FREE BIOLOGY AND STUDY GAMES ABOUT AP BIOLOGY

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FREE BIOLOGY AND STUDY GAMES ABOUT AP BIOLOGY

EXAM #4

Actual Qs and Ans Expert-Verified Explanation

This Exam contains:

-Guarantee passing score -63 Questions and Answers -format set of multiple-choice -Expert-Verified Explanation

Question 1: Why does the oxidation of organic compounds by molecular oxygen to

produce CO2 and water release free energy?

Answer:

Electrons are being moved from atoms that have a lower affinity for electrons (such as

• to atoms with a higher affinity for electrons (such as O).

Question 2: How does pyruvate enter the mitochondrion?

Answer:

active transport Question 3: How many carbon atoms are fed into the citric acid cycle as a result of the oxidation of one molecule of pyruvate?

Answer:

2 Question 4: Carbon skeletons for amino acid biosynthesis are supplied by intermediates of the citric acid cycle. Which intermediate would supply the carbon skeleton for synthesis of a five-carbon amino acid?

Answer:

?-ketoglutarate

Question 5: Which term most precisely describes the cellular process of breaking down large molecules into smaller ones?

Answer:

catabolism

Question 6: Which of the following is true of enzymes?

Answer:

Enzymes increase the rate of chemical reaction by lowering activation energy barriers.Question 7: Why is glycolysis described as having an investment phase and a payoff phase?

Answer:

It uses stored ATP and then forms a net increase in ATP.

Question 8: When a glucose molecule loses a hydrogen atom as the result of an

oxidation-reduction reaction, the molecules becomes

Answer:

oxidized.Question 9: Substrate-level phosphorylation accounts for approximately what percentage of the ATP formed during glycolysis?

Answer:

10% Question 10: What kind of metabolic poison would most directly interfere with glycolysis?

Answer:

an agent that closely mimics the structure of glucose but is not metabolized

Question 11: Which of the following best describes enthalpy (H)?

Answer:

the heat content of a chemical system

Question 12: Wjy are carbohydrates and fats considered high energy foods?

Answer:

They have a lot of electrons associated with hydrogen.

Question 13: The oxygen consumed during cellular respiration is involved directly in which process or event?

Answer:

accepting electrons at the end of the electron transport chain

Question 14: A molecule that is phosphorylated

Answer:

has an increased chemical reactivity; it is primed to do cellular work.Question 15: Which of the following statements is (are) true about enzyme-catalyzed reactions?

Answer:

The reaction is faster than the same reaction in the absence of the enzyme.Question 16: According to the induced fit hypothesis of enzyme catalysis, which of the following is correct?

Answer:

The binding of the substrate changes the shape of the enzyme's active site.

Question 17: The active site of an enzyme is the region that

Answer:

is involved in the catalytic reaction of the enzyme.

Question 18: The ATP made during glycolysis is generated by

Answer:

substrate-level phosphorylation.

Question 19: In addition to ATP, what are the end products of glycolysis?

Answer:

NADH and pyruvate

Question 20: Which of the following statements regarding enzymes is true?

Answer:

Enzymes increase the rate of a reaction.

Question 21: A solution of starch at room temperature does not readily decompose to form a solution of simple sugars because

Answer:

the activation energy barrier for this reaction cannot be surmounted.Question 22: Which of the following is a statement of the first law of thermodynamics?

Answer:

Energy cannot be created or destroyed.Question 23: Carbon dioxide (CO2) is released during which of the following stages of cellular respiration?

Answer:

oxidation of pyruvate to acetyl CoA and the citric acid cycle Question 24: Which of the following types of reactions would decrease the entropy within a cell?

Answer:

dehydration reactions Question 25: Among enzymes, kinases catalyze phosphorylation, while phosphatases catalyze removal of phosphate(s). A cell's use of these enzymes can therefore function as an on-off switch for various processes. Which of the following is probably involved?

Answer:

the change in a protein's charge leading to a conformational change

Question 26: Which is ATP an important molecule in metabolism?

Answer:

It provides energy coupling between exergonic and endergonic reactions.Question 27: What is the term for metabolic pathways that release stored energy by breaking down complex molecules?

Answer:

catabolic pathways