HS-LS1-7

Which of the following statements describes a common characteristic of catabolic pathways?

• They are endergonic and release energy that can be used for cellular work.

• They combine small molecules into larger, more energy-rich molecules.

• They require energy from ATP hydrolysis to break down polymers into monomers.

• They are exergonic and provide energy that can be used to produce ATP from ADP and P_i.

Tags

NGSS.HS-LS1-7

Zinc, an essential trace element for most organisms, is present in the active site of the enzyme carboxypeptidase. The zinc most likely functions as ________.

• a coenzyme derived from a vitamin

• a noncompetitive inhibitor of the enzyme

• an allosteric activator of the enzyme

• a cofactor necessary for enzyme activity