Question 1

Which of the following statements is most likely true of a protein that cotransports glucose and sodium ions into the intestinal cells of an animal?

Accepted Answer

A)  Sodium and glucose compete for the same binding site in the cotransporter. 
B)  Glucose entering the cell down its concentration gradient provides energy for uptake of sodium ions against the electrochemical gradient. 
C)  Sodium ions can move down their electrochemical gradient through the cotransporter whether or not glucose is present outside the cell. 
D)  A substance that blocks sodium ions from binding to the cotransport protein will also block the transport of glucose. 
A)  Sodium and glucose compete for the same binding site in the cotransporter. 
B)  Glucose entering the cell down its concentration gradient provides energy for uptake of sodium ions against the electrochemical gradient. 
C)  Sodium ions can move down their electrochemical gradient through the cotransporter whether or not glucose is present outside the cell. 
D)  A substance that blocks sodium ions from binding to the cotransport protein will also block the transport of glucose.

Question 2

An animal cell lacking carbohydrates on the external surface of its plasma membrane would likely be impaired in which function?

Accepted Answer

A)  transporting ions against an electrochemical gradient 
B)  cell-cell recognition 
C)  attaching the plasma membrane to the cytoskeleton 
D)  establishing a diffusion barrier to charged molecules 
A)  transporting ions against an electrochemical gradient 
B)  cell-cell recognition 
C)  attaching the plasma membrane to the cytoskeleton 
D)  establishing a diffusion barrier to charged molecules

Question 3

Three lab groups carried out an experiment to identify the concentration of sucrose in six solutions. Each unknown contained one of the following sucrose concentrations: 0.0 M, 0.2 M, 0.4 M, 0.6 M, 0.8 M, and -1.0 M. Cubes of sweet potato (1 cm3) were soaked for 24 hours in each solution and weighed to determine the change in mass. Each data entry represents the average of three sample replicates expressed as percent change in mass following a 24-hour soak in the unknown solutions. From the data given, which statement most accurately describes what is occurring in response to a particular unknown solution?
$$\begin{array} { | l | l | l | l | } 
\hline \text { Unknown } & \begin{array} { l } 
\text { Percent change in } \
\text { mass }
\end{array} & \begin{array} { l } 
\text { Percent change in } \
\text { mass }
\end{array} & \text { Percent change in } \
\hline & \text { Graup 1 } & \text { Group 2 } & \text { Group 3 } \
\hline \text { A } & 6.6 & 7.8 & 7.5 \
\hline B & 3.1 & 3.7 & 2.9 \
\hline \mathrm { C } & - 2.7 & - 3.5 & - 2.5 \
\hline \mathrm { D } & 0.7 & 0.5 & 1.1 \
\hline \text { E } & - 11.6 & - 12.3 & - 12.6 \
\hline \text { F } & - 5.2 & - 6.2 & - 4.9 \
\hline
\end{array}$$

Accepted Answer

A)  Unknown solution E contains the highest concentration of sucrose, and the change in mass is due to the active transport of sucrose out of the cell. 
B)  Osmosis of water molecules from unknown solution B likely caused the increase in mass observed. 
C)  Passive transport of sucrose out of the potato cells explains the change in mass observed for unknown solution F. 
D)  Unknown solution C represents a sucrose concentration slightly higher than the molarity of sweet potato cells, thus water is transported out of the cells. 
A)  Unknown solution E contains the highest concentration of sucrose, and the change in mass is due to the active transport of sucrose out of the cell. 
B)  Osmosis of water molecules from unknown solution B likely caused the increase in mass observed. 
C)  Passive transport of sucrose out of the potato cells explains the change in mass observed for unknown solution F. 
D)  Unknown solution C represents a sucrose concentration slightly higher than the molarity of sweet potato cells, thus water is transported out of the cells.

Question 4

Which of the following factors would tend to increase membrane fluidity?

Accepted Answer

A)  a greater proportion of unsaturated phospholipids 
B)  a greater proportion of saturated phospholipids 
C)  a lower temperature 
D)  a relatively high protein content in the membrane 
A)  a greater proportion of unsaturated phospholipids 
B)  a greater proportion of saturated phospholipids 
C)  a lower temperature 
D)  a relatively high protein content in the membrane

Question 5

Based on Figure 7.18, which of these experimental treatments would increase the rate of sucrose transport into a plant cell?

Accepted Answer

A)  decreasing extracellular sucrose concentration 
B)  decreasing extracellular pH 
C)  decreasing cytoplasmic pH 
D)  adding a substance that makes the membrane more permeable to hydrogen ions 
A)  decreasing extracellular sucrose concentration 
B)  decreasing extracellular pH 
C)  decreasing cytoplasmic pH 
D)  adding a substance that makes the membrane more permeable to hydrogen ions

Question 6

Cell membranes have distinct inside and outside faces. Which of the following statements is the most likely explanation for the membrane's asymmetrical nature?

Accepted Answer

A)  Since the cell membrane forms a border between one cell and another in tightly packed tissues such as epithelium, the membrane must be asymmetrical. 
B)  Since cell membranes communicate signals from one organism to another, the cell membranes must be asymmetrical. 
C)  The two sides of a cell membrane face different environments and carry out different functions. 
D)  Proteins only function on the cytoplasmic side of the cell membrane, which results in the membrane's asymmetrical nature. 
A)  Since the cell membrane forms a border between one cell and another in tightly packed tissues such as epithelium, the membrane must be asymmetrical. 
B)  Since cell membranes communicate signals from one organism to another, the cell membranes must be asymmetrical. 
C)  The two sides of a cell membrane face different environments and carry out different functions. 
D)  Proteins only function on the cytoplasmic side of the cell membrane, which results in the membrane's asymmetrical nature.

Question 7

Which of the following processes includes all of the others?

Accepted Answer

A)  osmosis 
B)  facilitated diffusion 
C)  passive transport 
D)  transport of an ion down its electrochemical gradient 
A)  osmosis 
B)  facilitated diffusion 
C)  passive transport 
D)  transport of an ion down its electrochemical gradient

Question 8

In some cells, there are many ion electrochemical gradients across the plasma membrane even though there are usually only one or two proton pumps present in the membrane. The gradients of the other ions are most likely accounted for by ________.

Accepted Answer

A)  cotransport proteins 
B)  ion channels 
C)  pores in the plasma membrane 
D)  passive diffusion across the plasma membrane 
A)  cotransport proteins 
B)  ion channels 
C)  pores in the plasma membrane 
D)  passive diffusion across the plasma membrane

Exam 7: Membrane Structure and Function

Which of the following statements is most likely true of a protein that cotransports glucose and sodium ions into the intestinal cells of an animal?

An animal cell lacking carbohydrates on the external surface of its plasma membrane would likely be impaired in which function?

Which of the following factors would tend to increase membrane fluidity?

Based on Figure 7.18, which of these experimental treatments would increase the rate of sucrose transport into a plant cell?

Cell membranes have distinct inside and outside faces. Which of the following statements is the most likely explanation for the membrane's asymmetrical nature?

Which of the following processes includes all of the others?

In some cells, there are many ion electrochemical gradients across the plasma membrane even though there are usually only one or two proton pumps present in the membrane. The gradients of the other ions are most likely accounted for by ________.

Evolution, the Themes of Biology, and Scientific Inquiry

The Chemical Context of Life

Water and Life

Carbon and the Molecular Diversity of Life

The Structure and Function of Large Biological Molecules

A Tour of the Cell

An Introduction to Metabolism

Cellular Respiration and Fermentation

Photosynthesis

Cell Communication

The Cell Cycle

Meiosis and Sexual Life Cycles

Mendel and the Gene Idea

The Chromosomal Basis of Inheritance

The Molecular Basis of Inheritance

Gene Expression: From Gene to Protein

Regulation of Gene Expression

Viruses

Dna Tools and Biotechnology

Genomes and Their Evolution

Descent With Modification: a Darwinian View of Life

The Evolution of Populations

The Origin of Species

The History of Life on Earth

Phylogeny and the Tree of Life

Bacteria and Archaea

Protists

Plant Diversity I: How Plants Colonised Land

Plant Diversity Ii: the Evolution of Seed Plants

Fungi

An Overview of Animal Diversity

An Introduction to Invertebrates

The Origin and Evolution of Vertebrates

Vascular Plant Structure, Growth, and Development

Resource Acquisition and Transport in Vascular Plants

Soil and Plant Nutrition

Angiosperm Reproduction and Biotechnology

Plant Responses to Internal and External Signals

Basic Principles of Animal Form and Function

Animal Nutrition

Circulation and Gas Exchange

The Immune System

Osmoregulation and Excretion

Hormones and the Endocrine System

Animal Reproduction

Animal Development

Neurons, Synapses, and Signalling

Nervous Systems

Sensory and Motor Mechanisms

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