Chapter 4

electron transport chain

- membrane-bound molecular complex that shuttles electrons to slowly extract their energy

endergonic reaction

-a chemical reaction that requires a net input of energy

kilocalorie

-a measure of the energy content in food; equal to one thousand calories or one food Calorie

positive feedback

-a process that reinforces an existing condition

exergonic reaction

-an energy-releasing chemical reaction

enzyme

-an organic molecule that catalyzes a chemical reaction without being consumed

competitive inhibition

-change in an enzyme's activity occurring when an inhibitor binds to the active site, competing with the enzyme's normal substrate

noncompetitive inhibition

-change in an enzyme's shape occurring when an inhibitor binds to a site other than the active site

oxidation-reduction ("redox") reactions

-chemical reaction in which one reactant is oxidized and another is reduced

isotonic

-condition in which a solute concentration is the same on both sides of a selectively permeable membrane

hypertonic

-describes a solution in which the solute concentration is higher than on the other side of selectively permeable membrane

hypotonic

-describes a solution in which the solute concentration is lower than on the other side of a selectively permeable membrane

concentration gradient

-difference in solute concentrations between two adjacent regions

first law of thermodynamics

-energy cannot be created or destroyed, just converted from one form to another

kinetic energy

-energy of motion

activation energy

-energy required for a chemical reaction to begin

second law of thermodynamics

-every reaction loses some energy to the surrounding as heat; entropy always increases

phagocytosis

-form of endocytosis in which the cell engulfs a large particle

facilitated diffusion

-form of passive transport in which a substance moves down its concentration gradient with the aid of a transport protein

endocytosis

-form of transport in which a membrane engulfs substances to bring them into a cell

exocytosis

-form of transport in which vessicles fuse with the cell membrane to carry materials out of a cell

simple diffusion

-from of passive transport in which a substance moves down its concentration gradient without the use of a transport protein

cofactors

-inorganic or organic substance required for activity of an enzyme

passive transport

-movement of a solute across a membrane without the direct expenditure of energy

active transport

-movement of a substance across a membrane against its concentration gradient, using a carrier protein and energy from ATP

diffusion

-movement of a substance from a region where it is highly concentrated to an area where it is less concentrated

sodium-potassium pump

-protein that uses energy from ATP to transport sodium out of cells and potassium into cells

negative feedback

-regulatory mechanism in which a change in a condition triggers action that reverses the change

osmosis

-simple diffusion of water through a selectively permeable membrane

potential energy

-stored energy available to do work

energy

-the ability to do work

phosphorylation

-the addition of a phosphate to a molecule

metabolism

-the biochemical reactions of a cell

calorie

-the energy required to raise the temperature of 1 gram of water by 1 degree Celsius under standard conditions

turgor pressure

-the force of water pressing against the cell wall

reduction

-the gain of one or more electrons by a participant in a chemical reaction

oxidation

-the loss of one or more electrons by a participant in a chemical reaction

active site

-the part of an enzyme to which substrates bind

selectively permeable/ selective permeability

-the property that enables a membrane to admit some substances and exclude others

coupled reactions

-two simultaneous chemical reactions, one of which provides the energy that drives the other

15. Whenever ATP is produced by a chemical reaction some energy is lost into the surroundings as heat. A) True B) False

A) True

24.Cofactors or coenzymes, required for correct action of some enzymes, are often present in our diets as the vitamins, and minerals. A) True B) False

A) True

26. When an end product of a reaction pathway is in excess and inhibits the first enzyme of the pathway, this is an example of negative feedback. A) True B) False

A) True

28. Phospholipid bilayer and the proteins in the cell membrane regulate the transport functions of the cell. A) True B) False

A) True

18. The region of an enzyme that catalyzes reactions is called a(n) A. active site. B. binding pocket. C. catalyst site. D. reaction site. E. cofactor site.

A. active site.

27. Simple diffusion A. does not require energy expenditure B. utilizes proteins to move molecules across a membrane. C. requires energy. D. cannot occur without a membrane present. E. moves molecules against a concentration gradient.

A. does not require energy expenditure

12. Coupled reactions are reactions in which a A. exergonic reaction drives an endergonic reaction. B. exergonic reaction drives a spontaneous reaction. C. endergonic reaction drives an exergonic reaction. D. endergonic reaction drives a spontaneous reaction.

A. exergonic reaction drives an endergonic reaction.

37. When a cell is in a solution where the concentration of solute is the same in the cell as in the solution, the solution is called ________. A. isotonic B. hypertonic C. hypotonic D. osmotonic

A. isotonic

40. If blood cells are placed in a hypertonic solution, A. the cells will shrink due to water loss by the cell. B. the cells will be unaffected since they have a cell membrane C. the cells will swell due to diffusion. D. the cells will burst due to active transport.

A. the cells will shrink due to water loss by the cell.

9. Oxidation means A. the loss of electrons from a molecule. B. the loss of oxygen by a cell. C. the gain of electrons by a molecule. D. the gain of oxygen by a cell.

A. the loss of electrons from a molecule.

8. Oxidation-reduction reactions A. transfer electrons from one molecule to another. B. increase the amount of oxygen in the cell. C. transfer protons from one molecule to another. D. are not used by living cells. E. reduce the amount of oxygen in the cell.

A. transfer electrons from one molecule to another.

25. Selective permeability of the cell membranes results in the equal amounts of substances inside and outside the cell. A) True B) False

B) False

4. A ripe peach hanging from a tree branch A) has a kinetic energy. B) has a potential energy. C) has both kinetic and potential energy. D) has heat energy. E) has entropy.

B) has a potential energy.

20.The molecule that fits into the active site of an enzyme and reacts with the enzyme is A. an analog. B. a substrate. C. always a carbohydrate. D. always broken down by the enzyme. E. always a protein.

B. a substrate.

16. An enzyme is A. may be a protein. B. an organic molecule that accelerates the cellular reactions. C. not necessary to sustain life in a cell. D. used up in a reaction. E. All of the answer choices are correct.

B. an organic molecule that accelerates the cellular reactions.

5. Entropy is a measure of ________ in nature A. complexity. B. disorder. C. order. D. kinetic energy. E. potential energy.

B. disorder.

7. The breakdown of the glucose to carbon dioxide and water is an A. exergonic reaction in the photosynthesis. B. exergonic reaction in the cellular respiration. C. endergonic reaction in the photosynthesis. D. endergonic reaction in the cellular respiration.

B. exergonic reaction in the cellular respiration.

30. What is the function of some of the embedded membrane proteins in plasma membrane? A. simple diffusion B. facilitated & active transport C. support for the membrane D. phagocytosis E. osmosis

B. facilitated & active transport

38. A white blood cell surrounds and engulfs an invading bacterial cell, forming a vesicle around. This process is called ________. A. active transport B. phagocytosis C. exocytosis D. facilitated diffusion

B. phagocytosis

10. Reduction means A. the loss of electrons by a molecule. B. the gain of electrons by a molecule. C. the loss of oxygen from a cell. D. the gain of oxygen by a cell.

B. the gain of electrons by a molecule.

22. Noncompetitive inhibition of enzyme occurs A. when a cofactor, instead of a reactant, binds to the enzyme active site. B. when a substance binds to an enzyme at a site away from the active site. C. by blocking the production of an enzyme. D. when a substance other than the substrate binds at the active site of an enzyme.

B. when a substance binds to an enzyme at a site away from the active site.

1. The two basic forms of energy are __________ and __________ energy. A) caloric, chemical B) mechanical, material C) kinetic, potential D) potential, chemical E) chemical, mechanical

C) kinetic, potential

6. ATP releases energy when ________. A. a ribose is added B. adenine is removed C. a last one phosphate is removed D. deoxyribose is added E. sunlight strikes it

C. a last one phosphate is removed

14. Once ATP donates its phosphate to a coupled reaction it becomes ADP. The ADP A. can be recharged in an exergonic reaction to form ATP. B. is a waste product that must be broken down. C. can be recharged in an endergonic reaction to form ATP. D. becomes the needed potential energy source for another coupled reaction. E. can be recharged in an oxidation reaction to form ATP.

C. can be recharged in an endergonic reaction to form ATP.

35. What prevents a plant cell from bursting in a hypotonic solution? A. plasma membrane B. transport proteins which help pump the excess water out of the cell C. cell wall D. because water is moving out of the cell

C. cell wall

39. Probable factors that affect the passage of the molecule across cell membranes include all of the following except ________. A. concentration B. size C. color D. time E. electrical charge (polarity)

C. color

32.The diffusion of water across a selectively permeable (biological) membrane is A. always beneficial to a cell B. active transport. C. osmosis. D. a rare occurrence. E. a process that always requires proteins.

C. osmosis.

21. Competitive inhibition of the enzyme occurs A. when a substance binds to an enzyme at a site away from the active site. B. when the product, instead of the reactant of a reaction binds to the active site. C. when a substance other than the substrate binds at the active site of an enzyme. D. when the product, or other substances, instead of the reactant, bind to the active site of the enzyme. E. by blocking the production of an enzyme.

C. when a substance other than the substrate binds at the active site of an enzyme.

19. The induced fit model of enzyme activity says that A) two substrates must bind simultaneously to the enzyme for catalysis to occur. B) only a small portion of the enzyme actually participates in the reaction. C) enzymes must be primed with ATP before they are active. D) the enzyme's active site changes in shape to allow for substrate binding.

D) the enzyme's active site changes in shape to allow for substrate binding.

13. The process of phosphorylation A. adds a phosphate group to a molecule. B. removes a phosphate group from a molecule. C. may change the shape of the target molecule. D. All of the answer choices are correct. E. may energize the target molecule.

D. All of the answer choices are correct.

33. Active transport is different from simple diffusion in that active transport A. moves molecules against a concentration gradient. B. requires energy. C. requires proteins embedded within the cell membrane. D. All of the answer choices are correct. E. moves molecules from an area of lower concentration to an area of higher concentration.

D. All of the answer choices are correct.

31. The sodium-potassium transport through a cell membrane protein, termed the sodium-potassium pump uses process of _________. A. equilibrium. B. facilitated diffusion. C. osmosis. D. active transport. E. diffusion.

D. active transport.

29. Molecules move from greater to lesser concentration (gradient) through a transport protein in the _____. A. simple diffusion B. active transport C. endocytosis D. facilitated diffusion E. phagocytosis

D. facilitated diffusion

23. What process typically regulates the enzymes involved in metabolic reactions? A. substrate inhibition B. entropy capture C. ATP blockage D. feedback inhibition E. temperature levels

D. feedback inhibition

17. Enzymes speed up the chemical reactions by A. supplying energy to the reaction process. B. raising the temperature of the surroundings. C. lowering the amount of reactants that are needed. D. lowering the energy required to start a chemical reaction. E. maintaining chemical equilibrium.

D. lowering the energy required to start a chemical reaction.

34. Which of the types of cellular activities listed below would not use the energy (ATP)? A. active transport B. muscular contraction C. flagella movement D. passive transport E. protein synthesis

D. passive transport

36. In the in a hypertonic solution the plant cell becomes ________. A. swollen or ruptured B. unchange C. isotonic plant cell D. plasmolyzed

D. plasmolyzed

3. Which of the following is not an example of kinetic energy? A. sound B. light C. heat D. the energy in chemical bonds (sugar) E. random molecular movement

D. the energy in chemical bonds (sugar)

2. Which statement is not part of the first law of thermodynamics? A. The amount of energy in the universe is constant. B. None of the answer choices are correct. C. Energy cannot be created or destroyed. D. Energy can be converted to other forms of energy. E. Any energy transformation loses some energy to its surroundings as heat.

E. Any energy transformation loses some energy to its surroundings as heat.

11. Oxidation-reduction (redox) reactions A. remove protons from one molecule and join them to another molecule. B. remove electrons from both molecules involved. C. remove oxygen from the cell. D. never occur at the same time. E. occur simultaneously.

E. occur simultaneously.

ATP (adenosine triphosphate)

a molecule whose high-energy phosphate bonds power many biological processes