Chapter 5
Most cellular work is accomplished by _____ energizing molecules by _____ them.
ATP ... phosphorylating
Which of the following is a difference between active transport and facilitated diffusion? (ebook Module 5.6) Facilitated diffusion can move solutes against a concentration gradient, and active transport cannot. Facilitated diffusion involves transport proteins, and active transport does not. Active transport involves transport proteins, and facilitated diffusion does not. Active transport requires the expenditure of cellular energy, and facilitated diffusion does not.
Active transport requires the expenditure of cellular energy, and facilitated diffusion does not.
Green olives may be preserved in brine, which is a 20-30% salt solution. How does this method prevent contamination by microorganisms? (ebook Module 5.5) Bacteria can't survive in a hypertonic solution because they lose water. Bacterial cell walls are shriveled up by salt, causing the cell to burst. High salt concentrations raise the pH, thus inhibiting the process of glycolysis. High salt concentrations lower the pH, thus inhibiting the process of glycolysis.
Bacteria can't survive in a hypertonic solution because they lose water.
What is kinetic energy?
Energy at work. The energy of motion.
Which of these statements describes what occurs in facilitated diffusion
Facilitated diffusion of solutes occurs through protein pores in the membrane
Which of these statements describes what occurs in facilitated diffusion? (ebook Module 5.5) Facilitated diffusion of solutes occurs through phospholipid pores in the membrane. Facilitated diffusion is another name for osmosis. Facilitated diffusion of solutes occurs through protein pores in the membrane. Facilitated diffusion requires energy from the cell to drive a concentration gradient.
Facilitated diffusion of solutes occurs through protein pores in the membrane.
Which of the following statements is true about passive transport? (ebook Module 5.3) Passive transport requires no expenditure of cellular energy. Passive transport phenomena can never reach equilibrium. Passive transport operates independently of concentration. Passive transport operates independently of diffusion.
Passive transport requires no expenditure of cellular energy. (Vận chuyển thụ động không đòi hỏi chi phí năng lượng của tế bào.)
Which of these statements about enzyme inhibitors is true?
The action of competitive inhibitors may be reversible or irreversible
Which of these statements about enzyme inhibitors is true? (ebook Module 5.15) A noncompetitive inhibitor does not change the shape of the active site. A competitive inhibitor binds to the enzyme outside the active site. When the product of an enzyme or an enzyme sequence acts as its inhibitor, this is known as positive feedback. The action of competitive inhibitors may be reversible or irreversible.
The action of competitive inhibitors may be reversible or irreversible.
Phospholipids are well suited to serve as the major component of the plasma membrane because they
have a water-soluble part and a water-insoluble part
If the volume of a cell increases when it is placed in an aqueous solution, that solution is said to be _____ to the cell. (ebook Module 5.5) hypotonic hypertonic isotonic osmotic
hypotonic
LDLs enter cells by means of
receptor-mediated endocytosis
When does Competitive inhibition occur?
when a molecule mimics the substrate
Why doesn't the antibiotic penicillin harm humans?
Human cells do not have cell walls
Which of the following statements is true about diffusion? (ebook Module 5.5) It requires expenditure of energy by the cell. It decreases the entropy of the cell, making it more ordered. It is a passive process. It occurs when molecules move from a region of lower concentration to a region of higher concentration.
It is a passive process.
What happens to the chemical energy that is extracted by cellular activities that is not used for cellular work?
The energy contributes to the entropy of the system
Why are phospholipids well suited to be the main structural components of membranes?
They form a selectively permeable structure.
NOT needed for active transport
a concentration gradient
What is the functions of pro tine membrane?
a. transport b. enzyme activity c. signal transduction d. intercellular joining e. cell-cell recognition f. attachment to the cytoskeleton and extracellular matrix
Cellular respiration is an example of _____. (ebook Module 5.11) bioenergetics thermodynamics an endergonic reaction an exergonic reaction
an exergonic reaction
If the entropy of a system is increasing, this means that
energy input will be needed to maintain organization
Some liver cells ingest bacteria, a function probably accomplished by
phagocytosis
The lipids in a cell membrane are arranged _____.
so that the nonpolar parts of two lipids point toward each other
Stability of an animal cell plasma membrane is enhanced (cải tiến) by _____. cholesterol molecules saturated triglycerides polyunsaturated triglycerides saturated phospholipids
cholesterol molecules
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 _____. (ebook Module 5.8) the concentration of the solute is lower inside the cell than outside it the concentration of the solute is higher inside the cell than outside it the lipid bilayer is permeable to the solute a transport protein is involved in the movement of the molecules
the concentration of the solute is lower inside the cell than outside it
Cells A and B are the same size and shape, but cell A is metabolically quiet and cell B is actively consuming oxygen. Oxygen will diffuse more quickly into cell _____ because _____. (ebook Module 5.5) A ... the diffusion gradient there is shallower B ... the oxygen molecules inside cell B have a higher kinetic energy B ... the diffusion gradient there is steeper A ... its membrane transport proteins will not be saturated
B ... the diffusion gradient there is steeper
Most cellular work is accomplished by _____ energizing molecules by _____ them. (ebook Module 5.12) ATP ... phosphorylating enzymes ... activating coenzyme ... activating substrates ... phosphorylating
ATP ... phosphorylating
What is potential energy?
Energy in Storage
Which type of enzyme research would be of greatest use to a pharmaceutical company?
Understanding the enzyme's structure would help pharmaceutical companies design molecules that fit to the binding site and alter activity.
Which of the following enables a cell to pick up and concentrate a specific kind of molecule? (ebook Module 5.9) diffusion receptor-mediated endocytosis osmosis passive transport
receptor-mediated endocytosis
A reaction is designated as exergonic rather than endergonic when _____. (ebook Module 5.11) no kinetic energy is released the potential energy of the products is less than the potential energy of the reactants activation energy exceeds net energy release activation energy is necessary
the potential energy of the products is less than the potential energy of the reactants
The phosphorylation of ADP to form ATP is an _____ reaction that _____ energy. (ebook Module 5.12) endergonic ... requires an input of exergonic ... requires an input of endergonic ... releases exergonic ... releases kinetic
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
endocytosis
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 _____. (ebook Module 5.9) osmosis active transport endocytosis passive transport
endocytosis (Endocytosis is the procedure that cells use to import large molecules across their membranes.)
If the entropy of a system is increasing, this means that _____. (ebook Module 5.10) heat is being used by organisms as a source of energy the first law of thermodynamics is being violated energy input will be needed to maintain organization the amount of usable energy in the system is increasing
energy input will be needed to maintain organization
Energy is _____. (ebook Module 5.10) the rearrangement of chemical molecules within matter the amount of food eaten movement the capacity to perform work
the capacity to perform work
Describe teh function of enzymes
An enzyme serves as a biological catalyst, increasing the rate of a reaction without being changed into a different molecule. An enzyme does not add energy to a reaction; instead, it speeds up a reaction by lowering the energy barrier.
Cells A and B are the same size and shape, but cell A is metabolically quiet and cell B is actively consuming oxygen. Oxygen will diffuse more quickly into cell ___ because _____________.
B ... the diffusion gradient there is steeper
What condition might result from an excess of aquaporins? (ebook Module 5.7) fluid retention in pregnant women hereditary diabetes insipidus malaria dehydration
fluid retention in pregnant women
The first law of thermodynamics _____. (ebook Module 5.10) deals with heat content states that entropy spontaneously increases states that energy is neither created nor destroyed predicts the direction of a reaction
states that energy is neither created nor destroyed
What is the second law of Thermodynamics?
states that every energy transformation makes the universe more disordered and that most energy transformations release heat.
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 concentration of the solute is lower inside the cell than outside it
a difference between active transport and facilitated diffusion?
Active transport requires the expenditure of cellular energy, and facilitated diffusion does not.
Which of the following statements about cell membrane transport is true? (ebook Module 5.8) Facilitated diffusion works without the assistance of proteins to move molecules from areas of high concentration to areas of low concentration. Passive transport works with the assistance of proteins to move molecules from areas of high concentration to areas of low concentration. Active transport works with the assistance of proteins to move molecules from areas of low concentration to areas of high concentration. Facilitated diffusion works with the assistance of proteins and energy to move molecules from areas of high concentration to areas of low concentration.
Active transport works with the assistance of proteins to move molecules from areas of low concentration to areas of high concentration.
The concentration of solutes in a red blood cell is about 2%. Sucrose cannot pass through the membrane, but water and urea can. Osmosis would cause red blood cells to shrink the most when immersed in which of the following solutions? (5.17)
a hypertonic sucrose solution
The concentration of solutes in a red blood cell is about 2%. Sucrose cannot pass through the membrane, but water and urea can. Osmosis would cause red blood cells to shrink the most when immersed in which of the following solutions? (ebook Module 5.5) a hypertonic sucrose solution a hypotonic urea solution a hypotonic sucrose solution a hypertonic urea solution
a hypertonic sucrose solution
When in solution, a molecule that moves slowly across an artificial membrane moves rapidly across a plasma membrane. This occurs regardless of whether the concentration of this molecule is higher inside or outside the cell. Using this information, which transport mechanism is most likely to be responsible for the movement of the molecule across a plasma membrane? (ebook Module 5.8) exocytosis phagocytosis active transport passive transport
active transport
Cellular respiration is an example of
an exergonic reaction, Cellular respiration is characterized by the breaking down of complex molecules and the release of energy.
Which one of the following is NOT involved in facilitated diffusion
an outside energy source
The secretion of neurotransmitters out of the nerve cell, from small vesicles at the end of the axon, can be considered an example of _____. (ebook Module 5.9) pinocytosis exocytosis phagocytosis endocytosis
exocytosis
Phospholipids are well suited to be the main structural components of membranes because they _____. (ebook Module 5.2) form a structure in which the hydrophobic portion faces outward are completely insoluble in water form a selectively permeable structure form a single sheet in water
form a selectively permeable structure
When considering the formation of membranes, they _____. (ebook Module 5.2) are constructed using specialized scaffolding proteins are formed under the direction of the cell's DNA form spontaneously in aqueous environments require enzymes to form into bilayer structures
form spontaneously in aqueous environments
If the volume of a cell increases when it is placed in an aqueous solution, that solution is said to be __________ to the cell.
hypotonic
Which of the following modifications do you predict would increase the amount of energy that could be stored in ATP?
if the negative charge of each phosphate group were increased
Where is the energy stored that cells use for work?
in the arrangement of atoms within molecules
If the tertiary structure of an enzyme is changed _____.
its substrate may not fit properly in the active site
If the tertiary structure of an enzyme is changed, _____. (ebook Module 5.14) it will be missing one of its polypeptides the helical coil will be stretched out its substrate may not fit properly in the active site the product of the reaction will be a different molecule
its substrate may not fit properly in the active site
The mechanism of enzyme action is to _____. (ebook Module 5.13) change the direction of thermodynamic equilibrium lower the energy of the activation of a reaction change endergonic into exergonic reactions create an energy barrier between substrates
lower the energy of the activation of a reaction
Which statement best describes phagocytosis?
A cell engulfs a particle by wrapping pseudopodia around it and packaging it within a vacuole.
Which statement regarding enzyme function is true?
Excessive salt ions can cause an enzyme to denature
Stability of the plasma membrane is enhanced by
cholesterol molecules
The movement of atoms, ions, or molecules from a region of higher concentration to regions of lower concentration is called _____. (ebook Module 5.4) diffusion spontaneous combustion crenation active transport
diffusion
LDLs enter cells by means of _____. (ebook Module 5.9) active transport osmosis protein-mediated exocytosis receptor-mediated endocytosis
eceptor-mediated endocytosis
Which statement best describes phagocytosis? (ebook Module 5.9) A cell engulfs a particle by wrapping pseudopodia around it and packaging it within a vacuole. Small droplets of extracellular fluid and all the dissolved solutes enter the cell by this process. A receptor on the plasma membrane binds to a molecule, and the cell engulfs both the receptor and the molecule. Cells use this process to export products such as insulin or thyroxine.
A cell engulfs a particle by wrapping pseudopodia around it and packaging it within a vacuole.
Which of the following terms specifically refers to the intake of very large particles by cells? (ebook Module 5.9) pinocytosis osmosis phagocytosis exocytosis
phagocytosis
What allows simple molecules to assemble into more complex molecules, and also disassemble, in cells but not in other non-biological environments?
Cells couple energy-releasing reactions to energy-requiring reactions.
What is an exergonic reaction?
Chemical reaction that releases energy
Why doesn't the antibiotic penicillin harm humans? (ebook Module 5.16) The dosage given to kill bacteria is too low to harm humans. Human cells do not have cell walls. Penicillin attacks plasma membranes. Penicillin attacks the nervous system.
Human cells do not have cell walls.
Review the figure below of passive transport, then choose one of the following statements as being descriptive of this process. Passive transport works with the help of proteins to bring molecules from an area of high concentration to an area of lower concentration. Passive transport requires energy from the cell to move molecules from an area of high concentration to an area of lower concentration. Passive transport works with the help of proteins to bring molecules from an area of low concentration to an area of higher concentration. Passive transport transports molecules without the assistance of proteins from an area of high concentration to an area of lower concentration.
Passive transport transports molecules without the assistance of proteins from an area of high concentration to an area of lower concentration.
Which of these situations accurately represents osmoregulation in organisms?
Plant cells need a hypotonic environment for their cells to stay turgid
Which of these situations accurately represents osmoregulation in organisms? (ebook Module 5.5) Plant cells need a hypotonic environment in order to stay turgid. Freshwater fish must all be isotonic to their environments. Seawater is hypotonic to human cells. Marine animals cannot be isotonic to seawater.
Plant cells need a hypotonic environment in order to stay turgid.
Proteins perform a number of functions within membranes. Which of the following statements is true about membrane proteins? Proteins can bind other molecules, which may trigger specific cellular functions. Proteins facilitate membrane stabilization. Proteins form the basis of the semipermeable membrane. Proteins keep the membrane fluid.
Proteins can bind other molecules, which may trigger specific cellular functions.
What is an endergonic reaction?
Requires a net input of energy
What is the first law of Thermodynamics?
States tgat the amount f available energy is finite but can be changed from one form to another
Which of the following is an example of the second law of thermodynamics? (ebook Module 5.10) All types of cellular respiration produce ATP. CO2 is exhaled as a by-product of aerobic respiration. Photosynthesis enables plants to create energy from sunlight. The aerobic respiration of glucose generates heat.
The aerobic respiration of glucose generates heat.
an example of the second law of thermodynamics
The aerobic respiration of glucose generates heat.
The membrane is referred to as a "fluid mosaic" structure. Which of the following statements is true? (
The fluid is phospholipid and the mosaic is protein
The membrane is referred to as a "fluid mosaic" structure. Which of the following statements is true? (ebook Module 5.2) The mosaic comprises the carbohydrate chains on the inner surface of the membrane. The fluid is protein, and the mosaic is phospholipid. The fluid is phospholipid, and the mosaic is carbohydrate. The fluid is phospholipid, and the mosaic is protein.
The fluid is phospholipid, and the mosaic is protein.
According to the second law of thermodynamics,
The ordering of one system depends on the disordering of another.
According to the second law of thermodynamics, which of the following is true? (ebook Module 5.10) 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.
The ordering of one system depends on the disordering of another.
How does the net amount of energy released during the breakdown of sucrose compare between a spontaneous reaction and one catalyzed by sucrase?
The sucrase-catalyzed reaction releases the same amount of energy as the spontaneous reaction
Consider a hypothetical metabolic pathway for the synthesis of the amino acid arginine: precursor A intermediate B arginine. Each reaction is catalyzed by a different enzyme. This metabolic pathway is controlled by feedback inhibition with arginine inhibiting the conversion of precursor A to intermediate B. In this case, arginine almost certainly acts as a _____ of the first enzyme in the pathway.
noncompetitive inhibitor
The diffusion of water across a selectively permeable membrane is called _____. (ebook Module 5.4) exocytosis active transport osmosis facilitated diffusion
osmosis
Some liver cells ingest bacteria, a function probably accomplished by _____. (ebook Module 5.9) receptor-mediated endocytosis exocytosis pinocytosis phagocytosis
phagocytosis
Which of the following best describes the general structure of a cell membrane?
proteins embedded in two layers of phospholipid
Which of the following best describes the general structure of a cell membrane? proteins sandwiched between two layers of phospholipid phospholipids sandwiched between two layers of protein proteins embedded in two layers of phospholipid a layer of protein coating a layer of phospholipid
proteins embedded in two layers of phospholipid
Which of the following enables a cell to pick up and concentrate a specific kind of molecule?
receptor-mediated endocytosis
Seawater is dangerous to drink because _____. (ebook Module 5.5) the salt causes hypertension and you will promptly die of a stroke seawater is hypertonic to your body tissues and drinking it will cause you to lose water by osmosis one cup of seawater contains enough sodium to poison you seawater is isotonic to your body fluids and you will absorb too much water, causing your cells to burst
seawater is hypertonic to your body tissues and drinking it will cause you to lose water by osmosis ( Seawater is hypertonic to our cells and will cause the cells to lose water and shrivel.)
The lipids in a cell membrane are arranged _____. on either side of a single layer of protein between two layers of protein so that the nonpolar parts of two lipids point toward each other so that the hydrophilic components are arranged to face each other
so that the nonpolar parts of two lipids point toward each other