Unit 3 Review MC Quiz

The rate of oxygen consumption in germinating pea seeds at 26ºC is

0.05 mL / min

The energy required to run the Calvin cycle reactions of photosynthesis comes from which two substances produced during the light-dependent reactions?

ATP and NADPH

n an experiment, a scientist isolates mitochondria from living cells and suspends them in two different buffered solutions. One solution is maintained at pH 4, while the other solution is maintained at pH 9. The scientist finds that mitochondria in the solution at pH 4 continue to produce ATP but those in the pH 9 solution do not. The results of the experiment can be used as evidence in support of which of the following scientific claims about mitochondrial activity?

ATP production in mitochondria requires a hydrogen ion gradient that favors movement of protons into the mitochondrial matrix.

-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.

Butterflies of the genus Colias live in the Rocky Mountains, where they experience a wide range of temperatures. Different variants of a particular glycolytic enzyme in the flight muscles are optimally active at different temperatures. Within the same population, some individual butterflies fly most effectively at 29°C , while others fly most effectively at 40°C. Still others can be equally active at both temperatures. Which of the following claims is most consistent with the observed butterfly behavior?

Butterflies that express two variants of the enzyme are active over a greater range of temperature.

The diagram below shows energy changes in a specific chemical reaction with and without the addition of an enzyme to the reaction. Which of the following questions can best be answered by the diagram?

Does the addition of an enzyme reduce the activation energy required for a reaction?

If an individual with diabetes consumes food that is high in simple carbohydrates, blood-sugar levels can rise above normal levels. Which of the following questions would provide the best direction for a researcher who wanted to study the impact of abnormally high blood-sugar levels on cellular homeostasis in diabetics?

Does water move from cells into blood vessels more rapidly in diabetics than in nondiabetics when blood-sugar levels are higher than normal?

Either a glucose molecule or a water molecule can fit in the active site of hexokinase. The presence of a water molecule in hexokinase's active site would result in the hydrolysis of ATP to ADP instead of the conversion of glucose to glucose-6-phosphate. -Which of the following statements best helps explain the reaction specificity of hexokinase?

Glucose has the right shape and charge to cause hexokinase to undergo a structural change needed for catalysis, whereas water does not.

Which metabolic process is common to both aerobic cellular respiration and alcoholic fermentation?

Glycolysis

The O2 released during photosynthesis comes from

H2O

Which of the following questions is most relevant to understanding the Calvin cycle?

How is ATP used in the formation of 3-carbon carbohydrates?

The following questions refer to an experiment that is set up to determine the relative volume of O2 consumed by germinating and nongerminating (dry) pea seeds at two different temperatures. The change in volume is detected by using a respirometer over a given period of time. The data are given below. -Which of the following conclusions is best supported by the data?

In pea seeds an increase in temperature results in an increase in oxygen consumption.

Which of the following questions will best direct an investigation of the mechanism of ATP synthase?

Is the phosphorylation of ADP by ATP synthase dependent on the formation of a proton gradient?

Which of the following statements best helps justify the inclusion of test tube 5 as a control in the experiment?

It will provide a measurement of product formation in the absence of the substrate.

Which of the following statements best justifies the inclusion of test tube V as a control in the experiment?

It will show the color change that occurs in the absence of enzyme activity.

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.

Which of the following actions will provide the most appropriate negative control for the experiment?

Repeating the experiment with denatured enzymes

Which of the following best describes why the disks rose to the surface faster in the more concentrated hydrogen peroxide solutions?

The higher substrate concentrations in the more concentrated solutions speeded the reaction.

In most freshwater fish, nitrogenous waste is primarily excreted as ammonia, which is highly soluble in water and is toxic at low concentrations. In terrestrial mammals, ammonia is converted to urea before it is excreted. Urea is also highly soluble in water but is less toxic than ammonia at low concentrations. Which of the following best explains why freshwater fish do not convert ammonia to urea for excretion?

The dilution of ammonia by direct excretion into freshwater conserves energy.

Which of the following is an important difference between light-dependent and light-independent reactions of photosynthesis?

The light-dependent reactions produce ATP and NADPH; the light-independent reactions use energy stored in ATP and NADPH.

According to the data, the mice at 10o C demonstrated greater oxygen consumption per gram of tissue than did the mice at 25o C. This is most likely explained by which of the following statements?

The mice at 10o C had a higher rate of ATP production than the mice at 25o C.

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 is true about the Krebs (citric acid) cycle and the Calvin (light-independent) cycle?

They both are carried out by enzymes located within an organelle matrix.

A researcher claims that some bacteria contain factors that influence the function of a particular enzyme but other bacteria do not. To test the claim experimentally, the researcher will grow two different bacterial strains in separate liquid cultures and isolate the contents of the cells in each culture. The researcher will add different combinations of cellular contents, substrate, and enzyme to test tubes containing a buffer solution adjusted to the optimal pH of the enzyme and then measure the rate of product formation. The design of the researcher's experiment is presented in Table 1.

They will show whether the isolated cellular contents have enzymatic activity.

Which of the following best describes why ice was used during this experiment?

To retard the breakdown of the catalase

The carbon 'that makes up organic molecules in plants is derived directly from

carbon fixed in photosynthesis

The reactions of glycolysis occur in the

cytosol

According to the chemiosmotic theory (chemiosmotic coupling), the energy required to move protons from the mitochondrial matrix to the intermembrane space against a concentration gradient comes most directly from

electrons flowing along the electron transportchain

ATP serves as a common energy source for organisms because

its energy can be easily transferred to do cellular work

Carbohydrate-synthesizing reactions of photosynthesis directly require

products of the light reactions

During respiration, most ATP is formed as a direct result of the net movement of

protons down a concentration gradient