bio 6-9
The internal solute concentration of a plant cell is about 0.8M. To demonstrate plasmolysis, it would be necessary to suspend the cell in what solution?
1.0M
Which of the following plant cells would exhibit the most turgor pressure?
A cell placed in a hypotonic solution
Which of the following would be least likely to diffuse through a plasma membrane without the help of a transport protein?
A large polar molecule
As ATP begins to build up in a cell, metabolism slows down. How does this happen?
ATP acts as an allosteric inhibitor to many of the enzymes involved in metabolism, thus slowing their function.
Cells use ATP constantly, but ATP is considered a renewable resource. What process makes this possible?
ATP can be regenerated by the addition of a phosphate group to ADP.
Which of the following correctly states the relationship between anabolic and catabolic pathways?
Anabolic pathways synthesize more complex organic molecules using the energy derived from catabolic pathway
How does cholesterol affect membrane fluidity?
At body temperature, it makes the membrane less fluid.
At low temperatures, a particular enzyme catalyzes a reaction, but at a slow rate. At high temperatures, the enzyme is completely inactive. What statement best explains the difference in how temperature affects the function of this enzyme?
At low temperatures, there is not enough free energy for the enzyme to function at a high rate, and at high temperatures, the enzyme is denatured, leaving it nonfunctional.
During aerobic respiration, molecular oxygen (O2) is used for which of the following purposes?
At the end of the electron transport chain to accept electrons and form H2O
Cells A and B are the same size, shape, and temperature, but cell A is metabolically less active than cell B; cell B is actively converting oxygen to water in cellular respiration. Oxygen will diffuse more rapidly into cell __________ because __________.
B; the diffusion gradient in cell B is steeper
Why is energy required for active transport?
Because it moves solutes against their concentration gradient
If a red blood cell and a plant cell were placed in seawater, what would happen to the two types of cells?
Both cells would lose water; the red blood cell would shrivel, and the plant plasma membrane would pull away from the cell wall.
How does ATP drive transport work inside a cell?
By phosphorylating a transport protein
Which of the following molecules is most likely to passively diffuse across the plasma membrane?
Carbon dioxide
What function do carbohydrates fulfill in the plasma membrane?
Cell-to-cell recognition
Which of the following is false in respect to cells' chromosomes?
Chromosomes are only visible as a cell is about to divide.
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 which process?
Endocytosis
Which of the following states the relevance of the first law of thermodynamics to biology?
Energy can be freely transformed among different forms as long as the total energy is conserved.
If the entropy of a living organism is decreasing, which of the following is most likely to be occurring simultaneously?
Energy input into the organism must be occurring to drive the decrease in entropy.
Which of the following statements about enzymes is true?
Enzymes speed up the rate of the reaction without changing the ΔG for the reaction.
In terms of cellular function, what is the most important difference between prokaryotic and eukaryotic cells?
Eukaryotic cells are compartmentalized, which allows for specialization.
The primary manner in which cells manage their energy resources in order to do work is called energy coupling. Which of the following statements accurately defines energy coupling?
Exergonic reactions drive endergonic reactions.
Which of the following processes and organelle(s) accounts for the replacement of lipids and proteins lost from the plasma membrane?
Exocytosis and smooth and rough ER
Which of the following statements is correct regarding kinetic and potential energy?
Kinetic energy is associated with the relative motion of objects, and potential energy is the energy that matter possesses because of its location or structure.
Which of the following is true regarding metabolic pathways?
Metabolic pathways consist of a series of reactions, each catalyzed by a different enzyme.
During the energy payoff phase of glycolysis, __________.
NADH and ATP are produced
In what molecule(s) is the majority of the chemical energy from pyruvate transferred during the citric acid cycle?
NADH and FADH2
Which of the following molecules are most abundant in the plasma membrane?
Phospholipids
Which of the following statements about the role of phospholipids in the structure and function of biological membranes is correct?
Phospholipids form a selectively permeable structure
Which of the following statements about the role of phospholipids in the structure and function of biological membranes is correct?
Phospholipids form a selectively permeable structure.
What would the value of ΔS be for a chemical reaction in which a molecule is broken down into smaller components?
Positive
Which of the following structural arrangements of the components in biological membranes facilitates the cell membrane's property of selective permeability?
Proteins embedded in two layers of phospholipids
Most of the electrons removed from glucose by cellular respiration are used for which of the following processes?
Reducing NAD+ to NADH in glycolysis and the citric acid cycle AND producing a proton gradient for ATP synthesis in the mitochondria.
Which of these statements about enzyme inhibitors is true?
The action of inhibitors may be reversible or irreversible.
Which of the following is changed by the presence of an enzyme in a reaction?
The activation energy
Which of the following statements about the active site of an enzyme is correct?
The active site may resemble a groove or pocket in the surface of a protein into which the substrate fits.
Your intestine is lined with individual cells. No fluids leak between these cells from the gut into your body. Why?
The intestinal cells are bound together by tight junctions.
A cell is placed into a solution and the cell shrinks. Which of the following is true regarding the solution?
The solution is hypertonic
Which of the following is correct regarding peripheral proteins?
These proteins are found only on the surface of the plasma membrane.
Which of the following is correct regarding integral proteins?
These proteins exhibit both hydrophilic and hydrophobic properties
What is the total production of ATP, NADH, and FADH2 in the citric acid cycle from one molecule of glucose?
Two ATP, six NADH, and two FADH2
Animal cells have unique organelles called __________ that are composed of structures called __________.
centrosomes; centrioles
In facilitated diffusion, __________ proteins provide openings in the plasma membrane for substances to flow through without changing structure, and __________ proteins allow passage of substances through the plasma membrane after undergoing a subtle change in shape.
channel; carrier
During the energy investment phase of glycolysis, __________.
glucose is phosphorylated before it is split into two three-carbon molecules
Bacterial cells are prokaryotic. Unlike a typical eukaryotic cell they __________.
have no membrane-bounded organelles in their cytoplasm
Observing a fluorescent micrograph cell with intermediate filaments would help you identify the cell as a __________.
human skin cell
The walls of plant cells are largely composed of polysaccharides and proteins that are synthesized __________.
in the rough endoplasmic reticulum and in the Golgi apparatus
The network of fibers that organizes structures and activities in a cell __________.
is the cytoskeleton
Cells are small because __________.
of the geometric relationships between surface and volume
Cell junctions in plant cells are called __________, and communicating junctions in animal cells are called __________.
plasmodesmata; gap junctions
Muscle tissues make lactate from pyruvate to do which of the following?
regenerate NAD+
An exergonic (spontaneous) reaction is a chemical reaction that __________.
releases energy when proceeding in the forward direction
An exergonic reaction __________ free energy, and an endergonic reaction __________ free energy.
releases; absorbs
Evidence that supports the prokaryotic origins of mitochondria and chloroplasts are all of the following except __________.
that mitochondria and chloroplasts have multiple copies of linear DNA molecules associated with their inner membranes
The sodium-potassium pump __________.
transports sodium ions out of the cell and transports potassium ions into the cell
Cell motility, which includes changes both in cell location and in the movement of cell parts, requires interactions of the cytoskeleton __________.
with motor proteins
Basal bodies are most closely associated with which of the following cell components?
Cilia
Which of the following pairs of pathways and their location in the cell is incorrectly matched?
Citric acid cycle: cytosol
Which of the following statements is correct regarding competitive and noncompetitive enzyme inhibitors?
Competitive inhibitors bind to the active site of an enzyme while noncompetitive inhibitors bind to an enzyme away from the active site.
Fermentation by itself produces no ATP but keeps glycolysis going, which produces a small amount of ATP. How does fermentation do this?
Fermentation oxidizes NADH to NAD+, which facilitates the production of ATP in glycolysis.
Which of the following reactions would be endergonic?
Glucose + fructose → sucrose
In which process is glucose oxidized to form two molecules of pyruvate?
Glycolysis
Most of the ATP in cellular respiration is produced by the process of chemiosmosis. How does this process produce ATP?
H+ flows across the inner mitochondrial membrane through the enzyme ATP synthase.
Which of the following statements about diffusion is true?
It is a passive process.
Which of the following is a correct description of the events of cellular respiration and the sequence of events in cellular respiration?
Oxidation of glucose to pyruvate; oxidation of pyruvate; oxidation of acetyl-coA; oxidative phosphorylation
All of the processes involved in cellular respiration produce ATP. Which of the following processes produces the most ATP?
Oxidative phosphorylation
__________ are membrane-bound metabolic compartments that specialize in the production of hydrogen peroxide (H2O2) and its conversion to water.
Peroxisomes
What is the functional connection between the nucleolus, nuclear pores, and the nuclear membrane?
Subunits of ribosomes are assembled in the nucleolus and pass through the nuclear membrane via the nuclear pores.
Red blood cells contain approximately a 2% concentration of solutes. A red blood cell is placed into a solution that contains a 4% concentration of solutes to which the cell is not permeable. What will happen to the red blood cell?
The cell will decrease in size as water flows out of it.
Most of the NADH that delivers electrons to the electron transport chain comes from which of the following processes?
The citric acid cycle
Which of the following statements is correct regarding ATP?
The energy in an ATP molecule is released through hydrolysis of one of the phosphate groups.
At low pH, a particular enzyme catalyzes a reaction at a high rate. At neutral pH, the enzyme is completely inactive. What statement best explains the difference in how pH affects the function of this enzyme?
The enzyme is adapted for low pH but is denatured at neutral pH, leaving it nonfunctional.
What best characterizes the role of ATP in cellular metabolism?
The free energy released by ATP hydrolysis that may be coupled to an endergonic process via the formation of a phosphorylated intermediate.
The extracellular matrix of the animal cell has all of the following molecular components except __________.
a middle lamella
The process of stabilizing the structure of an enzyme in its active form by the binding of a molecule is an example of __________.
allosteric regulation
The organelle that is a plant cell's compartment for the storage of inorganic ions such as potassium and chloride is the __________.
central vacuole
Fermentation is essentially glycolysis plus an extra step in which pyruvate is reduced to form lactate or alcohol and carbon dioxide. This last step __________.
enables the cell to recycle the reduced NADH to oxidized NAD+
ATP allosterically inhibits enzymes in ATP-producing pathways. The result of this is called __________.
feedback inhibition
In the overall process of glycolysis and cellular respiration, __________ is oxidized and __________ is reduced.
glucose; oxygen
All cells have voltages across their membranes. This voltage is called a(n) __________ and is often maintained by __________.
membrane potential; electrogenic pumps
The endosymbiont theory explains the origins of __________.
mitochondria and chloroplasts
Microfilaments function in cell motility including __________.
muscle contraction, amoeboid movement, and cytoplasmic streaming in plants
The endoplasmic reticulum is part of the endomembrane system, which also includes the __________.
nuclear envelope, the Golgi apparatus, lysosomes, and vesicles
The region of a bacterial cell that contains the genetic material is called the __________.
nucleoid
You would expect a cell with an extensive Golgi apparatus to __________
secrete a lot of protein
A substance moving from outside the cell into the cytoplasm must pass through __________.
the plasma membrane
The plasma membrane exhibits selective permeability. This means that __________.
the plasma membrane allows some substances to flow through it more easily than others
The function of the rough endoplasmic reticulum (RER) is __________.
to synthesize proteins that are secreted as glycoproteins
