Biology Chapter 5

Most cellular work is accomplished by the consumption of __________, which energizes molecules by __________ them. enzymes ... activating substrates ... phosphorylating ATP ... phosphorylating coenzymes ... activating

ATP ... phosphorylating

Which of the following is an accurate comparison of active transport and facilitated diffusion? -Active transport requires membrane proteins; facilitated diffusion does not require membrane proteins. -Facilitated diffusion requires the use of ATP; active transport does not require ATP. -Active transport moves solutes against their concentration gradient; facilitated diffusion moves substances down their concentration gradient. -In both types of movement, phosphate groups alter the shape of transport proteins.

Active transport moves solutes against their concentration gradient; facilitated diffusion moves substances down their concentration gradient.

Antibiotics - for example, penicillin - cannot be used to treat viral infections, such as the common cold. Why? -They may poison the patient. -Antibiotics enhance viral function. -Only protease inhibitors can be used to fight viral infections. -Antibiotics inhibit enzymes that are essential to the survival and/or reproduction of bacteria only, not enzymes important to humans.

Antibiotics inhibit enzymes that are essential to the survival and/or reproduction of bacteria only, not enzymes important to humans.

Green olives may be preserved in brine, which is a 20-30% salt solution. How does this method prevent contamination by microorganisms? -Bacterial cell walls are shriveled up by salt, causing the cell to burst. -Bacteria can't survive because they would lose water in a hypertonic solution. -High salt concentrations raise the pH, thus inhibiting the process of glycolysis, the first stage of the metabolism of glucose. -High salt concentrations lower the pH, thus inhibiting the process of glycolysis, the first stage of the metabolism of glucose.

Bacteria can't survive because they would lose water in a hypertonic solution.

Frequently, transplanted organs are rejected by the recipient's body. How is this reaction related to plasma membranes? -The fibers of the extracellular matrix differ from individual to individual. -Each person has a unique set of glycoproteins with carbohydrate chains attached to his or her plasma membranes. -Everyone's organs contain different amounts of cholesterol. -The phospholipid bilayers become disrupted during transplant and may never re-form, causing the tissues to lose their function.

Each person has a unique set of glycoproteins with carbohydrate chains attached to his or her plasma membranes.

Macrophages are white blood cells that roam the body searching for invading microbes. These invaders are destroyed inside macrophage vacuoles. How do the macrophages bring the microbes inside? -They are taken in by the form of exocytosis known as pinocytosis. -The invaders cross the membranes via facilitated transport through specific transport proteins. -The invaders cross the membranes via active transport through specific transport proteins. -Microbes are engulfed into the macrophage via phagocytosis.

Microbes are engulfed into the macrophage via phagocytosis.

The hydrolysis of DNA into nucleotides constitutes an exergonic reaction. Yet, DNA is quite stable. Why is this the case? -No enzymes exist to facilitate DNA hydrolysis. -Only endergonic reactions proceed rapidly. -DNA synthesis occurs at the same rate as DNA hydrolysis, so DNA only appears stable. -The activation energy required to initiate this reaction is seldom reached.

The activation energy required to initiate this reaction is seldom reached.

What happens to the portion of chemical energy that is extracted from molecules by cellular activities but that is not used for cellular work? -The energy is captured by other cells. -The energy is recycled by the cell. -The energy contributes to the entropy of the system. -It is used by plant cells for photosynthesis.

The energy contributes to the entropy of the system.

Cellular respiration is an example of __________. -an exergonic process -thermodynamics -bioenergetics -an endergonic process

an exergonic process

Fluidity of an animal cell plasma membrane is enhanced by __________. -saturated triglycerides -saturated phospholipids -cholesterol molecules -polyunsaturated triglycerides

cholesterol molecules

The movement of atoms, ions, or molecules from a region of higher concentration to regions of lower concentration is called _____. -plasmolysis -diffusion -spontaneous combustion -active transport

diffusion

The phosphorylation of ADP to form ATP is an _____ reaction that _____ energy. exergonic ... releases exergonic ... requires an input of endergonic ... requires an input of endergonic ... releases

endergonic ... requires an input of

A nursing infant is able to obtain disease-fighting antibodies, which are large protein molecules, from its mother's milk. These molecules probably enter the cells lining the baby's digestive tract via __________. -active transport -endocytosis -osmosis -passive transport

endocytosis

Identify Structure A.

glycoprotein

During enzymatic reactions, substrates are converted to products. A property of enzymes that facilitates this reaction is that they are catalysts and therefore _____. -provide activation energy for the reactions they facilitate -increase the rate of a reaction without being consumed by the reaction -are proteins -can make an endergonic reaction exergonic

increase the rate of a reaction without being consumed by the reaction

Endocytosis moves materials _____ a cell via _____. out of ... membranous vesicles into ... facilitated diffusion into ... a transport protein out of ... diffusion into ... membranous vesicles

into ... membranous vesicles

As a result of its involvement in a reaction, an enzyme _____. -is unchanged -loses energy -permanently alters its shape. -loses a phosphate group -is used up

is unchanged

Light is _____ energy, which is converted by plants into molecules that possess _____ energy. chemical ... kinetic chemical ... potential potential ... kinetic kinetic ... chemical

kinetic ... chemical

The diffusion of water across a selectively permeable membrane is called __________.

osmosis

The plasma membrane is selectively permeable. Which of the following can pass freely through the membrane with no assistance? oxygen and carbon dioxide sodium and hydrogen ions starch and cellulose glucose and lactose

oxygen and carbon dioxide

Facilitated diffusion is a type of _____. -pinocytosis -active transport -passive transport -phagocytosis

passive transport

Identify Structure D.

phospholipid bilayer of membrane

Most enzymes are _____. minerals carbohydrates lipids proteins nucleic acids

proteins

Overall, membranes seem to have a great deal in common, but on closer inspection it is revealed that membranes of different cells have unique properties. What is the primary component of membranes that gives them cell-specific properties? -phospholipids -cytoskeleton -proteins -cholesterol

proteins

Which of the following enables a cell to pick up and concentrate a specific kind of molecule? -passive transport -diffusion -receptor-mediated endocytosis -osmosis

receptor-mediated endocytosis

The lipids in a cell membrane are arranged _____. -on either side of a single layer of protein -so that the hydrophilic components are arranged to face each other -between two layers of protein -so that the nonpolar parts of two lipids point toward each other

so that the nonpolar parts of two lipids point toward each other

What is the function of Structure E?

stabilization of the phospholipids

What name is given to the reactants in an enzymatically catalyzed reaction? reactors active sites products substrate

substrate

For an enzyme to catalyze a reaction there must be a specific fit between the __________ and the enzyme's __________. cofactor ... coenzyme enzyme ... active site substrate ... active site substrate ... product

substrate ... active site

You can recognize the process of pinocytosis when _____. -a receptor protein is involved -the cell is engulfing a large particle -the cell is engulfing extracellular fluid

the cell is engulfing extracellular fluid

The transport of molecules of a particular solute from inside an animal cell across the cell membrane to the extracellular fluid always requires energy when _____. -the lipid bilayer is permeable to the solute -the concentration of the solute is lower inside the cell than outside it -a transport protein is involved in the movement of the molecules -the concentration of the solute is higher inside the cell than outside it

the concentration of the solute is lower inside the cell than outside it

Osmosis is often viewed incorrectly as a process driven directly by differences in solute concentration across a selectively permeable membrane. What really drives osmosis? -the difference in the height of water columns on either side of a selectively permeable membrane -the difference in sugar or ion concentration across a selectively permeable membrane -the difference in water concentration across a selectively permeable membrane -the first law of thermodynamics

the difference in water concentration across a selectively permeable membrane

What controls the net direction of the movement of oxygen molecules in passive transport? -the size of the oxygen molecule -the type of cell to or from which the oxygen molecule is moving -the direction of the oxygen concentration gradient -the amount of energy available to transport oxygen

the direction of the oxygen concentration gradient

Aquaporins are proteins that facilitate the transport of __________ across the membrane. -proteins -salt -urine -water

water

Recall from Chapter 4 that phospholipids have two parts: a nonpolar head and two nonpolar tails. In an oil-based, nonpolar environment, phospholipids would arrange themselves so that they __________. -would pack more tightly together than they would in a watery environment -would not pack together at all -would never associate but instead would remain as individual molecules completely dissolved in the oil -would stay together but in a reverse orientation, with their tails projecting outward

would stay together but in a reverse orientation, with their tails projecting outward

Which of these statements describes what occurs in facilitated diffusion? -Facilitated diffusion requires energy from the cell to drive a concentration gradient. -Facilitated diffusion of solutes occurs through phospholipid pores in the membrane. -Facilitated diffusion of solutes occurs through protein pores in the membrane. -Facilitated diffusion is another name for osmosis.

Facilitated diffusion of solutes occurs through protein pores in the membrane.

Which of the following best describes an enzyme? -Starting molecule that is changed into a product during a chemical reaction -Molecule that decreases the product of a chemical reaction -Molecule that increases the rate of a chemical reaction -Molecule that increases the energy released by a chemical reaction

Molecule that increases the rate of a chemical reaction

According to the second law of thermodynamics, which of the following is true? -The ordering of one system depends on the disordering of another. -The total amount of energy in the universe is constant. -Energy conversions increase the order in the universe. -The entropy of the universe is constantly decreasing.

The ordering of one system depends on the disordering of another.

Which of the following statements is true of an exergonic reaction but NOT true of an endergonic reaction? -activation energy exceeds net energy release -the potential energy of the products is less than the potential energy of the reactants -activation energy is necessary -no kinetic energy is released

the potential energy of the products is less than the potential energy of the reactants